A Numerical Comparison of Barrier and Modified Barrier Methods for Large-Scale Bound-Constrained Optimization

NASA Technical Reports Server (NTRS)

Nash, Stephen G.; Polyak, R.; Sofer, Ariela

1994-01-01

When a classical barrier method is applied to the solution of a nonlinear programming problem with inequality constraints, the Hessian matrix of the barrier function becomes increasingly ill-conditioned as the solution is approached. As a result, it may be desirable to consider alternative numerical algorithms. We compare the performance of two methods motivated by barrier functions. The first is a stabilized form of the classical barrier method, where a numerically stable approximation to the Newton direction is used when the barrier parameter is small. The second is a modified barrier method where a barrier function is applied to a shifted form of the problem, and the resulting barrier terms are scaled by estimates of the optimal Lagrange multipliers. The condition number of the Hessian matrix of the resulting modified barrier function remains bounded as the solution to the constrained optimization problem is approached. Both of these techniques can be used in the context of a truncated-Newton method, and hence can be applied to large problems, as well as on parallel computers. In this paper, both techniques are applied to problems with bound constraints and we compare their practical behavior.

Overcoming psychosocial and developmental barriers to blood and marrow transplantation (BMT) in an adolescent/young adult (AYA) transgender patient with chronic myelogenous leukemia.

PubMed

Khazal, Sajad; Abdel-Azim, Hisham; Kapoor, Neena; Mahadeo, Kris M

2014-11-01

Adolescents/young adults (AYAs) afflicted with cancer face unique barriers to potentially standard curative therapies, such as blood and marrow transplantation (BMT). Transgender AYAs face additional barriers and there is a dearth of published literature regarding their oncology-related experience. We present the case of an AYA male-to-female (MTF) transgender patient on cross-sex hormone therapy, with a history of Chronic Myelogenous Leukemia (CML) and significant psychosocial barriers, which initially served as a barrier to BMT at two different centers; we modified our standard consent and education process and was able to successfully proceed with BMT and subsequently cure her CML. Despite unique challenges, AYA and transgender patients with significant psychosocial barriers may achieve successful outcomes with BMT. Research is needed regarding guidelines for cross-sex hormone therapy administration for patients undergoing BMT and other issues, which may be unique to the transgender experience.

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout

NASA Astrophysics Data System (ADS)

Bläckberg, L.; El Fakhri, G.; Sabet, H.

2017-11-01

A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the laser induced optical barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to  >42%, and for rough interfaces  >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically pixelated array 35% with polished pixel surfaces and 59% with rough surfaces.

Simulation study of light transport in laser-processed LYSO:Ce detectors with single-side readout.

PubMed

Bläckberg, L; El Fakhri, G; Sabet, H

2017-10-19

A tightly focused pulsed laser beam can locally modify the crystal structure inside the bulk of a scintillator. The result is incorporation of so-called optical barriers with a refractive index different from that of the crystal bulk, that can be used to redirect the scintillation light and control the light spread in the detector. We here systematically study the scintillation light transport in detectors fabricated using the laser induced optical barrier technique, and objectively compare their potential performance characteristics with those of the two mainstream detector types: monolithic and mechanically pixelated arrays. Among countless optical barrier patterns, we explore barriers arranged in a pixel-like pattern extending all-the-way or half-way through a 20 mm thick LYSO:Ce crystal. We analyze the performance of the detectors coupled to MPPC arrays, in terms of light response functions, flood maps, line profiles, and light collection efficiency. Our results show that laser-processed detectors with both barrier patterns constitute a new detector category with a behavior between that of the two standard detector types. Results show that when the barrier-crystal interface is smooth, no DOI information can be obtained regardless of barrier refractive index (RI). However, with a rough barrier-crystal interface we can extract multiple levels of DOI. Lower barrier RI results in larger light confinement, leading to better transverse resolution. Furthermore we see that the laser-processed crystals have the potential to increase the light collection efficiency, which could lead to improved energy resolution and potentially better timing resolution due to higher signals. For a laser-processed detector with smooth barrier-crystal interfaces the light collection efficiency is simulated to  >42%, and for rough interfaces  >73%. The corresponding numbers for a monolithic crystal is 39% with polished surfaces, and 71% with rough surfaces, and for a mechanically pixelated array 35% with polished pixel surfaces and 59% with rough surfaces.

Visualizing changes in electron distribution in coupled chains of cytochrome bc(1) by modifying barrier for electron transfer between the FeS cluster and heme c(1).

PubMed

Cieluch, Ewelina; Pietryga, Krzysztof; Sarewicz, Marcin; Osyczka, Artur

2010-02-01

Cytochrome c(1) of Rhodobacter (Rba.) species provides a series of mutants which change barriers for electron transfer through the cofactor chains of cytochrome bc(1) by modifying heme c(1) redox midpoint potential. Analysis of post-flash electron distribution in such systems can provide useful information about the contribution of individual reactions to the overall electron flow. In Rba. capsulatus, the non-functional low-potential forms of cytochrome c(1) which are devoid of the disulfide bond naturally present in this protein revert spontaneously by introducing a second-site suppression (mutation A181T) that brings the potential of heme c(1) back to the functionally high levels, yet maintains it some 100 mV lower from the native value. Here we report that the disulfide and the mutation A181T can coexist in one protein but the mutation exerts a dominant effect on the redox properties of heme c(1) and the potential remains at the same lower value as in the disulfide-free form. This establishes effective means to modify a barrier for electron transfer between the FeS cluster and heme c(1) without breaking disulfide. A comparison of the flash-induced electron transfers in native and mutated cytochrome bc(1) revealed significant differences in the post-flash equilibrium distribution of electrons only when the connection of the chains with the quinone pool was interrupted at the level of either of the catalytic sites by the use of specific inhibitors, antimycin or myxothiazol. In the non-inhibited system no such differences were observed. We explain the results using a kinetic model in which a shift in the equilibrium of one reaction influences the equilibrium of all remaining reactions in the cofactor chains. It follows a rather simple description in which the direction of electron flow through the coupled chains of cytochrome bc(1) exclusively depends on the rates of all reversible partial reactions, including the Q/QH2 exchange rate to/from the catalytic sites. 2009 Elsevier B.V. All rights reserved.

The intestinal barrier in multiple sclerosis: implications for pathophysiology and therapeutics.

PubMed

Camara-Lemarroy, Carlos R; Metz, Luanne; Meddings, Jonathan B; Sharkey, Keith A; Wee Yong, V

2018-05-30

Biological barriers are essential for the maintenance of homeostasis in health and disease. Breakdown of the intestinal barrier is an essential aspect of the pathophysiology of gastrointestinal inflammatory diseases, such as inflammatory bowel disease. A wealth of recent studies has shown that the intestinal microbiome, part of the brain-gut axis, could play a role in the pathophysiology of multiple sclerosis. However, an essential component of this axis, the intestinal barrier, has received much less attention. In this review, we describe the intestinal barrier as the physical and functional zone of interaction between the luminal microbiome and the host. Besides its essential role in the regulation of homeostatic processes, the intestinal barrier contains the gut mucosal immune system, a guardian of the integrity of the intestinal tract and the whole organism. Gastrointestinal disorders with intestinal barrier breakdown show evidence of CNS demyelination, and content of the intestinal microbiome entering into the circulation can impact the functions of CNS microglia. We highlight currently available studies suggesting that there is intestinal barrier dysfunction in multiple sclerosis. Finally, we address the mechanisms by which commonly used disease-modifying drugs in multiple sclerosis could alter the intestinal barrier and the microbiome, and we discuss the potential of barrier-stabilizing strategies, including probiotics and stabilization of tight junctions, as novel therapeutic avenues in multiple sclerosis.

Built-in potential shift and Schottky-barrier narrowing in organic solar cells with UV-sensitive electron transport layers.

PubMed

Li, Cheng; Credgington, Dan; Ko, Doo-Hyun; Rong, Zhuxia; Wang, Jianpu; Greenham, Neil C

2014-06-28

The performance of organic solar cells incorporating solution-processed titanium suboxide (TiOx) as electron-collecting layers can be improved by UV illumination. We study the mechanism of this improvement using electrical measurements and electroabsorption spectroscopy. We propose a model in which UV illumination modifies the effective work function of the oxide layer through a significant increase in its free electron density. This leads to a dramatic improvement in device power conversion efficiency through several mechanisms - increasing the built-in potential by 0.3 V, increasing the conductivity of the TiOx layer and narrowing the interfacial Schottky barrier between the suboxide and the underlying transparent electrode. This work highlights the importance of considering Fermi-level equilibration when designing multi-layer transparent electrodes.

Novel Fabrication of Biodegradable Superabsorbent Microspheres with Diffusion Barrier through Thermo-Chemical Modification and Their Potential Agriculture Applications for Water Holding and Sustained Release of Fertilizer.

PubMed

Feng, Diejing; Bai, Bo; Wang, Honglun; Suo, Yourui

2017-07-26

Synergistic utilization of water and fertilizer has vital contribution to the modern production of agriculture. This work reports on a simple and facile strategy to prepare biodegradable yeast/sodium alginate/poly(vinyl alcohol) superabsorbent microspheres with a diffusion barrier merit by thermo-chemical modification route. The integrated performances, including water absorbency, water retention, water evaporation ratio, leaching loss control, sustained-release behaviors, and degradation in soil, were systematically investigated. The results revealed that the modified microspheres were a triumphant water and fertilizer manager to effectively hold water and control the unexpected leakage of fertilizer for sustained release. Therefore, this work provides a promising approach to ameliorate the utilization efficiency of water and fertilizer in potential agriculture applications.

Infection control procedures used in conjunction with computed dental radiography.

PubMed

Hubar, J S; Gardiner, D M

2000-10-01

Infection control guidelines for dental radiography have been modified since 1986, when the American Dental Association and the Centers for Disease Control and Prevention supported the concept of "universal blood and body fluid precautions." With the introduction of computed digital radiography, hardware manufacturers recommend that alternative infection control techniques are necessary to prevent potential damage to the digital x-ray sensors placed inside the patient's mouth. Thirty first-year dental hygiene students were asked to insert and remove a Schick CDR number 2 size intraoral digital x-ray sensor into modified Rinn XCP bitewing bite blocks and a modified Rinn Snap-a-ray five times with each of the recommended infection control covers. Reduced rates of cross contamination are possible if the plastic barrier envelope has an additional latex finger cot stretched over it and the x-ray sensor. Sole usage of a latex finger cot will result in a reduced incidence of contamination, but still not to acceptable levels. However, a plastic barrier envelope placed over the x-ray sensor and over the modified XCP bite block together or a covered sensor in a Snap-a-ray under normal conditions does not result in a perforation and is least likely to result in cross contamination.

Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

NASA Astrophysics Data System (ADS)

Samolyuk, G. D.; Osetsky, Y. N.; Stoller, R. E.

2015-10-01

We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascade production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (∼0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential. The Gao-Weber potential appears to give a more realistic description of cascade dynamics in SiC, but still has some shortcomings when the defect migration barriers are compared to the ab initio results.

Liposomes bi-functionalized with phosphatidic acid and an ApoE-derived peptide affect Aβ aggregation features and cross the blood-brain-barrier: implications for therapy of Alzheimer disease.

PubMed

Bana, Laura; Minniti, Stefania; Salvati, Elisa; Sesana, Silvia; Zambelli, Vanessa; Cagnotto, Alfredo; Orlando, Antonina; Cazzaniga, Emanuela; Zwart, Rob; Scheper, Wiep; Masserini, Massimo; Re, Francesca

2014-10-01

Targeting amyloid-β peptide (Aβ) within the brain is a strategy actively sought for therapy of Alzheimer's disease (AD). We investigated the ability of liposomes bi-functionalized with phosphatidic acid and with a modified ApoE-derived peptide (mApoE-PA-LIP) to affect Aβ aggregation/disaggregation features and to cross in vitro and in vivo the blood-brain barrier (BBB). Surface plasmon resonance showed that bi-functionalized liposomes strongly bind Aβ (kD=0.6 μM), while Thioflavin-T and SDS-PAGE/WB assays show that liposomes inhibit peptide aggregation (70% inhibition after 72 h) and trigger the disaggregation of preformed aggregates (60% decrease after 120 h incubation). Moreover, experiments with dually radiolabelled LIP suggest that bi-functionalization enhances the passage of radioactivity across the BBB either in vitro (permeability=2.5×10(-5) cm/min, 5-fold higher with respect to mono-functionalized liposomes) or in vivo in healthy mice. Taken together, our results suggest that mApoE-PA-LIP are valuable nanodevices with a potential applicability in vivo for the treatment of AD. From the clinical editor: Bi-functionalized liposomes with phosphatidic acid and a modified ApoE-derived peptide were demonstrated to influence Aβ aggregation/disaggregation as a potential treatment in an Alzheimer's model. The liposomes were able to cross the blood-brain barrier in vitro and in vivo. Similar liposomes may become clinically valuable nanodevices with a potential applicability for the treatment of Alzheimer's disease. Copyright © 2014 Elsevier Inc. All rights reserved.

An effect of nuclear electric quadrupole moments in thermonuclear fusion plasmas

NASA Technical Reports Server (NTRS)

De, B. R.; Srnka, L. J.

1978-01-01

Consideration of the nuclear electric quadrupole terms in the expression for the fusion Coulomb barrier suggests that this electrostatic barrier may be substantially modified from that calculated under the usual plasma assumption that the nuclei are electric monopoles. This effect is a result of the nonspherical potential shape and the spatial quantization of the nuclear spins of the fully stripped ions in the presence of a magnetic field. For monopole-quadrupole fuel cycles like p-B-11, the fusion cross-section may be substantially increased at low energies if the protons are injected at a small angle relative to the confining magnetic field.

Patient-perceived barriers to lifestyle interventions in cirrhosis.

PubMed

Ney, Michael; Gramlich, Leah; Mathiesen, Vanessa; Bailey, Robert J; Haykowsky, Mark; Ma, Mang; Abraldes, Juan G; Tandon, Puneeta

2017-01-01

Sarcopenia, muscle weakness, and physical frailty are independent predictors of mortality in cirrhosis. These adverse prognostic factors are potentially modifiable with lifestyle interventions, including adequate nutritional intake and physical activity. Our aim was to identify patient-perceived barriers and enablers to these interventions. Adult patients with cirrhosis were prospectively recruited from two tertiary care liver clinics. Patients were excluded if they had hepatocellular carcinoma beyond transplant criteria, other active malignancy, or advanced chronic disease. A total of 127 patients (mean age: 60 ± 9 years, 58% males, and 48% with Child-Pugh-B/C (CP-B/C) disease) were included. Two-thirds of the patients had cirrhosis related to alcohol or hepatitis C. CP-B/C patients were more likely to take oral nutritional supplements (56% vs 29%) and less likely to consume animal protein daily (66% vs 85%) when compared to CP-A patients. Early satiety, altered taste, and difficulty in buying/preparing meals were more common in CP-B/C patients and even present in 20-30% of CP-A patients. Most patients reported adequate funds to purchase food. As quantified by the International Physical Activity Questionnaire-Short Form, 47% reported low activity levels, with no significant differences between groups. CP-B/C patients were more fatigued with exercise, however, overall Exercise Benefits/Barriers Scale scores were similar across groups. Barriers to nutritional intake and physical activity are common in cirrhosis and should be evaluated and treated in all patients. Asking simple screening questions in clinic and referring at-risk patients to expert multidisciplinary providers is a reasonable strategy to address these barriers. Future research should evaluate techniques to overcome modifiable barriers and enhance enablers.

Uptake Mechanism of ApoE-Modified Nanoparticles on Brain Capillary Endothelial Cells as a Blood-Brain Barrier Model

PubMed Central

Wagner, Sylvia; Zensi, Anja; Wien, Sascha L.; Tschickardt, Sabrina E.; Maier, Wladislaw; Vogel, Tikva; Worek, Franz; Pietrzik, Claus U.; Kreuter, Jörg; von Briesen, Hagen

2012-01-01

Background The blood-brain barrier (BBB) represents an insurmountable obstacle for most drugs thus obstructing an effective treatment of many brain diseases. One solution for overcoming this barrier is a transport by binding of these drugs to surface-modified nanoparticles. Especially apolipoprotein E (ApoE) appears to play a major role in the nanoparticle-mediated drug transport across the BBB. However, at present the underlying mechanism is incompletely understood. Methodology/Principal Findings In this study, the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells was investigated to differentiate between active and passive uptake mechanism by flow cytometry and confocal laser scanning microscopy. Furthermore, different in vitro co-incubation experiments were performed with competing ligands of the respective receptor. Conclusions/Significance This study confirms an active endocytotic uptake mechanism and shows the involvement of low density lipoprotein receptor family members, notably the low density lipoprotein receptor related protein, on the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells. This knowledge of the uptake mechanism of ApoE-modified nanoparticles enables future developments to rationally create very specific and effective carriers to overcome the blood-brain barrier. PMID:22396775

Uptake mechanism of ApoE-modified nanoparticles on brain capillary endothelial cells as a blood-brain barrier model.

PubMed

Wagner, Sylvia; Zensi, Anja; Wien, Sascha L; Tschickardt, Sabrina E; Maier, Wladislaw; Vogel, Tikva; Worek, Franz; Pietrzik, Claus U; Kreuter, Jörg; von Briesen, Hagen

2012-01-01

The blood-brain barrier (BBB) represents an insurmountable obstacle for most drugs thus obstructing an effective treatment of many brain diseases. One solution for overcoming this barrier is a transport by binding of these drugs to surface-modified nanoparticles. Especially apolipoprotein E (ApoE) appears to play a major role in the nanoparticle-mediated drug transport across the BBB. However, at present the underlying mechanism is incompletely understood. In this study, the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells was investigated to differentiate between active and passive uptake mechanism by flow cytometry and confocal laser scanning microscopy. Furthermore, different in vitro co-incubation experiments were performed with competing ligands of the respective receptor. This study confirms an active endocytotic uptake mechanism and shows the involvement of low density lipoprotein receptor family members, notably the low density lipoprotein receptor related protein, on the uptake of the ApoE-modified nanoparticles into the brain capillary endothelial cells. This knowledge of the uptake mechanism of ApoE-modified nanoparticles enables future developments to rationally create very specific and effective carriers to overcome the blood-brain barrier.

Three dimensional α-tunneling in intense laser fields

NASA Astrophysics Data System (ADS)

Kis, Daniel P.; Szilvasi, Reka

2018-04-01

The width and life-time of the quasibound state of the α cluster in intense monochromatic electromagnetic (laser) field are discussed in details. The laser modified three dimensional potential barrier felt by the α particle is investigated analytically in long wave approximation and zero-order approximations with some different nuclear models: Coulomb potential with rectangular well, and with Woods-Saxon type potential. We show that the circularly polarized electromagnetic field and the special parameters of the nuclear potentials determine an enhancement of the decay probability, so the life-time of the quasibound state decreases in few times compared to the case of free field.

Solution of monotone complementarity and general convex programming problems using a modified potential reduction interior point method

DOE PAGES

Huang, Kuo -Ling; Mehrotra, Sanjay

2016-11-08

We present a homogeneous algorithm equipped with a modified potential function for the monotone complementarity problem. We show that this potential function is reduced by at least a constant amount if a scaled Lipschitz condition (SLC) is satisfied. A practical algorithm based on this potential function is implemented in a software package named iOptimize. The implementation in iOptimize maintains global linear and polynomial time convergence properties, while achieving practical performance. It either successfully solves the problem, or concludes that the SLC is not satisfied. When compared with the mature software package MOSEK (barrier solver version 6.0.0.106), iOptimize solves convex quadraticmore » programming problems, convex quadratically constrained quadratic programming problems, and general convex programming problems in fewer iterations. Moreover, several problems for which MOSEK fails are solved to optimality. In addition, we also find that iOptimize detects infeasibility more reliably than the general nonlinear solvers Ipopt (version 3.9.2) and Knitro (version 8.0).« less

The intriguing role of Rifaximin in gut barrier chronic inflammation and in the treatment of Crohn's disease.

PubMed

Lopetuso, Loris R; Napoli, Marco; Rizzatti, Gianenrico; Gasbarrini, Antonio

2018-06-04

The gastrointestinal tract acts as a functional unit organized as a semipermeable multilayer system, in which commensal gut microbiota represents the anatomical barrier. Recently,, several studies have highlighted the involvement of gut microbiota in IBD pathogenesis, in sustaining gut barrier chronic inflammation, and in conditioning disease course and therapeutical response. This evidence provides a rationale for treating patients with gut microbiota modifiers. Among these, Rifaximin represents a non-traditional antibiotic able to act as a "eubiotic" on intestinal barrier. Area covered: The purpose of this narrative review is to explore the impact of Rifaximin on gut barrier and gut microbiota in IBD, in particular in Crohn's disease, and to analyze its potential therapeutic applications. Expert opinion: The possibility of a beneficial activity of Rifaximin in chronic intestinal inflammation and Crohn's disease has been debated and evaluated with different studies having obtained promising but still preliminary data. Larger trials are therefore needed. This gut-specific antibiotic could represent an alternative to systemic antibiotics thanks to its favorable safety profile and promising efficacy data. Rifaximin could exert, when appropriate, a synergic effect with immunomodulators in IBD, acting on both the microbial and immunological sides of gut barrier impairment.

Permeable reactive barrier of surface hydrophobic granular activated carbon coupled with elemental iron for the removal of 2,4-dichlorophenol in water.

PubMed

Yang, Ji; Cao, Limei; Guo, Rui; Jia, Jinping

2010-12-15

Granular activated carbon was modified with dimethyl dichlorosilane to improve its surface hydrophobicity, and therefore to improve the performance of permeable reactive barrier constructed with the modified granular activated carbon and elemental iron. X-ray photoelectron spectroscopy shows that the surface silicon concentration of the modified granular activated carbon is higher than that of the original one, leading to the increased surface hydrophobicity. Although the specific surface area decreased from 895 to 835 m(2)g(-1), the modified granular activated carbon could adsorb 20% more 2,4-dichlorophenol than the original one did in water. It is also proven that the permeable reactive barrier with the modified granular activated carbon is more efficient at 2,4-dichlorophenol dechlorination, in which process 2,4-dichlorophenol is transformed to 2-chlorophenol or 4-chlorophenol then to phenol, or to phenol directly. Copyright © 2010 Elsevier B.V. All rights reserved.

Accelerated molecular dynamics: A promising and efficient simulation method for biomolecules

NASA Astrophysics Data System (ADS)

Hamelberg, Donald; Mongan, John; McCammon, J. Andrew

2004-06-01

Many interesting dynamic properties of biological molecules cannot be simulated directly using molecular dynamics because of nanosecond time scale limitations. These systems are trapped in potential energy minima with high free energy barriers for large numbers of computational steps. The dynamic evolution of many molecular systems occurs through a series of rare events as the system moves from one potential energy basin to another. Therefore, we have proposed a robust bias potential function that can be used in an efficient accelerated molecular dynamics approach to simulate the transition of high energy barriers without any advance knowledge of the location of either the potential energy wells or saddle points. In this method, the potential energy landscape is altered by adding a bias potential to the true potential such that the escape rates from potential wells are enhanced, which accelerates and extends the time scale in molecular dynamics simulations. Our definition of the bias potential echoes the underlying shape of the potential energy landscape on the modified surface, thus allowing for the potential energy minima to be well defined, and hence properly sampled during the simulation. We have shown that our approach, which can be extended to biomolecules, samples the conformational space more efficiently than normal molecular dynamics simulations, and converges to the correct canonical distribution.

Varistor piezotronics: Mechanically tuned conductivity in varistors

NASA Astrophysics Data System (ADS)

Baraki, Raschid; Novak, Nikola; Hofstätter, Michael; Supancic, Peter; Rödel, Jürgen; Frömling, Till

2015-08-01

The piezoelectric effect of ZnO has been investigated recently with the goal to modify metal/semiconductor Schottky-barriers and p-n-junctions by application of mechanical stress. This research area called "piezotronics" is so far focused on nano structured ZnO wires. At the same time, ZnO varistor materials are already widely utilized and may benefit from a piezotronic approach. In this instance, the grain boundary potential barriers in the ceramic can be tuned by mechanical stress. Polycrystalline varistors exhibit huge changes of resistivity upon applied electrical and mechanical fields and therefore offer descriptive model systems to study the piezotronic effect. If the influence of temperature is contemplated, our current mechanistic understanding can be interrogated and corroborated. In this paper, we present a physical model based on parallel conducting pathways. This affords qualitative and semi-quantitative rationalization of temperature dependent electrical properties. The investigations demonstrate that narrow conductive pathways contribute to the overall current, which becomes increasingly conductive with application of mechanical stress due to lowering of the barrier height. Rising temperature increases the thermionic current through the rest of the material with higher average potential barriers, which are hardly affected by the piezoelectric effect. Hence, relative changes in resistance due to application of stress are higher at low temperature.

The Infant Skin Barrier: Can We Preserve, Protect, and Enhance the Barrier?

PubMed Central

Telofski, Lorena S.; Morello, A. Peter; Mack Correa, M. Catherine; Stamatas, Georgios N.

2012-01-01

Infant skin is different from adult in structure, function, and composition. Despite these differences, the skin barrier is competent at birth in healthy, full-term neonates. The primary focus of this paper is on the developing skin barrier in healthy, full-term neonates and infants. Additionally, a brief discussion of the properties of the skin barrier in premature neonates and infants with abnormal skin conditions (i.e., atopic dermatitis and eczema) is included. As infant skin continues to mature through the first years of life, it is important that skin care products (e.g., cleansers and emollients) are formulated appropriately. Ideally, products that are used on infants should not interfere with skin surface pH or perturb the skin barrier. For cleansers, this can be achieved by choosing the right type of surfactant, by blending surfactants, or by blending hydrophobically-modified polymers (HMPs) with surfactants to increase product mildness. Similarly, choosing the right type of oil for emollients is important. Unlike some vegetable oils, mineral oil is more stable and is not subject to oxidation and hydrolysis. Although emollients can improve the skin barrier, more studies are needed to determine the potential long-term benefits of using emollients on healthy, full-term neonates and infants. PMID:22988452

Interfacial strain effects on lithium diffusion pathways in the spinel solid electrolyte Li-doped MgAl2O4

NASA Astrophysics Data System (ADS)

O'Rourke, Conn; Morgan, Benjamin J.

2018-04-01

The (Li,Al)-codoped magnesium spinel (LixMg1 -2 xAl2 +xO4 ) is a solid lithium-ion electrolyte with potential use in all-solid-state lithium-ion batteries. The spinel structure means that interfaces with spinel electrodes, such as LiyMn2O4 and Li4 +3 zTi5O12 , may be lattice matched, with potentially low interfacial resistances. Small lattice parameter differences across a lattice-matched interface are unavoidable, causing residual epitaxial strain. This strain potentially modifies lithium diffusion near the electrolyte-electrode interface, contributing to interfacial resistance. Here, we report a density functional theory study of strain effects on lithium diffusion pathways for (Li,Al)-codoped magnesium spinel, for xLi=0.25 and xLi=0.5 . We have calculated diffusion profiles for the unstrained materials, and for isotropic and biaxial tensile strains of up to 6 % , corresponding to {100 } epitaxial interfaces with LiyMn2O4 and Li4 +3 zTi5O12 . We find that isotropic tensile strain reduces lithium diffusion barriers by as much as 0.32 eV , with typical barriers reduced by ˜0.1 eV. This effect is associated with increased volumes of transitional octahedral sites, and broadly follows qualitative changes in local electrostatic potentials. For biaxial (epitaxial) strain, which more closely approximates strain at a lattice-matched electrolyte-electrode interface, changes in octahedral site volumes and in lithium diffusion barriers are much smaller than under isotropic strain. Typical barriers are reduced by only ˜0.05 eV. Individual effects, however, depend on the pathway considered and the relative strain orientation. These results predict that isotropic strain strongly affects ionic conductivities in (Li,Al)-codoped magnesium spinel electrolytes, and that tensile strain is a potential route to enhanced lithium transport. For a lattice-matched interface with candidate spinel-structured electrodes, however, epitaxial strain has a small, but complex, effect on lithium diffusion barriers.

Fission properties of Po isotopes in different macroscopic-microscopic models

NASA Astrophysics Data System (ADS)

Bartel, J.; Pomorski, K.; Nerlo-Pomorska, B.; Schmitt, Ch

2015-11-01

Fission-barrier heights of nuclei in the Po isotopic chain are investigated in several macroscopic-microscopic models. Using the Yukawa-folded single-particle potential, the Lublin-Strasbourg drop (LSD) model, the Strutinsky shell-correction method to yield the shell corrections and the BCS theory for the pairing contributions, fission-barrier heights are calculated and found in quite good agreement with the experimental data. This turns out, however, to be only the case when the underlying macroscopic, liquid-drop (LD) type, theory is well chosen. Together with the LSD approach, different LD parametrizations proposed by Moretto et al are tested. Four deformation parameters describing respectively elongation, neck-formation, reflectional-asymmetric, and non-axiality of the nuclear shape thus defining the so called modified Funny Hills shape parametrization are used in the calculation. The present study clearly demonstrates that nuclear fission-barrier heights constitute a challenging and selective tool to discern between such different macroscopic approaches.

The determination of modified barrier heights in Ti/GaN nano-Schottky diodes at high temperature.

PubMed

Lee, Seung-Yong; Kim, Tae-Hong; Chol, Nam-Kyu; Seong, Han-Kyu; Choi, Heon-Jin; Ahn, Byung-Guk; Lee, Sang-Kwon

2008-10-01

We have investigated the size-effect of the nano-Schottky diodes on the electrical transport properties and the temperature-dependent current transport mechanism in a metal-semiconductor nanowire junction (a Ti/GaN nano-Schottky diode) using current-voltage characterization in the range of 300-423 K. We found that the modified mean Schottky barrier height (SBH) was approximately 0.7 eV with a standard deviation of approximately 0.14 V using a Gaussian distribution model of the barrier heights. The slightly high value of the modified mean SBH (approximately 0.11 eV) compared to the results from the thin-film based Ti/GaN Schottky diodes could be due to an additional oxide layer at the interface between the Ti and GaN nanowires. Moreover, we found that the abnormal behavior of the barrier heights and the ideality factors in a Ti/GaN nano-Schottky diode at a temperature below 423 K could be explained by a combination of the enhancement of the tunneling current and a model with a Gaussian distribution of the barrier heights.

Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.

We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascademore » production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.« less

Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

DOE PAGES

Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.

2015-06-03

We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascademore » production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.« less

Effects of ultrathin oxides in conducting MIS structures on GaAs

NASA Technical Reports Server (NTRS)

Childs, R. B.; Ruths, J. M.; Sullivan, T. E.; Fonash, S. J.

1978-01-01

Schottky barrier-type GaAs baseline devices (semiconductor surface etched and then immediately metalized) and GaAs conducting metal oxide-semiconductor devices are fabricated and characterized. The baseline surfaces (no purposeful oxide) are prepared by a basic or an acidic etch, while the surface for the MIS devices are prepared by oxidizing after the etch step. The metallizations used are thin-film Au, Ag, Pd, and Al. It is shown that the introduction of purposeful oxide into these Schottky barrier-type structures examined on n-type GaAs modifies the barrier formation, and that thin interfacial layers can modify barrier formation through trapping and perhaps chemical reactions. For Au- and Pd-devices, enhanced photovoltaic performance of the MIS configuration is due to increased barrier height.

An Investigation of the Effects of Self-Assembled Monolayers on Protein Crystallisation

PubMed Central

Zhang, Chen-Yan; Shen, He-Fang; Wang, Qian-Jin; Guo, Yun-Zhu; He, Jin; Cao, Hui-Ling; Liu, Yong-Ming; Shang, Peng; Yin, Da-Chuan

2013-01-01

Most protein crystallisation begins from heterogeneous nucleation; in practice, crystallisation typically occurs in the presence of a solid surface in the solution. The solid surface provides a nucleation site such that the energy barrier for nucleation is lower on the surface than in the bulk solution. Different types of solid surfaces exhibit different surface energies, and the nucleation barriers depend on the characteristics of the solid surfaces. Therefore, treatment of the solid surface may alter the surface properties to increase the chance to obtain protein crystals. In this paper, we propose a method to modify the glass cover slip using a self-assembled monolayer (SAM) of functional groups (methyl, sulfydryl and amino), and we investigated the effect of each SAM on protein crystallisation. The results indicated that both crystallisation success rate in a reproducibility study, and crystallisation hits in a crystallisation screening study, were increased using the SAMs, among which, the methyl-modified SAM demonstrated the most significant improvement. These results illustrated that directly modifying the crystallisation plates or glass cover slips to create surfaces that favour heterogeneous nucleation can be potentially useful in practical protein crystallisation, and the utilisation of a SAM containing a functional group can be considered a promising technique for the treatment of the surfaces that will directly contact the crystallisation solution. PMID:23749116

Conformational switching upon phosphorylation: a predictive framework based on energy landscape principles.

PubMed

Lätzer, Joachim; Shen, Tongye; Wolynes, Peter G

2008-02-19

We investigate how post-translational phosphorylation modifies the global conformation of a protein by changing its free energy landscape using two test proteins, cystatin and NtrC. We first examine the changes in a free energy landscape caused by phosphorylation using a model containing information about both structural forms. For cystatin the free energy cost is fairly large indicating a low probability of sampling the phosphorylated conformation in a perfectly funneled landscape. The predicted barrier for NtrC conformational transition is several times larger than the barrier for cystatin, indicating that the switch protein NtrC most probably follows a partial unfolding mechanism to move from one basin to the other. Principal component analysis and linear response theory show how the naturally occurring conformational changes in unmodified proteins are captured and stabilized by the change of interaction potential. We also develop a partially guided structure prediction Hamiltonian which is capable of predicting the global structure of a phosphorylated protein using only knowledge of the structure of the unphosphorylated protein or vice versa. This algorithm makes use of a generic transferable long-range residue contact potential along with details of structure short range in sequence. By comparing the results obtained with this guided transferable potential to those from the native-only, perfectly funneled Hamiltonians, we show that the transferable Hamiltonian correctly captures the nature of the global conformational changes induced by phosphorylation and can sample substantially correct structures for the modified protein with high probability.

Barriers to lifestyle changes for prevention of cardiovascular disease - a survey among 40-60-year old Danes.

PubMed

Nielsen, Jesper Bo; Leppin, Anja; Gyrd-Hansen, Dort E; Jarbøl, Dorte Ejg; Søndergaard, Jens; Larsen, Pia Veldt

2017-09-12

Elimination of modifiable risk factors including unhealthy lifestyle has the potential for prevention of 80% of cardiovascular disease cases. The present study focuses on disclosing barriers for maintaining specific lifestyle changes by exploring associations between perceiving these barriers and various sociodemographic and health-related characteristics. Data were collected through a web-based questionnaire survey and included 962 respondents who initially accepted treatment for a hypothetical cardiovascular risk, and who subsequently stated that they preferred lifestyle changes to medication. Logistic regression was used to analyse associations between barriers to lifestyle changes and relevant covariates. A total of 45% of respondents were identified with at least one barrier to introducing 30 min extra exercise daily, 30% of respondents reported at least one barrier to dietary change, and among smokers at least one barrier to smoking cessation was reported by 62% of the respondents. The perception of specific barriers to lifestyle change depended on sociodemographic and health-related characteristics. We observed a considerable heterogeneity between different social groups in the population regarding a number of barriers to lifestyle change. Our study demonstrates that social inequality exists in the ability to take appropriate preventive measures through lifestyle changes to stay healthy. This finding underlines the challenge of social inequality even in populations with equal and cost-free access to health care. Our study suggests supplementing traditional public campaigns to counter cardiovascular disease by using individualized and targeted initiatives.

Interpreting the genomic landscape of speciation: a road map for finding barriers to gene flow.

PubMed

Ravinet, M; Faria, R; Butlin, R K; Galindo, J; Bierne, N; Rafajlović, M; Noor, M A F; Mehlig, B; Westram, A M

2017-08-01

Speciation, the evolution of reproductive isolation among populations, is continuous, complex, and involves multiple, interacting barriers. Until it is complete, the effects of this process vary along the genome and can lead to a heterogeneous genomic landscape with peaks and troughs of differentiation and divergence. When gene flow occurs during speciation, barriers restricting gene flow locally in the genome lead to patterns of heterogeneity. However, genomic heterogeneity can also be produced or modified by variation in factors such as background selection and selective sweeps, recombination and mutation rate variation, and heterogeneous gene density. Extracting the effects of gene flow, divergent selection and reproductive isolation from such modifying factors presents a major challenge to speciation genomics. We argue one of the principal aims of the field is to identify the barrier loci involved in limiting gene flow. We first summarize the expected signatures of selection at barrier loci, at the genomic regions linked to them and across the entire genome. We then discuss the modifying factors that complicate the interpretation of the observed genomic landscape. Finally, we end with a road map for future speciation research: a proposal for how to account for these modifying factors and to progress towards understanding the nature of barrier loci. Despite the difficulties of interpreting empirical data, we argue that the availability of promising technical and analytical methods will shed further light on the important roles that gene flow and divergent selection have in shaping the genomic landscape of speciation. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Macroscopic quantum tunneling escape of Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Zhao, Xinxin; Alcala, Diego A.; McLain, Marie A.; Maeda, Kenji; Potnis, Shreyas; Ramos, Ramon; Steinberg, Aephraim M.; Carr, Lincoln D.

2017-12-01

Recent experiments on macroscopic quantum tunneling reveal a nonexponential decay of the number of atoms trapped in a quasibound state behind a potential barrier. Through both experiment and theory, we demonstrate this nonexponential decay results from interactions between atoms. Quantum tunneling of tens of thousands of 87Rb atoms in a Bose-Einstein condensate is modeled by a modified Jeffreys-Wentzel-Kramers-Brillouin model, taking into account the effective time-dependent barrier induced by the mean field. Three-dimensional Gross-Pitaevskii simulations corroborate a mean-field result when compared with experiments. However, with one-dimensional modeling using time-evolving block decimation, we present an effective renormalized mean-field theory that suggests many-body dynamics for which a bare mean-field theory may not apply.

Salmosan, a β-galactomannan-rich product, in combination with Lactobacillus plantarum contributes to restore intestinal epithelial barrier function by modulation of cytokine production.

PubMed

Brufau, M Teresa; Campo-Sabariz, Joan; Carné, Sergi; Ferrer, Ruth; Martín-Venegas, Raquel

2017-03-01

Mannan-oligosaccharides (MOSs) are mannose-rich substrates with several intestinal health-promoting properties. The aim of this study was to investigate the potential capacity of Salmosan (S-βGM), a β-galactomannan-rich MOS product, to restore epithelial barrier function independently from its capacity to reduce bacterial invasion. In addition, the combination of S-βGM with the proven probiotic Lactobacillus plantarum (LP) was also tested. Paracellular permeability was assessed by transepithelial electrical resistance (TER) in co-cultures of Caco-2 cells and macrophages (differentiated from THP-1 cells) stimulated with LPS of Salmonella Enteritidis and in Caco-2 cell cultures stimulated with TNF-α in the absence or presence of 500 μg/ml S-βGM, LP (MOI 10) or a combination of both. In both culture models, TER was significantly reduced up to 25% by LPS or TNF-α stimulation, and the addition of S-βGM or LP alone did not modify TER, whereas the combination of both restored TER to values of nonstimulated cells. Under LPS stimulation, TNF-α production was significantly increased by 10-fold, whereas IL-10 and IL-6 levels were not modified. The combination of S-βGM and LP reduced TNF-α production to nonstimulated cell values and significantly increased IL-10 and IL-6 levels (5- and 7.5-fold, respectively). Moreover, S-βGM has the capacity to induce an increase of fivefold in LP growth. In conclusion, we have demonstrated that S-βGM in combination with LP protects epithelial barrier function by modulation of cytokine secretion, thus giving an additional value to this MOS as a potential symbiotic. Copyright © 2016 Elsevier Inc. All rights reserved.

Universal functions of nuclear proximity potential for Skyrme nucleus-nucleus interaction in a semiclassical approach

NASA Astrophysics Data System (ADS)

Gupta, Raj K.; Singh, Dalip; Kumar, Raj; Greiner, Walter

2009-07-01

The universal function of the nuclear proximity potential is obtained for the Skyrme nucleus-nucleus interaction in the semiclassical extended Thomas-Fermi (ETF) approach. This is obtained as a sum of the spin-orbit-density-independent and spin-orbit-density-dependent parts of the Hamiltonian density, since the two terms behave differently, the spin-orbit-density-independent part mainly attractive and the spin-orbit-density-dependent part mainly repulsive. The semiclassical expansions of kinetic energy density and spin-orbit density are allowed up to second order, and the two-parameter Fermi density, with its parameters fitted to experiments, is used for the nuclear density. The universal functions or the resulting nuclear proximity potential reproduce the 'exact' Skyrme nucleus-nucleus interaction potential in the semiclassical approach, within less than ~1 MeV of difference, both at the maximum attraction and in the surface region. An application of the resulting interaction potential to fusion excitation functions shows clearly that the parameterized universal functions of nuclear proximity potential substitute completely the 'exact' potential in the Skyrme energy density formalism based on the semiclassical ETF method, including also the modifications of interaction barriers at sub-barrier energies in terms of modifying the constants of the universal functions.

A generalized force-modified potential energy surface (G-FMPES) for mechanochemical simulations

DOE PAGES

Subramanian, Gopinath; Mathew, Nithin; Leiding, Jeffery A.

2015-10-05

We describe the modifications that a spatially varying external load produces on a Born-Oppenheimer potential energy surface (PES) by calculating static quantities of interest. The effects of the external loads are exemplified using electronic structure calculations (at the HF/6-31G** level) of two different molecules: ethane and hexahydro-1,3,5-trinitro-s-triazine (RDX). The calculated transition states and The Hessian matrices of stationary points show that spatially varying external loads shift the stationary points and modify the curvature of the PES, thereby affecting the harmonic transition rates by altering both the energy barrier as well as the prefactor. The harmonic spectra of both molecules aremore » blue-shifted with increasing compressive “pressure.” Some stationary points on the RDX-PES disappear under application of the external load, indicating the merging of an energy minimum with a saddle point.« less

Use of Edible Laminate Layers in Intermediate Moisture Food Rations to Inhibit Moisture Migration

DTIC Science & Technology

2016-04-29

methylcellulose, propylene glycol, citric acid, modified starch , white beeswax Water resistant coating on one side Watson, Inc. Dual-sided HPMC moisture...barrier film Hydroxypropyl methylcellulose, propylene glycol, citric acid, modified starch , white beeswax Water resistant coating on both sides...Moisture Barrier (BWMB) film #1 Pullulan*, beeswax, glycerin, propylene glycol, starch , polysorbate 80 Water soluble Watson, Inc. Pullulan BWMB film

Scattering of accelerated wave packets

NASA Astrophysics Data System (ADS)

Longhi, S.; Horsley, S. A. R.; Della Valle, G.

2018-03-01

Wave-packet scattering from a stationary potential is significantly modified when the wave packet is subject to an external time-dependent force during the interaction. In the semiclassical limit, wave-packet motion is simply described by Newtonian equations, and the external force can, for example, cancel the potential force, making a potential barrier transparent. Here we consider wave-packet scattering from reflectionless potentials, where in general the potential becomes reflective when probed by an accelerated wave packet. In the particular case of the recently introduced class of complex Kramers-Kronig potentials we show that a broad class of time-dependent forces can be applied without inducing any scattering, while there is a breakdown of the reflectionless property when there is a broadband distribution of initial particle momentum, involving both positive and negative components.

Potential in-class strategies to increase children's vegetable consumption.

PubMed

Sharp, Gemma; Pettigrew, Simone; Wright, Shannon; Pratt, Iain S; Blane, Sally; Biagioni, Nicole

2017-06-01

The Crunch&Sip programme is a school-based nutrition initiative designed to increase the fruit, vegetable and water intakes of primary-school children. In recognition of the notable deficits in children's vegetable consumption, the present study explored the receptivity of school staff to a realignment of the Crunch&Sip programme to feature a primary focus on vegetable consumption. This involved investigating school staff members' perceptions of relevant barriers, motivators and facilitators. A multi-method approach was adopted that involved four focus groups and a survey (administered in paper and online formats) containing a mixture of open- and closed-ended items. Western Australia. Staff from Western Australian schools participated in the focus groups (n 37) and survey (n 620). School staff were strongly supportive of modifying the Crunch&Sip programme to focus primarily on children's vegetable consumption and this was generally considered to be a feasible change to implement. Possible barriers identified included children's taste preferences and a perceived lack of parental support. Suggested strategies to overcome these barriers were education sessions for parents and children, teachers modelling vegetable consumption for their students and integrating vegetable-related topics into the school curriculum. School staff are likely to support the introduction of school-based nutrition programmes that specifically encourage the consumption of vegetables. Potential barriers may be overcome through strategies to engage parents and children.

Recruitment and training for home hemodialysis: experience and lessons from the Nocturnal Dialysis Trial.

PubMed

Pipkin, Mary; Eggers, Paul W; Larive, Brett; Rocco, Michael V; Stokes, John B; Suri, Rita S; Lockridge, Robert S

2010-09-01

We assessed perceived barriers and incentives to home hemodialysis and evaluated potential correlates with the duration of home hemodialysis training. Surveys were sent to the principal investigator and study coordinator for each clinical center in the Frequent Hemodialysis Network Nocturnal Trial. Baseline data were obtained on medical comorbidities, cognitive and physical functioning, sessions required for home hemodialysis training, and costs of home renovations. The most commonly perceived barriers included lack of patient motivation, unwillingness to change from in-center modality, and fear of self-cannulation. The most common incentives were greater scheduling flexibility and reduced travel time. The median costs for home renovations varied between $1191 and $4018. The mean number of home hemodialysis training sessions was 27.7 +/- 10.4 (11-59 days). Average training time was less for patients with experience in either self-care or both self-care and cannulation. The number of training sessions was unrelated to the score on the Modified Mini Mental Status or Trailmaking B tests or patient's education level. Training time also did not correlate with the SF-36 Physical Function subscale but did with the modified Charlson comorbidity score and older patient age. Lack of patient or family motivation and fear of the dialysis process are surmountable barriers for accepting home hemodialysis as a modality for renal replacement therapy. Formal education and scores on cognitive function tests are not predictors of training time.

Cerium oxide nanoparticles alter the salt stress tolerance of Brassica napus L. by modifying the formation of root apoplastic barriers.

PubMed

Rossi, Lorenzo; Zhang, Weilan; Ma, Xingmao

2017-10-01

Rapidly growing global population adds significant strains on the fresh water resources. Consequently, saline water is increasingly tapped for crop irrigation. Meanwhile, rapid advancement of nanotechnology is introducing more and more engineered nanoparticles into the environment and in agricultural soils. While some negative effects of ENPs on plant health at very high concentrations have been reported, more beneficial effects of ENPs at relatively low concentrations are increasingly noticed, opening doors for potential applications of nanotechnology in agriculture. In particular, we found that cerium oxide nanoparticles (CeO 2 NPs) improved plant photosynthesis in salt stressed plants. Due to the close connections between salt stress tolerance and the root anatomical structures, we postulated that CeO 2 NPs could modify plant root anatomy and improve plant salt stress tolerance. This study aimed at testing the hypothesis with Brassica napus in the presence of CeO 2 NPs (0, 500 mg kg -1 dry sand) and/or NaCl (0, 50 mM) in a growth chamber. Free hand sections of fresh roots were taken every seven days for three weeks and the suberin lamellae development was examined under a fluorescence microscope. The results confirmed the hypothesis that CeO 2 NPs modified the formation of the apoplastic barriers in Brassica roots. In salt stressed plants, CeO 2 NPs shortened the root apoplastic barriers which allowed more Na + transport to shoots and less accumulation of Na + in plant roots. The altered Na + fluxes and transport led to better physiological performance of Brassica and may lead to new applications of nanotechnology in agriculture. Copyright © 2017 Elsevier Ltd. All rights reserved.

Multicanonical molecular dynamics simulations combined with Metadynamics for the free energy landscape of a biomolecular system with high energy barriers

NASA Astrophysics Data System (ADS)

Yonezawa, Yasushige; Shimoyama, Hiromitsu; Nakamura, Haruki

2011-01-01

Multicanonical molecular-dynamics (McMD) simulation and Metadynamics (MetaD) are useful for obtaining the free-energies, and can be mutually complementary. We combined McMD with MetaD, and applied it to the conformational free energy calculations of a proline dipeptide. First, MetaD was performed along the dihedral angle at the prolyl bond and we obtained a coarse biasing potential. After adding the biasing potential to the dihedral angle potential energy, we conducted McMD with the modified potential energy. Enhanced sampling was achieved for all degrees-of-freedom, and the sampling of the dihedral angle space was facilitated. After reweighting, we obtained an accurate free energy landscape.

Improved performance of In0.83Ga0.17As/InP photodetectors through modifying the position of In0.66Ga0.34As/InAs superlattice electron barrier

NASA Astrophysics Data System (ADS)

Shi, Yan-hui; Zhang, Yong-gang; Ma, Ying-jie; Gu, Yi; Chen, Xing-you; Gong, Qian; Du, Ben; Zhang, Jian; Zhu, Yi

2018-03-01

The performance of wavelength extended In0.83Ga0.17As/InP photodetectors has been improved notably through modifying the position of electron barriers in absorption layer. In order to fully utilize the diffusion component of the photocurrent, the In0.66Ga0.34As/InAs superlattice electron barrier is moved to the edge of the depletion region. Enhanced peak photo responsivity up to 0.84 A/W is realized, which raises 24% compared to that of a reference detector with the superlattice barrier in the middle of the absorber. The dark current slightly increases by 25% at room temperature while decreases by more than an order of magnitude at 150 K, resulting in about 10% or more than twofold improvements for the detectivity, respectively. The results suggest that optimized barrier position is a necessity for barrier-type photodetectors to achieve better performances.

Engineering of Porphyrin Molecules for Use as Effective Cathode Interfacial Modifiers in Organic Solar Cells of Enhanced Efficiency and Stability.

PubMed

Tountas, Marinos; Verykios, Apostolis; Polydorou, Ermioni; Kaltzoglou, Andreas; Soultati, Anastasia; Balis, Nikolaos; Angaridis, Panagiotis A; Papadakis, Michael; Nikolaou, Vasilis; Auras, Florian; Palilis, Leonidas C; Tsikritzis, Dimitris; Evangelou, Evangelos K; Gardelis, Spyros; Koutsoureli, Matroni; Papaioannou, George; Petsalakis, Ioannis D; Kennou, Stella; Davazoglou, Dimitris; Argitis, Panagiotis; Falaras, Polycarpos; Coutsolelos, Athanassios G; Vasilopoulou, Maria

2018-06-20

In the present work, we effectively modify the TiO 2 electron transport layer of organic solar cells with an inverted architecture using appropriately engineered porphyrin molecules. The results show that the optimized porphyrin modifier bearing two carboxylic acids as the anchoring groups and a triazine electron-withdrawing spacer significantly reduces the work function of TiO 2 , thereby reducing the electron extraction barrier. Moreover, the lower surface energy of the porphyrin-modified substrate results in better physical compatibility between the latter and the photoactive blend. Upon employing porphyrin-modified TiO 2 electron transport layers in PTB7:PC 71 BM-based organic solar cells we obtained an improved average power conversion efficiency up to 8.73%. Importantly, porphyrin modification significantly increased the lifetime of the devices, which retained 80% of their initial efficiency after 500 h of storage in the dark. Because of its simplicity and efficacy, this approach should give tantalizing glimpses and generate an impact into the potential of porphyrins to facilitate electron transfer in organic solar cells and related devices.

Polymer/Silicate Nanocomposites Used to Manufacture Gas Storage Tanks With Reduced Permeability

NASA Technical Reports Server (NTRS)

Campbell, Sandi G.; Johnston, Chris

2004-01-01

Over the past decade, there has been considerable research in the area of polymer-layered silicate nanocomposites. This research has shown that the dispersion of small amounts of an organically modified layered silicate improves the polymer strength, modulus, thermal stability, and barrier properties. There have been several reports on the dispersion of layered silicates in an epoxy matrix. Potential enhancements to the barrier properties of epoxy/silicate nanocomposites make this material attractive for low permeability tankage. Polymer matrix composites (PMCs) have several advantages for cryogenic storage tanks. They are lightweight, strong, and stiff; therefore, a smaller fraction of a vehicle's potential payload capacity is used for propellant storage. Unfortunately, the resins typically used to make PMC tanks have higher gas permeability than metals. This can lead to hydrogen loss through the body of the tank instead of just at welds and fittings. One approach to eliminate this problem is to build composite tanks with thin metal liners. However, although these tanks provide good permeability performance, they suffer from a substantial mismatch in the coefficient of thermal expansion, which can lead to failure of the bond between the liner and the body of the tank. Both problems could be addressed with polymersilicate nanocomposites, which exhibit reduced hydrogen permeability, making them potential candidates for linerless PMC tanks. Through collaboration with Northrop Grumman and Michigan State University, nanocomposite test tanks were manufactured for the NASA Glenn Research Center, and the helium permeability was measured. An organically modified silicate was prepared at Michigan State University and dispersed in an epoxy matrix (EPON 826/JeffamineD230). The epoxy/silicate nanocomposites contained either 0 or 5 wt% of the organically modified silicate. The tanks were made by filament winding carbon fibers with the nanocomposite resin. Helium permeability was measured by Northrop Grumman, showing that the leak rate/day of the nanocomposite matrix tank was approximately 80-percent less than that of the neat epoxy matrix tank.

Ultralow-power complementary metal-oxide-semiconductor inverters constructed on Schottky barrier modified nanowire metal-oxide-semiconductor field-effect-transistors.

PubMed

Ma, R M; Peng, R M; Wen, X N; Dai, L; Liu, C; Sun, T; Xu, W J; Qin, G G

2010-10-01

We show that the threshold voltages of both n- and p-channel metal-oxide-semiconductor field-effect-transistors (MOSFETs) can be lowered to close to zero by adding extra Schottky contacts on top of nanowires (NWs). Novel complementary metal-oxide-semiconductor (CMOS) inverters are constructed on these Schottky barrier modified n- and p-channel NW MOSFETs. Based on the high performances of the modified n- and p-channel MOSFETs, especially the low threshold voltages, the as-fabricated CMOS inverters have low operating voltage, high voltage gain, and ultra-low static power dissipation.

Modification of PBDEs (BDE-15, BDE-47, BDE-85 and BDE-126) biological toxicity, bio-concentration, persistence and atmospheric long-range transport potential based on the pharmacophore modeling assistant with the full factor experimental design.

PubMed

Jiang, Long; Li, Yu

2016-04-15

In this study, the properties of AhR binding affinity, bio-concentration factor, half-life and vapor pressure were selected as the typical indicators of biological toxicity, bio-concentration, persistence and atmospheric long-range transport potential for polybrominated diphenyl ethers (PBDEs), respectively. A three-dimensional pharmacophore modeling assistant with a full factor experimental design for each property was used to reveal the significant pharmacophore features and the substituent effects to obtain reasonable modified schemes for the selected target PBDEs. Finally, the performances of the persistent organic pollutant (POP) properties, the synthesis feasibility and the fire resistance of the modified compounds were evaluated. The most influential pharmacophore feature for all POP properties was the hydrophobic group, especially the vinyl and propyl groups. Modified compounds with two additional hydrophobic groups exhibited a better regulatory performance. The average reduction in the proportions of the four POP properties for the modified compounds (except for 3-phenyl-BDE-15) was 70.60%, 52.44%, 47.04% and 70.88%. In addition, the energy and the C-Br bond dissociation enthalpy of the four typical PBDEs were higher than those of the modified compounds (except for 3-phenyl-BDE-15), indicating the synthesis feasibility and the lower energy barrier of the modified compounds to release Br free radicals to provide fire resistance. Copyright © 2015 Elsevier B.V. All rights reserved.

Targeting brain metastases in ALK-rearranged non-small-cell lung cancer.

PubMed

Zhang, Isabella; Zaorsky, Nicholas G; Palmer, Joshua D; Mehra, Ranee; Lu, Bo

2015-10-01

The incidence of brain metastases has increased as a result of improved systemic control and advances in imaging. However, development of novel therapeutics with CNS activity has not advanced at the same rate. Research on molecular markers has revealed many potential targets for antineoplastic agents, and a particularly important aberration is translocation in the ALK gene, identified in non-small-cell lung cancer (NSCLC). ALK inhibitors have shown systemic efficacy against ALK-rearranged NSCLC in many clinical trials, but the effectiveness of crizotinib in CNS disease is limited by poor blood-brain barrier penetration and acquired drug resistance. In this Review, we discuss potential pathways to target ALK-rearranged brain metastases, including next generation ALK inhibitors with greater CNS penetration and mechanisms to overcome resistance. Other important mechanisms to control CNS disease include targeting pathways downstream of ALK phosphorylation, increasing the permeability of the blood-brain barrier, modifying the tumour microenvironment, and adding concurrent radiotherapy. Copyright © 2015 Elsevier Ltd. All rights reserved.

Anticorrosion efficiency of ultrasonically deposited silica coatings on titanium

NASA Astrophysics Data System (ADS)

Ertaş, Fatma Sinem; Kaş, Recep; Mikó, Annamária; Birer, Özgür

2013-07-01

We utilized high intensity ultrasound to prepare coatings of silica and organically modified silica composed of multiple layers of densely packed nanoparticles. Ultrasound was used to collide nanoparticles onto an activated titanium surface with high speed. Large areas could be homogeneously coated by this method. These coatings were characterized by spectroscopy and microscopy methods and the anticorrosion efficiency in NaCl solution was evaluated by electrochemical measurements. The results indicated that the composite coatings provided good quality barrier layer on bare titanium and decreased the anodic corrosion rate. It was found that increase in the organic content of the coating shifted the passivation potential towards more positive direction. The comparison of the impedance results recorded at the corrosion potential pointed out that in each case a good quality barrier layer was formed on the titanium surface. The outstanding corrosion resistance of the composite coatings with only ~200 nm thickness shows that ultrasound assisted deposition can be a competitive method to obtain corrosion protective layers.

Detection of elder abuse: Exploring the potential use of the Elder Abuse Suspicion Index© by law enforcement in the field.

PubMed

Kurkurina, Elina; Lange, Brittany C L; Lama, Sonam D; Burk-Leaver, Erin; Yaffe, Mark J; Monin, Joan K; Humphries, Debbie

2018-01-01

There are no known instruments to aid law enforcement officers in the assessment of elder abuse (EA), despite officers' contact with older adults. This study aimed to identify: 1) officers' perceptions and knowledge of EA, 2) barriers in detecting EA in the field, 3) characteristics officers value in a detection tool, and to explore 4) the potential for officers to use the Elder Abuse Suspicion Index (EASI)©. Data was collected from 69 Connecticut officers who confirmed that barriers to effectively detecting EA included a lack of EA detection instruments, as well as a lack of training on warning signs and risk factors. Officers indicated that the important elements of a desirable tool for helping to detect EA included ease of use, clear instructions, and information on follow-up resources. Approximately 80% of respondents could see themselves using the EASI © in the field, and a modified version has been developed for this purpose.

Mental-Health Conditions, Barriers to Care, and Productivity Loss Among Officers in An Urban Police Department

PubMed Central

Fox, Justin; Desai, Mayur M.; Britten, Karissa; Lucas, Georgina; Luneau, Renee; Rosenthal, Marjorie S.

2014-01-01

Background Police officers are frequently exposed to situations that can negatively impact their mental health. Methods We conducted this study of an urban police department to determine 1) the prevalence of post-traumatic stress disorder (PTSD), depression, and alcohol abuse; 2) patterns of and barriers to mental-health services utilization; and 3) the impact these conditions have on productivity loss. Results Among 150 officers, PTSD (24%), depression (9%), and alcohol abuse (19%) were common. Only 46.7% had ever sought mental-health services; the most commonly cited barriers to accessing services were concerns regarding confidentiality and the potential “negative career impact.” Officers with mental-health conditions had higher productivity loss (5.9% vs 3.4%, P <0.001) at an annual cost of $ 4,489 per officer. Conclusion Mental-health conditions among police officers are common, and costly, yet most officers had never accessed mental-health services; many due to modifiable risk factors. PMID:23155671

Runge-Lenz wave packet in multichannel Stark photoionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Texier, F.

2005-01-01

In a previous slow photoionization experiment, modulations of ionization rings were manifested for Xe in a constant electric field. The present quantum calculation reveals that the modulation is an effect of the multichannel core scattering and of tunneling waves through the Coulomb-Stark potential barrier: the barrier reduces the number of oscillations that is observed relatively to the number of oscillations of the short range wave functions, and the nonhydrogenic core phase shifts modify the position of the ionization rings. We find a hidden difference, in the ionization process, for two close values of the energy depending on the resonance withmore » the barrier. The ionization intensity is interpreted as a Runge-Lenz wave packet; thus, we can relate the quantum modulation to the classical Coulomb-Stark trajectories. The Runge-Lenz wave packet differs from a usual temporal wave packet because its components are eigenstates of the Runge-Lenz vector z projection and its evolution is not temporal but spatial.« less

Horseradish peroxidase and toluidine blue covalently immobilized leak-free sol-gel composite biosensor for hydrogen peroxide.

PubMed

Thenmozhi, K; Narayanan, S Sriman

2017-01-01

The enzyme horseradish peroxidase and the water-soluble mediator toluidine blue were covalently immobilized to 3-aminopropyl trimethoxy silane precursor through glutaraldehyde crosslinker. A rigid ceramic composite electrode was fabricated from this modified silane along with graphite powder, which resulted in an amperometric biosensor for H 2 O 2 . The electrochemical behaviour of the modified biosensor was monitored using cyclic voltammetry in the potential range of 0.2V to -0.4V vs SCE. The biosensor exhibited a stable voltammogram with cathodic peak at -0.234V and anodic peak at -0.172V, with a formal potential of -0.203V. Various factors influencing the performance of the biosensor such as buffer solution, pH, temperature and potential were examined for optimizing the working conditions. The modified biosensor exhibited a good catalytic behaviour for the reduction of H 2 O 2 at a lower potential of -0.25V without any barrier from possible interferents. The analytical working range was found to be 0.429μM to 0.455mM of H 2 O 2 with a detection limit of 0.171μM. The fabricated biosensor is robust for long-term usage in addition to the high sensitivity, rapid response and having an advantage of surface renewability by simple mechanical polishing. Copyright © 2016 Elsevier B.V. All rights reserved.

Targeting receptor-mediated transport for delivery of biologics across the blood-brain barrier.

PubMed

Lajoie, Jason M; Shusta, Eric V

2015-01-01

Biologics are an emerging class of medicines with substantial promise to treat neurological disorders such as Alzheimer's disease, stroke, and multiple sclerosis. However, the blood-brain barrier (BBB) presents a formidable obstacle that appreciably limits brain uptake and hence the therapeutic potential of biologics following intravenous administration. One promising strategy for overcoming the BBB to deliver biologics is the targeting of endogenous receptor-mediated transport (RMT) systems that employ vesicular trafficking to transport ligands across the BBB endothelium. If a biologic is modified with an appropriate targeting ligand, it can gain improved access to the brain via RMT. Various RMT-targeting strategies have been developed over the past 20 years, and this review explores exciting recent advances, emphasizing studies that show brain targeting in vivo.

Protein adsorption capability on polyurethane and modified-polyurethane membrane for periodontal guided tissue regeneration applications.

PubMed

Sheikh, Zeeshan; Khan, Abdul Samad; Roohpour, Nima; Glogauer, Michael; Rehman, Ihtesham U

2016-11-01

Periodontal disease if left untreated can result in creation of defects within the alveolar ridge. Barrier membranes are frequently used with or without bone replacement graft materials for achieving periodontal guided tissue regeneration (GTR). Surface properties of barrier membranes play a vital role in their functionality and clinical success. In this study polyetherurethane (PEU) membranes were synthesized by using 4,4'-methylene-diphenyl diisocyanate (MDI), polytetramethylene oxide (PTMO) and 1,4-butane diol (BDO) as a chain extender via solution polymerization. Hydroxyl terminated polydimethylsiloxane (PDMS) due to having inherent surface orientation towards air was used for surface modification of PEU on one side of the membranes. This resulting membranes had one surface being PEU and the other being PDMS coated PEU. The prepared membranes were treated with solutions of bovine serum albumin (BSA) in de-ionized water at 37°C at a pH of 7.2. The surface protein adsorptive potential of PEU membranes was observed using Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (ATR-FTIR), Raman spectroscopy and Confocal Raman spectroscopy. The contact angle measurement, tensile strength and modulus of prepared membranes were also evaluated. PEU membrane (89.86±1.62°) exhibited less hydrophobic behavior than PEU-PDMS (105.87±3.16°). The ultimate tensile strength and elastic modulus of PEU (27±1MPa and 14±2MPa) and PEU-PDMS (8±1MPa and 26±1MPa) membranes was in required range. The spectral analysis revealed adsorption of BSA proteins on the surface of non PDMS coated PEU surface. The PDMS modified PEU membranes demonstrated a lack of BSA adsorption. The non PDMS coated side of the membrane which adsorbs proteins could potentially be used facing towards the defect attracting growth factors for periodontal tissue regeneration. Whereas, the PDMS coated side could serve as an occlusive barrier for preventing gingival epithelial cells from proliferating and migrating into the defect space by facing the soft tissue flaps. This study demonstrates the potential of a dual natured PEU barrier membrane for use in periodontal tissue engineering applications and further investigations are required. Copyright © 2016 Elsevier B.V. All rights reserved.

Negotiation of intracellular membrane barriers by TAT-modified gold nanoparticles.

PubMed

Krpetić, Zeljka; Saleemi, Samia; Prior, Ian A; Sée, Violaine; Qureshi, Rumana; Brust, Mathias

2011-06-28

This paper contributes to the debate on how nanosized objects negotiate membrane barriers inside biological cells. The uptake of peptide-modified gold nanoparticles by HeLa cells has been quantified using atomic emission spectroscopy. The TAT peptide from the HIV virus was singled out as a particularly effective promoter of cellular uptake. The evolution of the intracellular distribution of TAT-modified gold nanoparticles with time has been studied in detail by TEM and systematic image analysis. An unusual trend of particles disappearing from the cytosol and the nucleus and accumulating massively in vesicular bodies was observed. Subsequent release of the particles, both by membrane rupture and by direct transfer across the membrane boundary, was frequently found. Ultimately, near total clearing of particles from the cells occurred. This work provides support for the hypothesis that cell-penetrating peptides can enable small objects to negotiate membrane barriers also in the absence of dedicated transport mechanisms.

Tunable superlattice in graphene to control the number of Dirac points.

PubMed

Dubey, Sudipta; Singh, Vibhor; Bhat, Ajay K; Parikh, Pritesh; Grover, Sameer; Sensarma, Rajdeep; Tripathi, Vikram; Sengupta, K; Deshmukh, Mandar M

2013-09-11

Superlattice in graphene generates extra Dirac points in the band structure and their number depends on the superlattice potential strength. Here, we have created a lateral superlattice in a graphene device with a tunable barrier height using a combination of two gates. In this Letter, we demonstrate the use of lateral superlattice to modify the band structure of graphene leading to the emergence of new Dirac cones. This controlled modification of the band structure persists up to 100 K.

Psychiatric versus physical disabilities: A comparison of barriers and facilitators to employment.

PubMed

Sevak, Purvi; Khan, Shamima

2017-06-01

Guided by the social model of disability (Nagi, 1965), this study aims to better identify barriers to and facilitators of employment for individuals with psychiatric disabilities and how these factors may differ for individuals with physical disabilities. Our analysis uses data from the Survey of Disability and Employment on 2,148 individuals with psychiatric disabilities, physical disabilities, or both who in 2014 applied for services from 1 of 3 state vocational rehabilitation (VR) agencies. We identify type of disability based on respondents' open-ended descriptions of their impairments. We use univariate statistics and multivariate regression estimates to compare employment history, and potential barriers to and facilitators of employment between individuals with psychiatric and physical disabilities. VR applicants with psychiatric disabilities have had longer periods of nonemployment than individuals with physical disabilities alone. They are significantly more likely than individuals with physical disabilities alone to report nonhealth reasons, such as getting fired and lacking skills, as barriers to employment. We found that a number of accommodations, including flexible schedules and modified work duties, are significantly associated with continued employment. VR counselors should be aware that although most applicants with psychiatric disabilities place a great deal of importance on being employed, they face additional barriers to employment. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Effect of different intraorifice barriers on the fracture resistance of roots obturated with Resilon or gutta-percha.

PubMed

Nagas, Emre; Uyanik, Ozgur; Altundasar, Emre; Durmaz, Veli; Cehreli, Zafer C; Vallittu, Pekka K; Lassila, Lippo V J

2010-06-01

This study investigated and compared the root reinforcement potential of 3 different intraorifice barriers (mineral trioxide aggregate [MTA], resin-modified glass ionomer cement [Vitremer], and fiber-reinforced composite [FRC]) placed over root canals obturated with gutta-percha or Resilon. Crowns of 80 extracted human mandibular premolars were sectioned off to obtain 14-mm-long root specimens. After preparation of root canals with nickel-titanium rotary files, the roots were obturated with either the Resilon/Epiphany system or gutta-percha + AH Plus sealer. In both obturation groups, specimens were further subgrouped with respect to the intraorifice barrier material placed after removal of 3-mm coronal portion of the root fillings: (1) MTA, (2) Vitremer, and (3) FRC. The specimens were loaded vertically at 1 mm/min crosshead speed until vertical root fracture occurred. Results were evaluated statistically with two-way analysis of variance and Tukey tests. Fracture resistance of roots was significantly affected by the type of intraorifice barrier (P < .05), but not by the type of obturation system used (P > .05). The use of Vitremer and FRC significantly improved the fracture resistance, whereas MTA did not exhibit any reinforcing effect as an intraorifice barrier. Copyright 2010 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Structural and kinetic mapping of side-chain exposure onto the protein energy landscape.

PubMed

Bernstein, Rachel; Schmidt, Kierstin L; Harbury, Pehr B; Marqusee, Susan

2011-06-28

Identification and characterization of structural fluctuations that occur under native conditions is crucial for understanding protein folding and function, but such fluctuations are often rare and transient, making them difficult to study. Native-state hydrogen exchange (NSHX) has been a powerful tool for identifying such rarely populated conformations, but it generally reveals no information about the placement of these species along the folding reaction coordinate or the barriers separating them from the folded state and provides little insight into side-chain packing. To complement such studies, we have performed native-state alkyl-proton exchange, a method analogous to NSHX that monitors cysteine modification rather than backbone amide exchange, to examine the folding landscape of Escherichia coli ribonuclease H, a protein well characterized by hydrogen exchange. We have chosen experimental conditions such that the rate-limiting barrier acts as a kinetic partition: residues that become exposed only upon crossing the unfolding barrier are modified in the EX1 regime (alkylation rates report on the rate of unfolding), while those exposed on the native side of the barrier are modified predominantly in the EX2 regime (alkylation rates report on equilibrium populations). This kinetic partitioning allows for identification and placement of partially unfolded forms along the reaction coordinate. Using this approach we detect previously unidentified, rarely populated conformations residing on the native side of the barrier and identify side chains that are modified only upon crossing the unfolding barrier. Thus, in a single experiment under native conditions, both sides of the rate-limiting barrier are investigated.

Structural and kinetic mapping of side-chain exposure onto the protein energy landscape

PubMed Central

Bernstein, Rachel; Schmidt, Kierstin L.; Harbury, Pehr B.; Marqusee, Susan

2011-01-01

Identification and characterization of structural fluctuations that occur under native conditions is crucial for understanding protein folding and function, but such fluctuations are often rare and transient, making them difficult to study. Native-state hydrogen exchange (NSHX) has been a powerful tool for identifying such rarely populated conformations, but it generally reveals no information about the placement of these species along the folding reaction coordinate or the barriers separating them from the folded state and provides little insight into side-chain packing. To complement such studies, we have performed native-state alkyl-proton exchange, a method analogous to NSHX that monitors cysteine modification rather than backbone amide exchange, to examine the folding landscape of Escherichia coli ribonuclease H, a protein well characterized by hydrogen exchange. We have chosen experimental conditions such that the rate-limiting barrier acts as a kinetic partition: residues that become exposed only upon crossing the unfolding barrier are modified in the EX1 regime (alkylation rates report on the rate of unfolding), while those exposed on the native side of the barrier are modified predominantly in the EX2 regime (alkylation rates report on equilibrium populations). This kinetic partitioning allows for identification and placement of partially unfolded forms along the reaction coordinate. Using this approach we detect previously unidentified, rarely populated conformations residing on the native side of the barrier and identify side chains that are modified only upon crossing the unfolding barrier. Thus, in a single experiment under native conditions, both sides of the rate-limiting barrier are investigated. PMID:21670244

Exploring perceived barriers, drivers, impacts and the need for evaluation of public involvement in health and social care research: a modified Delphi study

PubMed Central

Snape, D; Kirkham, J; Britten, N; Froggatt, K; Gradinger, F; Lobban, F; Popay, Jennie; Wyatt, K; Jacoby, Ann

2014-01-01

Objective To explore areas of consensus and conflict in relation to perceived public involvement (PI) barriers and drivers, perceived impacts of PI and ways of evaluating PI approaches in health and social care research. Background Internationally and within the UK the recognition of potential benefits of PI in health and social care research is gathering momentum and PI is increasingly identified by organisations as a prerequisite for funding. However, there is relatively little examination of the impacts of PI and how those impacts might be measured. Design Mixed method, three-phase, modified Delphi technique, conducted as part of a larger MRC multiphase project. Sample Clinical and non-clinical academics, members of the public, research managers, commissioners and funders. Findings This study found high levels of consensus about the most important barriers and drivers to PI. There was acknowledgement that tokenism was common in relation to PI; and strong support for the view that demonstrating the impacts and value of PI was made more difficult by tokenistic practice. PI was seen as having intrinsic value; nonetheless, there was clear support for the importance of evaluating its impact. Research team cohesion and appropriate resources were considered essential to effective PI implementation. Panellists agreed that PI can be challenging, but can be facilitated by clear guidance, together with models of good practice and measurable standards. Conclusions This study is the first to present empirical evidence of the opinions voiced by key stakeholders on areas of consensus and conflict in relation to perceived PI barriers and drivers, perceived impacts of PI and the need to evaluate PI. As such it further contributes to debate around best practice in PI, the potential for tokenism and how best to evaluate the impacts of PI. These findings have been used in the development of the Public Involvement Impact Assessment Framework (PiiAF), an online resource which offers guidance to researchers and members of the public involved in the PI process. PMID:24939808

Patient recruitment for clinical trials on traditional Chinese medicine: Challenges, barriers, and strategies.

PubMed

King-Fai, Cheng; Ping-Chung, Leung; Lai-Yi, Wong; Yuet-Shim, Fong

2008-02-02

Failure to recruit sufficient numbers of participants is a major barrier to the completion of randomized controlled trials in traditional Chinese medicine (TCM) clinical trials. The purpose of this paper is to analyze the commonly used strategies for the recruitment of patients in TCM clinical trials, to identify the most common reasons for attrition and refusal, and to identify barriers and potential solutions to the difficulties. There are four stages in the actual recruitment process, which included introducing the project to the potential patients, explaining how to implement the project, assessing and intensifying the understanding and facilitating patient decision-making. When insufficient recruitment occurred, the following steps should be considered: reevaluating the required sample size; adding new sites to the trial; eliminating hospitals that had poor recruiting records; extending the patient recruitment period, modifying the patient inclusion/exclusion criteria; and shifting placebo-controlled to active-controlled arrangements. Success in reaching target recruitment depended largely on being able to directly contact patients through posters, newspaper advertisements, television interviews, patient support groups, and physician referrals in hospitals. Suspicions against the placebo and unwillingness to stop taking other herbal supplements made recruitment more difficult, time-consuming, and costly. In a Chinese community, open advertising in the local newspaper may be particularly attractive.

Exploring the facilitators and barriers to engagement in physical activity for people with multiple sclerosis.

PubMed

Kayes, Nicola M; McPherson, Kathryn M; Schluter, Philip; Taylor, Denise; Leete, Marta; Kolt, Gregory S

2011-01-01

To explore the relationship that cognitive behavioural and other previously identified variables have with physical activity engagement in people with multiple sclerosis (MS). This study adopted a cross-sectional questionnaire design. Participants were 282 individuals with MS. Outcome measures included the Physical Activity Disability Survey--Revised, Cognitive and Behavioural Responses to Symptoms Questionnaire, Barriers to Health Promoting Activities for Disabled Persons Scale, Multiple Sclerosis Self-efficacy Scale, Self-Efficacy for Chronic Diseases Scales and Chalder Fatigue Questionnaire. Multivariable stepwise regression analyses found that greater self-efficacy, greater reported mental fatigue and lower number of perceived barriers to physical activity accounted for a significant proportion of variance in physical activity behaviour, over that accounted for by illness-related variables. Although fear-avoidance beliefs accounted for a significant proportion of variance in the initial analyses, its effect was explained by other factors in the final multivariable analyses. Self-efficacy, mental fatigue and perceived barriers to physical activity are potentially modifiable variables which could be incorporated into interventions designed to improve physical activity engagement. Future research should explore whether a measurement tool tailored to capture beliefs about physical activity identified by people with MS would better predict participation in physical activity.

Attachment of a hydrophobically modified biopolymer at the oil-water interface in the treatment of oil spills.

PubMed

Venkataraman, Pradeep; Tang, Jingjian; Frenkel, Etham; McPherson, Gary L; He, Jibao; Raghavan, Srinivasa R; Kolesnichenko, Vladimir; Bose, Arijit; John, Vijay T

2013-05-01

The stability of crude oil droplets formed by adding chemical dispersants can be considerably enhanced by the use of the biopolymer, hydrophobically modified chitosan. Turbidimetric analyses show that emulsions of crude oil in saline water prepared using a combination of the biopolymer and the well-studied chemical dispersant (Corexit 9500A) remain stable for extended periods in comparison to emulsions stabilized by the dispersant alone. We hypothesize that the hydrophobic residues from the polymer preferentially anchor in the oil droplets, thereby forming a layer of the polymer around the droplets. The enhanced stability of the droplets is due to the polymer layer providing an increase in electrostatic and steric repulsions and thereby a large barrier to droplet coalescence. Our results show that the addition of hydrophobically modified chitosan following the application of chemical dispersant to an oil spill can potentially reduce the use of chemical dispersants. Increasing the molecular weight of the biopolymer changes the rheological properties of the oil-in-water emulsion to that of a weak gel. The ability of the biopolymer to tether the oil droplets in a gel-like matrix has potential applications in the immobilization of surface oil spills for enhanced removal.

The role of the intestinal microvasculature in inflammatory bowel disease: studies with a modified Caco-2 model including endothelial cells resembling the intestinal barrier in vitro.

PubMed

Kasper, Jennifer Y; Hermanns, Maria Iris; Cavelius, Christian; Kraegeloh, Annette; Jung, Thomas; Danzebrink, Rolf; Unger, Ronald E; Kirkpatrick, Charles James

The microvascular endothelium of the gut barrier plays a crucial role during inflammation in inflammatory bowel disease. We have modified a commonly used intestinal cell model based on the Caco-2 cells by adding microvascular endothelial cells (ISO-HAS-1). Transwell filters were used with intestinal barrier-forming Caco-2 cells on top and the ISO-HAS-1 on the bottom of the filter. The goal was to determine whether this coculture mimics the in vivo situation more closely, and whether the model is suitable to evaluate interactions of, for example, prospective nanosized drug vehicles or contrast agents with this coculture in a physiological and inflamed state as it would occur in inflammatory bowel disease. We monitored the inflammatory responsiveness of the cells (release of IL-8, soluble intercellular adhesion molecule 1, and soluble E-selectin) after exposure to inflammatory stimuli (lipopolysaccharide, TNF-α, INF-γ, IL1-β) and a nanoparticle (Ba/Gd: coprecipitated BaSO 4 and Gd(OH) 3 ), generally used as contrast agents. The barrier integrity of the coculture was evaluated via the determination of transepithelial electrical resistance and the apparent permeability coefficient (P app ) of NaFITC. The behavior of the coculture Caco-1/ISO-HAS-1 was compared to the respective monocultures Caco-2 and ISO-HAS-1. Based on transepithelial electrical resistance, the epithelial barrier integrity of the coculture remained stable during incubation with all stimuli, whereas the P app decreased after exposure to the cytokine mixture (TNF-α, INF-γ, IL1-β, and Ba/Gd). Both the endothelial and epithelial monocultures showed a high inflammatory response in both the upper and lower transwell-compartments. However, in the coculture, inflammatory mediators were only detected on the epithelial side and not on the endothelial side. Thus in the coculture, based on the P app , the epithelial barrier appears to prevent a potential inflammatory overreaction in the underlying endothelial cells. In summary, this coculture model exhibits in vivo-like features, which cannot be observed in conventional monocultures, making the former more suitable to study interactions with external stimuli.

Evaluation of the effects of hyaluronic acid-carboxymethyl cellulose barrier on ovarian tumor progression

PubMed Central

2014-01-01

Background Hyaluronic acid is a prognostic factor in ovarian cancers. It is also a component of Hyaluronic Acid-Carboxymethyl Cellulose (HA-CMC) barrier, an anti-adhesion membrane widely used during abdominal surgeries in particular for ovarian carcinosis. 70% of patients who undergo ovarian surgery will relapse due to the persistence of cancer cells. This study’s objective was to determine the oncological risk from use of this material, in the presence of residual disease, despite the benefit gained by it decreasing post-surgical adhesions in order to provide an unambiguous assessment of its appropriateness for use in ovarian surgical management. Methods We assessed the effects of HA-CMC barrier on the in vitro proliferation of human ovarian tumor cell lines (OVCAR-3, IGROV-1 and SKOV-3). We next evaluated, in vivo in nude mice, the capacity of this biomaterial to regulate the tumor progression of subcutaneous and intraperitoneal models of ovarian tumor xenografts. Results We showed that HA-CMC barrier does not increase in vitro proliferation of ovarian cancer cell lines compared to control. In vivo, HA-CMC barrier presence with subcutaneous xenografts induced neither an increase in tumor volume nor cell proliferation (Ki67 and mitotic index). With the exception of an increased murine carcinosis score in peritoneum, the presence of HA-CMC barrier with intraperitoneal xenografts modified neither macro nor microscopic tumor growth. Finally, protein analysis of survival (Akt), proliferation (ERK) and adhesion (FAK) pathways highlighted no activation on the xenografts imputable to HA-CMC barrier. Conclusions For the most part, our results support the lack of tumor progression activation due to HA-CMC barrier. We conclude that the benefits gained from using HA-CMC barrier membrane during ovarian cancer surgeries seem to outweigh the potential oncological risks. PMID:24739440

The Use of Permeable Barriers to Inhibit Virus Migration in the Subsurface

NASA Astrophysics Data System (ADS)

Schulze-Makuch, D.; Guan, H.; Totten, J.; Couroux, E.; Endley, S.; Hielscher, F.; Emmert, S.; Pillai, S. D.

2001-12-01

Ground water is susceptible to fecal contamination due to leaking sewer lines, faulty septic tanks and careless disposal of septic wastes; a problem especially common in low-income areas with no public sewage system. Under these conditions, viral and bacterial infection rates have been shown to increase. However, potential for viral infections can be reduced if the viruses are prevented from reaching the drinking water wells. Laboratory and field studies were conducted to determine whether iron-coated sand (ICS), pure zeolite (PZ) and surfactant modified zeolites (SMZ) could be used to retard virus migration in soils. In the laboratory, using a model aquifer and MS2 bacteriophage (as an enteric virus indicator) we showed that ICS and especially SMZ was able to remove more than 90 % of the injected viruses under various conditions. The removal efficiency of viruses was also tested under field conditions using septic effluent and a constructed submerged wetland. The performance of the wetland was greatly enhanced when using SMZ as filter pack for a pumping well that withdrew water at a downstream location from the wetland. Our results suggest that submerged wetlands, particularly if combined with a pumping well that has a filter pack consisting of surfactant modified zeolite (rather than the usual sand and gravel pack), are efficient in removing viruses from septic effluent. The permeable barrier materials tested here are economical and could significantly reduce the potential for viral contamination of drinking water wells. >http://www.geo.utep.edu/pub/dirksm/geobiowater/geobiowater.htm

A qualitative study into the perceived barriers of accessing healthcare among a vulnerable population involved with a community centre in Romania.

PubMed

George, Siân; Daniels, Katy; Fioratou, Evridiki

2018-04-03

Minority vulnerable communities, such as the European Roma, often face numerous barriers to accessing healthcare services, resulting in negative health outcomes. Both these barriers and outcomes have been reported extensively in the literature. However, reports on barriers faced by European non-Roma native communities are limited. The "Health Care Access Barriers" (HCAB) model identifies pertinent financial, structural and cognitive barriers that can be measured and potentially modified. The present study thus aims to explore the barriers to accessing healthcare for a vulnerable population of mixed ethnicity from a charity community centre in Romania, as perceived by the centre's family users and staff members, and assess whether these reflect the barriers identified from the HCAB model. Eleven community members whose children attend the centre and seven staff members working at the centre participated in face-to-face semi-structured interviews, exploring personal experiences and views on accessing healthcare. The interviews were transcribed and analysed using an initial deductive and secondary inductive approach to identify HCAB themes and other emerging themes and subthemes. Identified themes from both groups aligned with HCAB's themes of financial, structural and cognitive barriers and emergent subthemes important to the specific population were identified. Specifically, financial barriers related mostly to health insurance and bribery issues, structural barriers related mostly to service availability and accessibility, and cognitive barriers related mostly to healthcare professionals' attitudes and discrimination and the vulnerable population's lack of education and health literacy. A unique theme of psychological barriers emerged from both groups with associated subthemes of mistrust, hopelessness, fear and anxiety of this vulnerable population. The current study highlights healthcare access barriers to a vulnerable non-Roma native population involved with a charity community centre in Romania. The "Healthcare Access Barriers for Vulnerable Populations" (HABVP) model is proposed as an adaption to the existing HCAB model to account for the unique perceived barriers to healthcare for this population. Recommendations for future resolution of these identified barriers are proposed.

Overcoming translational barriers impeding development of Alzheimer's disease modifying therapies.

PubMed

Golde, Todd E

2016-10-01

It has now been ~ 30 years since the Alzheimer's disease (AD) research entered what may be termed the 'molecular era' that began with the identification of the amyloid β protein (Aβ) as the primary component of amyloid within senile plaques and cerebrovascular amyloid and the microtubule-associated protein tau as the primary component of neurofibrillary tangles in the AD brain. These pivotal discoveries and the subsequent genetic, pathological, and modeling studies supporting pivotal roles for tau and Aβ aggregation and accumulation have provided firm rationale for a new generation of AD therapies designed not to just provide symptomatic benefit, but as disease modifying agents that would slow or even reverse the disease course. Indeed, over the last 20 years numerous therapeutic strategies for disease modification have emerged, been preclinically validated, and advanced through various stages of clinical testing. Unfortunately, no therapy has yet to show significant clinical disease modification. In this review, I describe 10 translational barriers to successful disease modification, highlight current efforts addressing some of these barriers, and discuss how the field could focus future efforts to overcome barriers that are not major foci of current research efforts. Seminal discoveries made over the past 25 years have provided firm rationale for a new generation of Alzheimer's disease (AD) therapies designed as disease modifying agents that would slow or even reverse the disease course. Unfortunately, no therapy has yet to show significant clinical disease modification. In this review, I describe 10 translational barriers to successful AD disease modification, highlight current efforts addressing some of these barriers, and discuss how the field could focus future efforts to overcome these barriers. This article is part of the 60th Anniversary special issue. © 2016 International Society for Neurochemistry.

Improving Behavioral Support for Smoking Cessation in Pregnancy: What Are the Barriers to Stopping and Which Behavior Change Techniques Can Influence Them? Application of Theoretical Domains Framework

PubMed Central

Coleman-Haynes, Tom; Lorencatto, Fabiana; Ussher, Michael; Dyas, Jane; Coleman, Tim

2018-01-01

Behavioral support interventions are used to help pregnant smokers stop; however, of those tested, few are proven effective. Systematic research developing effective pregnancy-specific behavior change techniques (BCTs) is ongoing. This paper reports contributory work identifying potentially-effective BCTs relative to known important barriers and facilitators (B&Fs) to smoking cessation in pregnancy; to detect priority areas for BCTs development. A Nominal Group Technique with cessation experts (n = 12) elicited an expert consensus on B&Fs most influencing women’s smoking cessation and those most modifiable through behavioral support. Effective cessation interventions in randomized trials from a recent Cochrane review were coded into component BCTs using existing taxonomies. B&Fs were categorized using Theoretical Domains Framework (TDF) domains. Matrices, mapping BCT taxonomies against TDF domains, were consulted to investigate the extent to which BCTs in existing interventions target key B&Fs. Experts ranked ‘smoking a social norm’ and ‘quitting not a priority’ as most important barriers and ‘desire to protect baby’ an important facilitator to quitting. From 14 trials, 23 potentially-effective BCTs were identified (e.g., ‘information about consequences). Most B&Fs fell into ‘Social Influences’, ‘Knowledge’, ‘Emotions’ and ‘Intentions’ TDF domains; few potentially-effective BCTs mapped onto every TDF domain. B&Fs identified by experts as important to cessation, are not sufficiently targeted by BCT’s currently within interventions for smoking cessation in pregnancy. PMID:29462994

Improving Behavioral Support for Smoking Cessation in Pregnancy: What Are the Barriers to Stopping and Which Behavior Change Techniques Can Influence These? Application of Theoretical Domains Framework.

PubMed

Campbell, Katarzyna A; Fergie, Libby; Coleman-Haynes, Tom; Cooper, Sue; Lorencatto, Fabiana; Ussher, Michael; Dyas, Jane; Coleman, Tim

2018-02-17

Behavioral support interventions are used to help pregnant smokers stop; however, of those tested, few are proven effective. Systematic research developing effective pregnancy-specific behavior change techniques (BCTs) is ongoing. This paper reports contributory work identifying potentially-effective BCTs relative to known important barriers and facilitators (B&Fs) to smoking cessation in pregnancy; to detect priority areas for BCTs development. A Nominal Group Technique with cessation experts ( n = 12) elicited an expert consensus on B&Fs most influencing women's smoking cessation and those most modifiable through behavioral support. Effective cessation interventions in randomized trials from a recent Cochrane review were coded into component BCTs using existing taxonomies. B&Fs were categorized using Theoretical Domains Framework (TDF) domains. Matrices, mapping BCT taxonomies against TDF domains, were consulted to investigate the extent to which BCTs in existing interventions target key B&Fs. Experts ranked "smoking a social norm" and "quitting not a priority" as most important barriers and "desire to protect baby" an important facilitator to quitting. From 14 trials, 23 potentially-effective BCTs were identified (e.g., information about consequences). Most B&Fs fell into "Social Influences", "Knowledge", "Emotions" and "Intentions" TDF domains; few potentially-effective BCTs mapped onto every TDF domain. B&Fs identified by experts as important to cessation, are not sufficiently targeted by BCT's currently within interventions for smoking cessation in pregnancy.

Morphological and antibacterial properties of modified paper by PS nanocomposites for packaging applications.

PubMed

Youssef, Ahmed M; Kamel, S; El-Samahy, M A

2013-10-15

With the increasing sustainability trend with packaging materials, paper and polymer nanocomposites represent a novel class of packaging materials. This study evaluates the potential achievement of alternative sustainable materials as antibacterial packaging application. Paper sheet from rice straw coated with 5 or 10% polystyrene (PS) nanocomposites using titanium dioxide nanoparticles (TiO2-NPs) doped or undoped with sliver nanoparticles (Ag-NPs) were prepared. The morphology of the uncoated and coated paper sheets was studied by SEM. The treated paper sheets were analyzed for their elemental composition using EDAX. The Barrier, air permeability, cob test, as well as mechanical properties and tensile strength were also evaluated. The inhibitory effect of modified paper sheets against Pseudomonas, Staphylococcus aureus, Candida, and Staphylococcus were investigated. Copyright © 2013 Elsevier Ltd. All rights reserved.

Pressure Injury Prevention in a Saudi Arabian Intensive Care Unit: Registered Nurse Attitudes Toward Prevention Strategies and Perceived Facilitators and Barriers to Evidence Implementation.

PubMed

Tayyib, Nahla; Coyer, Fiona; Lewis, Peter

2016-01-01

The purpose of this study was to examine RNs' attitudes toward pressure injury (PI) prevention strategies. Barriers and facilitators perceived by RNs to potentially impact on the adoption and implementation of PI prevention interventions in the intensive care unit (ICU) were examined. Descriptive cross-sectional survey. The target population was RNs practicing in an intensive care unit (ICU) of a major tertiary hospital, King Abdul-Aziz, Mecca, in Saudi Arabia. Fifty-six of the available 60 ICU RNs participated in this study. Data were collected via survey using the Attitude towards Pressure injury Prevention instrument, which included 13 items rated with 4-point Likert scale, and the modified Barriers and Facilitators tool, which included 27 items. The survey was organized into 3 parts: demographic information, potential barriers to optimal skin care, and potential facilitators to skin care. The survey took 10 to 15 minutes to complete. Data were analyzed with descriptive-correlation statistics and multiple regression analysis. Thematic analysis was undertaken for qualitative data. Participants demonstrated positive attitudes toward PI prevention (μ = 38.19/52; 73.44%). No significant differences were found between demographic characteristics of the participants with the RNs' Attitude subscale and perceived barriers and facilitators associated with implementing PI prevention in the critical care setting. Several barriers influenced the ability of RNs to implement PI prevention strategies including time demands (β = .388; P = .011), limitation of RNs' knowledge (β = -.632; P = .022), and current documentation format (β = .344; P = .046). Statistically significant facilitating factors that increased respondents ability to undertake PI prevention were ease of obtaining pressure-reduction surfaces (β = -.388; P = .007), collaboration with interdisciplinary teams (β = .37; P = .02), and availability of appropriate skin care products (β = .44; P = .015). Thematic analysis of open-ended questions highlighted workload as a barrier that impedes the implementation of care specific to PI prevention. Findings from this study highlighted that ICU RNs had a positive attitude toward PI prevention. This study also identified perceived factors influencing PI prevention in the ICU, both facilitators and barriers. Perceived facilitators included availability of pressure-relieving support surfaces and appropriate skin care products and collaboration with the healthcare professional team. However, perceived barriers included limited PI prevention knowledge of the nurse and RN workflow (time demands and documentation format). Findings from this study provide important information identifying context-specific factors that may influence the adoption and implementation of PI prevention interventions in the ICU.

DFMSPH14: A C-code for the double folding interaction potential of two spherical nuclei

NASA Astrophysics Data System (ADS)

Gontchar, I. I.; Chushnyakova, M. V.

2016-09-01

This is a new version of the DFMSPH code designed to obtain the nucleus-nucleus potential by using the double folding model (DFM) and in particular to find the Coulomb barrier. The new version uses the charge, proton, and neutron density distributions provided by the user. Also we added an option for fitting the DFM potential by the Gross-Kalinowski profile. The main functionalities of the original code (e.g. the nucleus-nucleus potential as a function of the distance between the centers of mass of colliding nuclei, the Coulomb barrier characteristics, etc.) have not been modified. Catalog identifier: AEFH_v2_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFH_v2_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland. Licensing provisions: GNU General Public License, version 3 No. of lines in distributed program, including test data, etc.: 7211 No. of bytes in distributed program, including test data, etc.: 114404 Distribution format: tar.gz Programming language: C Computer: PC and Mac Operation system: Windows XP and higher, MacOS, Unix/Linux Memory required to execute with typical data: below 10 Mbyte Classification: 17.9 Catalog identifier of previous version: AEFH_v1_0 Journal reference of previous version: Comp. Phys. Comm. 181 (2010) 168 Does the new version supersede the previous version?: Yes Nature of physical problem: The code calculates in a semimicroscopic way the bare interaction potential between two colliding spherical nuclei as a function of the center of mass distance. The height and the position of the Coulomb barrier are found. The calculated potential is approximated by an analytical profile (Woods-Saxon or Gross-Kalinowski) near the barrier. Dependence of the barrier parameters upon the characteristics of the effective NN forces (like, e.g. the range of the exchange part of the nuclear term) can be investigated. Method of solution: The nucleus-nucleus potential is calculated using the double folding model with the Coulomb and the effective M3Y NN interactions. For the direct parts of the Coulomb and the nuclear terms, the Fourier transform method is used. In order to calculate the exchange parts, the density matrix expansion method is applied. Typical running time: less than 1 minute. Reason for new version: Many users asked us how to implement their own density distributions in the DFMSPH. Now this option has been added. Also we found that the calculated Double-Folding Potential (DFP) is approximated more accurately by the Gross-Kalinowski (GK) profile. This option has been also added.

Organically modified low-grade kaolin as a secondary containment material for underground storage tanks.

PubMed

Moon, Chul-Hwan; Lee, Jai-Young; Oh, Byung-Taek; Choi, Sang-Il

2007-08-01

Batch scale reactions were conducted to evaluate the efficacy of modified low-grade kaolin for the treatment of petroleum contaminants. Low-grade kaolin, which has been unvalued as material in the mining process because of its low quality for commercial products, was modified with HDTMA (hexadecyl-trimethylammonium), and its efficiency was compared with that of HDTMA-modified bentonite, which is used as a secondary containment barrier for underground storage tanks. The sorption capacity and hydraulic conductivity of both the HDTMA-modified bentonite and low-grade kaolin were investigated and showed distribution coefficients in the sorption of benzene, toluene, ethylbenzene and xylene ranging between 45.7 and 583.7 and 57.0 and 525.1, respectively. The hydraulic conductivities were 2.53 x 10(-8) and 5.62 x 10(-8) cm/s for the HDTMA-modified bentonite and low-grade kaolin, respectively. These results suggest that HDTMA-modified low-grade kaolin could be used as a hydraulic barrier against advection migration of petroleum contaminants. Simulation of the one-dimensional transport of benzene through a liner made of either one of the compounds was also performed. These results also showed that HDTMA-modified kaolin more effectively retards the transport of benzene.

Correlates of motivation to quit smoking among alcohol dependent patients in residential treatment

PubMed Central

Martin, Rosemarie A.; Rohsenow, Damaris J.; MacKinnon, Selene Varney; Abrams, David B.; Monti, Peter M.

2006-01-01

Substance use and smoking co-occur at high rates and substance abusers smoke more and have greater difficulty quitting smoking compared to the general population. Methods of increasing smoking cessation among alcoholics are needed to improve their health. This study investigated predictors of motivation to quit smoking among patients early in residential treatment for substance abuse. The 198 alcohol dependent patients were participating is a larger smoking study at an inner-city residential substance abuse treatment program. Motivation was measured by the Contemplation Ladder. A hierarchical multiple regression was conducted to assess whether perceived barriers to smoking cessation and self-efficacy about quitting were associated with motivation to quit smoking independent of the influence of degree of tobacco involvement, substance use, and comorbid depressive symptoms. Motivation was higher with longer previous smoking abstinence, fewer barriers to quitting, and greater self-efficacy but was not influenced by smoking rate, dependence, or gender. While the combination of alcohol and drug use, alcohol and drug problem severity, and depressive symptoms predicted motivation, no one of these variables was significant. Since barriers to change and self-efficacy are potentially modifiable in treatment, these could be salient targets for intervention efforts. This could be integrated into treatment by assessing barriers and providing corrective information about consequences and methods of overcoming barriers and by providing coping skills to increase confidence in one’s ability to quit smoking. PMID:16314049

Barriers to physical activity in chronic hemodialysis patients: a single-center pilot study in an Italian dialysis facility.

PubMed

Fiaccadori, Enrico; Sabatino, Alice; Schito, Franco; Angella, Francesca; Malagoli, Martina; Tucci, Marco; Cupisti, Adamasco; Capitanini, Alessandro; Regolisti, Giuseppe

2014-01-01

In patients on chronic dialysis a sedentary lifestyle is a strong, yet potentially modifiable, predictor of mortality. The present single-center pilot study evaluated social, psychological and clinical barriers that may hinder physical activity in this population. We explored the association between barriers to physical activity and sedentarism in adult patients at a chronic dialysis facility in Parma, Italy. We used different questionnaries exploring participation in physical activity, physical functioning, patient attitudes and preferences, and barriers to physical activity perceived by either patients or dialysis doctors and nurses. We enrolled 104 patients, (67 males, 65%), mean age 69 years (79% of patients older than 60 years); median dialysis vintage 60 months (range 8-440); mean Charlson score 5.55, ADL (Activities of Daily Living) score 5.5. Ninety-two participants (88.5%) reported at least one barrier to physical activity. At multivariable analysis, after adjusting for age and sex, feeling to have too many medical problems (OR 2.99, 95% CI 1.27 to 7.07; P=0.012), chest pain (OR 10.78, 95% CI 1.28 to 90.28; P=0.029) and sadness (OR 2.59, 95% CI 1.10 to 6.09; P=0.030) were independently associated with physical inactivity. Lack of time for exercise counseling and the firm belief about low compliance/interest by the patients toward exercise were the most frequent barriers reported by doctors and nurses. We identified a number of patient-related and health personnel-related barriers to physical activity in patients on chronic dialysis. Solutions for these barriers should be addressed in future studies aimed at increasing the level of physical activity in this population. © 2014 S. Karger AG, Basel.

Polyelectrolyte/Graphene Oxide Barrier Film for Flexible OLED.

PubMed

Yang, Seung-Yeol; Park, Jongwhan; Kim, Yong-Seog

2015-10-01

Ultra-thin flexible nano-composite barrier layer consists of graphene oxide and polyelectrolyte was prepared using the layer-by-layer processing method. Microstructures of the barrier layer was optimized via modifying coating conditions and inducing chemical reactions. Although the barrier layer consists of hydrophilic polyelectrolyte was not effective in blocking the water vapor permeation, the chemical reduction of graphene oxide as well as conversion of polyelectrolyte to hydrophobic nature were very effective in reducing the permeation.

Nanoparticles of alkylglyceryl-dextran-graft-poly(lactic acid) for drug delivery to the brain: Preparation and in vitro investigation.

PubMed

Toman, Petr; Lien, Chun-Fu; Ahmad, Zeeshan; Dietrich, Susanne; Smith, James R; An, Qian; Molnár, Éva; Pilkington, Geoffrey J; Górecki, Darek C; Tsibouklis, John; Barbu, Eugen

2015-09-01

Poly(lactic acid), which has an inherent tendency to form colloidal systems of low polydispersity, and alkylglyceryl-modified dextran - a material designed to combine the non-immunogenic and stabilising properties of dextran with the demonstrated permeation enhancing ability of alkylglycerols - have been combined for the development of nanoparticulate, blood-brain barrier-permeating, non-viral vectors. To this end, dextran, that had been functionalised via treatment with epoxide precursors of alkylglycerol, was covalently linked to poly(lactic acid) using a carbodiimide cross-linker to form alkylglyceryl-modified dextran-graft-poly(lactic acid). Solvent displacement and electrospray methods allowed the formulation of these materials into nanoparticles having a unimodal size distribution profile of about 100-200nm and good stability at physiologically relevant pH (7.4). The nanoparticles were characterised in terms of hydrodynamic size (by Dynamic Light Scattering and Nanoparticle Tracking Analysis), morphology (by Scanning Electron Microscopy and Atomic Force Microscopy) and zeta potential, and their toxicity was evaluated using MTT and PrestoBlue assays. Cellular uptake was evidenced by confocal microscopy employing nanoparticles that had been loaded with the easy-to-detect Rhodamine B fluorescent marker. Transwell-model experiments employing mouse (bEnd3) and human (hCMEC/D3) brain endothelial cells revealed enhanced permeation (statistically significant for hCMEC/D3) of the fluorescent markers in the presence of the nanoparticles. Results of studies using Electric Cell Substrate Impedance Sensing suggested a transient decrease of the barrier function in an in vitro blood-brain barrier model following incubation with these nanoformulations. An in ovo study using 3-day chicken embryos indicated the absence of whole-organism acute toxicity effects. The collective in vitro data suggest that these alkylglyceryl-modified dextran-graft-poly(lactic acid) nanoparticles are promising candidates for in vivo evaluations that would test their capability to transport therapeutic actives to the brain. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Isopropyl Myristate-Modified Polyether-Urethane Coatings as Protective Barriers for Implantable Medical Devices

PubMed Central

Roohpour, Nima; Wasikiewicz, Jaroslaw M.; Moshaverinia, Alireza; Paul, Deepen; Rehman, Ihtesham U.; Vadgama, Pankaj

2009-01-01

Polyurethane films have potential applications in medicine, especially for packaging implantable medical devices. Although polyether-urethanes have superior mechanical properties and are biocompatible, achieving water resistance is still a challenge. Polyether based polyurethanes with two different molecular weights (PTMO1000, PTMO2000) were prepared from 4,4’-diphenylmethane diisocyanate and poly(tetra-methylene oxide). Polymer films were introduced using different concentrations (0.5-10 wt %) of isopropyl myristate lipid (IPM) as a non-toxic modifying agent. The physical and mechanical properties of these polymers were characterised using physical and spectroscopy techniques (FTIR, Raman, DSC, DMA, tensile testing). Water contact angle and water uptake of the membranes as a function of IPM concentration was also determined accordingly. The FTIR and Raman data indicate that IPM is dispersed in polyurethane at ≤ 2wt% and thermal analysis confirmed this miscibility to be dependent on soft segment length. Modified polymers showed increased tensile strength and failure strain as well as reduced water uptake by up to 24% at 1-2 wt% IPM.

Physical properties and biocompatibility of oligochitosan membrane film as wound dressing.

PubMed

Ujang, Zanariah; Abdul Rashid, Ahmad Hazri; Suboh, Siti Kasmarizawaty; Halim, Ahmad Sukari; Lim, Chin Keong

2014-12-30

The physical and biological characteristics of oligochitosan (O-C) film, including its barrier and mechanical properties, in vitro cytotoxicity and in vivo biocompatibility, were studied to assess its potential use as a wound dressing. Membrane films were prepared from water-soluble O-C solution blended with various concentrations of glycerol to modify the physical properties of the films. In vitro and in vivo biocompatibility evaluations were performed using primary human skin fibroblast cultures and subcutaneous implantation in a rat model, respectively. Addition of glycerol significantly influenced the barrier and mechanical properties of the films. Water absorption capacity was in the range of 80%-160%, whereas water vapor transmission rate varied from 1,180 to 1,618 g/m2 per day. Both properties increased with increasing glycerol concentration. Tensile strength decreased while elongation at break increased with the addition of glycerol. O-C films were found to be noncytotoxic to human fibroblast cultures and histological examination proved that films are biocompatible. These results indicate that the membrane film from O-C has potential application as a wound-dressing material.

Schottky Barrier Height Tuning via the Dopant Segregation Technique through Low-Temperature Microwave Annealing.

PubMed

Fu, Chaochao; Zhou, Xiangbiao; Wang, Yan; Xu, Peng; Xu, Ming; Wu, Dongping; Luo, Jun; Zhao, Chao; Zhang, Shi-Li

2016-04-27

The Schottky junction source/drain structure has great potential to replace the traditional p/n junction source/drain structure of the future ultra-scaled metal-oxide-semiconductor field effect transistors (MOSFETs), as it can form ultimately shallow junctions. However, the effective Schottky barrier height (SBH) of the Schottky junction needs to be tuned to be lower than 100 meV in order to obtain a high driving current. In this paper, microwave annealing is employed to modify the effective SBH of NiSi on Si via boron or arsenic dopant segregation. The barrier height decreased from 0.4-0.7 eV to 0.2-0.1 eV for both conduction polarities by annealing below 400 °C. Compared with the required temperature in traditional rapid thermal annealing, the temperature demanded in microwave annealing is ~60 °C lower, and the mechanisms of this observation are briefly discussed. Microwave annealing is hence of high interest to future semiconductor processing owing to its unique capability of forming the metal/semiconductor contact at a remarkably lower temperature.

Schottky Barrier Height Tuning via the Dopant Segregation Technique through Low-Temperature Microwave Annealing

PubMed Central

Fu, Chaochao; Zhou, Xiangbiao; Wang, Yan; Xu, Peng; Xu, Ming; Wu, Dongping; Luo, Jun; Zhao, Chao; Zhang, Shi-Li

2016-01-01

The Schottky junction source/drain structure has great potential to replace the traditional p/n junction source/drain structure of the future ultra-scaled metal-oxide-semiconductor field effect transistors (MOSFETs), as it can form ultimately shallow junctions. However, the effective Schottky barrier height (SBH) of the Schottky junction needs to be tuned to be lower than 100 meV in order to obtain a high driving current. In this paper, microwave annealing is employed to modify the effective SBH of NiSi on Si via boron or arsenic dopant segregation. The barrier height decreased from 0.4–0.7 eV to 0.2–0.1 eV for both conduction polarities by annealing below 400 °C. Compared with the required temperature in traditional rapid thermal annealing, the temperature demanded in microwave annealing is ~60 °C lower, and the mechanisms of this observation are briefly discussed. Microwave annealing is hence of high interest to future semiconductor processing owing to its unique capability of forming the metal/semiconductor contact at a remarkably lower temperature. PMID:28773440

Accelerated relative sea-level rise and rapid coastal erosion: Testing a causal relationship for the Louisiana barrier islands

USGS Publications Warehouse

List, J.H.; Sallenger, A.H.; Hansen, M.E.; Jaffe, B.E.

1997-01-01

The role of relative sea-level rise as a cause for the rapid erosion of Louisiana's barrier island coast is investigated through a numerical implementation of a modified Bruun rule that accounts for the low percentage of sand-sized sediment in the eroding Louisiana shoreface. Shore-normal profiles from 150 km of coastline west of the Mississippi delta are derived from bathymetric surveys conducted during the 1880s. 1930s and 1980s. An RMS difference criterion is employed to test whether an equilibrium profile form is maintained between survey years. Only about half the studied profiles meet the equilibrium Criterion this represents a significant limitation on the potential applicability of the Bruun rule. The profiles meeting the equilibrium criterion, along with measured rates of relative sea-level rise, are used to hindcast shoreline retreat rates at 37 locations within the study area. Modeled and observed shoreline retreat rates show no significant correlation. Thus in terms of the Bruun approach relative sea-level rise has no power for hindcasting (and presumably forecasting) rates of coastal erosion for the Louisiana barrier islands.

The propagation of ion-acoustic waves carrying orbital angular momentum in the electron-positron-ion plasmas

NASA Astrophysics Data System (ADS)

Mehdian, H.; Nobahar, D.; Hajisharifi, K.

2018-02-01

Ion-acoustic (IA) waves carrying orbital angular momentum (OAM) are investigated in an unmagnetized, uniform, and collisionless electron-positron-ion (e-p-i) plasma system. Employing the hydrodynamic theory, the paraxial equation in term of ion perturbed number density is derived and discussed about its Laguerre-Gaussian (LG) beam solutions. Obtaining an approximate solution for the electrostatic potential, the IA wave characteristics including helical electric field structure, energy density, and OAM density are theoretically studied. Based on the numerical analysis, the effects of positron concentration, radial and angular mode number as well as beam waist on the obtained potential profile are investigated. It is shown that the depth (height) and width of the LG potential profile wells (barriers) are considerably modify by the variation of positron concentration.

Universal time-dependent dispersion properties for diffusion in a one-dimensional critically tilted potential

NASA Astrophysics Data System (ADS)

Guérin, T.; Dean, D. S.

2017-01-01

We consider the time-dependent dispersion properties of overdamped tracer particles diffusing in a one-dimensional periodic potential under the influence of an additional constant tilting force F . The system is studied in the region where the force is close to the critical value Fc at which the barriers separating neighboring potential wells disappear. We show that, when F crosses the critical value, the shape of the mean-square displacement (MSD) curves is strongly modified. We identify a diffusive regime at intermediate-time scales with an effective diffusion coefficient which is much larger than the late-time diffusion coefficient for F >Fc , whereas for F

Mitigation methods for temporary concrete traffic barrier effects on flood water flows.

DOT National Transportation Integrated Search

2011-07-01

A combined experimental and analytical approach was put together to evaluate the hydraulic performance and : stability of TxDOT standard and modified temporary concrete traffic barriers (TCTBs) in extreme flood. : Rating curves are developed for diff...

On the interpretation of Langmuir probe data inside a spacecraft sheath

NASA Astrophysics Data System (ADS)

Olson, J.; Brenning, N.; Wahlund, J.-E.; Gunell, H.

2010-10-01

If a Langmuir probe is located inside the sheath of a negatively charged spacecraft, there is a risk that the probe characteristic is modified compared to that of a free probe in the ambient plasma. We have studied this probe-in-spacecraft-sheath problem in the parameter range of a small Langmuir probe (with radius rLP<<λD) using a modified version of the orbit motion limited (OML) probe theory. We find that the ambient electron contribution Ie(ULP) to the probe characteristic is suitably analyzed in terms of three regions of applied probe potential ULP. In region I, where the probe is negatively charged (i.e., ULPU1, there is first a transition region II in applied potential, U1

Systematic analysis of hot Yb* isotopes using the energy density formalism

NASA Astrophysics Data System (ADS)

Jain, Deepika; Sharma, Manoj K.; Rajni; Kumar, Raj; Gupta, Raj K.

2014-10-01

A systematic study of the spin-orbit density interaction potential is carried out, with spherical as well as deformed choices of nuclei, for a variety of near-symmetric and asymmetric colliding nuclei leading to various isotopes of the compound nucleus Yb*, using the semiclassical extended Thomas-Fermi formulation (ETF) of the Skyrme energy density formalism (SEDF). We observe that the spin-orbit density interaction barrier height ( and barrier position ( increase systematically with the increase in number of neutrons in both the projectile and target, for spherical systems. On allowing deformation effects with optimum orientations, the barrier-height increases by a large order of magnitude, as compared to the spherical case, in going from 156Yb* to 172Yb* nuclear systems formed via near-symmetric Ni+Mo or asymmetric O+Sm colliding nuclei, except that for the oblate-shaped nuclei, the is the highest and shifts towards a smaller (compact) interaction radius. The temperature does not change the behavior of spin-orbit density dependent ( and independent ( interaction potentials, except for some minor changes in the magnitude. The orientation degree of freedom also plays an important role in modifying the barrier characteristics and hence produces a large effect on the fusion cross section. The fusion excitation function of the compound nuclei 160, 164Yb* formed in different incoming channels, show clearly that the new forces GSkI and KDE0v1 respond better than the old SIII force. Among the first two, KDE0v1 seems to perform better. The fusion cross-sections are also predicted for a few other isotopes of Yb*.

Investigation of ultrahigh sensitivity in GaInAsP nanolaser biosensor

NASA Astrophysics Data System (ADS)

Saijo, Yoshito; Watanabe, Takumi; Hasegawa, Yu; Nishijima, Yoshiaki; Baba, Toshihiko

2018-02-01

We have developed GaInAsP semiconductor photonic crystal nanolaser biosensor and demonstrated the detection of ultralow-concentration (fM to aM) proteins and deoxyribonucleic acids (DNAs) adsorbed on the device surface. In general, this type of photonic sensors exploiting optical resonance has been considered to detect the refractive index of biomolecules via the wavelength shift. However, this principle cannot explain the detection of such ultralowconcentration. Therefore, we investigated another candidate principle, i.e., ion sensitivity. We consider such a process that 1) the electric charge of biomolecules changes the nanolaser's surface charge, 2) the Schottky barrier near the semiconductor surface is increased or decreased, 3) the distribution of photopumped carriers is modified by the barrier, 4) the refractive index of the semiconductor is changed by the carrier effects, and 5) the laser wavelength shifts. To confirm this process, we electrochemically measured the zeta and flatband potentials when charged electrolyte polymers were adsorbed in water. We clearly observed that these potentials temporally behaved consistently with that of the laser wavelength, which suggests that polymers significantly acted on the Schottky barrier. The same behaviors were also observed for the adsorption of 1 fM DNA. We consider that a limited number of charged DNA changed the surface functional group of the entire device surface. Such charge effects will be the key that achieves the ultrahigh sensitivity in the nanolaser biosensor.

Using Sound to Modify Fish Behavior at Power-Production and Water-Control Facilities: A Workshop December 12-13, 1995. Phase II: Final Report.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, Thomas J.; Popper, Arthur N.

1997-06-01

A workshop on ``Use of Sound for Fish Protection at Power-Production and Water-Control Facilities`` was held in Portland, Oregon on December 12--13, 1995. This workshop convened a 22-member panel of international experts from universities, industry, and government to share knowledge, questions, and ideas about using sound for fish guidance. Discussions involved in a broad range of indigenous migratory and resident fish species and fish-protection issues in river systems, with particular focus on the Columbia River Basin. Because the use of sound behavioral barriers for fish is very much in its infancy, the workshop was designed to address the many questionsmore » being asked by fishery managers and researchers about the feasibility and potential benefits of using sound to augment physical barriers for fish protection in the Columbia River system.« less

Attitudes and beliefs regarding cardiovascular risk factors among Bangladeshi immigrants in the US.

PubMed

Patel, Mihir; Phillips-Caesar, Erica; Boutin-Foster, Carla

2014-10-01

The US has increasingly growing Bangladeshi population, a South Asian sub-ethnic group with a high prevalence of cardiovascular disease (CVD). We conducted a qualitative study using individual in-depth interviews to explore attitudes towards and difficulties with modifying CVD related behaviors among a Bangladeshi cohort. We interviewed 55 patients before reaching data saturation. Bangladeshis discussed the meaning of health and heart disease in the context of how disease can potentially impact their ability to care for their family. Behavioral and psychological factors were discussed as the causes of CVD. Internal forces and external forces were brought up to explain difficulties addressing the causes of CVD. Bangladeshi individuals in our study were aware of CVD, but felt unable to address behavioral risk factors. They cite a combination of internal and external factors as barriers to lifestyle modification. Interventions to address these barriers must simultaneously addressing self-efficacy and work-life balance.

Attitudes and Beliefs Regarding Cardiovascular Risk Factors Among Bangladeshi Immigrants in the US

PubMed Central

Phillips-Caesar, Erica; Boutin-Foster, Carla

2015-01-01

The US has increasingly growing Bangladeshi population, a South Asian sub-ethnic group with a high prevalence of cardiovascular disease (CVD). We conducted a qualitative study using individual in-depth interviews to explore attitudes towards and difficulties with modifying CVD related behaviors among a Bangladeshi cohort. We interviewed 55 patients before reaching data saturation. Bangladeshis discussed the meaning of health and heart disease in the context of how disease can potentially impact their ability to care for their family. Behavioral and psychological factors were discussed as the causes of CVD. Internal forces and external forces were brought up to explain difficulties addressing the causes of CVD. Bangladeshi individuals in our study were aware of CVD, but felt unable to address behavioral risk factors. They cite a combination of internal and external factors as barriers to lifestyle modification. Interventions to address these barriers must simultaneously addressing self-efficacy and work-life balance. PMID:23861069

Understanding the Knowledge Gap Experienced by U.S. Safety Net Patients in Teleretinal Screening.

PubMed

George, Sheba M; Hayes, Erin Moran; Fish, Allison; Daskivich, Lauren Patty; Ogunyemi, Omolola I

2016-01-01

Safety-net patients' socioeconomic barriers interact with limited digital and health literacies to produce a "knowledge gap" that impacts the delivery of healthcare via telehealth technologies. Six focus groups (2 African- American and 4 Latino) were conducted with patients who received teleretinal screening in a U.S. urban safety-net setting. Focus groups were analyzed using a modified grounded theory methodology. Findings indicate that patients' knowledge gap is primarily produced at three points during the delivery of care: (1) exacerbation of patients' pre-existing personal barriers in the clinical setting; (2) encounters with technology during screening; and (3) lack of follow up after the visit. This knowledge gap produces confusion, potentially limiting patients' perceptions of care and their ability to manage their own care. It may be ameliorated through delivery of patient education focused on both disease pathology and specific role of telehealth technologies in disease management.

Entropic Barriers for Two-Dimensional Quantum Memories

NASA Astrophysics Data System (ADS)

Brown, Benjamin J.; Al-Shimary, Abbas; Pachos, Jiannis K.

2014-03-01

Comprehensive no-go theorems show that information encoded over local two-dimensional topologically ordered systems cannot support macroscopic energy barriers, and hence will not maintain stable quantum information at finite temperatures for macroscopic time scales. However, it is still well motivated to study low-dimensional quantum memories due to their experimental amenability. Here we introduce a grid of defect lines to Kitaev's quantum double model where different anyonic excitations carry different masses. This setting produces a complex energy landscape which entropically suppresses the diffusion of excitations that cause logical errors. We show numerically that entropically suppressed errors give rise to superexponential inverse temperature scaling and polynomial system size scaling for small system sizes over a low-temperature regime. Curiously, these entropic effects are not present below a certain low temperature. We show that we can vary the system to modify this bound and potentially extend the described effects to zero temperature.

Safety Challenges and Improvement Strategies of Ethnic Minority Construction Workers: A Case Study in Hong Kong.

PubMed

Wu, Chunlin; Luo, Xiaowei; Wang, Tao; Wang, Yue; Sapkota, Bibek

2018-04-18

Due to cultural differences, ethnic minority construction workers are more difficult to manage and more vulnerable to accidents. This study aims to identify the major barriers faced by ethnic minority workers from their own perspectives and determine potential strategies to enhance safety climate of construction projects, thus ultimately improve their safety performance. A survey with modified Nordic safety climate questionnaire was conducted in a certain sub-contractor in Hong Kong. In-depth interviews, status quo description, major challenge investigation and safety knowledge tests were carried as well. The top three most important safety challenges identified are improper stereotypes from the whole industry, lack of opportunities for job assignment, and language barriers. To improve the safety performance, employers should allocate sufficient personal protective equipment and governments should organize unannounced site visits more frequently. Besides, the higher-level management should avoid giving contradictory instructions to foremen against to the standards of supervisors.

Modifications to the modular three-dimensional finite-difference ground-water flow model used for the Columbia Plateau Regional Aquifer-System Analysis, Washington, Oregon, and Idaho

USGS Publications Warehouse

Hansen, A.J.

1993-01-01

The report documents modifications to the U.S. Geological Survey's modular three-dimensional finite-difference ground-water flow model used for a regional aquifer-system analysis of the Columbia Plateau. The report, which describes the concepts and mathematical basis for the modifications, is intended for potential users who are familiar with the original modular model. The modifications permit flow from a layer to any adjacent layer, allow the model to retain a cell of a layer that has been cut completely through by a canyon, and allow placing ground-water flow barriers on only specified branch conductances; a special version of the modified model uses a convergent grid. The report describes the data-input items that this modified model must read.

Creating a Culture of Wellness in Residency.

PubMed

Edmondson, Emma K; Kumar, Anupam A; Smith, Stephanie M

2018-04-17

Despite increased awareness and recognition of the prevalence of physician burnout and the associated risks of depression and suicide, there is a paucity of actionable guidelines for residency programs to mitigate these risks for their residents. In this Invited Commentary, the authors acknowledge that, although there are inherent barriers to resident wellness, there are numerous modifiable barriers that present opportunities for programs to enable culture change and improve resident wellbeing. The authors frame the discussion with a personal narrative written by a resident in their internal medicine program who experienced burnout, depression, and suicidality during his intern year. They aim to inspire residency programs and hospital leadership to identify and intervene upon the modifiable barriers to wellness for residents in their programs in order to shape meaningful cultural change.

The sensitization potential of sunscreen after ablative fractional skin resurfacing using modified human repeated insult patch test.

PubMed

Boonchai, Waranya; Sathaworawong, Angkana; Wongpraparut, Chanisada; Wanitphakdeedecha, Rungsima

2015-10-01

Ablative fractional skin resurfacing has become popular and proven to be useful in treating scars, photoaging and wrinkles. Although post-inflammatory hyperpigmentation (PIH) is the most common complication especially in dark-skinned patients like Asian. Several modalities have been used to overcome the PIH. To determine the sensitization potential of sunscreen applied immediately after ablative fractional skin resurfacing. Sixty volunteers were recruited. Of these 30 subjects were from previous ablative fractional skin resurfacing study who applied broad-spectrum sunscreen containing anti-inflammatory agent starting on the first day after resurfacing and another 30 non-resurfacing subjects had applied the same sunscreen on the intact skin. All subjects were patch/photopatch tested for sensitization study by using modified human repeated insult patch test (HRIPT). There were significantly higher sensitization rate of UV-filter, octocrylene and the sunscreen in resurfacing group than in non-resurfacing group. Early application of sunscreen after ablative fractional skin resurfacing has increased the incidence of sensitization potential of sunscreen. The sunscreen is recommended to start using from D3 after fractional ablative skin resurfacing to ensure the complete recovery of skin barrier and minimize the risk of sensitization.

Mechanism of H adatoms improving the O2 reduction reaction on the Zn-modified anatase TiO2 (101) surface studied by first principles calculation.

PubMed

Liu, Liangliang; Li, Chongyang; Jiang, Man; Li, Xiaodong; Huang, Xiaowei; Wang, Zhu; Jia, Yu

2018-06-05

First principles calculations were performed to cast insight into the mechanism of the improvement of O2 reduction reaction (ORR) activity by Zn and H interstitials on the anatase TiO2 (101) surface. For the Zn-modified anatase TiO2 (101) surface, both surface and subsurface Zn interstitials could contribute to O2 adsorption and dissociation, but the dissociation barriers of O2 molecules are still too high, which limits the ORR activity. After a H adatom is introduced onto the Zn-modified anatase TiO2 (101) surface, the highest energy barriers are greatly reduced compared with those of the Zn-modified surface. Meanwhile, it is observed that the dissociation barriers decrease almost linearly with the increase of the charge difference of adsorption O2 between initial and transition state configurations. Specifically, subsurface Zn and surface H interstitials facilitate O2 dissociation and subsequent oxidation reactions, and further frequency analysis shows that these dissociation processes are frequent even at the room temperature of 300 K. In a word, this work provides a theoretical support to design a high ORR activity catalyst of the TiO2 nanocrystal comparable to precious Pt catalysts.

Nature-based care opportunities and barriers in oncology contexts: a modified international e-Delphi survey.

PubMed

Blaschke, Sarah; O'Callaghan, Clare C; Schofield, Penelope

2017-10-16

To develop recommendations regarding opportunities and barriers for nature-based care in oncology contexts using a structured knowledge generation process involving relevant healthcare and design experts. Four-round modified electronic Delphi study. Oncology patients' nature-based recommendations, uncovered in preceding qualitative investigation, were included in the first round for the expert participants' consideration. Key items (opportunities and barriers) were developed using data aggregation and synthesis, followed by item prioritisation and 10-point Likert scale ranking (1=not important, 10=very important). Descriptive statistics were calculated to assess items of highest importance representing expert recommendations. Online Delphi process constituting an electronic international survey. A purposive sample of 200 potential panellists (recruitment target n=40) comprising healthcare practitioners, managers, designers, architects and researchers were invited to participate; experts were identified via research networks, snowballing and systematic literature review. 38 experts across seven countries (Australia, USA, UK, New Zealand, Canada, Denmark and Sweden) returned questionnaire 1, which determined consent and acceptance for participation. Initial response rate was 19%, and subsequent response rates were 84%, 82% and 84% for rounds 2, 3 and 4, respectively. The Delphi panel developed recommendations consisting of 10 opportunities and 10 barriers. The following opportunities were rated to be of highest importance: window views from clinical areas onto nature; outdoor settings, gardens and courtyards with easy and effortless access; and nature-based physical exercise adapted to patient requirements. Highest-rated barriers for nature-based oncology care included lack of knowledge and awareness about benefits of nature engagement and inaccessibility, not considering access requirements for the very sick and frail. Experts suggested and agreed on a set of recommendations, which represent critical considerations for the safe adoption of nature-based oncology opportunities. These findings fill a gap in understanding about helpful nature-based oncology care and may translate into oncology design and innovation. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Potential barrier classification by short-time measurement

NASA Astrophysics Data System (ADS)

Granot, Er'El; Marchewka, Avi

2006-03-01

We investigate the short-time dynamics of a delta-function potential barrier on an initially confined wave packet. There are mainly two conclusions: (A) At short times the probability density of the first particles that passed through the barrier is unaffected by it. (B) When the barrier is absorptive (i.e., its potential is imaginary) it affects the transmitted wave function at shorter times than a real potential barrier. Therefore, it is possible to distinguish between an imaginary and a real potential barrier by measuring its effect at short times only on the transmitting wave function.

Neighborhood walking among overweight and obese adults: age variations in barriers and motivators.

PubMed

Lee, Chanam; Ory, Marcia G; Yoon, Jeongjae; Forjuoh, Samuel N

2013-02-01

Walking is a popular form of physical activity that can bring many public health benefits. It can be even more beneficial to those who are currently obese or overweight. However, many barriers discourage people from walking, ranging from lack of motivation to unsafe neighborhood environments, and such barriers vary with age. This study addresses barriers and motivators to walking among overweight and obese adults, and examines their age variations. Particular emphasis was given to modifiable environmental factors as the priority intervention targets. A survey of 161 overweight and obese adults recruited from a large integrated healthcare system in central Texas provided data on walking, demographics, motivators and barriers. Descriptive statistics and correlation analysis were conducted. The respondents had a mean age of 48.4 (20-86), and were predominantly female (80.8%), non-Hispanic White (86.0%), and obese (mean BMI = 32.5). Popular environmental barriers to walking were: bad weather, inadequate lighting, no shade, unattended dogs, disconnected sidewalks, poor walking surfaces, no interesting places to walk nearby, and no benches (74.5-38.5%). Even and smooth walking surfaces and benches were more frequently reported by older adults as motivators. Proximity to recreational facilities was a stronger motivator for younger adults. Two safety related barriers, fear of injury (older adults) and traffic safety concerns (younger adults), also showed significant age differences. Overweight and obese adults experience substantial environmental barriers to walking, but many of them are modifiable. Observed age variations suggest that future interventions may be more effective if tailored to address age-specific barriers.

Determining when a set of compute nodes participating in a barrier operation on a parallel computer are ready to exit the barrier operation

DOEpatents

Blocksome, Michael A [Rochester, MN

2011-12-20

Methods, apparatus, and products are disclosed for determining when a set of compute nodes participating in a barrier operation on a parallel computer are ready to exit the barrier operation that includes, for each compute node in the set: initializing a barrier counter with no counter underflow interrupt; configuring, upon entering the barrier operation, the barrier counter with a value in dependence upon a number of compute nodes in the set; broadcasting, by a DMA engine on the compute node to each of the other compute nodes upon entering the barrier operation, a barrier control packet; receiving, by the DMA engine from each of the other compute nodes, a barrier control packet; modifying, by the DMA engine, the value for the barrier counter in dependence upon each of the received barrier control packets; exiting the barrier operation if the value for the barrier counter matches the exit value.

Delocalization via Sliding in Solid 4He: Is It Plausible?

NASA Astrophysics Data System (ADS)

Krainyukova, N. V.

2010-02-01

The modified Debye approach was used to calculate the Gibbs free energy for solid 4He and energetic profiles for different atomic displacements with respect to an equilibrium lattice. Atoms interact via the applied Aziz potential. We have found that individual atomic displacements may hardly give rise to any delocalization because of huge barriers but cooperative plane sliding is highly plausible especially in the intermediate phase, which was found to be more favorable than hcp for small cluster sizes. In the latter case the roughness of the potential profile is less than one kelvin. In some particular sliding cases the energy levels in the nearest wells nearly coincide that is a well-known precursor for the delocalization effect.

Gaseous modification of MCrAlY coatings

DOEpatents

Vance, Steven J.; Goedjen, John G.; Sabol, Stephen M.; Sloan, Kelly M.

2000-01-01

The present invention generally describes methods for modifying MCrAlY coatings by using gaseous carburization, gaseous nitriding or gaseous carbonitriding. The modified MCrAlY coatings are useful in thermal barrier coating systems, which may be used in gas turbine engines.

Effect of a direct current bias on the electrohydrodynamic performance of a surface dielectric barrier discharge actuator for airflow control

NASA Astrophysics Data System (ADS)

Yan, Huijie; Yang, Liang; Qi, Xiaohua; Ren, Chunsheng

2015-02-01

The effect of a DC bias on the electrohydrodynamics (EHD) force induced by a surface dielectric barrier AC discharge actuator for airflow control at the atmospheric pressure is investigated. The measurement of the surface potential due to charge deposition at different DC biases is carried out by using a special designed corona like discharge potential probe. From the surface potential data, the plasma electromotive force is shown not affected much by the DC biases except for some reduction of the DC bias near the exposed electrode edge for the sheath-like configuration. The total thrust is measured by an analytical balance, and an almost linear relationship to the potential voltage at the exposed electrode edge is found for the direct thrust force. The temporally averaged ionic wind characteristics are investigated by Pitot tube sensor and schlieren visualization system. It is found that the ionic wind velocity profiles with different DC biases are almost the same in the AC discharge plasma area but gradually diversified in the further downstream area as well as the upper space away from the discharge plasma area. Also, the DC bias can significantly modify the topology of the ionic wind produced by the AC discharge actuator. These results can provide an insight into how the DC biases to affect the force generation.

Methods and apparatuses for reagent delivery, reactive barrier formation, and pest control

DOEpatents

Gilmore, Tyler [Pasco, WA; Kaplan, Daniel I [Aiken, SC; Last, George [Richland, WA

2002-07-09

A reagent delivery method includes positioning reagent delivery tubes in contact with soil. The tubes can include a wall that is permeable to a soil-modifying reagent. The method further includes supplying the reagent in the tubes, diffusing the reagent through the permeable wall and into the soil, and chemically modifying a selected component of the soil using the reagent. The tubes can be in subsurface contact with soil, including groundwater, and can be placed with directional drilling equipment independent of groundwater well casings. The soil-modifying reagent includes a variety of gases, liquids, colloids, and adsorbents that may be reactive or non-reactive with soil components. The method may be used inter alia to form reactive barriers, control pests, and enhance soil nutrients for microbes and plants.

Health worker perspectives on barriers to delivery of routine tuberculosis diagnostic evaluation services in Uganda: a qualitative study to guide clinic-based interventions.

PubMed

Cattamanchi, Adithya; Miller, Cecily R; Tapley, Asa; Haguma, Priscilla; Ochom, Emmanuel; Ackerman, Sara; Davis, J Lucian; Katamba, Achilles; Handley, Margaret A

2015-01-22

Studies of the quality of tuberculosis (TB) diagnostic evaluation of patients in high burden countries have generally shown poor adherence to international or national guidelines. Health worker perspectives on barriers to improving TB diagnostic evaluation are critical for developing clinic-level interventions to improve guideline implementation. We conducted structured, in-depth interviews with staff at six district-level health centers in Uganda to elicit their perceptions regarding barriers to TB evaluation. Interviews were transcribed, coded with a standardized framework, and analyzed to identify emergent themes. We used thematic analysis to develop a logic model depicting health system and contextual barriers to recommended TB evaluation practices. To identify possible clinic-level interventions to improve TB evaluation, we categorized findings into predisposing, enabling, and reinforcing factors as described by the PRECEDE model, focusing on potentially modifiable behaviors at the clinic-level. We interviewed 22 health center staff between February 2010 and November 2011. Participants identified key health system barriers hindering TB evaluation, including: stock-outs of drugs/supplies, inadequate space and infrastructure, lack of training, high workload, low staff motivation, and poor coordination of health center services. Contextual barrier challenges to TB evaluation were also reported, including the time and costs borne by patients to seek and complete TB evaluation, poor health literacy, and stigma against patients with TB. These contextual barriers interacted with health system barriers to contribute to sub-standard TB evaluation. Examples of intervention strategies that could address these barriers and are related to PRECEDE model components include: assigned mentors/peer coaching for new staff (targets predisposing factor of low motivation and need for support to conduct job duties); facilitated workshops to implement same day microscopy (targets enabling factor of patient barriers to completing TB evaluation), and recognition/incentives for good TB screening practices (targets low motivation and self-efficacy). Our findings suggest that health system and contextual barriers work together to impede TB diagnosis at health centers and, if not addressed, could hinder TB case detection efforts. Qualitative research that improves understanding of the barriers facing TB providers is critical to developing targeted interventions to improve TB care.

Universal time-dependent dispersion properties for diffusion in a one-dimensional critically tilted potential.

PubMed

Guérin, T; Dean, D S

2017-01-01

We consider the time-dependent dispersion properties of overdamped tracer particles diffusing in a one-dimensional periodic potential under the influence of an additional constant tilting force F. The system is studied in the region where the force is close to the critical value F_{c} at which the barriers separating neighboring potential wells disappear. We show that, when F crosses the critical value, the shape of the mean-square displacement (MSD) curves is strongly modified. We identify a diffusive regime at intermediate-time scales with an effective diffusion coefficient which is much larger than the late-time diffusion coefficient for F>F_{c}, whereas for F

Thorough exploration of complex environments with a space-based potential field

NASA Astrophysics Data System (ADS)

Kenealy, Alina; Primiano, Nicholas; Keyes, Alex; Lyons, Damian M.

2015-01-01

Robotic exploration, for the purposes of search and rescue or explosive device detection, can be improved by using a team of multiple robots. Potential field navigation methods offer natural and efficient distributed exploration algorithms in which team members are mutually repelled to spread out and cover the area efficiently. However, they also suffer from field minima issues. Liu and Lyons proposed a Space-Based Potential Field (SBPF) algorithm that disperses robots efficiently and also ensures they are driven in a distributed fashion to cover complex geometry. In this paper, the approach is modified to handle two problems with the original SBPF method: fast exploration of enclosed spaces, and fast navigation of convex obstacles. Firstly, a "gate-sensing" function was implemented. The function draws the robot to narrow openings, such as doors or corridors that it might otherwise pass by, to ensure every room can be explored. Secondly, an improved obstacle field conveyor belt function was developed which allows the robot to avoid walls and barriers while using their surface as a motion guide to avoid being trapped. Simulation results, where the modified SPBF program controls the MobileSim Pioneer 3-AT simulator program, are presented for a selection of maps that capture difficult to explore geometries. Physical robot results are also presented, where a team of Pioneer 3-AT robots is controlled by the modified SBPF program. Data collected prior to the improvements, new simulation results, and robot experiments are presented as evidence of performance improvements.

Enablers and barriers to using two-way information technology in the management of adults with diabetes: A descriptive systematic review.

PubMed

Macdonald, Emma M; Perrin, Byron M; Kingsley, Michael Ic

2017-01-01

Background This systematic review aimed to explore the enablers and barriers faced by adults with diabetes using two-way information communication technologies to support diabetes self-management. Methods Relevant literature was obtained from five databases using search strategies combining four major constructs: adults with diabetes, biomedical technology, communication technology and patient utilisation. Results Of 8430 unique articles identified, 48 were included for review. Risk of bias was assessed using either the Newcastle-Ottowa or Cochrane risk of bias assessment tools. Seventy-one percent of studies were of cohort design with the majority of studies assessed at high or unclear risk of bias. Consistently identified barriers included poorly designed interfaces requiring manual data entry and systems that lacked functionalities valued by patients. Commonly cited enablers included access to reliable technology, highly automated data entry and transmission, graphical display of data with immediate feedback, and supportive health care professionals and family members. Conclusions People with diabetes face a number of potentially modifiable barriers in using technology to support their diabetes management. In order to address these barriers, end users should be consulted in the design process and consideration given to theories of technology adoption to inform design and implementation. Systems should be designed to solve clinical or behavioural problems that are identified by patients as priorities. Technology should be as automated, streamlined, mobile, low cost and integrated as possible in order to limit the burden of usage for the patient and maximise clinical usefulness.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Liwen, E-mail: lwcheng@yzu.edu.cn; Wu, Shudong; Xia, Changquan

In this work, graded barrier InGaN light-emitting diodes with increasing indium composition barriers are proposed and investigated numerically. When the conventional GaN barriers are replaced by this unique graded InGaN barrier design, the forward voltage at 100 mA is reduced from 3.32 V to 3.27 V, and the efficiency droop is improved from 46.6% to 7.5%. The simulation results observed in this work indicate that these improvements can be attributed to increased electron confinement and enhanced hole injection efficiency caused by the modified energy band diagram.

How Landscape Plants Modify the Environment.

ERIC Educational Resources Information Center

Blankenship, Sylvia; Wise, Kevin

1993-01-01

Presents three experiments that provide examples of how plants modify their surroundings and create microenvironments. Examples demonstrate (1) how types of ground cover influence water quality; (2) how plants can create a thermal microenvironment; and (3) how plants can serve as barriers to wind. (MDH)

Decay analysis of compound nuclei with masses A ≈30 - 200 formed in reactions involving loosely bound projectiles

NASA Astrophysics Data System (ADS)

Kaur, Mandeep; Singh, BirBikram; Sharma, Manoj K.; Gupta, Raj K.

2015-08-01

The dynamics of compound nuclei formed in the reactions using loosely bound projectiles are analyzed within the framework of the dynamical cluster-decay model (DCM) of Gupta and Collaborators. We have considered the reactions with neutron-rich and neutron-deficient projectiles, respectively, as 7Li , 9Be , and 7Be , on various targets at three different Elab energies, forming compound nuclei in the mass region A ˜30 - 200. For these reactions, the contributions of light-particle (LP, A ≤4 ) cross sections σLP, energetically favored intermediate-mass-fragment (IMF, 5 ≤A2≤20 ) cross sections σIMF, as well as the fusion-fission ff cross sections σff constitute the σfus(=σLP+σIMF+σff ), i.e., the contributions of the emitted LPs, IMFs, and ff fragments are added for all the angular momenta up to the ℓmax value for the respective reactions. Interestingly, we find that the empirically fitted neck-length parameter Δ Remp , the only parameter of the DCM, is uniquely fixed to address σfus for all the reactions having the same loosely bound projectile at a chosen incident laboratory energy. It may be noted that, in DCM, the dynamical collective mass motion of preformed LPs, IMFs, and ff fragments or clusters, through the modified interaction potential barrier, are treated on parallel footing. The modification of the barrier is due to nonzero Δ Remp , and the values of corresponding modified interaction-barrier heights Δ VBemp for such reactions are almost of the same order, specifically at the respective ℓmax value.

Probiotic E. coli Nissle 1917 biofilms on silicone substrates for bacterial interference against pathogen colonization.

PubMed

Chen, Quan; Zhu, Zhiling; Wang, Jun; Lopez, Analette I; Li, Siheng; Kumar, Amit; Yu, Fei; Chen, Haoqing; Cai, Chengzhi; Zhang, Lijuan

2017-03-01

Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, a non-pathogenic bacterial biofilm is used as a live, protective barrier to fence off pathogen colonization. In this work, biofilms formed by probiotic Escherichia coli strain Nissle 1917 (EcN) are investigated for their potential for long-term bacterial interference against infections associated with silicone-based urinary catheters and indwelling catheters used in the digestive system, such as feeding tubes and voice prostheses. We have shown that EcN can form stable biofilms on silicone substrates, particularly those modified with a biphenyl mannoside derivative. These biofilms greatly reduced the colonization by pathogenic Enterococcus faecalis in Lysogeny broth (LB) for 11days. Bacterial interference is an alternative strategy to fight against device-associated bacterial infections. Pursuing this strategy, we use non-pathogenic bacteria to form a biofilm that serves as a live, protective barrier against pathogen colonization. Herein, we report the first use of preformed probiotic E. coli Nissle 1917 biofilms on the mannoside-presenting silicone substrates to prevent pathogen colonization. The biofilms serve as a live, protective barrier to fence off the pathogens, whereas current antimicrobial/antifouling coatings are subjected to gradual coverage by the biomass from the rapidly growing pathogens in a high-nutrient environment. It should be noted that E. coli Nissle 1917 is commercially available and has been used in many clinical trials. We also demonstrated that this probiotic strain performed significantly better than the non-commercial, genetically modified E. coli strain that we previously reported. Copyright © 2017 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Directional mass transport in an atmospheric pressure surface barrier discharge.

PubMed

Dickenson, A; Morabit, Y; Hasan, M I; Walsh, J L

2017-10-25

In an atmospheric pressure surface barrier discharge the inherent physical separation between the plasma generation region and downstream point of application reduces the flux of reactive chemical species reaching the sample, potentially limiting application efficacy. This contribution explores the impact of manipulating the phase angle of the applied voltage to exert a level of control over the electrohydrodynamic forces generated by the plasma. As these forces produce a convective flow which is the primary mechanism of species transport, the technique facilitates the targeted delivery of reactive species to a downstream point without compromising the underpinning species generation mechanisms. Particle Imaging Velocimetry measurements are used to demonstrate that a phase shift between sinusoidal voltages applied to adjacent electrodes in a surface barrier discharge results in a significant deviation in the direction of the plasma induced gas flow. Using a two-dimensional numerical air plasma model, it is shown that the phase shift impacts the spatial distribution of the deposited charge on the dielectric surface between the adjacent electrodes. The modified surface charge distribution reduces the propagation length of the discharge ignited on the lagging electrode, causing an imbalance in the generated forces and consequently a variation in the direction of the resulting gas flow.

Self-learning kinetic Monte Carlo simulations of Al diffusion in Mg

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nandipati, Giridhar; Govind, Niranjan; Andersen, Amity

2016-03-16

Atomistic on-lattice self-learning kinetic Monte Carlo (SLKMC) method was used to examine the vacancy-mediated diffusion of an Al atom in pure hcp Mg. Local atomic environment dependent activation barriers for vacancy-atom exchange processes were calculated on-the-fly using climbing image nudged-elastic band method (CI-NEB) and using a Mg-Al binary modified embedded-atom method (MEAM) interatomic potential. Diffusivities of vacancy and Al atom in pure Mg were obtained from SLKMC simulations and are compared with values available in the literature that are obtained from experiments and first-principle calculations. Al Diffusivities obtained from SLKMC simulations are lower, due to larger activation barriers and lowermore » diffusivity prefactors, than those available in the literature but have same order of magnitude. We present all vacancy-Mg and vacancy-Al atom exchange processes and their activation barriers that were identified in SLKMC simulations. We will describe a simple mapping scheme to map a hcp lattice on to a simple cubic lattice that would enable hcp lattices to be simulated in an on-lattice KMC framework. We also present the pattern recognition scheme used in SLKMC simulations.« less

Surface modification of polyvinyl alcohol/malonic acid nanofibers by gaseous dielectric barrier discharge plasma for glucose oxidase immobilization

NASA Astrophysics Data System (ADS)

Afshari, Esmail; Mazinani, Saeedeh; Ranaei-Siadat, Seyed-Omid; Ghomi, Hamid

2016-11-01

Polymeric nanofiber prepares a suitable situation for enzyme immobilization for variety of applications. In this research, we have fabricated polyvinyl alcohol (PVA)/malonic acid nanofibers using electrospinning. After fabrication of nanofibers, the effect of air, nitrogen, CO2, and argon DBD (dielectric barrier discharge) plasmas on PVA/malonic acid nanofibers were analysed. Among them, air plasma had the most significant effect on glucose oxidase (GOx) immobilization. Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrum analysis and X-ray photoelectron spectroscopy (XPS) results revealed that in case of air plasma modified nanofibers, the carboxyl groups on the surface are increased. The scanning electron microscopy (SEM) images showed that, after GOx immobilization, the modified nanofibers with plasma has retained its nanofiber structure. Finally, we analysed reusability and storage stability of GOx immobilized on plasma modified and unmodified nanofibers. The results were more satisfactory for modified nanofibers with respect to unmodified ones.

What is killing? People's knowledge about coronary heart disease, attitude towards prevention and main risk reduction barriers in Ismailia, Egypt (descriptive cross-sectional study).

PubMed

Seef, Sameh; Jeppsson, Anders; Stafström, Martin

2013-01-01

Cardiovascular diseases are a public health concern everywhere, especially ischemic or coronary heart diseases (CHD) which are on top of causes list of mortality and morbidity in both genders globally. From which nearly 80% can be because of modifiable risks. In Egypt, there is a lack of studies on the knowledge of people about coronary heart diseases and its modifiable risks. So, this research reported here we designed to measure the dimensions of peoples knowledge about CHD and their attitude towards prevention, and to identify the main risk reduction barriers. By using comprehensive cross-sectional, descriptive research design, all adult individuals attending the family health clinic at Suez Canal University Hospital were eligible for inclusion with total number 125 participants. An interview questionnaire designed and used to collect data. The study revealed that (10.4%) of participants had a history of CHD, and (7.2%) had a family history of CHD. 79.2% Had a satisfactory total knowledge about CHD, and (94.4%) had a positive total attitude towards prevention. Risk reduction barriers as a medical setting barriers were (24%), patient related barriers were (22.4%). Community-societal barriers were almost the same as knowledge barriers which were around (16%). At last the systemic-organizational barriers were (9.6%). The findings settled that, total knowledge about CHD was satisfactory but lower than the level total of attitude. More effort the health system needs to improve the settings and engage patients in their plans and breaking related barriers, with development of health education programs based on needs assessment. Further studies we recommend to explore the reasons and follow up the changes.

Barriers and facilitators to disease-modifying antirheumatic drug use in patients with inflammatory rheumatic diseases: a qualitative theory-based study.

PubMed

Voshaar, Marieke; Vriezekolk, Johanna; van Dulmen, Sandra; van den Bemt, Bart; van de Laar, Mart

2016-10-21

Although disease-modifying anti-rheumatic drugs (DMARDs) are the cornerstone of treatment for inflammatory rheumatic diseases, medication adherence to DMARDs is often suboptimal. Effective interventions to improve adherence to DMARDs are lacking, and new targets are needed to improve adherence. The aim of the present study was to explore patients' barriers and facilitators of optimal DMARD use. These factors might be used as targets for adherence interventions. In a mixed method study design, patients (n = 120) with inflammatory arthritis (IA) completed a questionnaire based on an existing adapted Theoretical Domains Framework (TDF) to identify facilitators and barriers of DMARD use. A subgroup of these patients (n = 21) participated in focus groups to provide insights into their facilitators and barriers. The answers to the questionnaires and responses of the focus groups were thematically coded by three researchers independently and subsequently categorized. The barriers and facilitators that were reported by IA patients presented large inter-individual variations. The identified barriers and facilitators could be captured in the following domains based on an adapted TDF: (i) knowledge, (ii) emotions, (iii) attention, memory, and decision processes, (iv) social influences, (v) beliefs about capability, (vi) beliefs about consequences, (vii) motivation and goals, (viii) goal conflict, (ix) environmental context and resources, and (x) skills. Patients with IA have a variety of barriers and facilitators with regard to their DMARD use. All of these barriers and facilitators could be categorized into adapted domains of the TDF. Interventions that address individual facilitators and barriers, based on capability, opportunity, and motivation, are needed to develop strategies for medication adherence that are tailored to individual patient needs.

A seesaw-type approach for enhancing nonlinear energy harvesting

NASA Astrophysics Data System (ADS)

Deng, Huaxia; Wang, Zhemin; Du, Yu; Zhang, Jin; Ma, Mengchao; Zhong, Xiang

2018-05-01

Harvesting sustainable mechanical energy is the ultimate objective of nonlinear energy harvesters. However, overcoming potential barriers, especially without the use of extra excitations, poses a great challenge for the development of nonlinear generators. In contrast to the existing methods, which typically modify the barrier height or utilize additional excitations, this letter proposes a seesaw-type approach to facilitate escape from potential wells by transfer of internal energy, even under low-intensity excitation. This approach is adopted in the design of a seesaw-type nonlinear piezoelectric energy harvester and the energy transfer process is analyzed by deriving expressions for the energy to reveal the working mechanism. Comparison experiments demonstrate that this approach improves energy harvesting in terms of an increase in the working frequency bandwidth by a factor of 60.14 and an increase in the maximum output voltage by a factor of 5.1. Moreover, the output power is increased by a factor of 51.3, which indicates that this approach significantly improves energy collection efficiency. This seesaw-type approach provides a welcome boost to the development of renewable energy collection methods by improving the efficiency of harvesting of low-intensity ambient mechanical energy.

Enhancing antimicrobial activity of TiO2/Ti by torularhodin bioinspired surface modification.

PubMed

Ungureanu, Camelia; Dumitriu, Cristina; Popescu, Simona; Enculescu, Monica; Tofan, Vlad; Popescu, Marian; Pirvu, Cristian

2016-02-01

Implant-associated infections are a major cause of morbidity and mortality. This study was performed using titanium samples coated by anodization with a titanium dioxide (TiO2) shielded nanotube layer. TiO2/Ti surface was modified by simple immersion in torularhodin solution and by using a mussel-inspired method based on polydopamine as bio adhesive for torularhodin immobilization. SEM analysis revealed tubular microstructures of torularhodin and the PDA ability to function as a catchy anchor between torularhodin and TiO2 surface. Corrosion resistance was associated with TiO2 barrier oxide layer and nano-organized oxide layer and the torularhodin surface modification does not bring significant changes in resistance of the oxide layer. Our results demonstrated that the torularhodin modified TiO2/Ti surface could effectively prevent adhesion and proliferation of Escherichia coli, Staphylococcus aureus, Enterococcus faecalis, Bacillus subtilis, and Pseudomonas aeruginosa. The new modified titanium surface showed good biocompatibility and well-behaved haemocompatibility. This biomaterial with enhanced antimicrobial activity holds great potential for future biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

Barriers, Benefits, and Behaviors Related to Breakfast Consumption among Rural Adolescents

ERIC Educational Resources Information Center

Hearst, Mary O.; Shanafelt, Amy; Wang, Qi; Leduc, Robert; Nanney, Marilyn S.

2016-01-01

Background: We sought to determine if perceived barriers, benefits, and modifiable behaviors support or interfere with breakfast consumption in a racially and economically diverse rural high school population. Methods: The participants were 832 Minnesota adolescents from 16 rural high schools. We used baseline data from a group randomized trial…

Dielectric barrier discharge atmospheric cold plasma inhibits Escherichia coli 0157:H7, Salmonella, Listeria monocytogenes, and Tulane virus in Romaine lettuce

USDA-ARS?s Scientific Manuscript database

The present study investigated the effects of dielectric barrier discharge atmospheric cold plasma (DACP) treatment on the inactivation of Escherichia coli O157:H7, Salmonella, Listeria monocytogenes, and Tulane virus (TV) on Romaine lettuce, assessing the influences of moisture vaporization, modifi...

Numerical investigation of dielectric barrier discharges

NASA Astrophysics Data System (ADS)

Li, Jing

1997-12-01

A dielectric barrier discharge (DBD) is a transient discharge occurring between two electrodes in coaxial or planar arrangements separated by one or two layers of dielectric material. The charge accumulated on the dielectric barrier generates a field in a direction opposite to the applied field. The discharge is quenched before an arc is formed. It is one of the few non-thermal discharges that operates at atmospheric pressure and has the potential for use in pollution control. In this work, a numerical model of the dielectric barrier discharge is developed, along with the numerical approach. Adaptive grids based on the charge distribution is used. A self-consistent method is used to solve for the electric field and charge densities. The Successive Overrelaxation (SOR) method in a non-uniform grid spacing is used to solve the Poisson's equation in the cylindrically-symmetric coordinate. The Flux Corrected Transport (FCT) method is modified to solve the continuity equations in the non-uniform grid spacing. Parametric studies of dielectric barrier discharges are conducted. General characteristics of dielectric barrier discharges in both anode-directed and cathode-directed streamer are studied. Effects of the dielectric capacitance, the applied field, the resistance in external circuit and the type of gases (O2, air, N2) are investigated. We conclude that the SOR method in an adaptive grid spacing for the solution of the Poisson's equation in the cylindrically-symmetric coordinate is convergent and effective. The dielectric capacitance has little effect on the g-factor of radical production, but it determines the strength of the dielectric barrier discharge. The applied field and the type of gases used have a significant role on the current peak, current pulse duration and radical generation efficiency, discharge strength, and microstreamer radius, whereas the external series resistance has very little effect on the streamer properties. The results are helpful in further understanding the ozone generation and pollution control process in a dielectric barrier discharge.

Generation of dark solitons and their instability dynamics in two-dimensional condensates

NASA Astrophysics Data System (ADS)

Verma, Gunjan; Rapol, Umakant D.; Nath, Rejish

2017-04-01

We analyze numerically the formation and the subsequent dynamics of two-dimensional matter wave dark solitons in a Thomas-Fermi rubidium condensate using various techniques. An initially imprinted sharp phase gradient leads to the dynamical formation of a stationary soliton as well as very shallow gray solitons, whereas a smooth gradient only creates gray solitons. The depth and hence, the velocity of the soliton is provided by the spatial width of the phase gradient, and it also strongly influences the snake-instability dynamics of the two-dimensional solitons. The vortex dipoles stemming from the unstable soliton exhibit rich dynamics. Notably, the annihilation of a vortex dipole via a transient dark lump or a vortexonium state, the exchange of vortices between either a pair of vortex dipoles or a vortex dipole and a single vortex, and so on. For sufficiently large width of the initial phase gradient, the solitons may decay directly into vortexoniums instead of vortex pairs, and also the decay rate is augmented. Later, we discuss alternative techniques to generate dark solitons, which involve a Gaussian potential barrier and time-dependent interactions, both linear and periodic. The properties of the solitons can be controlled by tuning the amplitude or the width of the potential barrier. In the linear case, the number of solitons and their depths are determined by the quench time of the interactions. For the periodic modulation, a transient soliton lattice emerges with its periodicity depending on the modulation frequency, through a wave number selection governed by the local Bogoliubov spectrum. Interestingly, for sufficiently low barrier potential, both Faraday pattern and soliton lattice coexist. The snake instability dynamics of the soliton lattice is characteristically modified if the Faraday pattern is present.

Schooling Increases Risk Exposure for Fish Navigating Past Artificial Barriers

PubMed Central

Lemasson, Bertrand H.; Haefner, James W.; Bowen, Mark D.

2014-01-01

Artificial barriers have become ubiquitous features in freshwater ecosystems and they can significantly impact a region's biodiversity. Assessing the risk faced by fish forced to navigate their way around artificial barriers is largely based on assays of individual swimming behavior. However, social interactions can significantly influence fish movement patterns and alter their risk exposure. Using an experimental flume, we assessed the effects of social interactions on the amount of time required for juvenile palmetto bass (Morone chrysops × M. saxatilis) to navigate downstream past an artificial barrier. Fish were released either individually or in groups into the flume using flow conditions that approached the limit of their expected swimming stamina. We compared fish swimming behaviors under solitary and schooling conditions and measured risk as the time individuals spent exposed to the barrier. Solitary fish generally turned with the current and moved quickly downstream past the barrier, while fish in groups swam against the current and displayed a 23-fold increase in exposure time. Solitary individuals also showed greater signs of skittish behavior than those released in groups, which was reflected by larger changes in their accelerations and turning profiles. While groups displayed fission-fusion dynamics, inter-individual positions were highly structured and remained steady over time. These spatial patterns align with theoretical positions necessary to reduce swimming exertion through either wake capturing or velocity sheltering, but diverge from any potential gains from channeling effects between adjacent neighbors. We conclude that isolated performance trials and projections based on individual behaviors can lead to erroneous predictions of risk exposure along engineered structures. Our results also suggest that risk perception and behavior may be more important than a fish's swimming stamina in artificially modified systems. PMID:25268736

Schooling increases risk exposure for fish navigating past artificial barriers.

PubMed

Lemasson, Bertrand H; Haefner, James W; Bowen, Mark D

2014-01-01

Artificial barriers have become ubiquitous features in freshwater ecosystems and they can significantly impact a region's biodiversity. Assessing the risk faced by fish forced to navigate their way around artificial barriers is largely based on assays of individual swimming behavior. However, social interactions can significantly influence fish movement patterns and alter their risk exposure. Using an experimental flume, we assessed the effects of social interactions on the amount of time required for juvenile palmetto bass (Morone chrysops × M. saxatilis) to navigate downstream past an artificial barrier. Fish were released either individually or in groups into the flume using flow conditions that approached the limit of their expected swimming stamina. We compared fish swimming behaviors under solitary and schooling conditions and measured risk as the time individuals spent exposed to the barrier. Solitary fish generally turned with the current and moved quickly downstream past the barrier, while fish in groups swam against the current and displayed a 23-fold increase in exposure time. Solitary individuals also showed greater signs of skittish behavior than those released in groups, which was reflected by larger changes in their accelerations and turning profiles. While groups displayed fission-fusion dynamics, inter-individual positions were highly structured and remained steady over time. These spatial patterns align with theoretical positions necessary to reduce swimming exertion through either wake capturing or velocity sheltering, but diverge from any potential gains from channeling effects between adjacent neighbors. We conclude that isolated performance trials and projections based on individual behaviors can lead to erroneous predictions of risk exposure along engineered structures. Our results also suggest that risk perception and behavior may be more important than a fish's swimming stamina in artificially modified systems.

A Qualitative Study of Doctors of Chiropractic in a Nova Scotian Practice-based Research Network: Barriers and Facilitators to the Screening and Management of Psychosocial Factors for Patients With Low Back Pain.

PubMed

Stilwell, Peter; Hayden, Jill A; Des Rosiers, Piaf; Harman, Katherine; French, Simon D; Curran, Janet A; Hefford, Warren

2018-01-01

This study aimed to assess chiropractors' awareness of clinical practice guidelines for low back pain and to identify barriers and facilitators to the screening and management of psychosocial factors in patients with low back pain. This qualitative study used semi-structured interviews informed by the Theoretical Domains Framework with 10 Nova Scotian chiropractors who were members of a practice-based research network. The participants correctly identified what the guidelines generally recommend and described the value of psychosocial factors; however, none of the participants could name specific clinical practice guidelines for low back pain. We identified 6 themes related to barriers and facilitators for chiropractors screening and managing psychosocial factors. The themes revolved around the participants' desire to fulfill patients' anatomy-focused treatment expectations and a perceived lack of training for managing psychosocial factors. Participants had concerns about going beyond the chiropractic scope of practice, and they perceived a lack of practical psychosocial screening and management resources. Social factors, such as the influence of other health care practitioners, were reported as both barriers and facilitators to screening and managing psychosocial factors. The participants in this study reported that they mostly treated with an anatomical and biomechanical focus and that they did not always address psychosocial factors identified in their patients with low back pain. Although these findings are limited to Nova Scotian chiropractors, the barriers identified appeared to be potentially modifiable and could be considered in other groups. Low-cost interventions, such as continuing education using evidence-informed behavior change techniques, could be considered to address these barriers. Copyright © 2017. Published by Elsevier Inc.

Barriers to the use of Information and Communication Technology by occupational therapists working in a rural area of New South Wales, Australia.

PubMed

Chedid, Rebecca Jean; Dew, Angela; Veitch, Craig

2013-06-01

This qualitative study formed part of a large-scale, multi-phase study into the delivery of therapy services to people with a disability, living in one rural area of New South Wales, Australia. The study's purpose was to identify the impact of Information and Communication Technology on the workforce practices of occupational therapists' working in a rural area of New South Wales. Individual semi-structured telephone interviews were conducted with 13 occupational therapists working in disability, health and private practice in a rural area of New South Wales. Participants were asked about access to, skills and limitations of using Information and Communication Technology. A modified grounded theory approach, based on thematic analysis and constant comparison, was used to analyse the interview transcripts. This study found widespread use of technology by rurally based occupational therapists working in the disability sector in New South Wales. However, Information and Communication Technology was primarily used for client contact, professional development and professional networking rather than therapy provision. The study identified individual, workplace and community barriers to greater uptake of Information and Communication Technology by this group. The individual barriers included: age cohort, knowledge and personal preferences. The workplace barriers included: support and training and availability of resources. The community barriers included: infrastructure and perceptions of clients' acceptance. The potential exists for Information and Communication Technology to supplement face-to-face therapy provision, enhance access to professional development and reduce professional isolation thereby addressing the rural challenges of large distances, travel times and geographic isolation. To overcome these challenges, individual, workplace and community Information and Communication Technology barriers should be addressed concurrently. © 2012 The Authors Australian Occupational Therapy Journal © 2012 Occupational Therapy Australia.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Kuo -Ling; Mehrotra, Sanjay

We present a homogeneous algorithm equipped with a modified potential function for the monotone complementarity problem. We show that this potential function is reduced by at least a constant amount if a scaled Lipschitz condition (SLC) is satisfied. A practical algorithm based on this potential function is implemented in a software package named iOptimize. The implementation in iOptimize maintains global linear and polynomial time convergence properties, while achieving practical performance. It either successfully solves the problem, or concludes that the SLC is not satisfied. When compared with the mature software package MOSEK (barrier solver version 6.0.0.106), iOptimize solves convex quadraticmore » programming problems, convex quadratically constrained quadratic programming problems, and general convex programming problems in fewer iterations. Moreover, several problems for which MOSEK fails are solved to optimality. In addition, we also find that iOptimize detects infeasibility more reliably than the general nonlinear solvers Ipopt (version 3.9.2) and Knitro (version 8.0).« less

Prebiotics: A Potential Treatment Strategy for the Chemotherapy-damaged Gut?

PubMed

Wang, Hanru; Geier, Mark S; Howarth, Gordon S

2016-01-01

Mucositis, characterized by ulcerative lesions along the alimentary tract, is a common consequence of many chemotherapy regimens. Chemotherapy negatively disrupts the intestinal microbiota, resulting in increased numbers of potentially pathogenic bacteria, such as Clostridia and Enterobacteriaceae, and decreased numbers of "beneficial" bacteria, such as Lactobacilli and Bifidobacteria. Agents capable of restoring homeostasis in the bowel microbiota could, therefore, be applicable to mucositis. Prebiotics are indigestible compounds, commonly oligosaccharides, that seek to reverse chemotherapy-induced intestinal dysbiosis through selective colonization of the intestinal microbiota by probiotic bacteria. In addition, evidence is emerging that certain prebiotics contribute to nutrient digestibility and absorption, modulate intestinal barrier function through effects on mucin expression, and also modify mucosal immune responses, possibly via inflammasome-mediated processes. This review examines the known mechanisms of prebiotic action, and explores their potential for reducing the severity of chemotherapy-induced mucositis in the intestine.

The choroid plexus: function, pathology and therapeutic potential of its transplantation.

PubMed

Emerich, Dwaine F; Vasconcellos, Alfred V; Elliott, Robert B; Skinner, Stephen J M; Borlongan, Cesario V

2004-08-01

The choroid plexus (CP) produces cerebrospinal fluid (CSF) and forms the blood-CSF barrier. However, the CP may have additional functions in the CNS beyond these traditional roles. Preclinical and clinical studies in ageing and neurodegeneration demonstrate anatomical and physiological changes in CP, suggesting roles in normal and pathological conditions and potentially endogenous repair processes following trauma. One of the broadest functions of the CP is establishing and maintaining the extracellular milieu throughout the brain and spinal cord, in part by secreting numerous growth factors into the CSF. The endogenous secretion of growth factors raises the possibility that transplantable CP might enable delivery of these molecules to the brain, while avoiding the conventional molecular and genetic alterations associated with modifying cells to secrete selected products. This review describes some of the anatomical and functional changes of CP in ageing and neurodegeneration, and recent demonstrations of the therapeutic potential of transplanted CP for neural trauma.

Myristic Acid-Modified DA7R Peptide for Whole-Process Glioma-Targeted Drug Delivery.

PubMed

Ying, Man; Wang, Songli; Zhang, Mingfei; Wang, Ruifeng; Zhu, Hangchang; Ruan, Huitong; Ran, Danni; Chai, Zhilan; Wang, Xiaoyi; Lu, Weiyue

2018-06-13

The clinical treatment of aggressive glioma has been a great challenge, mainly because of the complexity of the glioma microenvironment and the existence of the blood-brain tumor barrier (BBTB)/blood-brain barrier (BBB), which severely hampers the effective accumulation of most therapeutic agents in the glioma region. Additionally, vasculogenic mimicry (VM), angiogenesis, and glioma stem cells (GSC) in malignant glioma also lead to the failure of clinical therapy. To address the aforementioned issues, a whole-process glioma-targeted drug delivery strategy was proposed. The D A7R peptide has effective BBTB-penetrating and notable glioma-, angiogenesis-, and VM-targeting abilities. Herein, we designed a myristic acid modified D A7R ligand (MC- D A7R), which combines tumor-homing D A7R with BBB-penetrable MC. MC- D A7R was then immobilized to PEGylated liposomes (MC- D A7R-LS) to form a whole-process glioma-targeting system. MC- D A7R-LS exhibited exceptional internalization in glioma, tumor neovascular, and brain capillary endothelial cells. Enhanced BBTB- and BBB-traversing efficiencies were also observed on MC- D A7R-LS. Ex vivo imaging on brain tumors also demonstrated the feasibility of MC- D A7R-LS in intracranial glioma-homing, whereas the immunofluorescence studies demonstrated its GSC and angiogenesis homing. Furthermore, doxorubicin-loaded MC- D A7R-LS accomplished a remarkable therapeutic outcome, as a result of a synergistic improvement on the glioma microenvironment. Our study highlights the potential of the MC-modified D A7R peptide as a great candidate for the whole-process glioma-targeted drug delivery.

Modified Pressure Imaging for Egg Crack Detection and Resulting Egg Quality

USDA-ARS?s Scientific Manuscript database

Cracks in the shell surface impair the primary barrier for external microbial contamination of the egg. Microcracks are very small cracks in the shell surface which are difficult to detect by human graders. New technology has been developed which utilizes modified pressure and imaging to detect mi...

Modified Interior Distance Functions (Theory and Methods)

NASA Technical Reports Server (NTRS)

Polyak, Roman A.

1995-01-01

In this paper we introduced and developed the theory of Modified Interior Distance Functions (MIDF's). The MIDF is a Classical Lagrangian (CL) for a constrained optimization problem which is equivalent to the initial one and can be obtained from the latter by monotone transformation both the objective function and constraints. In contrast to the Interior Distance Functions (IDF's), which played a fundamental role in Interior Point Methods (IPM's), the MIDF's are defined on an extended feasible set and along with center, have two extra tools, which control the computational process: the barrier parameter and the vector of Lagrange multipliers. The extra tools allow to attach to the MEDF's very important properties of Augmented Lagrangeans. One can consider the MIDFs as Interior Augmented Lagrangeans. It makes MIDF's similar in spirit to Modified Barrier Functions (MBF's), although there is a fundamental difference between them both in theory and methods. Based on MIDF's theory, Modified Center Methods (MCM's) have been developed and analyzed. The MCM's find an unconstrained minimizer in primal space and update the Lagrange multipliers, while both the center and the barrier parameter can be fixed or updated at each step. The MCM's convergence was investigated, and their rate of convergence was estimated. The extension of the feasible set and the special role of the Lagrange multipliers allow to develop MCM's, which produce, in case of nondegenerate constrained optimization, a primal and dual sequences that converge to the primal-dual solutions with linear rate, even when both the center and the barrier parameter are fixed. Moreover, every Lagrange multipliers update shrinks the distance to the primal dual solution by a factor 0 less than gamma less than 1 which can be made as small as one wants by choosing a fixed interior point as a 'center' and a fixed but large enough barrier parameter. The numericai realization of MCM leads to the Newton MCM (NMCM). The approximation for the primal minimizer one finds by Newton Method followed by the Lagrange multipliers update. Due to the MCM convergence, when both the center and the barrier parameter are fixed, the condition of the MDF Hessism and the neighborhood of the primal ninimizer where Newton method is 'well' defined remains stable. It contributes to both the complexity and the numerical stability of the NMCM.

Perceptions of reporting practices and barriers to reporting incidents among registered nurses and physicians in accredited and nonaccredited Jordanian hospitals.

PubMed

AbuAlRub, Raeda F; Al-Akour, Nemeh A; Alatari, Nour H

2015-10-01

To explore the awareness of the incident reporting system, incident reporting practices and barriers to reporting incidents among Jordanian staff nurses and physicians in accredited and nonaccredited hospitals. Reporting medical incidents is an important element of patient safety enhancement and quality of care improvement and it should be an integral part of the organisational culture. A descriptive exploratory survey was used for the present study. A modified version of the Incident Reporting Questionnaire was used to collect data from 307 nurses and 144 physicians at seven hospitals (four accredited and three not accredited) in Jordan. The response rate was 28·8% for nurses and 58·8% for physicians. Nurses were more aware of the incident reporting system than physicians. Physicians were less likely to report any incident on 50% or more of occasions. The major three barriers to reporting incidents were believing that there was no point in reporting near misses, lack of feedback and fear of disciplinary actions. The study showed significant differences between nurses in accredited and nonaccredited hospitals regarding barriers to reporting incidents and reporting practices. Nurse administrators should modify existing systems for reporting incidents to overcome the barriers as shown in the present study. © 2015 John Wiley & Sons Ltd.

Validating the Modified Drug Adherence Work-Up (M-DRAW) Tool to Identify and Address Barriers to Medication Adherence.

PubMed

Lee, Sun; Bae, Yuna H; Worley, Marcia; Law, Anandi

2017-09-08

Barriers to medication adherence stem from multiple factors. An effective and convenient tool is needed to identify these barriers so that clinicians can provide a tailored, patient-centered consultation with patients. The Modified Drug Adherence Work-up Tool (M-DRAW) was developed as a 13-item checklist questionnaire to identify barriers to medication adherence. The response scale was a 4-point Likert scale of frequency of occurrence (1 = never to 4 = often). The checklist was accompanied by a GUIDE that provided corresponding motivational interview-based intervention strategies for each identified barrier. The current pilot study examined the psychometric properties of the M-DRAW checklist (reliability, responsiveness and discriminant validity) in patients taking one or more prescription medication(s) for chronic conditions. A cross-sectional sample of 26 patients was recruited between December 2015 and March 2016 at an academic medical center pharmacy in Southern California. A priming question that assessed self-reported adherence was used to separate participants into the control group of 17 "adherers" (65.4%), and into the intervention group of nine "unintentional and intentional non-adherers" (34.6%). Comparable baseline characteristics were observed between the two groups. The M-DRAW checklist showed acceptable reliability (13 item; alpha = 0.74) for identifying factors and barriers leading to medication non-adherence. Discriminant validity of the tool and the priming question was established by the four-fold number of barriers to adherence identified within the self-selected intervention group compared to the control group (4.4 versus 1.2 barriers, p < 0.05). The current study did not investigate construct validity due to small sample size and challenges on follow-up with patients. Future testing of the tool will include construct validation.

Midwest Guardrail System with round timber posts

Treesearch

Ronald K. Faller; John D. Reid; David E. Kretschmann; Jason A. Hascall; Dean L. Sicking

2009-01-01

A modified Midwest Guardrail System (MGS) was developed by using small-diameter round wood posts. The barrier system was configured with three timber species: Douglas fir (DF), ponderosa pine (PP), and southern yellow pine (SYP). Barrier VII computer simulation, combined with cantilever post testing in a rigid sleeve and soil, was used to determine the required post...

Sorption of nonpolar aromatic contaminants by chlorosilane surface modified natural minerals.

PubMed

Huttenloch, P; Roehl, K E; Czurda, K

2001-11-01

The efficacy of the surface modification of natural diatomite and zeolite material by chlorosilanes is demonstrated. Chlorosilanes used were trimethylchlorosilane (TMSCI), tert-butyldimethylchlorosilane (TBDMSCI), dimethyloctadecylchlorosilane (DMODSCI), and diphenyldichlorosilane (DPDSCI) possessing different headgroups and chemical properties. Silanol groups of the diatomite and zeolite were modified by chemical reaction with the chlorosilanes resulting in a stable covalent attachment of the organosilanes to the mineral surface. The alteration of surface properties of the modified material was proved by measurements of water adsorption capacity, total organic carbon (TOC) content, and thermoanalytical data. The surface modified material showed great stability even when exposed to extremes in ionic strength, pH, and to pure organic solvents. Sorption of toluene, o-xylene, and naphthalene from water was greatly enhanced by the surface modification compared to the untreated materials which showed no measurable sorption of these compounds. The enhanced sorption was dependent on the organic carbon content as well as on chemical characteristics of the chlorosilanes used. Batch sorption experiments showed that the phenyl headgroups of DPDSCI have the best affinity for aromatic compounds. Removal from an aqueous solution of 10 mg/L of naphthalene, o-xylene, and toluene was 71%, 60%, and 30% for surface modified diatomite and 51%, 30%, and 16% for modified clinoptilolite, respectively. Sorption data were well described by the Freundlich isotherm equation, which indicated physical adsorption onto the lipophilic surface rather than partitioning into the surface organic phase. The chlorosilane modified materials have an apparent potential for application in environmental technologies such as permeable reactive barriers (PRB) or wastewater treatment.

A pushing chronic care forward in Abu Dhabi by identifying priorities and addressing barriers: a modified Delphi technique

PubMed Central

Loney, Tom; Lapão, Luis V

2018-01-01

Objective This study aimed to elucidate the top five key priorities and barriers to chronic care in the health system of Abu Dhabi, United Arab Emirates (UAE). Design A modified Delphi study was performed to reach consensus on priority areas and barriers to the development of the Chronic Care Model in the health system of Abu Dhabi. Individual wireless audience response devices (keypads) linked to a computer were used to reduce 28 priorities and 20 barriers to the top five during three iterative rounds over three consecutive days. Setting Chronic care services for patients with diabetes, cardiovascular diseases and cancer, in both private and publicly funded healthcare services in the emirate of Abu Dhabi. Participants A purposive sample of 20 health systems’ experts were recruited. They were front-line healthcare workers from the public and private sector working in the delivery of care for patients with diabetes, cardiovascular diseases and cancer. Results The ‘overall organizational leadership in chronic illness care’ was ranked as the most important priority to address (26.3%) and ‘patient compliance’ was ranked as the most important barrier (36.8%) to the development of the Chronic Care Model. Conclusions This study has identified the current priorities and barriers to improving chronic care within Abu Dhabi’s healthcare system. Our paper addresses the UAE’s 2021 Agenda of achieving a world-class healthcare system, and findings may help inform strategic changes required to achieve this mission. PMID:29866724

Discovery of novel propargylamine-modified 4-aminoalkyl imidazole substituted pyrimidinylthiourea derivatives as multifunctional agents for the treatment of Alzheimer's disease.

PubMed

Xu, Yi-Xiang; Wang, Huan; Li, Xiao-Kang; Dong, Sheng-Nan; Liu, Wen-Wen; Gong, Qi; Wang, Tian-Duan-Yi; Tang, Yun; Zhu, Jin; Li, Jian; Zhang, Hai-Yan; Mao, Fei

2018-01-01

A series of novel propargylamine-modified pyrimidinylthiourea derivatives (1-3) were designed and synthesized as multifunctional agents for Alzheimer's disease (AD) therapy, and their potential was evaluated through various biological experiments. Among these derivatives, compound 1b displayed good selective inhibitory activity against AChE (vs BuChE, IC 50  = 0.324 μM, SI > 123) and MAO-B (vs MAO-A, IC 50  = 1.427 μM, SI > 35). Molecular docking study showed that the pyrimidinylthiourea moiety of 1b could bind to the catalytic active site (CAS) of AChE, and the propargylamine moiety interacted directly with the flavin adenine dinucleotide (FAD) of MAO-B. Moreover, 1b demonstrated mild antioxidant ability, good copper chelating property, effective inhibitory activity against Cu 2+ -induced Aβ 1-42 aggregation, moderate neuroprotection, low cytotoxicity, and appropriate blood-brain barrier (BBB) permeability in vitro and was capable of ameliorating scopolamine-induced cognitive impairment in mice. These results indicated that 1b has the potential to be a multifunctional candidate for the treatment of Alzheimer's disease. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Modifications of adenovirus hexon allow for either hepatocyte detargeting or targeting with potential evasion from Kupffer cells.

PubMed

Prill, Jan-Michael; Espenlaub, Sigrid; Samen, Ulrike; Engler, Tatjana; Schmidt, Erika; Vetrini, Francesco; Rosewell, Amanda; Grove, Nathan; Palmer, Donna; Ng, Philip; Kochanek, Stefan; Kreppel, Florian

2011-01-01

In vivo gene transfer with adenovirus vectors would significantly benefit from a tight control of the adenovirus-inherent liver tropism. For efficient hepatocyte transduction, adenovirus vectors need to evade from Kupffer cell scavenging while delivery to peripheral tissues or tumors could be improved if both scavenging by Kupffer cells and uptake by hepatocytes were blocked. Here, we provide evidence that a single point mutation in the hexon capsomere designed to enable defined chemical capsid modifications may permit both detargeting from and targeting to hepatocytes with evasion from Kupffer cell scavenging. Vector particles modified with small polyethylene glycol (PEG) moieties specifically on hexon exhibited decreased transduction of hepatocytes by shielding from blood coagulation factor binding. Vector particles modified with transferrin or, surprisingly, 5,000 Da PEG or dextran increased hepatocyte transduction up to 18-fold independent of the presence of Kupffer cells. We further show that our strategy can be used to target high-capacity adenovirus vectors to hepatocytes emphasizing the potential for therapeutic liver-directed gene transfer. Our approach may lead to a detailed understanding of the interactions between adenovirus vectors and Kupffer cells, one of the most important barriers for adenovirus-mediated gene delivery.

Simple Things Matter! How Reassurance and Pain Management Strategies Can Improve Outcomes in Physiotherapy: A Case Report

ERIC Educational Resources Information Center

Leonard, Guillaume; Tousignant-Laflamme, Yannick; Mercier, Catherine

2013-01-01

Psychological barriers to rehabilitation are generally viewed as pre-existing patient traits that clinicians are asked to evaluate and modify. In the present case report, we provide evidence that these barriers can also be involuntarily created or perpetuated by the clinician himself when too much attention is placed on physical abnormalities.…

Development of modified flyash as a permeable reactive barrier medium for a former manufactured gas plant site, Northern Ireland

NASA Astrophysics Data System (ADS)

Doherty, R.; Phillips, D. H.; McGeough, K. L.; Walsh, K. P.; Kalin, R. M.

2006-05-01

A sequential biological permeable reactive barrier (PRB) was determined to be the best option for remediating groundwater that has become contaminated with a wide range of organic contaminants (i.e., benzene, toluene, ethylbenzene, xylene and polyaromatic hydrocarbons), heavy metals (i.e., lead and arsenic), and cyanide at a former manufactured gas plant after 150 years of operation in Portadown, Northern Ireland. The objective of this study was to develop a modified flyash that could be used in the initial cell within a sequential biological PRB to filter complex contaminated groundwater containing ammonium. Flyash modified with lime (CaOH) and alum was subjected to a series of batch tests which investigated the modified cation exchange capacity (CEC) and rate of removal of anions and cations from the solution. These tests showed that a high flyash composition medium (80%) could remove 8.65 mol of ammonium contaminant for every kilogram of medium. The modified CEC procedure ruled out the possibility of cation exchange as the major removal mechanism. The medium could also adsorb anions as well as cations (i.e., Pb and Cr), but not with the same capacity. The initial mechanism for Pb and Cr removal is probably precipitation. This is followed by sorption, which is possibly the only mechanism for the removal of dichromate anions. Scanning electron microscopic analysis revealed very small (<1 μm) cubic highly crystalline precipitates on the flyash, although this new crystalline zeolite growth did not occur rapidly enough to enable productive zeolite formation. Surface area measurements showed that biofilm growth on the medium could be a major factor in the comparative reduction of surface area between real and synthetic contaminant groundwaters. The modified flyash was found to be a highly sorptive granular material that did not inhibit microbiological activity, however, leaching tests revealed that the medium would fail as a long-term barrier material.

Biomechanics and Thermodynamics of Nanoparticle Interactions with Plasma and Endosomal Membrane Lipids in Cellular Uptake and Endosomal Escape

PubMed Central

2015-01-01

To be effective for cytoplasmic delivery of therapeutics, nanoparticles (NPs) taken up via endocytic pathways must efficiently transport across the cell membrane and subsequently escape from the secondary endosomes. We hypothesized that the biomechanical and thermodynamic interactions of NPs with plasma and endosomal membrane lipids are involved in these processes. Using model plasma and endosomal lipid membranes, we compared the interactions of cationic NPs composed of poly(d,l-lactide-co-glycolide) modified with the dichain surfactant didodecyldimethylammonium bromide (DMAB) or the single-chain surfactant cetyltrimethylammonium bromide (CTAB) vs anionic unmodified NPs of similar size. We validated our hypothesis in doxorubicin-sensitive (MCF-7, with relatively fluid membranes) and resistant breast cancer cells (MCF-7/ADR, with rigid membranes). Despite their cationic surface charges, DMAB- and CTAB-modified NPs showed different patterns of biophysical interaction: DMAB-modified NPs induced bending of the model plasma membrane, whereas CTAB-modified NPs condensed the membrane, thereby resisted bending. Unmodified NPs showed no effects on bending. DMAB-modified NPs also induced thermodynamic instability of the model endosomal membrane, whereas CTAB-modified and unmodified NPs had no effect. Since bending of the plasma membrane and destabilization of the endosomal membrane are critical biophysical processes in NP cellular uptake and endosomal escape, respectively, we tested these NPs for cellular uptake and drug efficacy. Confocal imaging showed that in both sensitive and resistant cells DMAB-modified NPs exhibited greater cellular uptake and escape from endosomes than CTAB-modified or unmodified NPs. Further, paclitaxel-loaded DMAB-modified NPs induced greater cytotoxicity even in resistant cells than CTAB-modified or unmodified NPs or drug in solution, demonstrating the potential of DMAB-modified NPs to overcome the transport barrier in resistant cells. In conclusion, biomechanical interactions with membrane lipids are involved in cellular uptake and endosomal escape of NPs. Biophysical interaction studies could help us better understand the role of membrane lipids in cellular uptake and intracellular trafficking of NPs. PMID:24911361

Assessing parents' receptiveness to a vegetable-focussed in-school nutrition intervention.

PubMed

Jongenelis, Michelle I; Pettigrew, Simone; Pratt, Iain S; Wright, Shannon; Myers, Gael

2017-10-01

Crunch&Sip is an Australian school-based initiative designed to increase the consumption of fruit, vegetables, and water among primary school children. To address the significant deficiencies in children's vegetable intake, the present study aimed to examine the responsiveness of parents (the main providers of food for Crunch&Sip) to a modified version of the program that focuses primarily on vegetable consumption. A total of 329 Western Australian parents completed an online questionnaire examining their support for a vegetable focus for Crunch&Sip and any perceived barriers, motivators, and facilitators. Most (80%) parents were supportive of a shift to a vegetable focus for Crunch&Sip. Belief in the effectiveness of Crunch&Sip at improving children's attitudes towards vegetables and increasing children's vegetable consumption was found to be significantly associated with levels of support. The most commonly nominated motivator was to improve their children's eating habits and the main facilitator was the perceived ability of teachers and peers to influence children's food consumption behaviours. Identified potential barriers included the difficulties associated with providing a variety of vegetables, maintaining freshness, and the preparation time required. The primary suggested strategy to overcome these barriers was for schools to conduct education sessions to provide information about vegetable provision options. The results suggest that parents can be supportive of school-based nutrition programs that specifically encourage the consumption of vegetables but they may require guidance to reduce the identified barriers related to vegetable provision. Copyright © 2017 Elsevier Ltd. All rights reserved.

Fission Meter Information Barrier Attribute Measurement System: Task 1 Report: Document existing Fission Meter neutron IB system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerr, P. L.

An SNM attribute Information Barrier (IB) system was developed for a 2011 US/UK Exercise. The system was modified and extensively tested in a 2013-2014 US-UK Measurement Campaign. This work demonstrated rapid deployment of an IB system for potential treaty use. The system utilizes an Ortec Fission Meter neutron multiplicity counter and custom computer code. The system demonstrates a proof-of-principle automated Pu-240 mass determination with an information barrier. After a software start command is issued, the system automatically acquires and downloads data, performs an analysis, and displays the results. This system conveys the results of a Pu mass threshold measurements inmore » a way the does not reveal sensitive information. In full IB mode, only red/green ‘lights’ are displayed in the software. In test mode, more detailed information is displayed. The code can also read in, analyze, and display results from previously acquired or simulated data. Because the equipment is commercial-off-the-shelf (COTS), the system demonstrates a low-cost short-lead-time technology for treaty SNM attribute measurements. A deployed system will likely require integration of additional authentication and tamper-indicating technologies. This will be discussed for the project in this and future progress reports.« less

Natural and sexual selection giveth and taketh away reproductive barriers: models of population divergence in guppies.

PubMed

Labonne, Jacques; Hendry, Andrew P

2010-07-01

The standard predictions of ecological speciation might be nuanced by the interaction between natural and sexual selection. We investigated this hypothesis with an individual-based model tailored to the biology of guppies (Poecilia reticulata). We specifically modeled the situation where a high-predation population below a waterfall colonizes a low-predation population above a waterfall. Focusing on the evolution of male color, we confirm that divergent selection causes the appreciable evolution of male color within 20 generations. The rate and magnitude of this divergence were reduced when dispersal rates were high and when female choice did not differ between environments. Adaptive divergence was always coupled to the evolution of two reproductive barriers: viability selection against immigrants and hybrids. Different types of sexual selection, however, led to contrasting results for another potential reproductive barrier: mating success of immigrants. In some cases, the effects of natural and sexual selection offset each other, leading to no overall reproductive isolation despite strong adaptive divergence. Sexual selection acting through female choice can thus strongly modify the effects of divergent natural selection and thereby alter the standard predictions of ecological speciation. We also found that under no circumstances did divergent selection cause appreciable divergence in neutral genetic markers.

Patient perception and the barriers to practicing patient-centered communication: A survey and in-depth interview of Chinese patients and physicians.

PubMed

Ting, Xu; Yong, Bao; Yin, Liang; Mi, Tian

2016-03-01

To investigate patient perceptions of patient-centered communication (PCC) in doctor-patient consultations and explore barriers to PCC implementation in China. This study was conducted in public teaching hospital in Guiyang, Guizhou, China. In Phase 1, patient attitudes to PCC were quantitatively assessed in 317 outpatients using modified Patient-Practitioner Orientation Scale (PPOS). In Phase 2, we conducted in-depth interviews with 20 outpatients to explore their views on PCC and expose potential barriers to PCC implementation. Participants communicated "patient-centered" preferences, particularly with regard to their doctors' empathy, communication skills, time and information sharing. Patients were more concerned about doctors exhibiting caring perspective than power sharing. Younger and highly educated patients were more likely to prefer PCC and highly educated patients paid more attention to power sharing. Several factors including inadequate time for PCC resulting from doctors' high patient-load, doctor-patient communication difficulties and excessive treatment due to inappropriate medical payment system affected PCC implementation in China. Patients expressed moderate enthusiasm for PCC in China. They expressed strong preferences concerning physician respect for patient perspective, but less concern for power sharing. Government should improve health care system by implementing PCC in daily healthcare practice to improve patient awareness and preferences. Copyright © 2016. Published by Elsevier Ireland Ltd.

Robust Superhydrophobic Graphene-Based Composite Coatings with Self-Cleaning and Corrosion Barrier Properties.

PubMed

Nine, Md J; Cole, Martin A; Johnson, Lucas; Tran, Diana N H; Losic, Dusan

2015-12-30

Superhydrophobic surfaces for self-cleaning applications often suffer from mechanical instability and do not function well after abrasion/scratching. To address this problem, we present a method to prepare graphene-based superhydrophobic composite coatings with robust mechanical strength, self-cleaning, and barrier properties. A suspension has been formulated that contains a mixture of reduced graphene oxide (rGO) and diatomaceous earth (DE) modified with polydimethylsiloxane (PDMS) that can be applied on any surface using common coating methods such as spraying, brush painting, and dip coating. Inclusion of TiO2 nanoparticles to the formulation shows further increase in water contact angle (WCA) from 159 ± 2° to 170 ± 2° due to the structural improvement with hierarchical surface roughness. Mechanical stability and durability of the coatings has been achieved by using a commercial adhesive to bond the superhydrophobic "paint" to various substrates. Excellent retention of superhydrophobicity was observed even after sandpaper abrasion and crosscut scratching. A potentiodynamic polarization study revealed excellent corrosion resistance (96.78%) properties, and an acid was used to provide further insight into coating barrier properties. The ease of application and remarkable properties of this graphene-based composite coating show considerable potential for broad application as a self-cleaning and protective layer.

Method for formation of subsurface barriers using viscous colloids

DOEpatents

Apps, J.A.; Persoff, P.; Moridis, G.; Pruess, K.

1998-11-17

A method is described for formation of subsurface barriers using viscous liquids where a viscous liquid solidifies at a controlled rate after injection into soil and forms impermeable isolation of the material enclosed within the subsurface barriers. The viscous liquid is selected from the group consisting of polybutenes, polysiloxanes, colloidal silica and modified colloidal silica of which solidification is controlled by gelling, cooling or cross-linking. Solidification timing is controlled by dilution, addition of brines, coating with alumina, stabilization with various agents and by temperature. 17 figs.

Effect of polyethyleneimine modified graphene on the mechanical and water vapor barrier properties of methyl cellulose composite films.

PubMed

Liu, Hongyu; Liu, Cuiyun; Peng, Shuge; Pan, Bingli; Lu, Chang

2018-02-15

A series of novel methyl cellulose (MC) composite films were prepared using polyethyleneimine reduced graphene oxide (PEI-RGO) as an effective filler for water vapor barrier application. The as-prepared PEI-RGO/MC composites were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, tensile test and scanning electron microscopy. The experimental and theoretical results exhibited that PEI-RGO was uniformly dispersed in the MC matrix without aggregation and formed an aligned dispersion. The addition of PEI-RGO resulted in an enhanced surface hydrophobicity and a tortuous diffusion pathway for water molecules. Water vapor permeability of PEI-RGO/MC with loading of 3.0% of surface modified graphene was as low as 5.98×10 -11 gmm -2 s -1 Pa -1 . The synergistic effects of enhanced surface hydrophobicity and tortuous diffusion pathway were accounted for the improved water vapor barrier performance of the PEI-RGO/MC composite films. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strongly reduced Ehrlich-Schwoebel barriers at the Cu (111) stepped surface with In and Pb surfactants

NASA Astrophysics Data System (ADS)

Hao, Jialei; Zhang, Lixin

2018-01-01

A surfactant can modify the properties of the surface and induce different mode of epitaxy growth. The atomistic mechanism is not fully understood yet. In this first-principles study, taking Cu homoepitaxy along (111) direction as an example, we show that the distribution of the surfactant atoms on the surface is the key. For In and Pb, they prefer to locate at the step edges and remain isolated. Once the growth is started, the distribution can be further modified by Cu adatoms. The uniquely decorated step edges have much lowered Ehrlich-Schwoebel (ES) barriers than that of the clean edges, thus the two dimensional growth on Cu (111) surface is promoted significantly. On the other hand, for Rh, Ir, and Au, these atoms are not favored at the step edges. The ES barriers can't be affected and these metals are not surfactants. The result is very helpful for searching of the optimal surfactants in metal homoepitaxy.

Modifiable barriers to leisure-time physical activity during pregnancy: a qualitative study investigating first time mother's views and experiences.

PubMed

Connelly, Megan; Brown, Helen; van der Pligt, Paige; Teychenne, Megan

2015-04-22

Evidence suggests physical activity often declines during pregnancy, however explanations for the decline are not well understood. The aim of this study was to identify modifiable barriers to leisure-time physical activity among women who did not meet physical activity guidelines during pregnancy. Analyses were based on data from 133 mothers (~3-months postpartum) who were recruited from the Melbourne InFANT Extend study (2012/2013). Women completed a self-report survey at baseline in which they reported their leisure-time physical activity levels during pregnancy as well provided an open-ended written response regarding the key barriers that they perceived prevented them from meeting the physical activity guidelines during their pregnancy. Thematic analyses were conducted to identify key themes. The qualitative data revealed six themes relating to the barriers of leisure-time physical activity during pregnancy. These included work-related factors (most commonly reported), tiredness, pregnancy-related symptoms, being active but not meeting the guidelines, lack of motivation, and a lack of knowledge of recommendations. Considering work-related barriers were suggested to be key factors to preventing women from meeting the physical activity guidelines during pregnancy, workplace interventions aimed at providing time management skills along with supporting physical activity programs for pregnant workers should be considered. Such interventions should also incorporate knowledge and education components, providing advice for undertaking leisure-time physical activity during pregnancy.

Position of Proline Mediates the Reactivity of S-Palmitoylation.

PubMed

Khanal, Neelam; Pejaver, Vikas; Li, Zhiyu; Radivojac, Predrag; Clemmer, David E; Mukhopadhyay, Suchetana

2015-11-20

Palmitoylation, a post-translational modification in which a saturated 16-carbon chain is added predominantly to a cysteine residue, participates in various biological functions. The position of proline relative to other residues being post-translationally modified has been previously reported as being important. We determined that proline is statistically enriched around cysteines known to be S-palmitoylated. The goal of this work was to determine how the position of proline influences the palmitoylation of the cysteine residue. We established a mass spectrometry-based approach to investigate time- and temperature-dependent kinetics of autopalmitoylation in vitro and to derive the thermodynamic parameters of the transition state associated with palmitoylation; to the best of our knowledge, our work is the first to study the kinetics and activation properties of the palmitoylation process. We then used these thermochemical parameters to determine if the position of proline relative to the modified cysteine is important for palmitoylation. Our results show that peptides with proline at the -1 position of cysteine in their sequence (PC) have lower enthalpic barriers and higher entropic barriers in comparison to the same peptides with proline at the +1 position of cysteine (CP); interestingly, the free-energy barriers for both pairs are almost identical. Molecular dynamics studies demonstrate that the flexibility of the cysteine backbone in the PC-containing peptide when compared to the CP-containing peptide explains the increased entropic barrier and decreased enthalpic barrier observed experimentally.

Nanoscale-Barrier Formation Induced by Low-Dose Electron-Beam Exposure in Ultrathin MoS2 Transistors.

PubMed

Matsunaga, Masahiro; Higuchi, Ayaka; He, Guanchen; Yamada, Tetsushi; Krüger, Peter; Ochiai, Yuichi; Gong, Yongji; Vajtai, Robert; Ajayan, Pulickel M; Bird, Jonathan P; Aoki, Nobuyuki

2016-10-05

Utilizing an innovative combination of scanning-probe and spectroscopic techniques, supported by first-principles calculations, we demonstrate how electron-beam exposure of field-effect transistors, implemented from ultrathin molybdenum disulfide (MoS 2 ), may cause nanoscale structural modifications that in turn significantly modify the electrical operation of these devices. Quite surprisingly, these modifications are induced by even the relatively low electron doses used in conventional electron-beam lithography, which are found to induce compressive strain in the atomically thin MoS 2 . Likely arising from sulfur-vacancy formation in the exposed regions, the strain gives rise to a local widening of the MoS 2 bandgap, an idea that is supported both by our experiment and by the results of first-principles calculations. A nanoscale potential barrier develops at the boundary between exposed and unexposed regions and may cause extrinsic variations in the resulting electrical characteristics exhibited by the transistor. The widespread use of electron-beam lithography in nanofabrication implies that the presence of such strain must be carefully considered when seeking to harness the potential of atomically thin transistors. At the same time, this work also promises the possibility of exploiting the strain as a means to achieve "bandstructure engineering" in such devices.

Magnetospheric Reconnection in Modified Current-Sheet Equilibria

NASA Astrophysics Data System (ADS)

Newman, D. L.; Goldman, M. V.; Lapenta, G.; Markidis, S.

2012-10-01

Particle simulations of magnetic reconnection in Earth's magnetosphere are frequently initialized with a current-carrying Harris equilibrium superposed on a current-free uniform background plasma. The Harris equilibrium satisfies local charge neutrality, but requires that the sheet current be dominated by the hotter species -- often the ions in Earth's magnetosphere. This constraint is not necessarily consistent with observations. A modified kinetic equilibrium that relaxes this constraint on the currents was proposed by Yamada et al. [Phys. Plasmas., 7, 1781 (2000)] with no background population. These modified equilibria were characterized by an asymptotic converging or diverging electrostatic field normal to the current sheet. By reintroducing the background plasma, we have developed new families of equilibria where the asymptotic fields are suppressed by Debye shielding. Because the electrostatic potential profiles of these new equilibria contain wells and/or barriers capable of spatially isolating different populations of electrons and/or ions, these solutions can be further generalized to include classes of asymmetric kinetic equilibria. Examples of both symmetric and asymmetric equilibria will be presented. The dynamical evolution of these equilibria, when perturbed, will be further explored by means of implicit 2D PIC reconnection simulations, including comparisons with simulations employing standard Harris-equilibrium initializations.

Molecular basis of the interaction between gating modifier spider toxins and the voltage sensor of voltage-gated ion channels

NASA Astrophysics Data System (ADS)

Lau, Carus H. Y.; King, Glenn F.; Mobli, Mehdi

2016-09-01

Voltage-sensor domains (VSDs) are modular transmembrane domains of voltage-gated ion channels that respond to changes in membrane potential by undergoing conformational changes that are coupled to gating of the ion-conducting pore. Most spider-venom peptides function as gating modifiers by binding to the VSDs of voltage-gated channels and trapping them in a closed or open state. To understand the molecular basis underlying this mode of action, we used nuclear magnetic resonance to delineate the atomic details of the interaction between the VSD of the voltage-gated potassium channel KvAP and the spider-venom peptide VSTx1. Our data reveal that the toxin interacts with residues in an aqueous cleft formed between the extracellular S1-S2 and S3-S4 loops of the VSD whilst maintaining lipid interactions in the gaps formed between the S1-S4 and S2-S3 helices. The resulting network of interactions increases the energetic barrier to the conformational changes required for channel gating, and we propose that this is the mechanism by which gating modifier toxins inhibit voltage-gated ion channels.

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants.

PubMed

Simal-Gándara, J; Sarria-Vidal, M; Koorevaar, A; Rijk, R

2000-08-01

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 microns-thick oriented PP) into the food stimulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.

A Contextual Overview of the Modified Consent Decree in the Los Angeles Unified School District

ERIC Educational Resources Information Center

Weintraub, Frederick J.; Myers, Robert M.; Hehir, Thomas; Jaque-Anton, Donnalyn

2008-01-01

Since 1996, the Los Angeles Unified School District (LAUSD), located in Southern California, has been under a federal court consent decree requiring compliance with laws pertaining to the delivery of special education services and the elimination of architectural barriers in schools. In 2003, the consent decree was modified, creating…

Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control.

PubMed

Lin, Jhih-Hong; Chiang, Mao-Hsiung

2016-08-25

Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved.

Tracking Control of a Magnetic Shape Memory Actuator Using an Inverse Preisach Model with Modified Fuzzy Sliding Mode Control

PubMed Central

Lin, Jhih-Hong; Chiang, Mao-Hsiung

2016-01-01

Magnetic shape memory (MSM) alloys are a new class of smart materials with extraordinary strains up to 12% and frequencies in the range of 1 to 2 kHz. The MSM actuator is a potential device which can achieve high performance electromagnetic actuation by using the properties of MSM alloys. However, significant non-linear hysteresis behavior is a significant barrier to control the MSM actuator. In this paper, the Preisach model was used, by capturing experiments from different input signals and output responses, to model the hysteresis of MSM actuator, and the inverse Preisach model, as a feedforward control, provided compensational signals to the MSM actuator to linearize the hysteresis non-linearity. The control strategy for path tracking combined the hysteresis compensator and the modified fuzzy sliding mode control (MFSMC) which served as a path controller. Based on the experimental results, it was verified that a tracking error in the order of micrometers was achieved. PMID:27571081

Targeted transport of nanocarriers into brain for theranosis with rabies virus glycoprotein-derived peptide.

PubMed

Fu, Chen; Xiang, Yonggang; Li, Xiaorong; Fu, Ailing

2018-06-01

For successful theranosis of brain diseases, limited access of therapeutic molecules across blood-brain barrier (BBB) needs be overcome in brain delivery. Currently, peptide derivatives of rabies virus glycoprotein (RVG) have been exploited as delivery ligands to transport nanocarriers across BBB and specifically into the brain. The targeting peptides usually conjugate to the nanocarrier surface, and the cargoes, including siRNA, miRNA, DNA, proteins and small molecular chemicals, are complexed or encapsulated in the nanocarriers. The peptide ligand of the RVG-modified nanocarriers introduces the conjugated targeted-delivery into the brain, and the cargoes are involved in disease theranosis. The peptide-modified nanocarriers have been applied to diagnose and treat various brain diseases, such as glioma, Alzheimer's disease, ischemic injury, protein misfolding diseases etc. Since the targeting delivery system has displayed good biocompatibility and desirable therapeutic effect, it will raise a potential application in treating brain diseases. Copyright © 2017 Elsevier B.V. All rights reserved.

Understanding and Improving Blind Students' Access to Visual Information in Computer Science Education

NASA Astrophysics Data System (ADS)

Baker, Catherine M.

Teaching people with disabilities tech skills empowers them to create solutions to problems they encounter and prepares them for careers. However, computer science is typically taught in a highly visual manner which can present barriers for people who are blind. The goal of this dissertation is to understand and decrease those barriers. The first projects I present looked at the barriers that blind students face. I first present the results of my survey and interviews with blind students with degrees in computer science or related fields. This work highlighted the many barriers that these blind students faced. I then followed-up on one of the barriers mentioned, access to technology, by doing a preliminary accessibility evaluation of six popular integrated development environments (IDEs) and code editors. I found that half were unusable and all had some inaccessible portions. As access to visual information is a barrier in computer science education, I present three projects I have done to decrease this barrier. The first project is Tactile Graphics with a Voice (TGV). This project investigated an alternative to Braille labels for those who do not know Braille and showed that TGV was a potential alternative. The next project was StructJumper, which created a modified abstract syntax tree that blind programmers could use to navigate through code with their screen reader. The evaluation showed that users could navigate more quickly and easily determine the relationships of lines of code when they were using StructJumper compared to when they were not. Finally, I present a tool for dynamic graphs (the type with nodes and edges) which had two different modes for handling focus changes when moving between graphs. I found that the modes support different approaches for exploring the graphs and therefore preferences are mixed based on the user's preferred approach. However, both modes had similar accuracy in completing the tasks. These projects are a first step towards the goal of making computer science education more accessible to blind students. By identifying the barriers that exist and creating solutions to overcome them, we can support increasing the number of blind students in computer science.

Density function theory study of the adsorption and dissociation of carbon monoxide on tungsten nanoparticles.

PubMed

Weng, Meng-Hsiung; Ju, Shin-Pon; Chen, Hsin-Tsung; Chen, Hui-Lung; Lu, Jian-Ming; Lin, Ken-Huang; Lin, Jenn-Sen; Hsieh, Jin-Yuan; Yang, Hsi-Wen

2013-02-01

The adsorption and dissociation properties of carbon monoxide (CO) molecule on tungsten W(n) (n = 10-15) nanoparticles have been investigated by density-functional theory (DFT) calculations. The lowest-energy structures for W(n) (n = 10-15) nanoparticles are found by the basin-hopping method and big-bang method with the modified tight-binding many-body potential. We calculated the corresponding adsorption energies, C-O bond lengths and dissociation barriers for adsorption of CO on nanoparticles. The electronic properties of CO on nanoparticles are studied by the analysis of density of state and charge density. The characteristic of CO on W(n) nanoparticles are also compared with that of W bulk.

Timely Diagnosis for Alzheimer's Disease: A Literature Review on Benefits and Challenges.

PubMed

Dubois, Bruno; Padovani, Alessandro; Scheltens, Philip; Rossi, Andrea; Dell'Agnello, Grazia

2016-01-01

Timely diagnosis of Alzheimer's disease (AD) refers to a diagnosis at the stage when patients come to the attention of clinicians because of concerns about changes in cognition, behavior, or functioning and can be still free of dementia and functionally independent. To comprehensively review existing scientific evidence on the benefits and potential challenges of making a timely diagnosis of AD. Relevant studies were identified by searching electronic databases (Medline, Embase) and bibliographies for studies published in English between 1 January 2000 and 2 June 2014 on the consequences of a timely diagnosis of AD. Nine studies were identified that investigated the consequences of diagnosing AD at the initial stages; none were specifically focused on prodromal AD. A timely diagnosis potentially offers the opportunities of early intervention, implementation of coordinated care plans, better management of symptoms, patient safety, cost savings, and postponement of institutionalization. Barriers to making a timely diagnosis include stigma, suicide risk, lack of training, diagnostic uncertainty, shortage of specialized diagnostic services, and the reluctance of healthcare providers to make a diagnosis when no effective disease-modifying options are available. Despite its potential benefits, few published studies have explored the advantages or risks of a timely diagnosis of AD. In light of the cultural shift toward diagnosis at the initial stage of the disease continuum, when the patient does not yet have dementia, more investigations are needed to evaluate the benefits and address the barriers that may impede making a timely AD diagnosis.

Improvement of interfacial interactions using natural polyphenol-inspired tannic acid-coated nanoclay enhancement of soy protein isolate biofilms

NASA Astrophysics Data System (ADS)

Wang, Zhong; Kang, Haijiao; Zhang, Wei; Zhang, Shifeng; Li, Jianzhang

2017-04-01

In this study, a novel and economic surface modification technique for montmorillonite (MMT) nanosheets, a biocompatible coupling cross-linking agent, was developed on an attempt at improving the interfacial adhesion with soy protein isolate (SPI) matrix. Inspired by natural polyphenol, the "green dip-coating" method using tannic acid (TA) to surface-modify MMT (TA@MMT). SPI nanocomposite films modified with MMT or TA@MMT, as well as the control ones, were prepared via the casting method. The TA layer was successfully coated on the MMT surface through the (FeIII) ions coordination chemistry and the synthetic samples were characterized by the Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The compatibility and interfacial interactions between modified MMT and SPI matrix were greatly enhanced by the TA-FeIII coating on the MMT surface. The mechanical properties, water resistance, and thermal stability of the resultant biofilm were increased accordingly. Compared with that of the unmodified SPI film, the tensile strength of the nanocomposite films modified by the green dip-coating was increased by 113.3%. These SPI-based nanocomposite films showed the favorable potential in terms of food packing applications due to their efficient barriers to water vapor and UV and/or visible light.

Studying the Impact of Modified Saccharides on the Molecular Dynamics and Crystallization Tendencies of Model API Nifedipine.

PubMed

Kaminska, E; Tarnacka, M; Wlodarczyk, P; Jurkiewicz, K; Kolodziejczyk, K; Dulski, M; Haznar-Garbacz, D; Hawelek, L; Kaminski, K; Wlodarczyk, A; Paluch, M

2015-08-03

Molecular dynamics of pure nifedipine and its solid dispersions with modified carbohydrates as well as the crystallization kinetics of active pharmaceutical ingredient (API) above and below the glass transition temperature were studied in detail by means of broadband dielectric spectroscopy (BDS), differential scanning calorimetry (DSC), and X-ray diffraction method. It was found that the activation barrier of crystallization increases in molecular dispersions composed of acetylated disaccharides, whereas it slightly decreases in those consisting of modified monocarbohydrates for the experiments carried out above the glass transition temperature. As shown by molecular dynamics simulations it can be related to the strength, character, and structure of intermolecular interactions between API and saccharides, which vary dependently on the excipient. Long-term physical stability studies showed that, in solid dispersions consisting of acetylated maltose and acetylated sucrose, the crystallization of nifedipine is dramatically slowed down, although it is still observable for a low concentration of excipients. With increasing content of modified carbohydrates, the crystallization of API becomes completely suppressed. This is most likely due to additional barriers relating to the intermolecular interactions and diffusion of nifedipine that must be overcome to trigger the crystallization process.

Field Techniques: Atlantic Barrier System. Field Guidebook. National Association of Geology Teachers Eastern Section Annual Field Conference (Lewes, Delaware, April 26-29, 1984).

ERIC Educational Resources Information Center

O'Connor, James V., Ed.; Tormey, Brian B., Ed.

The Atlantic barrier system is used as a focal point in this manual of field exercises. A collection of activities and posed questions provide students with opportunities to develop skills basic to the development of sound field techniques. Investigations can be adapted and modified by teachers to specific subject areas and developmental needs.…

The role of quantum effects in proton transfer reactions in enzymes: quantum tunneling in a noisy environment?

NASA Astrophysics Data System (ADS)

Bothma, Jacques P.; Gilmore, Joel B.; McKenzie, Ross H.

2010-05-01

We consider the role of quantum effects in the transfer of hydrogen-like species in enzyme-catalyzed reactions. This review is stimulated by claims that the observed magnitude and temperature dependence of kinetic isotope effects (KIEs) implies that quantum tunneling below the energy barrier associated with the transition state significantly enhances the reaction rate in many enzymes. We review the path integral approach and the Caldeira-Leggett model, which provides a general framework to describe and understand tunneling in a quantum system that interacts with a noisy environment at nonzero temperature. Here the quantum system is the active site of the enzyme, and the environment is the surrounding protein and water. Tunneling well below the barrier only occurs for temperatures less than a temperature T0, which is determined by the curvature of the potential energy surface near the top of the barrier. We argue that for most enzymes this temperature is less than room temperature. We review typical values for the parameters in the Caldeira-Leggett Hamiltonian, including the frequency-dependent friction and noise due to the environment. For physically reasonable parameters, we show that quantum transition state theory gives a quantitative description of the temperature dependence and magnitude of KIEs for two classes of enzymes that have been claimed to exhibit signatures of quantum tunneling. The only quantum effects are those associated with the transition state, both reflection at the barrier top and tunneling just below the barrier. We establish that the friction and noise due to the environment are weak and only slightly modify the reaction rate. Furthermore, at room temperature and for typical energy barriers environmental fluctuations with frequencies much less than 1000 cm-1 do not have a significant effect on quantum corrections to the reaction rate. This is essentially because the time scales associated with the dynamics of proton transfer are faster than much of the low-frequency noise associated with the protein and solvent.

Implementation of power barrier option valuation

NASA Astrophysics Data System (ADS)

Cahyani, Agatha C. P.; Sumarti, Novriana

2015-09-01

Options are financial instruments that can be utilized to reduce risk in stock investment. Barrier options are one of the major types of options actively used in financial markets where its life period depends on the path of the underlying stock prices. The features of the barrier option can be used to modify other types of options. In this research, the barrier option will be implemented into power option, so it is called power barrier option. This option is an extension of the vanilla barrier options where the Call payoff being considered is defined as P C =max (STβ-Kβ,0 ) , and the Put payoff being considered is defined as P P =max (Kβ-STβ,0 ) . Here β > 0 and β ≠ 1, K is the strike price of the option, and ST is the price of the underlying stock at time maturity T. In this paper, we generate the prices of stock using binomial method which is adjusted to the power option. In the conclusion, the price of American power barrier option is more expensive than the price of European power barrier option.

Wetting transitions on patterned surfaces with diffuse interaction potentials embedded in a Young-Laplace formulation

NASA Astrophysics Data System (ADS)

Pashos, G.; Kokkoris, G.; Papathanasiou, A. G.; Boudouvis, A. G.

2016-01-01

The Minimum Energy Paths (MEPs) of wetting transitions on pillared surfaces are computed with the Young-Laplace equation, augmented with a pressure term that accounts for liquid-solid interactions. The interactions are smoothed over a short range from the solid phase, therefore facilitating the numerical solution of problems concerning wetting on complex surface patterns. The patterns may include abrupt geometric features, e.g., arrays of rectangular pillars, where the application of the unmodified Young-Laplace is not practical. The MEPs are obtained by coupling the augmented Young-Laplace with the modified string method from which the energy barriers of wetting transitions are eventually extracted. We demonstrate the method on a wetting transition that is associated with the breakdown of superhydrophobic behavior, i.e., the transition from the Cassie-Baxter state to the Wenzel state, taking place on a superhydrophobic pillared surface. The computed energy barriers quantify the resistance of the system to these transitions and therefore, they can be used to evaluate superhydrophobic performance or provide guidelines for optimal pattern design.

Implementing clinical governance in Isfahan hospitals: Barriers and solutions, 2014.

PubMed

Ferdosi, Masoud; Ziyari, Farhad Bahman; Ollahi, Mehran Nemat; Salmani, Amaneh Rahim; Niknam, Noureddin

2016-01-01

In the new approach, all health care providers have been obligated to maintain and improve the quality and have been accountable for it. One of the ways is the implementation of clinical governance (CG). More accurate understanding of its challenges can help to improve its performance. In this study, barriers of CG implementation are investigated from the perspective of the hospitals involved. Besides, some solutions are suggested based on stakeholders' opinions. This study used combined method (qualitative content analysis and questionnaire) in hospitals affiliated to Isfahan University of Medical Sciences in 2014. First, experts, and stakeholders talked about CG implementation obstacles in a semi-structured interview. Interviews were confirmed by the interviewee (double check). After analyzing the interviews using reduction coding the questionnaire was drawn up. The questionnaire "validity was confirmed by Cronbach's alpha (0/891)" and its reliability was obtained using experts confirmation. Data analyzing was performed using SPSS (18) software. According to results staffing and management factors were the main obstacles. After them, were factors related to organizational culture, infrastructure elements, information, sociocultural and then process factors. The learning barriers were in final rank. Thirty-four solutions was proposed by experts and divided into subset of eight major barriers. Most solutions were offered on modifying processes and minimal solutions about modifying of organizational culture, sociocultural, and educational factors. Removing the obstacles, especially management and human resource factors can be effective by facilitating and accelerating CG. Furthermore, use of experts and stakeholders opinions can help to remove CG barriers.

Revival of cloaking effect in a driven bilayer graphene vector barrier

NASA Astrophysics Data System (ADS)

Maiti, S.; Panigrahi, A.; Biswas, R.; Sinha, C.

2018-05-01

Transmission profiles in bilayer graphene are studied theoretically through a rectangular vector potential (magnetic) barrier with and without the presence of an oscillatory potential. Unlike the electrostatic barrier, the Fano resonances (FR) are noted in the transmission spectra both for normal and glancing incidences due to non-conservation of chirality for a static vector barrier. The results for normal incidence indicate that the cloaking effect is a manifestation of the chirality conservation in charge transport through bilayer graphene scalar barriers. It is also noted that the aforesaid FR for a static vector barrier might disappear (photon induced electronic cloaking effect) due to the predominant photon exchange processes in presence of an external oscillating potential. The study of Fano resonances in transmission spectrum is in high demand in respect of localization of charge carriers in graphene nano structures for its potential applications in digital device fabrications.

Measuring the mechanical properties of molecular conformers

NASA Astrophysics Data System (ADS)

Jarvis, S. P.; Taylor, S.; Baran, J. D.; Champness, N. R.; Larsson, J. A.; Moriarty, P.

2015-09-01

Scanning probe-actuated single molecule manipulation has proven to be an exceptionally powerful tool for the systematic atomic-scale interrogation of molecular adsorbates. To date, however, the extent to which molecular conformation affects the force required to push or pull a single molecule has not been explored. Here we probe the mechanochemical response of two tetra(4-bromophenyl)porphyrin conformers using non-contact atomic force microscopy where we find a large difference between the lateral forces required for manipulation. Remarkably, despite sharing very similar adsorption characteristics, variations in the potential energy surface are capable of prohibiting probe-induced positioning of one conformer, while simultaneously permitting manipulation of the alternative conformational form. Our results are interpreted in the context of dispersion-corrected density functional theory calculations which reveal significant differences in the diffusion barriers for each conformer. These results demonstrate that conformational variation significantly modifies the mechanical response of even simple porpyhrins, potentially affecting many other flexible molecules.

In Situ Formation Of Reactive Barriers For Pollution Control

DOEpatents

Gilmore, Tyler J.; Riley, Robert G.

2004-04-27

A method of treating soil contamination by forming one or more zones of oxidized material in the path of percolating groundwater is disclosed. The zone or barrier region is formed by delivering an oxidizing agent into the ground for reaction with an existing soil component. The oxidizing agent modifies the existing soil component creating the oxidized zone. Subsequently when soil contaminates migrate into the zone, the oxidized material is available to react with the contaminates and degrade them into benign products. The existing soil component can be an oxidizable mineral such as manganese, and the oxidizing agent can be ozone gas or hydrogen peroxide. Soil contaminates can be volatile organic compounds. Oxidized barriers can be used single or in combination with other barriers.

Factors influencing worker use of personal protective eyewear.

PubMed

Lombardi, David A; Verma, Santosh K; Brennan, Melanye J; Perry, Melissa J

2009-07-01

To identify and describe the array of factors that influence a workers' decision to wear personal protective eyewear (PPE) and the barriers that exist in preventing their use. A series of focus groups enrolled workers and supervisors primarily from manufacturing, construction, or service/retail industries that had potential exposure to eye injury hazards in their job tasks. Focus group sessions were facilitated to collect qualitative and quantitative data in two categories, "sought information" and "emergent themes", related to the factors influencing use of PPE. We conducted a series of 7 groups with 51 participants, 36 (71%) males and 15 (29%) females ranging in age from 19 to 64 years old, from a variety of occupations including construction (24%), production (22%), installation, repair and maintenance (14%), and healthcare (10%). Most were highly experienced in their occupation (>10 years); males (86%) and females (53%), and had received some safety training in the past (82%). The majority of workers in this study were required to wear PPE on their worksite (78%), however only 55% had a dedicated safety officer. A conceptual model that summarizes the "sought information" and "emergent themes" is presented that depicts the decision making process for the factors influencing use of PPE and consists of three primary branches; perceptions of hazards and risks, "barriers" to PPE usage, and enforcement and reinforcement. Lack of comfort/fit, and fogging and scratching of the eyewear were suggested as the most important barriers to PPE usage. Younger age and lack of safety training were other important factors affecting use of PPE. Several potentially modifiable factors identified would lead to an increase in workers' PPE use and encourage supervisors to provide ongoing positive feedback on the continuous use of PPE by workers at risk for an eye injury.

Controlling Brochothrix thermosphacta as a spoilage risk using in-package atmospheric cold plasma.

PubMed

Patange, Apurva; Boehm, Daniela; Bueno-Ferrer, Carmen; Cullen, P J; Bourke, Paula

2017-09-01

Brochothrix thermosphacta is the predominant spoilage microorganism in meat and its control in processing environments is important to maintain meat product quality. Atmospheric cold plasma is of interest for control of pathogenic and spoilage microorganisms in foods. This study ascertained the potential of dielectric barrier discharge atmospheric cold plasma (DBD-ACP) for control of B. thermosphacta, taking microbial and food environment factors into consideration, and investigated the shelf-life of lamb chop after in-package plasma treatment in modified atmosphere. Community profiling was used to assess the treatment effects on the lamb microflora. ACP treatment (80 kV) for 30s inactivated B. thermosphacta populations below detection levels in PBS, while 5 min treatment achieved a 2 Log cycle reduction using a complex meat model medium and attached cells. The antimicrobial efficacy of plasma was reduced but still apparent on lamb chop surface-inoculated with high concentrations of B. thermosphacta. Lamb chop treated under modified atmosphere exhibited reduced microbial growth over the product shelf-life and community profiling showed no evident changes to the microbial populations after the treatment. The overall results indicated potential of ACP to enhance microbial control leading to meat storage life extension through adjusting the modality of treatment. Copyright © 2017 Elsevier Ltd. All rights reserved.

NOx Direct Decomposition: Potentially Enhanced Thermodynamics and Kinetics on Chemically Modified Ferroelectric Surfaces

NASA Astrophysics Data System (ADS)

Kakekhani, Arvin; Ismail-Beigi, Sohrab

2014-03-01

NOx are regulated pollutants produced during automotive combustion. As part of an effort to design catalysts for NOx decomposition that operate in oxygen rich environment and permit greater fuel efficiency, we study chemistry of NOx on (001) ferroelectric surfaces. Changing the polarization at such surfaces modifies electronic properties and leads to switchable surface chemistry. Using first principles theory, our previous work has shown that addition of catalytic RuO2 monolayer on ferroelectric PbTiO3 surface makes direct decomposition of NO thermodynamically favorable for one polarization. Furthermore, the usual problem of blockage of catalytic sites by strong oxygen binding is overcome by flipping polarization that helps desorb the oxygen. We describe a thermodynamic cycle for direct NO decomposition followed by desorption of N2 and O2. We provide energy barriers and transition states for key steps of the cycle as well as describing their dependence on polarization direction. We end by pointing out how a switchable order parameter of substrate,in this case ferroelectric polarization, allows us to break away from some standard compromises for catalyst design(e.g. the Sabatier principle). This enlarges the set of potentially catalytic metals. Primary support from Toyota Motor Engineering and Manufacturing, North America, Inc.

Psychological predictors of dietary intentions in pregnancy.

PubMed

Gardner, B; Croker, H; Barr, S; Briley, A; Poston, L; Wardle, J

2012-08-01

Consuming a healthy diet in pregnancy has the potential to improve obstetric outcome, including minimising the risk of macrosomia. Effective promotion of dietary change depends on identifying and targeting determinants of gestational diet. The present study aimed to model psychological predictors of intentions to reduce intake of high-fat and high-sugar foods, and increase fruit and vegetable consumption, among pregnant women. One hundred and three pregnant women completed questionnaire measures of intentions to modify the consumption of the target foods, current intake, perceived vulnerability to and severity of adverse outcomes of unhealthful consumption of these foods (i.e. 'threat'), benefits of dietary change to mother and baby, barriers to dietary changes, and social approval for dietary change ('subjective norms'). A cross-sectional design was used. Logistic regression analyses were undertaken to model dietary change intentions. Participants who reported excessive current intake of high-fat and high-sugar foods were more likely to intend to reduce the intake of these foods. Perceived benefits for mother and baby enhanced intentions to eat more fruit and vegetables and eat less high-fat, and marginally significantly increased high-sugar reduction intentions. There were no effects of threat, barriers or subjective norms. Lack of effects for barriers, threat and subjective norms may indicate that pregnant women discount barriers to health-promoting behaviour, understand the threat posed by unhealthy eating and perceive social approval from others. Dietary change interventions for pregnant women should emphasise likely positive outcomes for both mother and child. © 2012 The Authors. Journal of Human Nutrition and Dietetics © 2012 The British Dietetic Association Ltd.

Associations between physical home environmental factors and vegetable consumption among Norwegian 3-5-year-olds: the BRA-study.

PubMed

Kristiansen, Anne Lene; Bjelland, Mona; Himberg-Sundet, Anne; Lien, Nanna; Andersen, Lene Frost

2017-05-01

First, to explore item pools developed to measure the physical home environment of pre-school children and assess the psychometric properties of these item pools; second, to explore associations between this environment and vegetable consumption among Norwegian 3-5-year-olds. Data were collected in three steps: (i) a parental web-based questionnaire assessing the child's vegetable intake and factors potentially influencing the child's vegetable consumption; (ii) direct observation of the children's fruit, berry and vegetable intakes at two meals in one day in the kindergarten; and (iii) a parental web-based 24 h recall. The target group for this study was pre-school children born in 2010 and 2011, attending public or private kindergartens in the counties of Vestfold and Buskerud, Norway. A total of 633 children participated. Principal component analysis on the thirteen-item pool assessing availability/accessibility resulted in two factors labelled 'availability at home' and 'accessibility at home', while the eight-item pool assessing barriers resulted in two factors labelled 'serving barriers' and 'purchase barriers'. The psychometric properties of these factors were satisfactory. Linear regression of the associations between vegetable intake and the factors showed generally positive associations with 'availability at home' and 'accessibility at home' and negative associations with 'serving barriers'. This age group has so far been understudied and there is a need for comparable studies. Our findings highlight the importance of targeting the physical home environment of pre-school children in future interventions as there are important modifiable factors that both promote and hinder vegetable consumption in this environment.

New Perspective in the Formulation and Characterization of Didodecyldimethylammonium Bromide (DMAB) Stabilized Poly(Lactic-co-Glycolic Acid) (PLGA) Nanoparticles

PubMed Central

Gossmann, Rebecca; Langer, Klaus; Mulac, Dennis

2015-01-01

Over the last few decades the establishment of nanoparticles as suitable drug carriers with the transport of drugs across biological barriers such as the gastrointestinal barrier moved into the focus of many research groups. Besides drug transport such carrier systems are well suited for the protection of drugs against enzymatic and chemical degradation. The preparation of biocompatible and biodegradable nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) is intensively described in literature, while especially nanoparticles with cationic properties show a promising increased cellular uptake. This is due to the electrostatic interaction between the cationic surface and the negatively charged lipid membrane of the cells. Even though several studies achieved the successful preparation of nanoparticles stabilized with the cationic surfactants such as didodecyldimethylammonium bromide (DMAB), in most cases insufficient attention was paid to a precise analytical characterization of the nanoparticle system. The aim of the present work was to overcome this deficit by presenting a new perspective in the formulation and characterization of DMAB-stabilized PLGA nanoparticles. Therefore these nanoparticles were carefully examined with regard to particle diameter, zeta potential, the effect of variation in stabilizer concentration, residual DMAB content, and electrolyte stability. Without any steric stabilization, the DMAB-modified nanoparticles were sensitive to typical electrolyte concentrations of biological environments due to compression of the electrical double layer in conjunction with a decrease in zeta potential. To handle this problem, the present study proposed two modifications to enable electrolyte stability. Both polyvinyl alcohol (PVA) and polyethylene glycol (PEG) modified DMAB-PLGA-nanoparticles were stable during electrolyte addition. Furthermore, in contrast to unmodified DMAB-PLGA-nanoparticles and free DMAB, such modifications led to a lower cytotoxic activity against Caco-2 cells. In conclusion this study offers a closer and critical point of view on preparation, in vitro and analytical evaluation of DMAB-stabilized PLGA nanoparticles for the physiological use. PMID:26147338

New Perspective in the Formulation and Characterization of Didodecyldimethylammonium Bromide (DMAB) Stabilized Poly(Lactic-co-Glycolic Acid) (PLGA) Nanoparticles.

PubMed

Gossmann, Rebecca; Langer, Klaus; Mulac, Dennis

2015-01-01

Over the last few decades the establishment of nanoparticles as suitable drug carriers with the transport of drugs across biological barriers such as the gastrointestinal barrier moved into the focus of many research groups. Besides drug transport such carrier systems are well suited for the protection of drugs against enzymatic and chemical degradation. The preparation of biocompatible and biodegradable nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) is intensively described in literature, while especially nanoparticles with cationic properties show a promising increased cellular uptake. This is due to the electrostatic interaction between the cationic surface and the negatively charged lipid membrane of the cells. Even though several studies achieved the successful preparation of nanoparticles stabilized with the cationic surfactants such as didodecyldimethylammonium bromide (DMAB), in most cases insufficient attention was paid to a precise analytical characterization of the nanoparticle system. The aim of the present work was to overcome this deficit by presenting a new perspective in the formulation and characterization of DMAB-stabilized PLGA nanoparticles. Therefore these nanoparticles were carefully examined with regard to particle diameter, zeta potential, the effect of variation in stabilizer concentration, residual DMAB content, and electrolyte stability. Without any steric stabilization, the DMAB-modified nanoparticles were sensitive to typical electrolyte concentrations of biological environments due to compression of the electrical double layer in conjunction with a decrease in zeta potential. To handle this problem, the present study proposed two modifications to enable electrolyte stability. Both polyvinyl alcohol (PVA) and polyethylene glycol (PEG) modified DMAB-PLGA-nanoparticles were stable during electrolyte addition. Furthermore, in contrast to unmodified DMAB-PLGA-nanoparticles and free DMAB, such modifications led to a lower cytotoxic activity against Caco-2 cells. In conclusion this study offers a closer and critical point of view on preparation, in vitro and analytical evaluation of DMAB-stabilized PLGA nanoparticles for the physiological use.

Performance of Poly(lactic acid) Surface Modified Films for Food Packaging Application

PubMed Central

Dalla Rosa, Marco; Iordanskii, Alexey L.

2017-01-01

Five Poly(lactic acid) (PLA) film samples were analyzed to study the gas barrier behavior, thermal stability and mechanical performance for food packaging application. O2, CO2, N2, N2O, and C2H4 pure gases; Air; and Modified Atmosphere (MA, 79% N2O/21% O2) were used to analyze the influence of the chemical structure, storage temperature and crystalline phase on the gas barrier behavior. The kinetic of the permeation process was investigated at different temperatures, ranging from 5 °C to 40 °C. Annealing thermal treatment on the samples led to the crystalline percentage, influencing especially the gas solubility process. Thermal properties such as Tg and χc, and mechanical properties such as tensile strength and modulus were remarkably improved with surface PLA modification. A more pronounced reinforcing effect was noted in the case of metallization, as well as improved gas barrier performance. Tensile testing and tensile cycling tests confirmed the rigidity of the films, with about a 20% loss of elasticity after 25 cycles loading. PMID:28773210

Application of the modified transient plane source technique for early detection of liquid explosives

NASA Astrophysics Data System (ADS)

Bateman, Robert; Harris, Adam; Lee, Linda; Howle, Christopher R.; Ackermann, Sarah L. G.

2016-05-01

The paper will review the feasibility of adapting the Modified Transient Plane Source (MTPS) method as a screening tool for early-detection of explosives and hazardous materials. Materials can be distinguished from others based on their inherent thermal properties (e.g. thermal effusivity) in testing through different types of barrier materials. A complimentary advantage to this technique relative to other traditional detection technologies is that it can penetrate reflective barrier materials, such as aluminum, easily. A strong proof-of-principle is presented on application of the MTPS transient thermal property measuring in the early-screening of liquid explosives. The work demonstrates a significant sensitivity to distinguishing a wide range of fluids based on their thermal properties through a barrier material. The work covers various complicating factors to the longer-term adoption of such a method including the impact of carbonization and viscosity. While some technical challenges remain, the technique offers significant advantages in complimenting existing detection methods in being able to penetrate reflective metal containers (e.g. aluminum soft drinkscans) with ease.

The ground state tunneling splitting and the zero point energy of malonaldehyde: a quantum Monte Carlo determination.

PubMed

Viel, Alexandra; Coutinho-Neto, Maurício D; Manthe, Uwe

2007-01-14

Quantum dynamics calculations of the ground state tunneling splitting and of the zero point energy of malonaldehyde on the full dimensional potential energy surface proposed by Yagi et al. [J. Chem. Phys. 1154, 10647 (2001)] are reported. The exact diffusion Monte Carlo and the projection operator imaginary time spectral evolution methods are used to compute accurate benchmark results for this 21-dimensional ab initio potential energy surface. A tunneling splitting of 25.7+/-0.3 cm-1 is obtained, and the vibrational ground state energy is found to be 15 122+/-4 cm-1. Isotopic substitution of the tunneling hydrogen modifies the tunneling splitting down to 3.21+/-0.09 cm-1 and the vibrational ground state energy to 14 385+/-2 cm-1. The computed tunneling splittings are slightly higher than the experimental values as expected from the potential energy surface which slightly underestimates the barrier height, and they are slightly lower than the results from the instanton theory obtained using the same potential energy surface.

Opportunities for Automated Demand Response in California Agricultural Irrigation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olsen, Daniel; Aghajanzadeh, Arian; McKane, Aimee

Pumping water for agricultural irrigation represents a significant share of California’s annual electricity use and peak demand. It also represents a large source of potential flexibility, as farms possess a form of storage in their wetted soil. By carefully modifying their irrigation schedules, growers can participate in demand response without adverse effects on their crops. This report describes the potential for participation in demand response and automated demand response by agricultural irrigators in California, as well as barriers to widespread participation. The report first describes the magnitude, timing, location, purpose, and manner of energy use in California. Typical on-­farm controlsmore » are discussed, as well as common impediments to participation in demand response and automated demand response programs. Case studies of demand response programs in California and across the country are reviewed, and their results along with overall California demand estimates are used to estimate statewide demand response potential. Finally, recommendations are made for future research that can enhance the understanding of demand response potential in this industry.« less

Influence of rotational energy barriers to the conformational search of protein loops in molecular dynamics and ranking the conformations.

PubMed

Tappura, K

2001-08-15

An adjustable-barrier dihedral angle potential was added as an extension to a novel, previously presented soft-core potential to study its contribution to the efficacy of the search of the conformational space in molecular dynamics. As opposed to the conventional soft-core potential functions, the leading principle in the design of the new soft-core potential, as well as of its extension, the soft-core and adjustable-barrier dihedral angle (SCADA) potential (referred as the SCADA potential), was to maintain the main equilibrium properties of the original force field. This qualifies the methods for a variety of a priori modeling problems without need for additional restraints typically required with the conventional soft-core potentials. In the present study, the different potential energy functions are applied to the problem of predicting loop conformations in proteins. Comparison of the performance of the soft-core and SCADA potential showed that the main hurdles for the efficient sampling of the conformational space of (loops in) proteins are related to the high-energy barriers caused by the Lennard-Jones and Coulombic energy terms, and not to the rotational barriers, although the conformational search can be further enhanced by lowering the rotational barriers of the dihedral angles. Finally, different evaluation methods were studied and a few promising criteria found to distinguish the near-native loop conformations from the wrong ones.

Atomic Force Microscope Studies of the Fusion of Floating Lipid Bilayers

PubMed Central

Abdulreda, Midhat H.; Moy, Vincent T.

2007-01-01

This study investigated the fusion of apposing floating bilayers of egg L-α-phosphatidylcholine (egg PC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine. Atomic force microscope measurements of fusion forces under different compression rates were acquired to reveal the energy landscape of the fusion process under varied lipid composition and temperature. Between compression rates of ∼1000 and ∼100,000 pN/s, applied forces in the range from ∼100 to ∼500 pN resulted in fusion of floating bilayers. Our atomic force microscope measurements indicated that one main energy barrier dominated the fusion process. The acquired dynamic force spectra were fit with a simple model based on the transition state theory with the assumption that the fusion activation potential is linear. A significant shift in the energy landscape was observed when bilayer fluidity and composition were modified, respectively, by temperature and different cholesterol concentrations (15% ≤ chol ≤ 25%). Such modifications resulted in a more than twofold increase in the width of the fusion energy barrier for egg PC and 1,2-dimyristoyl-sn-glycero-3-phosphocholine floating bilayers. The addition of 25% cholesterol to egg PC bilayers increased the activation energy by ∼1.0 kBT compared with that of bilayers with egg PC alone. These results reveal that widening of the energy barrier and consequently reduction in its slope facilitated membrane fusion. PMID:17400691

Atomic force microscope studies of the fusion of floating lipid bilayers.

PubMed

Abdulreda, Midhat H; Moy, Vincent T

2007-06-15

This study investigated the fusion of apposing floating bilayers of egg L-alpha-phosphatidylcholine (egg PC) or 1,2-dimyristoyl-sn-glycero-3-phosphocholine. Atomic force microscope measurements of fusion forces under different compression rates were acquired to reveal the energy landscape of the fusion process under varied lipid composition and temperature. Between compression rates of approximately 1000 and approximately 100,000 pN/s, applied forces in the range from approximately 100 to approximately 500 pN resulted in fusion of floating bilayers. Our atomic force microscope measurements indicated that one main energy barrier dominated the fusion process. The acquired dynamic force spectra were fit with a simple model based on the transition state theory with the assumption that the fusion activation potential is linear. A significant shift in the energy landscape was observed when bilayer fluidity and composition were modified, respectively, by temperature and different cholesterol concentrations (15% < or = chol < or = 25%). Such modifications resulted in a more than twofold increase in the width of the fusion energy barrier for egg PC and 1,2-dimyristoyl-sn-glycero-3-phosphocholine floating bilayers. The addition of 25% cholesterol to egg PC bilayers increased the activation energy by approximately 1.0 k(B)T compared with that of bilayers with egg PC alone. These results reveal that widening of the energy barrier and consequently reduction in its slope facilitated membrane fusion.

Is the metaphor of 'barriers to change' useful in understanding implementation? Evidence from general medical practice.

PubMed

Checkland, Kath; Harrison, Stephen; Marshall, Martin

2007-04-01

To investigate how general medical practices in the UK react to bureaucratic initiatives, such as National Health Service (NHS) National Service Frameworks (NSFs), and to explore the value of the metaphor of 'barriers to change' for understanding this. Interviews, non-participant observation and documentary analysis within case studies of four practices in northern England. The practices had not actively implemented NSFs. At interview, various 'barriers' that had prevented implementation were listed, including the complexity of the documents and lack of time. Observation suggested that these barriers were constructions used by the participants to make sense of the situation in which they found themselves. The metaphor of 'removing barriers to change' was of limited use in a context where non-implementation of policy was an emergent property of underlying organizational realities, likely to be modifiable only if these realities were addressed.

Race Attribution Modifies the Association Between Daily Discrimination and Major Depressive Disorder Among Blacks: the Role of Gender and Ethnicity.

PubMed

Assari, Shervin; Watkins, Daphne C; Caldwell, Cleopatra H

2015-06-01

Although the association between discrimination and depression among Blacks is well-known, we do not know if this effect is influenced by race attribution. In this current study, we investigated the effect modification of race attribution on the association between everyday discrimination and major depressive disorder (MDD) among Blacks in the United States, and whether this effect modification is influenced by the intersection of ethnicity and gender. With a cross-sectional design, this study used data from the National Survey of American Life (NSAL), 2001-2003. The study included a nationally representative sample of Blacks (n = 5,008), composed of 3,570 African Americans and 1,438 Caribbean Blacks. Everyday discrimination, two single-item measures of race attribution (race as the major barrier against upward social mobility, and race as the main cause for being discriminated against) and 12-month MDD were measured. In the first step, we fit logistic regressions to the pooled sample. In the next step, we ran regressions specific to the intersections of ethnicity and gender. Interaction between race attribution and discrimination were also entered into the models. Among Caribbean Black men, the belief that race is a major barrier against one's own upward social mobility modified the association between exposure to daily discrimination and MDD. In this group, the association between discrimination and MDD was weaker among those who believed that race is a major barrier against one's own upward social mobility. Race attribution did not modify the association between discrimination and MDD among African American men, African American women, and Caribbean Black women. The other measure of race attribution (race as the main cause of being discriminated against) did not modify the association between discrimination and MDD in any ethnicity by gender subgroups. Among Caribbean Black men, the link between everyday discrimination and depression may depend on seeing race as the main barrier against upward social mobility. Among African American men and women, however, the link between discrimination and MDD does not depend on race attribution. Our results suggest that ethnicity, gender, and race attribution may alter the association between discrimination and risk of MDD among Blacks.

Barrier inhomogeneities and electronic transport of Pt contacts to relatively highly doped n-type 4H-SiC

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, Lingqin, E-mail: lqhuang@jsnu.edu.cn, E-mail: dwang121@dlut.edu.cn; Wang, Dejun, E-mail: lqhuang@jsnu.edu.cn, E-mail: dwang121@dlut.edu.cn

The barrier characteristics of Pt contacts to relatively highly doped (∼1 × 10{sup 18 }cm{sup −3}) 4H-SiC were investigated using current-voltage (I-V) and capacitance-voltage (C-V) measurements in the temperature range of 160–573 K. The barrier height and ideally factor estimated from the I-V characteristics based on the thermionic emission model are abnormally temperature-dependent, which can be explained by assuming the presence of a double Gaussian distribution (GD) of inhomogeneous barrier heights. However, in the low temperature region (160–323 K), the obtained mean barrier height according to GD is lower than the actual mean value from C-V measurement. The values of barrier height determined from themore » thermionic field emission model are well consistent with those from the C-V measurements, which suggest that the current transport process could be modified by electron tunneling at low temperatures.« less

Barriers to advancement in academic surgery: views of senior residents and early career faculty.

PubMed

Cochran, Amalia; Elder, William B; Crandall, Marie; Brasel, Karen; Hauschild, Tricia; Neumayer, Leigh

2013-11-01

A significant faculty attrition rate exists in academic surgery. The authors hypothesized that senior residents and early-career faculty members have different perceptions of advancement barriers in academic surgery. A modified version of the Career Barriers Inventory-Revised was administered electronically to surgical residents and early-career surgical faculty members at 8 academic medical centers. Residents identified a lack of mentorship as a career barrier about half as often as faculty members. Residents were twice as likely as faculty members to view childbearing as a career barrier. Many early-career faculty members cite a lack of mentors as a limitation to their career development in academic surgery. Childbearing remains a complex perceived influence for female faculty members in particular. Female faculty members commonly perceive differential treatment and barriers on the basis of their sex. Faculty development programs should address both systemic and sex-specific obstacles if academic surgery is to remain a vibrant field. Copyright © 2013 Elsevier Inc. All rights reserved.

Conductance and refraction across a Barrier in Phosphorene

NASA Astrophysics Data System (ADS)

Dahal, Dipendra; Gumbs, Godfrey

The transmission coefficient and ballistic conductance for monolayer black phosphorene is calculated when a potential step or square barrier is present. The Landauer-B¨uttiker formalism is employed in our calculations of the conductance. We obtain the refractive index for the step potential barrier when an incident beam of electron travel along different paths so as to observe what role the anisotropy of the energy bands plays. Numerical results are presented for various potential heights and barrier widths and these are compared with those for gapless and gapped graphene.

Intranasal gene delivery for treating Parkinson's disease: overcoming the blood-brain barrier.

PubMed

Aly, Amirah E-E; Waszczak, Barbara L

2015-01-01

Developing a disease-modifying gene therapy for Parkinson's disease (PD) has been a high priority for over a decade. However, due to the inability of large biomolecules to cross the blood-brain barrier (BBB), the only means of delivery to the brain has been intracerebral infusion. Intranasal administration offers a non-surgical means of bypassing the BBB to deliver neurotrophic factors, and the genes encoding them, directly to the brain. This review summarizes: i) evidence demonstrating intranasal delivery to the brain of a number of biomolecules having therapeutic potential for various CNS disorders; and ii) evidence demonstrating neuroprotective efficacy of a subset of biomolecules specifically for PD. The intersection of these two spheres represents the area of opportunity for development of new intranasal gene therapies for PD. To that end, our laboratory showed that intranasal administration of glial cell line-derived neurotrophic factor (GDNF), or plasmid DNA nanoparticles encoding GDNF, provides neuroprotection in a rat model of PD, and that the cells transfected by the nanoparticle vector are likely to be pericytes. A number of genes encoding neurotrophic factors have therapeutic potential for PD, but few have been tested by the intranasal route and shown to be neuroprotective in a model of PD. Intranasal delivery provides a largely unexplored, promising approach for development of a non-invasive gene therapy for PD.

Comparison of atmospheric microplasma and plasma jet irradiation for increasing of skin permeability

NASA Astrophysics Data System (ADS)

Shimizu, K.; Tran, N. A.; Hayashida, K.; Blajan, M.

2016-08-01

Atmospheric plasma is attracting interest for medical applications such as sterilization, treatment of cancer cells and blood coagulation. Application of atmospheric plasma in dermatology has potential as a novel tool for wound healing, skin rejuvenation and treatment of wrinkles. In this study, we investigated the enhancement of percutaneous absorption of dye as alternative agents of transdermal drugs. Hypodermic needles are often the only way to deliver large-molecule drugs into the dermis, although a safe transdermal drug delivery method that does not require needles would be desirable. We therefore explored the feasibility of using atmospheric microplasma irradiation to enhance percutaneous absorption of drugs, as an alternative delivery method to conventional hypodermic needles. Pig skin was used as a biological sample, exposed to atmospheric microplasma, and analyzed by attenuated total reflection-Fourier transform infrared spectroscopy. A tape stripping test, a representative method for evaluating skin barrier performance, was also conducted for comparison. Transepidermal water loss (TEWL) was measured and compared with and without atmospheric microplasma irradiation, to quantify water evaporation from the inner body through the skin barrier. The results show that the stratum corneum, the outermost skin layer, could be chemically and physically modified by atmospheric microplasma irradiation. Physical damage to the skin by microplasma irradiation and an atmospheric plasma jet was also assessed by observing the skin surface. The results suggest that atmospheric microplasma has the potential to enhance percutaneous absorption.

Permselective SPEEK/Nafion Composite-Coated Separator as a Potential Polysulfide Crossover Barrier Layer for Li-S Batteries.

PubMed

Babu, Dasari Bosu; Giribabu, Krishnan; Ramesha, Kannadka

2018-06-13

Minimizing the shuttle effect by constraining polysulfides to the cathode compartment and activating the passive layer between cathode and separator are highly important for improving the Li-S cell performance, Coulombic efficiency, and cycle life. Here, we report a submicron thin coating of permselective sulfonated poly(ether ether ketone) (SPEEK) composite layer on the separator that would reduce polysulfide crossover, imparting a significant improvement in cycle life. It is observed that SPEEK increases the stability, and adding Nafion improves the capacity value. Among different ratios of Nafion and SPEEK (25:75, 50:50, and 75:25), the composite with a SPEEK/Nafion ratio of 50:50 showed a controlled shuttle effect with a stable cell capacity of 600 mA h g -1 up to 300 cycles. This modified separator with permselective coatings not only reduces the polysulfide shuttle but also improves the wettability and interfacial contact, which results in an improvement in average cell potential and lithium diffusivity. It is demonstrated here that the combination of functional (ionomer coating on separator) and nonfunctional (extra cathode layer) physical barriers effectively suppresses the polysulfide crossover and improves the electrochemical performance of Li-S batteries. The cell shows an initial capacity of 1300 mA h g -1 and a capacity retention of 650 mA h g -1 over 500 cycles with a 6 mg/cm 2 sulfur loading.

Challenges and barriers for implementation of the World Health Organization Global Disability Action Plan in low- and middle- income countries.

PubMed

Khan, Fary; Owolabi, Mayowa Ojo; Amatya, Bhasker; Hamzat, Talhatu Kolapo; Ogunniyi, Adesola; Oshinowo, Helen; Elmalik, Alaeldin; Galea, Mary P

2018-04-18

To identify potential barriers and facilitators for implementation of the World Health Organization Global Disability Action Plan (GDAP) in Nigeria and compare these with other low- and middle-income countries. A rehabilitation team from the Royal Melbourne Hospital, Parkville, Australia, conducted intensive workshops at medical/academic institutions in Nigeria for healthcare professionals from various local Physical Medicine and Rehabilitation facilities. A modified Delphi method identified challenges for person with disability, using 3 GDAP objectives. Findings were compared with similar exercises in Madagascar, Pakistan and Mongolia. Despite differences in the healthcare system and practice, the challenges reported in Nigeria were similar to those in other 3 low- and middle-income countries, at both macro (governmental/policymakers) and micro levels (community/social/individual). Common challenges identified were: limited knowledge of disability services, limited Physical Medicine and Rehabilitation workforce, guidelines and accreditation standards; coordination amongst healthcare sectors; social issues; data and research; legislation and political commitment. Common potential facilitators included: need for strong leadership; advocacy of disability-inclusive development; investment in infrastructure/human resources; coordination/partnerships in healthcare sector; and research. Disability care is an emerging priority in low- and middle-income countries to address the needs of people with disability. The challenges identified in Nigeria are common to most low- and middle-income countries. The GDAP framework can facilitate access and strengthen Physical Medicine and Rehabilitation services.

Statistical and dynamical modeling of heavy-ion fusion-fission reactions

NASA Astrophysics Data System (ADS)

Eslamizadeh, H.; Razazzadeh, H.

2018-02-01

A modified statistical model and a four dimensional dynamical model based on Langevin equations have been used to simulate the fission process of the excited compound nuclei 207At and 216Ra produced in the fusion 19F + 188Os and 19F + 197Au reactions. The evaporation residue cross section, the fission cross section, the pre-scission neutron, proton and alpha multiplicities and the anisotropy of fission fragments angular distribution have been calculated for the excited compound nuclei 207At and 216Ra. In the modified statistical model the effects of spin K about the symmetry axis and temperature have been considered in calculations of the fission widths and the potential energy surfaces. It was shown that the modified statistical model can reproduce the above mentioned experimental data by using appropriate values of the temperature coefficient of the effective potential equal to λ = 0.0180 ± 0.0055, 0.0080 ± 0.0030 MeV-2 and the scaling factor of the fission barrier height equal to rs = 1.0015 ± 0.0025, 1.0040 ± 0.0020 for the compound nuclei 207At and 216Ra, respectively. Three collective shape coordinates plus the projection of total spin of the compound nucleus on the symmetry axis, K, were considered in the four dimensional dynamical model. In the dynamical calculations, dissipation was generated through the chaos weighted wall and window friction formula. Comparison of the theoretical results with the experimental data showed that two models make it possible to reproduce satisfactorily the above mentioned experimental data for the excited compound nuclei 207At and 216Ra.

Potential use of polymeric nanoparticles for drug delivery across the blood-brain barrier.

PubMed

Tosi, G; Bortot, B; Ruozi, B; Dolcetta, D; Vandelli, M A; Forni, F; Severini, G M

2013-01-01

Nanomedicine is certainly one of the scientific and technological challenges of the coming years. In particular, biodegradable nanoparticles formulated from poly (D,L-lactide-co-glycolide) (PLGA) have been extensively investigated for sustained and targeted delivery of different agents, including recombinant proteins, plasmid DNA, and low molecular weight compounds. PLGA NPs present some very attractive properties such as biodegradability and biocompatibility, protection of drug from degradation, possibility of sustained release, and the possibility to modify surface properties to target nanoparticles to specific organs or cells. Moreover, PLGA NPs have received the FDA and European Medicine Agency approval in drug delivery systems for parenteral administration, thus reducing the time for human clinical applications. This review in particular deals on surface modification of PLGA NPs and their possibility of clinical applications, including treatment for brain pathologies such as brain tumors and Lysosomal Storage Disorders with neurological involvement. Since a great number of pharmacologically active molecules are not able to cross the Blood-Brain Barrier (BBB) and reach the Central Nervous System (CNS), new brain targeted polymeric PLGA NPs modified with glycopeptides (g7- NPs) have been recently produced. In this review several in vivo biodistribution studies and pharmacological proof-of evidence of brain delivery of model drugs are reported, demonstrating the ability of g7-NPs to create BBB interaction and trigger an efficacious BBB crossing. Moreover, another relevant development of NPs surface engineering was achieved by conjugating to the surface of g7-NPs, some specific and selective antibodies to drive NPs directly to a specific cell type once inside the CNS parenchyma.

Biological Risks and Laboratory-Acquired Infections: A Reality That Cannot be Ignored in Health Biotechnology

PubMed Central

Coelho, Ana Cláudia; García Díez, Juan

2015-01-01

Advances and research in biotechnology have applications over a wide range of areas, such as microbiology, medicine, the food industry, agriculture, genetically modified organisms, and nanotechnology, among others. However, research with pathogenic agents, such as virus, parasites, fungi, rickettsia, bacterial microorganisms, or genetic modified organisms, has generated concern because of their potential biological risk – not only for people, but also for the environment due to their unpredictable behavior. In addition, concern for biosafety is associated with the emergence of new diseases or re-emergence of diseases that were already under control. Biotechnology laboratories require biosafety measures designed to protect their staff, the population, and the environment, which may be exposed to hazardous organisms and materials. Laboratory staff training and education is essential, not only to acquire a good understanding about the direct handling of hazardous biological agents but also knowledge of the epidemiology, pathogenicity, and human susceptibility to the biological materials used in research. Biological risk can be reduced and controlled by the correct application of internationally recognized procedures such as proper microbiological techniques, proper containment apparatus, adequate facilities, protective barriers, and special training and education of laboratory workers. To avoid occupational infections, knowledge about standardized microbiological procedures and techniques and the use of containment devices, facilities, and protective barriers is necessary. Training and education about the epidemiology, pathogenicity, and biohazards of the microorganisms involved may prevent or decrease the risk. In this way, the scientific community may benefit from the lessons learned in the past to anticipate future problems. PMID:25973418

Tat-modified leptin is more accessible to hypothalamus through brain-blood barrier with a significant inhibition of body-weight gain in high-fat-diet fed mice.

PubMed

Zhang, C; Su, Z; Zhao, B; Qu, Q; Tan, Y; Cai, L; Li, X

2010-01-01

Obesity in human was found mainly due to the poor transportation of leptin through brain-blood barrier (BBB), called as leptin resistance. To produce a leptin capable of penetrating BBB, we have added Tat-PTD(9) to the C terminal of leptin to construct a fusion protein. The fusion Tat-leptin and native leptin genes were synthesized by single-step insertion of a polymerase chain reaction and expressed in Escherichia coli BL21 (Rosseta). The expressing products were purified and renatured by Ni-NTA affinity chromatography, and identified by the molecular size in SDS-PAGE gel and by its immunoreactivity to specific antibody with Western-blotting assay. To bio-functionally evaluate the fusion protein, Balb/c mice fed with high-fat diet (HFD) were given Tat-leptin, leptin or saline for 19 days. The immunohistochemical staining showed the increases in positive stains for the leptin in the region of hypothalamus of the HFD mice with either Tat-leptin or leptin as compared to saline group, but the staining intensity and frequency in the group with Tat-leptin were stronger and higher than those in the group with leptin. Furthermore, the most efficiency in preventing the body-weight gain caused by HFD was found in Tat-leptin group among these three groups. These results suggest that Tat-modified leptin may become a great potential candidate for the prevention or therapy of obese patients. J. A. Barth Verlag in Georg Thieme Verlag KG Stuttgart , New York.

Self-efficacy for physical activity and insight into its benefits are modifiable factors associated with physical activity in people with COPD: a mixed-methods study.

PubMed

Hartman, Jorine E; ten Hacken, Nick H T; Boezen, H Marike; de Greef, Mathieu H G

2013-06-01

What are the perceived reasons for people with chronic obstructive pulmonary disease (COPD) to be physically active or sedentary? Are those reasons related to the actual measured level of physical activity? A mixed-methods study combining qualitative and quantitative approaches. People with mild to very severe COPD. Participants underwent a semi-structured interview and physical activity was measured by a triaxial accelerometer worn for one week. Of 118 enrolled, 115 participants (68% male, mean age 65 years, mean FEV1 57% predicted, mean modified Medical Research Council dyspnoea score 1.4) completed the study. The most frequently reported reason to be physically active was health benefits, followed by enjoyment, continuation of an active lifestyle from the past, and functional reasons. The most frequently reported reason to be sedentary was the weather, followed by health problems, and lack of intrinsic motivation. Mean steps per day ranged between 236 and 18 433 steps. A high physical activity level was related to enjoyment and self-efficacy for physical activity. A low physical activity level was related to the weather influencing health, financial constraints, health and shame. We identified important facilitators to being physically active and barriers that could be amenable to change. Furthermore, we distinguished three important potential strategies for increasing physical activity in sedentary people with COPD, namely reducing barriers and increasing insight into health benefits, tailoring type of activity, and improvement of self-efficacy. Copyright © 2013 Australian Physiotherapy Association. Published by .. All rights reserved.

Economic analysis of opportunities to accelerate Alzheimer’s disease research and development

PubMed Central

Scott, Troy J; O'Connor, Alan C; Link, Albert N; Beaulieu, Travis J

2014-01-01

The development of disease-modifying treatments for Alzheimer's disease (AD) faces a number of barriers. Among these are the lack of surrogate biomarkers, the exceptional size and duration of clinical trials, difficulties in identifying appropriate populations for clinical trials, and the limitations of monotherapies in addressing such a complex multifactorial disease. This study sets out to first estimate the consequent impact on the expected cost of developing disease-modifying treatments for AD and then to estimate the potential benefits of bringing together industry, academic, and government stakeholders to co-invest in, for example, developing better biomarkers and cognitive assessment tools, building out advanced registries and clinical trial-readiness cohorts, and establishing clinical trial platforms to investigate combinations of candidate drugs and biomarkers from the portfolios of multiple companies. Estimates based on interviews with experts on AD research and development suggest that the cost of one new drug is now $5.7 billion (95% confidence interval (CI) $3.7–9.5 billion) and could be reduced to $2.0 billion (95% CI $1.5–2.9 billion). The associated acceleration in the arrival of disease-modifying treatments could reduce the number of case years of dementia by 7.0 million (95% CI 4.4–9.4 million) in the United States from 2025 through 2040. PMID:24673372

Total quality management: Strengths and barriers to implementation and cultural adaptation

NASA Technical Reports Server (NTRS)

Siegfeldt, Denise V.; Glenn, Michael; Hamilton, Louise

1992-01-01

NASA/Langley Research Center (LaRC) is in the process of implementing Total Quality Management (TQM) throughout the organization in order to improve productivity and make the Center an even better place to work. The purpose of this project was to determine strengths and barriers to TQM being implemented and becoming a part of the organizational culture of the Human Resources Management Division (HRMD) at Langley. The target population for this project was both supervisory and nonsupervisory staff of the HMRD. In order to generate data on strengths and barriers to TQM implementation and cultural adaptation, a modified nominal group technique was used.

Improving particle beam acceleration in plasmas

NASA Astrophysics Data System (ADS)

C. de Sousa, M.; L. Caldas, I.

2018-04-01

The dynamics of wave-particle interactions in magnetized plasmas restricts the wave amplitude to moderate values for particle beam acceleration from rest energy. We analyze how a perturbing invariant robust barrier modifies the phase space of the system and enlarges the wave amplitude interval for particle acceleration. For low values of the wave amplitude, the acceleration becomes effective for particles with initial energy close to the rest energy. For higher values of the wave amplitude, the robust barrier controls chaos in the system and restores the acceleration process. We also determine the best position for the perturbing barrier in phase space in order to increase the final energy of the particles.

Effect of inhomogeneous Schottky barrier height of SnO2 nanowires device

NASA Astrophysics Data System (ADS)

Amorim, Cleber A.; Bernardo, Eric P.; Leite, Edson R.; Chiquito, Adenilson J.

2018-05-01

The current–voltage (I–V) characteristics of metal–semiconductor junction (Au–Ni/SnO2/Au–Ni) Schottky barrier in SnO2 nanowires were investigated over a wide temperature range. By using the Schottky–Mott model, the zero bias barrier height Φ B was estimated from I–V characteristics, and it was found to increase with increasing temperature; on the other hand the ideality factor (n) was found to decrease with increasing temperature. The variation in the Schottky barrier and n was attributed to the spatial inhomogeneity of the Schottky barrier height. The experimental I–V characteristics exhibited a Gaussian distribution having mean barrier heights {\\overline{{{Φ }}}}B of 0.30 eV and standard deviation σ s of 60 meV. Additionally, the Richardson modified constant was obtained to be 70 A cm‑2 K‑2, leading to an effective mass of 0.58m 0. Consequently, the temperature dependence of I–V characteristics of the SnO2 nanowire devices can be successfully explained on the Schottky–Mott theory framework taking into account a Gaussian distribution of barrier heights.

75 FR 28663 - Government-Owned Inventions, Available for Licensing

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-21

... Crack Arresting Barrier. NASA Case No. MFS-32605-1-CIP: Neutron Guides and Methods of Fabrication. NASA...-32697-1: Friction Modifier Using Adherent Metallic Multilayered or Mixed Element Layer Conversion...

Motivators and barriers to a healthy postpartum lifestyle in women at increased cardiovascular and metabolic risk: a focus-group study.

PubMed

Hoedjes, Meeke; Berks, Durk; Vogel, Ineke; Franx, Arie; Duvekot, Johannes J; Oenema, Anke; Steegers, Eric A P; Raat, Hein

2012-01-01

To describe the motivators and barriers to the adoption of a healthy postpartum lifestyle after a pregnancy complicated by preeclampsia, intrauterine growth restriction, and/or gestational diabetes. Thirty-six women with complicated pregnancies participated in six focus-group interviews that aimed to explore the perceptions of modifiable determinants of postpartum lifestyle. Although women expressed that they intended to live a healthy postpartum lifestyle, it was generally not achieved. The motivators included improving their own current health condition as well as modeling a healthy lifestyle for their children. Important barriers were reported to be lack of knowledge, poor recovery, and lack of professional support after delivery. The reported motivators and barriers can be used to develop a postpartum lifestyle intervention.

Advanced Environmental Barrier Coatings Development for Si-Based Ceramics

NASA Technical Reports Server (NTRS)

Zhu, Dong-Ming; Choi, R. Sung; Robinson, Raymond C.; Lee, Kang N.; Bhatt, Ramakrishna T.; Miller, Robert A.

2005-01-01

Advanced environmental barrier coating concepts based on multi-component HfO2 (ZrO2) and modified mullite systems are developed for monolithic Si3N4 and SiC/SiC ceramic matrix composite (CMC) applications. Comprehensive testing approaches were established using the water vapor cyclic furnace, high pressure burner rig and laser heat flux steam rig to evaluate the coating water vapor stability, cyclic durability, radiation and erosion resistance under simulated engine environments. Test results demonstrated the feasibility and durability of the environmental barrier coating systems for 2700 to 3000 F monolithic Si3N4 and SiC/SiC CMC component applications. The high-temperature-capable environmental barrier coating systems are being further developed and optimized in collaboration with engine companies for advanced turbine engine applications.

Understanding the modifiable health systems barriers to hypertension management in Malaysia: a multi-method health systems appraisal approach.

PubMed

Risso-Gill, Isabelle; Balabanova, Dina; Majid, Fadhlina; Ng, Kien Keat; Yusoff, Khalid; Mustapha, Feisul; Kuhlbrandt, Charlotte; Nieuwlaat, Robby; Schwalm, J-D; McCready, Tara; Teo, Koon K; Yusuf, Salim; McKee, Martin

2015-07-03

The growing burden of non-communicable diseases in middle-income countries demands models of care that are appropriate to local contexts and acceptable to patients in order to be effective. We describe a multi-method health system appraisal to inform the design of an intervention that will be used in a cluster randomized controlled trial to improve hypertension control in Malaysia. A health systems appraisal was undertaken in the capital, Kuala Lumpur, and poorer-resourced rural sites in Peninsular Malaysia and Sabah. Building on two systematic reviews of barriers to hypertension control, a conceptual framework was developed that guided analysis of survey data, documentary review and semi-structured interviews with key informants, health professionals and patients. The analysis followed the patients as they move through the health system, exploring the main modifiable system-level barriers to effective hypertension management, and seeking to explain obstacles to improved access and health outcomes. The study highlighted the need for the proposed intervention to take account of how Malaysian patients seek treatment in both the public and private sectors, and from western and various traditional practitioners, with many patients choosing to seek care across different services. Patients typically choose private care if they can afford to, while others attend heavily subsidised public clinics. Public hypertension clinics are often overwhelmed by numbers of patients attending, so health workers have little time to engage effectively with patients. Treatment adherence is poor, with a widespread belief, stemming from concepts of traditional medicine, that hypertension is a transient disturbance rather than a permanent asymptomatic condition. Drug supplies can be erratic in rural areas. Hypertension awareness and education material are limited, and what exist are poorly developed and ineffective. Despite having a relatively well funded health system offering good access to care, Malaysia's health system still has significant barriers to effective hypertension management. The study uncovered major patient-related barriers to the detection and control of hypertension which will have an impact on the design and implementation of any hypertension intervention. Appropriate models of care must take account of the patient modifiable health systems barriers if they are to have any realistic chance of success; these findings are relevant to many countries seeking to effectively control hypertension despite resource constraints.

The Role of eHealth in Optimizing Preventive Care in the Primary Care Setting.

PubMed

Carey, Mariko; Noble, Natasha; Mansfield, Elise; Waller, Amy; Henskens, Frans; Sanson-Fisher, Rob

2015-05-22

Modifiable health risk behaviors such as smoking, overweight and obesity, risky alcohol consumption, physical inactivity, and poor nutrition contribute to a substantial proportion of the world's morbidity and mortality burden. General practitioners (GPs) play a key role in identifying and managing modifiable health risk behaviors. However, these are often underdetected and undermanaged in the primary care setting. We describe the potential of eHealth to help patients and GPs to overcome some of the barriers to managing health risk behaviors. In particular, we discuss (1) the role of eHealth in facilitating routine collection of patient-reported data on lifestyle risk factors, and (2) the role of eHealth in improving clinical management of identified risk factors through provision of tailored feedback, point-of-care reminders, tailored educational materials, and referral to online self-management programs. Strategies to harness the capacity of the eHealth medium, including the use of dynamic features and tailoring to help end users engage with, understand, and apply information need to be considered and maximized. Finally, the potential challenges in implementing eHealth solutions in the primary care setting are discussed. In conclusion, there is significant potential for innovative eHealth solutions to make a contribution to improving preventive care in the primary care setting. However, attention to issues such as data security and designing eHealth interfaces that maximize engagement from end users will be important to moving this field forward.

The management of pain in arthritis and the use of cyclooxygenase-2 inhibitors: new paradigms and insights.

PubMed

Ross, Edgar

2004-12-01

Chronic pain from arthritis has been one of the biggest causes of disability and loss of function in the United States. This is still the case despite many new insights into the pathophysiology of pain, effective treatment approaches, and new safer medications that can be used for long-term use. There are many different types of arthritic problems. New disease- modifying agents that are available for some of these types of arthritic diseases such as rheumatoid arthritis have the potential to have a substantial impact on improvement in the long-term prognosis. Despite this optimistic outlook, pain often is a significant problem and should be treated whenever it becomes a barrier to function.

Temperature and voltage stress dependent dielectric relaxation process of the doped Ba0.67Sr0.33TiO3 ceramics

NASA Astrophysics Data System (ADS)

Yan, Shiguang; Mao, Chaoliang; Wang, Genshui; Yao, Chunhua; Cao, Fei; Dong, Xianlin

2013-09-01

The current decay characteristic in the time domain is studied in Y3+ and Mn2+ modified Ba0.67Sr0.33TiO3 ceramics under different temperatures (25 °C-213 °C) and voltage stresses (0 V-800 V). The decay of the current is correlated with the overlapping of the relaxation process and leakage current. With respect to the inherent remarkable dielectric nonlinearity, a simple method through curve fitting is derived to differentiate these two currents. Two mechanisms of the relaxation process are proposed: a distribution of the potential barriers mode around room temperature and an electron injection mode at the elevated temperature of 110 °C.

In silico direct folding of thrombin-binding aptamer G-quadruplex at all-atom level

PubMed Central

Yang, Changwon; Kulkarni, Mandar; Lim, Manho

2017-01-01

Abstract The reversible folding of the thrombin-binding DNA aptamer G-quadruplexes (GQs) (TBA-15) starting from fully unfolded states was demonstrated using a prolonged time scale (10–12 μs) parallel tempering metadynamics (PTMetaD) simulation method in conjunction with a modified version of the AMBER bsc1 force field. For unbiased descriptions of the folding free energy landscape of TBA-15, this force field was minimally modified. From this direct folding simulation using the modified bsc1 force field, reasonably converged free energy landscapes were obtained in K+-rich aqueous solution (150 mM), providing detailed atomistic pictures of GQ folding mechanisms for TBA-15. This study found that the TBA folding occurred via multiple folding pathways with two major free energy barriers of 13 and 15 kcal/mol in the presence of several intermediate states of G-triplex variants. The early formation of these intermediates was associated with a single K+ ion capturing. Interestingly, these intermediate states appear to undergo facile transitions among themselves through relatively small energy barriers. PMID:29112755

Spectroscopic investigation of a dielectric barrier discharge in modified atmosphere packaging

NASA Astrophysics Data System (ADS)

Milosavljević, Vladimir; Cullen, Patrick J.

2017-11-01

Diagnostics of a dielectric barrier discharge (DBD), in a sealed package (with and without meat) filled with gas mixtures of oxygen and carbon-dioxide (O2-CO2), is reported. The generation and evaluation of the plasma chemistry induced within the confines of the sealed package is studied. The plasma discharges were analyzed by optical emission spectroscopy (OES) and optical absorption spectroscopy (OAS) over a range of plasma process parameters. The study includes a detailed experimental investigation of the spatial and temporal spectroscopic data and links them with plasma kinetics. The results from the spectral radiation from package provide information about the electron energy distribution function. The experimental data indicates that the humidity level in the package with and without meat is unchanged, and that the gas temperature was not significantly modified. Oxygen and nitrogen radicals (trapped gas atmosphere and modified atmosphere) are increased in the package containing meat; at the same time there is no evidence of the presence of carbon monoxide molecules. The role of the nitrogen molecule in the quenching of O2 and CO2 molecules is also evaluated.

[Adhesion prevention after Cesarean section by short-term biological barrier of modified chitosan].

PubMed

Shen, Wei; Shen, Guofang; Li, Lüwei

2014-02-25

To evaluate the efficacies of modified chitosan, an adhesive prevention substance, as a biological barrier for preventing adhesion after Cesarean section. A total of 250 cases undergoing primary Cesarean section from January 2011 to June 2012 at our hospital were recruited. They were randomly divided into experiment (n = 130) and control (n = 120) groups. The experiment group received modified chitosan during Cesarean section while no adhesive prevention substance was offered for the control group. Postoperative flatus time, postoperative infection and pelvic adhesion were used to evaluate the clinical efficacies. For the experiment group, the average postoperative flatus time was (25 ± 7) hours. Three cases had postoperative infections with a postoperative infection rate of 2.3%. There were 2 cases of pelvic adhesion (pelvic adhesion rate: 1.5%) during the postoperative follow-up period. For the control group, the average postoperative flatus time was (34 ± 11) hours. Five cases had postoperative infections with a postoperative infection rate of 4.2%. There were 5 cases of pelvic adhesion (pelvic adhesion rate: 4.2%) during the postoperative follow-up period. There were significant inter-group differences in postoperative flatus time, postoperative infection and pelvic adhesion (P < 0.05). Modified chitosan can prevent pelvic adhesion after Cesarean section.

Tailoring Lipid and Polymeric Nanoparticles as siRNA Carriers towards the Blood-Brain Barrier - from Targeting to Safe Administration.

PubMed

Gomes, Maria João; Fernandes, Carlos; Martins, Susana; Borges, Fernanda; Sarmento, Bruno

2017-03-01

Blood-brain barrier is a tightly packed layer of endothelial cells surrounding the brain that acts as the main obstacle for drugs enter the central nervous system (CNS), due to its unique features, as tight junctions and drug efflux systems. Therefore, since the incidence of CNS disorders is increasing worldwide, medical therapeutics need to be improved. Consequently, aiming to surpass blood-brain barrier and overcome CNS disabilities, silencing P-glycoprotein as a drug efflux transporter at brain endothelial cells through siRNA is considered a promising approach. For siRNA enzymatic protection and efficient delivery to its target, two different nanoparticles platforms, solid lipid (SLN) and poly-lactic-co-glycolic (PLGA) nanoparticles were used in this study. Polymeric PLGA nanoparticles were around 115 nm in size and had 50 % of siRNA association efficiency, while SLN presented 150 nm and association efficiency close to 52 %. Their surface was functionalized with a peptide-binding transferrin receptor, in a site-oriented manner confirmed by NMR, and their targeting ability against human brain endothelial cells was successfully demonstrated by fluorescence microscopy and flow cytometry. The interaction of modified nanoparticles with brain endothelial cells increased 3-fold compared to non-modified lipid nanoparticles, and 4-fold compared to non-modified PLGA nanoparticles, respectively. These nanosystems, which were also demonstrated to be safe for human brain endothelial cells, without significant cytotoxicity, bring a new hopeful breath to the future of brain diseases therapies.

Achieving Crossed Strong Barrier Coverage in Wireless Sensor Network.

PubMed

Han, Ruisong; Yang, Wei; Zhang, Li

2018-02-10

Barrier coverage has been widely used to detect intrusions in wireless sensor networks (WSNs). It can fulfill the monitoring task while extending the lifetime of the network. Though barrier coverage in WSNs has been intensively studied in recent years, previous research failed to consider the problem of intrusion in transversal directions. If an intruder knows the deployment configuration of sensor nodes, then there is a high probability that it may traverse the whole target region from particular directions, without being detected. In this paper, we introduce the concept of crossed barrier coverage that can overcome this defect. We prove that the problem of finding the maximum number of crossed barriers is NP-hard and integer linear programming (ILP) is used to formulate the optimization problem. The branch-and-bound algorithm is adopted to determine the maximum number of crossed barriers. In addition, we also propose a multi-round shortest path algorithm (MSPA) to solve the optimization problem, which works heuristically to guarantee efficiency while maintaining near-optimal solutions. Several conventional algorithms for finding the maximum number of disjoint strong barriers are also modified to solve the crossed barrier problem and for the purpose of comparison. Extensive simulation studies demonstrate the effectiveness of MSPA.

Women physicians as healthcare leaders: a qualitative study.

PubMed

Roth, Virginia R; Theriault, Anne; Clement, Chris; Worthington, Jim

2016-06-20

Purpose - The purpose of this paper is to explore the under-representation of women physicians in clinical leadership by examining the issue from their perspective. Design/methodology/approach - The authors used large group engagement methods to explore the experiences and perceptions of women physicians. In order to capture common themes across this group as a whole, participants were selected using purposeful sampling. Data were analysed using a structured thematic analysis procedure. Findings - This paper provides empirical insights into the influences affecting women physicians' decision to participate in leadership. The authors found that they often exclude themselves because the costs of leadership outweigh the benefits. Potential barriers unique to healthcare include the undervaluing of leadership by physician peers and perceived lack of support by nursing. Research limitations/implications - This study provides an in-depth examination of why women physicians are under-represented in clinical leadership from the perspective of those directly involved. Further studies are needed to confirm the generalizability of these findings and potential differences between demographic groups of physicians. Practical implications - Healthcare organizations seeking to increase the participation of women physicians in leadership should focus on modifying the perceived costs of leadership and highlighting the potential benefits. Large group engagement methods can be an effective approach to engage physicians on specific issues and mobilize grass-roots support for change. Originality/value - This exploratory study provides insights on the barriers and enablers to leadership specific to women physicians in the clinical setting. It provides a reference for healthcare organizations seeking to develop and diversify their leadership talent.

Investigating the complementary value of discrete choice experiments for the evaluation of barriers and facilitators in implementation research: a questionnaire survey

PubMed Central

van Helvoort-Postulart, Debby; van der Weijden, Trudy; Dellaert, Benedict GC; de Kok, Mascha; von Meyenfeldt, Maarten F; Dirksen, Carmen D

2009-01-01

Background The potential barriers and facilitators to change should guide the choice of implementation strategy. Implementation researchers believe that existing methods for the evaluation of potential barriers and facilitators are not satisfactory. Discrete choice experiments (DCE) are relatively new in the health care sector to investigate preferences, and may be of value in the field of implementation research. The objective of our study was to investigate the complementary value of DCE for the evaluation of barriers and facilitators in implementation research. Methods Clinical subject was the implementation of the guideline for breast cancer surgery in day care. We identified 17 potential barriers and facilitators to the implementation of this guideline. We used a traditional questionnaire that was made up of statements about the potential barriers and facilitators. Respondents answered 17 statements on a five-point scale ranging from one (fully disagree) to five (fully agree). The potential barriers and facilitators were included in the DCE as decision attributes. Data were gathered among anaesthesiologists, surgical oncologists, and breast care nurses by means of a paper-and-pencil questionnaire. Results The overall response was 10%. The most striking finding was that the responses to the traditional questionnaire hardly differentiated between barriers. Forty-seven percent of the respondents thought that DCE is an inappropriate method. These respondents considered DCE too difficult and too time-consuming. Unlike the traditional questionnaire, the results of a DCE provide implementation researchers and clinicians with a relative attribute importance ranking that can be used to prioritize potential barriers and facilitators to change, and hence to better fine-tune the implementation strategies to the specific problems and challenges of a particular implementation process. Conclusion The results of our DCE and traditional questionnaire would probably lead to different implementation strategies. Although there is no 'gold standard' for prioritising potential barriers and facilitators to the implementation of change, theoretically, DCE would be the method of choice. However, the feasibility of using DCE was less favourable. Further empirical applications should investigate whether DCE can really make a valuable contribution to the implementation science. PMID:19250555

Energy shift and conduction-to-valence band transition mediated by a time-dependent potential barrier in graphene

NASA Astrophysics Data System (ADS)

Chaves, Andrey; da Costa, D. R.; de Sousa, G. O.; Pereira, J. M.; Farias, G. A.

2015-09-01

We investigate the scattering of a wave packet describing low-energy electrons in graphene by a time-dependent finite-step potential barrier. Our results demonstrate that, after Klein tunneling through the barrier, the electron acquires an extra energy which depends on the rate of change of the barrier height with time. If this rate is negative, the electron loses energy and ends up as a valence band state after leaving the barrier, which effectively behaves as a positively charged quasiparticle.

Characteristics of sequential targeting of brain glioma for transferrin-modified cisplatin liposome.

PubMed

Lv, Qing; Li, Li-Min; Han, Min; Tang, Xin-Jiang; Yao, Jin-Na; Ying, Xiao-Ying; Li, Fan-Zhu; Gao, Jian-Qing

2013-02-28

Methods on how to improve the sequential targeting of glioma subsequent to passing of drug through the blood-brain barrier (BBB) have been occasionally reported. However, the characteristics involved are poorly understood. In the present study, cisplatin (Cis) liposome (lipo) was modified with transferrin (Tf) to investigate the characteristics of potential sequential targeting to glioma. In bEnd3/C6 co-culture BBB models, higher transport efficiency across the BBB and cytotoxicity in basal C6 cells induced by Cis-lipo(Tf) than Cis-lipo and Cis-solution, suggest its sequential targeting effect. Interestingly, similar liposomal morphology as that of donor compartment was first demonstrated in the receptor solution of BBB models. Meanwhile, a greater acquisition in the lysosome of bEnd3, distributed sequentially into the nucleus of C6 cells were found for the Cis-lipo(Tf). Pre-incubation of chlorpromazine and Tf inhibited this process, indicating that a clathrin-dependent endocytosis is involved in the transport of Cis-lipo(Tf) across the BBB. Copyright © 2013 Elsevier B.V. All rights reserved.

Bridging the Gap between Research and Clinical Practice in Asymptomatic Alzheimer's Disease.

PubMed

Downing, A M; Yaari, R; Ball, D E; Selzler, K J; Devous, M D

2016-01-01

Due to the growing global health impact of Alzheimer's disease (AD), there is a greater need for interventions that prevent or delay the onset of clinical symptoms of this debilitating disease. Clinical trials for disease-modifying compounds in AD have shifted towards earlier stages in the spectrum of illness, including the stage prior to cognitive symptoms. A population of specific interest for clinical research includes individuals with evidence of Alzheimer's disease pathology who are asymptomatic (ADPa). The challenges and barriers regarding medical treatment of ADPa must be identified and addressed prior to the completion of a positive clinical trial in order to accelerate the translation of research findings to clinical practice. This report applies an existing public health impact model from Spencer and colleagues (2013) to evaluate the readiness of the clinical practice environment to treat ADPa individuals if a disease-modifying agent achieves approval. We contrast the current clinical practice environment with a potential future state through investigating the effectiveness, reach, feasibility, sustainability, and transferability of the practice of treating ADPa individuals.

Energy barriers, entropy barriers, and non-Arrhenius behavior in a minimal glassy model.

PubMed

Du, Xin; Weeks, Eric R

2016-06-01

We study glassy dynamics using a simulation of three soft Brownian particles confined to a two-dimensional circular region. If the circular region is large, the disks freely rearrange, but rearrangements are rarer for smaller system sizes. We directly measure a one-dimensional free-energy landscape characterizing the dynamics. This landscape has two local minima corresponding to the two distinct disk configurations, separated by a free-energy barrier that governs the rearrangement rate. We study several different interaction potentials and demonstrate that the free-energy barrier is composed of a potential-energy barrier and an entropic barrier. The heights of both of these barriers depend on temperature and system size, demonstrating how non-Arrhenius behavior can arise close to the glass transition.

Legislative history of recent primary safety belt laws

DOT National Transportation Integrated Search

1999-01-01

This document summarizes the strategies that supported or opposed new legislative provisions and the barriers encountered in modifying safety belt laws prior to December 1997. This study developed legislative analyses of six jurisdictions that upgrad...

Feasibility of remote administration of the Fundamentals of Laparoscopic Surgery (FLS) skills test.

PubMed

Okrainec, Allan; Vassiliou, Melina; Kapoor, Andrew; Pitzul, Kristen; Henao, Oscar; Kaneva, Pepa; Jackson, Timothy; Ritter, E Matt

2013-11-01

Fundamentals of Laparoscopic Surgery (FLS) certification testing currently is offered at accredited test centers or at select surgical conferences. Maintaining these test centers requires considerable investment in human and financial resources. Additionally, it can be challenging for individuals outside North America to become FLS certified. The objective of this pilot study was to assess the feasibility of remotely administering and scoring the FLS examination using live videoconferencing compared with standard onsite testing. This parallel mixed-methods study used both FLS scoring data and participant feedback to determine the barriers to feasibility of remote proctoring for the FLS examination. Participants were tested at two accredited FLS testing centers. An official FLS proctor administered and scored the FLS exam remotely while another onsite proctor provided a live score of participants' performance. Participant feedback was collected during testing. Interrater reliabilities of onsite and remote FLS scoring data were compared using intraclass correlation coefficients (ICCs). Participant feedback was analyzed using modified grounded theory to identify themes for barriers to feasibility. The scores of the remote and onsite proctors showed excellent interrater reliability in the total FLS (ICC 0.995, CI [0.985-0.998]). Several barriers led to critical errors in remote scoring, but most were accompanied by a solution incorporated into the study protocol. The most common barrier was the chain of custody for exam accessories. The results of this pilot study suggest that remote administration of the FLS has the potential to decrease costs without altering test-taker scores or exam validity. Further research is required to validate protocols for remote and onsite proctors and to direct execution of these protocols in a controlled environment identical to current FLS test administration.

Effects of water activity and low molecular weight humectants on skin permeability and hydration dynamics - a double-blind, randomized and controlled study.

PubMed

Albèr, C; Buraczewska-Norin, I; Kocherbitov, V; Saleem, S; Lodén, M; Engblom, J

2014-10-01

The mammalian skin is a barrier that effectively separates the water-rich interior of the body from the normally dryer exterior. Changes in the external conditions, for example ambient humidity, have been shown to affect the skin barrier properties. The prime objective of this study was to evaluate the effect of water activity of a topical formulation on skin hydration and permeability. A second objective was to gain more understanding on how two commonly used humectants, urea and glycerol, affect skin barrier function in vivo. Simple aqueous formulations were applied under occlusion to the volar forearm of healthy volunteers. Following 4-h exposure, skin water loss (by transepidermal water loss measurements), skin hydration (by Corneometry) and skin permeability (by time to vasodilation due to benzyl nicotinate exposure) were monitored. The results demonstrate that a relatively small change in the water activity of a topical formulation is sufficient to induce considerable effects on stratum corneum hydration and permeability to exogenous substances. Exposing the skin to high water activity leads to increased skin hydration and also increased permeability. Furthermore, urea and glycerol promote skin hydration and permeability even at reduced water activity of the applied formulation. These results highlight the importance of considering the water activity in topically applied formulations and the potential benefit of using humectants. The results may impact formulation optimization in how to facilitate skin hydration and to modify skin permeability by temporarily open and close the skin barrier. © 2014 Society of Cosmetic Scientists and the Société Française de Cosmétologie.

Bio-based coatings as potential barriers to chemical contaminants from recycled paper and board for food packaging.

PubMed

Guazzotti, V; Marti, A; Piergiovanni, L; Limbo, S

2014-01-01

Partition and diffusion experiments were carried out with paper and board samples coated with different biopolymers. The aim was to evaluate the physicochemical behaviour and barrier properties of bio-coatings against migration of typical contaminants from recycled paper packaging. Focus was directed towards water-based, renewable biopolymers, such as modified starches (cationic starch and cationic waxy starch), plant and animal proteins (gluten and gelatine), poured onto paper with an automatic applicator. Additionally, a comparison with polyethylene-laminated paper was performed. Microstructural observations of the bio-coated paper allowed the characterisation of samples. From the partitioning studies, considerable differences in the adsorption behaviour of the selected contaminants between bio-coated or uncoated paper and air were highlighted. For both the polar and non-polar compounds considered (benzophenone and diisobutyl phthalate, respectively), the lowest values of partition coefficients were found when paper was bio-coated, making it evident that biopolymers acted as chemical/physical barriers towards these contaminants. These findings are discussed considering the characteristics of the tested biopolymers. Diffusion studies into the solid food simulant poly 2,6-diphenyl-p-phenylene oxide, also known as Tenax(®), confirmed that all the tested biopolymers slowed down migration. The Weibull kinetic model was fitted to the experimental data to compare migration from paper and bio-coated paper. Values found for β, an index determining the pattern of curvature, ranged from 1.1 to 1.7 for uncoated and polyethylene paper, whereas for bio-coated papers they ranged from 2.2 to 4.9, corresponding to the presence of an evident lag phase due to barrier properties of the tested bio-coatings.

A mechanism study of sound wave-trapping barriers.

PubMed

Yang, Cheng; Pan, Jie; Cheng, Li

2013-09-01

The performance of a sound barrier is usually degraded if a large reflecting surface is placed on the source side. A wave-trapping barrier (WTB), with its inner surface covered by wedge-shaped structures, has been proposed to confine waves within the area between the barrier and the reflecting surface, and thus improve the performance. In this paper, the deterioration in performance of a conventional sound barrier due to the reflecting surface is first explained in terms of the resonance effect of the trapped modes. At each resonance frequency, a strong and mode-controlled sound field is generated by the noise source both within and in the vicinity outside the region bounded by the sound barrier and the reflecting surface. It is found that the peak sound pressures in the barrier's shadow zone, which correspond to the minimum values in the barrier's insertion loss, are largely determined by the resonance frequencies and by the shapes and losses of the trapped modes. These peak pressures usually result in high sound intensity component impinging normal to the barrier surface near the top. The WTB can alter the sound wave diffraction at the top of the barrier if the wavelengths of the sound wave are comparable or smaller than the dimensions of the wedge. In this case, the modified barrier profile is capable of re-organizing the pressure distribution within the bounded domain and altering the acoustic properties near the top of the sound barrier.

Studies of the Electrohydrodynamic Force Produced in a Dielectric Barrier Discharge for Flow Control. Report no. 2, Phase 3

DTIC Science & Technology

2010-02-01

applied between the electrodes at a repetition rate of a few kHz (for spanwise as well as streamwise configurations of the DBD actuators with respect to...the electronic version) 1. Introduction Surface dielectric barrier discharges ( DBDs ) at atmospheric pressure can generate a flow or modify the...to the momentum transfer from charged particles to neutral molecules in a gas discharge. In recent papers [7–9], we presented studies of surface DBDs

Predicting drug penetration across the blood-brain barrier: comparison of micellar liquid chromatography and immobilized artificial membrane liquid chromatography.

PubMed

De Vrieze, Mike; Lynen, Frédéric; Chen, Kai; Szucs, Roman; Sandra, Pat

2013-07-01

Several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier (BBB) into the central nervous system (CNS). In this article, the performance of a variety of micellar liquid chromatographic (MLC) methods and immobilized artificial membrane (IAM) liquid chromatographic approaches were compared for a set of 45 solutes. MLC measurements were performed on a C18 column with sodium dodecyl sulfate (SDS), polyoxyethylene (23) lauryl ether (Brij35), or sodium deoxycholate (SDC) as surfactant in the micellar mobile phase. IAM liquid chromatography measurements were performed with Dulbecco's phosphate-buffered saline (DPBS) and methanol as organic modifier in the mobile phase. The corresponding retention and computed descriptor data for each solute were used for construction of models to predict transport across the blood-brain barrier (log BB). All data were correlated with experimental log BB values and the relative performance of the models was studied. SDS-based models proved most suitable for prediction of log BB values, followed closely by a simplified IAM method, in which it could be observed that extrapolation of retention data to 0% modifier in the mobile phase was unnecessary.

Human serum albumin nanoparticles modified with apolipoprotein A-I cross the blood-brain barrier and enter the rodent brain.

PubMed

Zensi, Anja; Begley, David; Pontikis, Charles; Legros, Celine; Mihoreanu, Larisa; Büchel, Claudia; Kreuter, Jörg

2010-12-01

Nanoparticles made of human serum albumin (HSA) and modified with apolipoproteins have previously been shown to transport drugs, which normally do not enter the brain, across the blood-brain barrier (BBB). However the precise mechanism by which nanoparticles with different apolipoproteins on their surface can target to the brain, as yet, has not been totally elucidated. In the present study, HSA nanoparticles with covalently bound apolipoprotein A-I (Apo A-I) as a targetor for brain capillary endothelial cells were injected intravenously into SV 129 mice and Wistar rats. The rodents were sacrificed after 15 or 30 min, and their brains were examined by transmission electron microscopy. Apo A-I nanoparticles could be found inside the endothelial cells of brain capillaries as well as within parenchymal brain tissue of both, mice and rats, whereas control particles without Apo A-I on their surface did not cross the BBB during our experiments. The maintenance of tight junction integrity and barrier function during treatment with nanoparticles was demonstrated by perfusion with a fixative containing lanthanum nitrate as an electron dense marker for the permeability of tight junctions.

Band-selective filter in a zigzag graphene nanoribbon.

PubMed

Nakabayashi, Jun; Yamamoto, Daisuke; Kurihara, Susumu

2009-02-13

Electric transport of a zigzag graphene nanoribbon through a steplike potential and a barrier potential is investigated by using the recursive Green's function method. In the case of the steplike potential, we demonstrate numerically that scattering processes obey a selection rule for the band indices when the number of zigzag chains is even; the electrons belonging to the "even" ("odd") bands are scattered only into the even (odd) bands so that the parity of the wave functions is preserved. In the case of the barrier potential, by tuning the barrier height to be an appropriate value, we show that it can work as the "band-selective filter", which transmits electrons selectively with respect to the indices of the bands to which the incident electrons belong. Finally, we suggest that this selection rule can be observed in the conductance by applying two barrier potentials.

The expert's guide to mealtime interventions - A Delphi method survey.

PubMed

Conchin, Simone; Carey, Sharon

2017-09-27

Prevalence of malnutrition and a myriad of barriers to adequate oral diet in hospitalised patients warrants further investment to improve the patient mealtime experience. The aim of this study was to explore barriers and enablers to implementing effective mealtime interventions and develop a process framework to guide clinicians and researchers in the area. Potential experts in the area of hospital mealtime intervention were identified as having published in this field of work within the Australasian setting. Further information was sought by email and telephone communication on professional background; research experience; interest; and capacity to participate. Recruited participants were surveyed using a modified Delphi method to establish opinion and experience in the area of mealtime interventions. Results were collated and content was coded using a thematic analysis approach by the primary researcher and two additional reviewers. Thirty-two Australian authors in the area of mealtime interventions within the hospital environment were identified from publication. Twenty-one participants were able to be contacted and nineteen of these consented to enrol in the study. Participants included those from a dietetic (n = 14), nursing (n = 4) and medical (n = 1) background. Participants were deemed to have expert knowledge if they had significant involvement in the published research and demonstrated a deep level of understanding of hospital mealtime interventions. All participants provided key insights into barriers to oral intake in the hospital environment and suggestions for interventions to address these barriers. From the survey, an eight step framework to guide mealtime interventions was developed. Hospital mealtime interventions are complex processes. Interventions should be implemented after careful consideration of the local context and baseline data; and tailored to address barriers. Roles and responsibilities for nutrition care should be clear and consistent. Implementation planning is recommended to ensure that an ongoing process is in place to engage executive support and staff involvement, foster project team resilience and ensure sustainability of interventions. Crown Copyright © 2017. Published by Elsevier Ltd. All rights reserved.

Barriers to Point-of-Care Testing in India: Results from Qualitative Research across Different Settings, Users and Major Diseases

PubMed Central

Engel, Nora; Ganesh, Gayatri; Patil, Mamata; Yellappa, Vijayashree; Pant Pai, Nitika; Vadnais, Caroline; Pai, Madhukar

2015-01-01

Background Successful point-of-care testing, namely ensuring the completion of the test and treat cycle in the same encounter, has immense potential to reduce diagnostic and treatment delays, and impact patient outcomes. However, having rapid tests is not enough, as many barriers may prevent their successful implementation in point-of-care testing programs. Qualitative research on diagnostic practices may help identify such barriers across different points of care in health systems. Methods In this exploratory qualitative study, we conducted 78 semi-structured interviews and 13 focus group discussions in an urban and rural area of Karnataka, India, with healthcare providers (doctors, nurses, specialists, traditional healers, and informal providers), patients, community health workers, test manufacturers, laboratory technicians, program managers and policy-makers. Participants were purposively sampled to represent settings of hospitals, peripheral labs, clinics, communities and homes, in both the public and private sectors. Results In the Indian context, the onus is on the patient to ensure successful point-of-care testing across homes, clinics, labs and hospitals, amidst uncoordinated providers with divergent and often competing practices, in settings lacking material, money and human resources. We identified three overarching themes affecting point-of-care testing: the main theme is ‘relationships’ among providers and between providers and patients, influenced by the cross-cutting theme of ‘infrastructure’. Challenges with both result in ‘modified practices’ often favouring empirical (symptomatic) treatment over treatment guided by testing. Conclusions Even if tests can be conducted on the spot and infrastructure challenges have been resolved, relationships among providers and between patients and providers are crucial for successful point-of-care testing. Furthermore, these barriers do not act in isolation, but are interlinked and need to be examined as such. Also, a test alone has only limited power to overcome those difficulties. Test developers, policy-makers, healthcare providers and funders need to use these insights in overcoming barriers to point-of-care testing programs. PMID:26275231

Stakeholders identify similar barriers but different strategies to facilitate return-to-work: A vignette of a worker with an upper extremity condition.

PubMed

Peters, Susan E; Truong, Anthony P; Johnston, Venerina

2018-01-01

Stakeholders involved in the return-to-work (RTW) process have different roles and qualificationsOBJECTIVE:To explore the perspectives of Australian stakeholders of the RTW barriers and strategies for a worker with an upper extremity condition and a complex workers' compensation case. Using a case vignette, stakeholders were asked to identify barriers and recommend strategies to facilitate RTW. Content analysis was performed on the open-ended responses. The responses were categorised into RTW barriers and strategies using the biopsychosocial model. Pearson's Chi Square and ANOVA were performed to establish group differences. 621 participants (488 healthcare providers (HCPs), 62 employers, 55 insurers and 16 lawyers) identified 36 barriers (31 modifiable): 4 demographic; 8 biological; 15 psychological and 9 social barriers. 484 participants reported 16 RTW strategies: 4 biological; 6 psychological and 6 social strategies. 'Work relationship stressors' (83.4%) and 'Personal relationship stressors' (64.7%) were the most frequently nominated barriers. HCPs most frequently nominated 'Pain management' (49.6%), while employers, insurers and lawyers nominated 'RTW planning/Suitable duties programs' (40.5%; 42.9%; 80%). Stakeholders perceived similar barriers for RTW but recommended different strategies. Stakeholders appeared to be more proficient in identifying barriers than recommending strategies. Future research should focus on tools to both identify RTW barriers and direct intervention.

Resonant tunneling of spin-wave packets via quantized states in potential wells.

PubMed

Hansen, Ulf-Hendrik; Gatzen, Marius; Demidov, Vladislav E; Demokritov, Sergej O

2007-09-21

We have studied the tunneling of spin-wave pulses through a system of two closely situated potential barriers. The barriers represent two areas of inhomogeneity of the static magnetic field, where the existence of spin waves is forbidden. We show that for certain values of the spin-wave frequency corresponding to the quantized spin-wave states existing in the well formed between the barriers, the tunneling has a resonant character. As a result, transmission of spin-wave packets through the double-barrier structure is much more efficient than the sequent tunneling through two single barriers.

Quantum scattering in one-dimensional systems satisfying the minimal length uncertainty relation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernardo, Reginald Christian S., E-mail: rcbernardo@nip.upd.edu.ph; Esguerra, Jose Perico H., E-mail: jesguerra@nip.upd.edu.ph

In quantum gravity theories, when the scattering energy is comparable to the Planck energy the Heisenberg uncertainty principle breaks down and is replaced by the minimal length uncertainty relation. In this paper, the consequences of the minimal length uncertainty relation on one-dimensional quantum scattering are studied using an approach involving a recently proposed second-order differential equation. An exact analytical expression for the tunneling probability through a locally-periodic rectangular potential barrier system is obtained. Results show that the existence of a non-zero minimal length uncertainty tends to shift the resonant tunneling energies to the positive direction. Scattering through a locally-periodic potentialmore » composed of double-rectangular potential barriers shows that the first band of resonant tunneling energies widens for minimal length cases when the double-rectangular potential barrier is symmetric but narrows down when the double-rectangular potential barrier is asymmetric. A numerical solution which exploits the use of Wronskians is used to calculate the transmission probabilities through the Pöschl–Teller well, Gaussian barrier, and double-Gaussian barrier. Results show that the probability of passage through the Pöschl–Teller well and Gaussian barrier is smaller in the minimal length cases compared to the non-minimal length case. For the double-Gaussian barrier, the probability of passage for energies that are more positive than the resonant tunneling energy is larger in the minimal length cases compared to the non-minimal length case. The approach is exact and applicable to many types of scattering potential.« less

Intervening in disease through genetically-modified bacteria.

PubMed

Ferreira, Adilson K; Mambelli, Lisley I; Pillai, Saravanan Y

2017-12-01

The comprehension of the molecular basis of different diseases is rapidly being dissected as a consequence of advancing technology. Consequently, proteins with potential therapeutic usefulness, including cytokines and signaling molecules have been identified in the last decades. However, their clinical use is hampered by disadvantageous functional and economic considerations. One of the most important of these considerations is targeted topical delivery and also the synthesis of such proteins, which for intravenous use requires rigorous purification whereas proteins often do not withstand digestive degradation and thus cannot be applied per os. Recently, the idea of using genetically modified bacteria has emerged as an attempt to evade these important barriers. Using such bacteria can deliver therapeutic proteins or other molecules at place of disease, especially when disease is at a mucosal surface. Further, whereas intravenously applied therapeutic proteins require expensive methodology in order to become endotoxin-free, this is not necessary for local application of therapeutic proteins in the intestine. In addition, once created further propagation of genetically modified bacteria is both cheap and requires relatively little in conditioning with respect to transport of the medication, making such organisms also suitable for combating disease in developing countries with poor infrastructure. Although first human trials with such bacteria were already performed more as a decade ago, the recent revolution in our understanding of the role of human gut microbiome in health and diseases has unleashed a revolution in this field resulting in a plethora of potential novel prophylactic and therapeutic intervention against disease onset and development employing such organisms. Today, the engineering of human microbiome for health benefits and related applications now chances many aspects of biology, nanotechnology and chemistry. Here, we review genetically modified bacteria methodology as possible carriers of drug delivering and provided the origin and inspirations for new drug delivery systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Polyethylenimine functionalized magnetic nanoparticles as a potential non-viral vector for gene delivery.

PubMed

Zhou, Yangbo; Tang, Zhaomin; Shi, Chunli; Shi, Shuai; Qian, Zhiyong; Zhou, Shaobing

2012-11-01

Polyethylenimine (PEI) functionalized magnetic nanoparticles were synthesized as a potential non-viral vector for gene delivery. The nanoparticles could provide the magnetic-targeting, and the cationic polymer PEI could condense DNA and avoid in vitro barriers. The magnetic nanoparticles were characterized by Fourier transform infrared spectroscopy, X-ray powder diffraction, dynamic light scattering measurements, transmission electron microscopy, vibrating sample magnetometer and atomic force microscopy. Agarose gel electrophoresis was used to asses DNA binding and perform a DNase I protection assay. The Alamar blue assay was used to evaluate negative effects on the metabolic activity of cells incubated with PEI modified magnetic nanoparticles and their complexes with DNA both in the presence or absence of an external magnetic field. Flow cytometry and fluorescent microscopy were also performed to investigate the transfection efficiency of the DNA-loaded magnetic nanoparticles in A549 and B16-F10 tumor cells with (+M) or without (-M) the magnetic field. The in vitro transfection efficiency of magnetic nanoparticles was improved obviously in a permanent magnetic field. Therefore, the magnetic nanoparticles show considerable potential as nanocarriers for gene delivery.

Linked Clinical Trials – The Development of New Clinical Learning Studies in Parkinson’s Disease Using Screening of Multiple Prospective New Treatments

PubMed Central

Brundin, Patrik; Barker, Roger A.; Conn, P. Jeffrey; Dawson, Ted M.; Kieburtz, Karl; Lees, Andrew J.; Schwarzschild, Michael A.; Tanner, Caroline M.; Isaacs, Tom; Duffen, Joy; Matthews, Helen; Wyse, Richard K.H.

2015-01-01

Finding new therapies for Parkinson’s disease (PD) is a slow process. We assembled an international committee of experts to examine drugs potentially suitable for repurposing to modify PD progression. This committee evaluated multiple drugs currently used, or being developed, in other therapeutic areas, as well as considering several natural, non-pharmaceutical compounds. The committee prioritized which of these putative treatments were most suited to move immediately into pilot clinical trials. Aspects considered included known modes of action, safety, blood-brain-barrier penetration, preclinical data in animal models of PD and the possibility to monitor target engagement in the brain. Of the 26 potential interventions, 10 were considered worth moving forward into small, parallel ‘learning’ clinical trials in PD patients. These trials could be funded in a multitude of ways through support from industry, research grants and directed philanthropic donations. The committee-based approach to select the candidate compounds might help rapidly identify new potential PD treatment strategies for use in clinical trials. PMID:24018336

Synthesis and Characterization of a Novel Phenolic Lipid for Use as Potential Lipophilic Antioxidant and as a Prodrug of Butyric Acid.

PubMed

Kaki, Shiva Shanker; Kunduru, Konda Reddy; Kanjilal, Sanjit; Narayana Prasad, Rachapudi Badari

2015-01-01

Ferulic acid was modified to produce a novel phenolipid containing butyl chains. Ferulic acid was esterified with butanol to produce butyl ferulate which was further dihydroxylated followed by esterification with butyric anhydride to produce the phenolipid containing butyric acid. IR, NMR and MS techniques confirmed the structure of the synthesized structured lipophilic phenolic compound. The synthesized compound was tested for in vitro antioxidant and antimicrobial activities. The produced phenolipid showed moderate antioxidant activity in DPPH (2, 2-diphenyl-1-picrylhydrazyl) radical scavenging assay but in linoleic acid oxidation method, it exhibited good activity compared with the parent compound and the reference compounds. The prepared derivative could find applications as antioxidant in lipophilic systems and also as a potential prodrug of butyric acid. It also showed antibacterial effect against the four bacterial strains studied. The drug-likeness properties of the prepared molecule calculated were in the acceptable ranges according to Lipinski's rule of 5 and suggest that it has potential to cross the blood-brain barrier.

Alloyed coatings for dispersion strengthened alloys

NASA Technical Reports Server (NTRS)

Wermuth, F. R.; Stetson, A. R.

1971-01-01

Processing techniques were developed for applying several diffusion barriers to TD-Ni and TD-NiCr. Barrier coated specimens of both substrates were clad with Ni-Cr-Al and Fe-Cr-Al alloys and diffusion annealed in argon. Measurement of the aluminum distribution after annealing showed that, of the readily applicable diffusion barriers, a slurry applied tungsten barrier most effectively inhibited the diffusion of aluminum from the Ni-Cr-Al clad into the TD-alloy substrates. No barrier effectively limited interdiffusion of the Fe-Cr-Al clad with the substrates. A duplex process was then developed for applying Ni-Cr-Al coating compositions to the tungsten barrier coated substrates. A Ni-(16 to 32)Cr-3Si modifier was applied by slurry spraying and firing in vacuum, and was then aluminized by a fusion slurry process. Cyclic oxidation tests at 2300 F resulted in early coating failure due to inadequate edge coverage and areas of coating porosity. EMP analysis showed that oxidation had consumed 70 to 80 percent of the aluminum in the coating in less than 50 hours.

Listeriolysin S: A bacteriocin from epidemic Listeria monocytogenes strains that targets the gut microbiota.

PubMed

Quereda, Juan J; Meza-Torres, Jazmín; Cossart, Pascale; Pizarro-Cerdá, Javier

2017-07-04

Listeria monocytogenes is a Gram-positive food-borne pathogen that in humans may traverse the intestinal, placental and blood/brain barriers, causing gastroenteritis, abortions and meningitis. Crossing of these barriers is dependent on the bacterial ability to enter host cells, and several L. monocytogenes surface and secreted virulence factors are known to facilitate entry and the intracellular lifecycle. The study of L. monocytogenes strains associated to human listeriosis epidemics has revealed the presence of novel virulence factors. One such factor is Listeriolysin S, a thiazole/oxazole modified microcin that displays bactericidal activity and modifies the host microbiota during infection. Our recent results therefore highlight the interaction of L. monocytogenes with gut microbes as a crucial step in epidemic listeriosis. In this article, we will discuss novel implications for this family of toxins in the pathogenesis of diverse medically relevant microorganisms.

Listeriolysin S: A bacteriocin from epidemic Listeria monocytogenes strains that targets the gut microbiota

PubMed Central

Quereda, Juan J.; Meza-Torres, Jazmín; Cossart, Pascale; Pizarro-Cerdá, Javier

2017-01-01

ABSTRACT Listeria monocytogenes is a Gram-positive food-borne pathogen that in humans may traverse the intestinal, placental and blood/brain barriers, causing gastroenteritis, abortions and meningitis. Crossing of these barriers is dependent on the bacterial ability to enter host cells, and several L. monocytogenes surface and secreted virulence factors are known to facilitate entry and the intracellular lifecycle. The study of L. monocytogenes strains associated to human listeriosis epidemics has revealed the presence of novel virulence factors. One such factor is Listeriolysin S, a thiazole/oxazole modified microcin that displays bactericidal activity and modifies the host microbiota during infection. Our recent results therefore highlight the interaction of L. monocytogenes with gut microbes as a crucial step in epidemic listeriosis. In this article, we will discuss novel implications for this family of toxins in the pathogenesis of diverse medically relevant microorganisms. PMID:28156183

Electromechanically Actuated Multifunctional Wireless Auxetic Device for Wound Management.

PubMed

Mir, Mariam; Ansari, Umar; Ali, Murtaza Najabat; Iftikhar, Muhammad Hassan Ul; Qayyum, Faisal

2017-01-01

The design and fabrication of a wound healing device for chronic wounds, with multiple functions for controlled drug delivery and exudate removal, has been described in this paper. The structural features have been machined and modified through laser cutting in a biocompatible polymer cast. Miniaturized versions of electronically actuated (lead-screw and pulley) mechanisms are used for the specific purpose of controlled drug delivery. These mechanisms have been studied and tested, being controlled through a microcontroller setup. An auxetic polymeric barrier membrane has been used for restricting the drug quantities administered. Drug delivery mechanisms are powered wirelessly, through an external, active RF component; this communicates with a passive component that is buried inside the wound healing device. The exudate removal efficiency of the device has been assessed through several simple tests using simulated wound exudate. It has been found that reasonably precise quantities of drug dosages to be administered to the wound site can be controlled through both drug delivery mechanisms; however, the lead-screw mechanism provides a better control of auxetic barrier membrane actuation and hence controlled drug delivery. We propose that this device can have potential clinical significance in controlled drug delivery and exudate removal in the management of chronic wounds.

Silica- and perfluoro-based nanoparticular polymeric network for the skin protection against organophosphates

NASA Astrophysics Data System (ADS)

Bignon, Cécile; Amigoni, Sonia; Guittard, Frédéric

2016-06-01

Due to their small size, nanoparticles possess unique properties such as high absorption or pollutant degradation, making them useful for skin protection against chemicals. By covalently grafting to a hydrophobically modified alkali-soluble emulsion (HASE), a thickening polymer, nanoparticles can be dispersed as gels in water at neutral pH. With this modification the potential aggregation and toxicity typical of nanoparticles are avoided. Once integrated into a cosmetic formula, these gels can be spread onto skin to afford protective barriers. This paper reports (1) the benefit of SiO2 nanoparticles grafted to a perfluorocarbon HASE polymer (HASE-F/SiO2) which is then integrated into a new formula and it is influence on the efficacy against the penetration of paraoxone, as well as (2) the stability of the barrier cream (BC) and (3) how the homogenous dispersion of nanoparticles maintains a high active surface area of SiO2 nanoparticles. The efficiency of the new active topical skin protectant was proved at different doses (5-27 mg cm-2), under occlusive conditions and validated on human skin. Therefore, the combination of the HASE-F polymer, nanoparticle grafting, and polyvinylpyrrolidone and glycerol formulation led to a very effective active BC.

Efficacy of NGR peptide-modified PEGylated quantum dots for crossing the blood-brain barrier and targeted fluorescence imaging of glioma and tumor vasculature.

PubMed

Huang, Ning; Cheng, Si; Zhang, Xiang; Tian, Qi; Pi, Jiangli; Tang, Jun; Huang, Qing; Wang, Feng; Chen, Jin; Xie, Zongyi; Xu, Zhongye; Chen, Weifu; Zheng, Huzhi; Cheng, Yuan

2017-01-01

Delivery of imaging agents to brain glioma is challenging because the blood-brain barrier (BBB) functions as a physiological checkpoint guarding the central nervous system from circulating large molecules. Moreover, the ability of existing probes to target glioma has been insufficient and needs to be improved. In present study, PEG-based long circulation, CdSe/ZnS quantum dots (QDs)-based nanoscale and fluorescence, asparagines-glycine-arginine peptides (NGR)-based specific CD13 recognition were integrated to design and synthesize a novel nanoprobe by conjugating biotinylated NGR peptides to avidin-PEG-coated QDs. Our data showed that the NGR-PEG-QDs were nanoscale with less than 100 nm and were stable in various pH (4.0~8.0). These nanomaterials with non-toxic concentrations could cross the BBB and target CD13-overexpressing glioma and tumor vasculature in vitro and in vivo, contributing to fluorescence imaging of this brain malignancy. These achievements allowed groundbreaking technological advances in targeted fluorescence imaging for the diagnosis and surgical removal of glioma, facilitating potential transformation toward clinical nanomedicine. Copyright © 2016 Elsevier Inc. All rights reserved.

Evaluation of lung clearance of inhaled pertechnegas.

PubMed

Fanti, S; Compagnone, G; Pancaldi, D; Franchi, R; Corbelli, C; Marengo, M; Onofri, C; Galassi, R; Levorato, M; Monetti, N

1996-02-01

Pertechnegas is a new ventilation agent produced by modifying the atmosphere of combustion of Technegas. Due to its rapid disappearance from the lungs, Pertechnegas has been suggested as useful in measuring pulmonary epithelial permeability. This study aimed to assess the reliability of ventilation scans with Pertechnegas to evaluate alveolar-capillary permeability. Six non-smokers with no evidence of pulmonary disease were investigated. Scintigraphic data were used to evaluate the site of Pertechnegas deposition (by assessing the Penetration Index [PI] of the gas), its clearance rate (by calculating the time to half-clearance [T1/2]) and its lung distribution (by means of a pixel-by-pixel analysis. PI measurements produced a mean value of 88.8 +/- 13.3% (range 69-117%). Time activity curves showed a fast clearance in all cases (mean T1/2 = 10.7 +/- 2.1 min, range 8.1-14.3 min). Comparison of statistical indices of uniform deposition (skewness and kurtosis) indicated satisfactory homogeneity of Pertechnegas distribution throughout the lungs. These data show that after inhalation Pertechnegas has a peripheral deposition and a homogeneous distribution in the lungs and is rapidly cleared through the alveolar-capillary barrier. In conclusion Pertechnegas can be recommended as a potential radiopharmaceutical for studying the pulmonary epithelial barrier.

Spatial averaging for small molecule diffusion in condensed phase environments

NASA Astrophysics Data System (ADS)

Plattner, Nuria; Doll, J. D.; Meuwly, Markus

2010-07-01

Spatial averaging is a new approach for sampling rare-event problems. The approach modifies the importance function which improves the sampling efficiency while keeping a defined relation to the original statistical distribution. In this work, spatial averaging is applied to multidimensional systems for typical problems arising in physical chemistry. They include (I) a CO molecule diffusing on an amorphous ice surface, (II) a hydrogen molecule probing favorable positions in amorphous ice, and (III) CO migration in myoglobin. The systems encompass a wide range of energy barriers and for all of them spatial averaging is found to outperform conventional Metropolis Monte Carlo. It is also found that optimal simulation parameters are surprisingly similar for the different systems studied, in particular, the radius of the point cloud over which the potential energy function is averaged. For H2 diffusing in amorphous ice it is found that facile migration is possible which is in agreement with previous suggestions from experiment. The free energy barriers involved are typically lower than 1 kcal/mol. Spatial averaging simulations for CO in myoglobin are able to locate all currently characterized metastable states. Overall, it is found that spatial averaging considerably improves the sampling of configurational space.

Silicon oxide permeation barrier coating of PET bottles and foils

NASA Astrophysics Data System (ADS)

Steves, Simon; Deilmann, Michael; Awakowicz, Peter

2009-10-01

Modern packaging materials such as polyethylene terephthalate (PET) have displaced established materials in many areas of food and beverage packaging. Plastic packing materials offer are various advantages concerning production and handling. PET bottles for instance are non-breakable and lightweight compared to glass and metal containers. However, PET offers poor barrier properties against gas permeation. Therefore, the shelf live of packaged food is reduced. Permeation of gases can be reduced by depositing transparent plasma polymerized silicon oxide (SiOx) barrier coatings. A microwave (2.45 GHz) driven low pressure plasma reactor is developed based on a modified Plasmaline antenna to treat PET foils or bottles. To increase the barrier properties of the coatings furthermore a RF substrate bias (13.56 MHz) is applied. The composition of the coatings is analyzed by means of Fourier transform infrared (FTIR) spectroscopy regarding carbon and hydrogen content. Influence of gas phase composition and substrate bias on chemical composition of the coatings is discussed. A strong relation between barrier properties and film composition is found: good oxygen barriers are observed as carbon content is reduced and films become quartz-like. Regarding oxygen permeation a barrier improvement factor (BIF) of 70 is achieved.

Function of Platelet-Induced Epithelial Attachment at Titanium Surfaces Inhibits Microbial Colonization.

PubMed

Maeno, M; Lee, C; Kim, D M; Da Silva, J; Nagai, S; Sugawara, S; Nara, Y; Kihara, H; Nagai, M

2017-06-01

The aim of this study was to evaluate the barrier function of platelet-induced epithelial sheets on titanium surfaces. The lack of functional peri-implant epithelial sealing with basal lamina (BL) attachment at the interface of the implant and the adjacent epithelium allows for bacterial invasion, which may lead to peri-implantitis. Although various approaches have been reported to combat bacterial infection by surface modifications to titanium, none of these have been successful in a clinical application. In our previous study, surface modification with protease-activated receptor 4-activating peptide (PAR4-AP), which induced platelet activation and aggregation, was successful in demonstrating epithelial attachment via BL and epithelial sheet formation on the titanium surface. We hypothesized that the platelet-induced epithelial sheet on PAR4-AP-modified titanium surfaces would reduce bacterial attachment, penetration, and invasion. Titanium surface was modified with PAR4-AP and incubated with platelet-rich plasma (PRP). The aggregated platelets released collagen IV, a critical BL component, onto the PAR4-AP-modified titanium surface. Then, human gingival epithelial cells were seeded on the modified titanium surface and formed epithelial sheets. Green fluorescent protein (GFP)-expressing Escherichia coli was cultured onto PAR4-AP-modified titanium with and without epithelial sheet formation. While Escherichia coli accumulated densely onto the PAR4-AP titanium lacking epithelial sheet, few Escherichia coli were observed on the epithelial sheet on the PAR4-AP surface. No bacterial invasion into the interface of the epithelial sheet and the titanium surface was observed. These in vitro results indicate the efficacy of a platelet-induced epithelial barrier that functions to prevent bacterial attachment, penetration, and invasion on PAR4-AP-modified titanium.

Shoreline Evolution and Coastal Resiliency at Two Military Installations: Investigating the Potential for and Impacts of Loss of Protecting Barriers

DTIC Science & Technology

2014-05-01

control barrier morphology and migration (and potentially drowning). We have developed a numerical model of barrier evolution over the centennial ...required to maintain barrier geometries over centennial timescales. Long-term storm histories for each region show a consistent picture of...landward of the flood tidal delta is an area of over 40km2 that is over 9m deep, with some depressions as deep as 12m. During periods of rising sea-level

Universal potential-barrier penetration by initially confined wave packets

NASA Astrophysics Data System (ADS)

Granot, Er'El; Marchewka, Avi

2007-07-01

The dynamics of an initially sharp-boundary wave packet in the presence of an arbitrary potential barrier is investigated. It is shown that the penetration through the barrier is universal in the sense that it depends only on the values of the wave function and its derivatives at the boundary. The dependence on the derivatives vanishes at long distances from the barrier, where the dynamics is governed solely by the initial value of the wave function at the boundary.

A multi-modal intervention for Activating Patients at Risk for Osteoporosis (APROPOS): Rationale, design, and uptake of online study intervention material.

PubMed

Danila, Maria I; Outman, Ryan C; Rahn, Elizabeth J; Mudano, Amy S; Thomas, Tammi F; Redden, David T; Allison, Jeroan J; Anderson, Fred A; Anderson, Julia P; Cram, Peter M; Curtis, Jeffrey R; Fraenkel, Liana; Greenspan, Susan L; LaCroix, Andrea Z; Majumdar, Sumit R; Miller, Michael J; Nieves, Jeri W; Safford, Monika M; Silverman, Stuart L; Siris, Ethel S; Solomon, Daniel H; Warriner, Amy H; Watts, Nelson B; Yood, Robert A; Saag, Kenneth G

2016-12-15

To develop an innovative and effective educational intervention to inform patients about the need for osteoporosis treatment and to determine factors associated with its online uptake. Postmenopausal women with a prior fracture and not currently using osteoporosis therapy were eligible to be included in the Activating Patients at Risk for OsteoPOroSis (APROPOS). Four nominal groups with a total of 18 racially/ethnically diverse women identified osteoporosis treatment barriers. We used the Information, Motivation, Behavior Skills conceptual model to develop a direct-to-patient intervention to mitigate potentially modifiable barriers to osteoporosis therapy. The intervention included videos tailored by participants' race/ethnicity and their survey responses: ranked barriers to osteoporosis treatment, deduced barriers to treatment, readiness to behavior change, and osteoporosis treatment history. Videos consisted of "storytelling" narratives, based on osteoporosis patient experiences and portrayed by actresses of patient-identified race/ethnicity. We also delivered personalized brief phone calls followed by an interactive voice-response phone messages aimed to promote uptake of the videos. To address the factors associated with online intervention uptake, we focused on participants assigned to the intervention arm (n = 1342). These participants were 92.9% Caucasian, with a mean (SD) age 74.9 (8.0) years and the majority (77.7%) had some college education. Preference for natural treatments was the barrier ranked #1 by most (n = 130; 27%), while concern about osteonecrosis of the jaw was the most frequently reported barrier (at any level; n = 322; 67%). Overall, 28.1% (n = 377) of participants in the intervention group accessed the videos online. After adjusting for relevant covariates, the participants who provided an email address had 6.07 (95% CI 4.53-8.14) higher adjusted odds of accessing their online videos compared to those who did not. We developed and implemented a novel tailored multi-modal intervention to improve initiation of osteoporosis therapy. An email address provided on the survey was the most important factor independently associated with accessing the intervention online. The design and uptake of this intervention may have implications for future studies in osteoporosis or other chronic diseases.

Simulation of solute transport across low-permeability barrier walls

USGS Publications Warehouse

Harte, P.T.; Konikow, Leonard F.; Hornberger, G.Z.

2006-01-01

Low-permeability, non-reactive barrier walls are often used to contain contaminants in an aquifer. Rates of solute transport through such barriers are typically many orders of magnitude slower than rates through the aquifer. Nevertheless, the success of remedial actions may be sensitive to these low rates of transport. Two numerical simulation methods for representing low-permeability barriers in a finite-difference groundwater-flow and transport model were tested. In the first method, the hydraulic properties of the barrier were represented directly on grid cells and in the second method, the intercell hydraulic-conductance values were adjusted to approximate the reduction in horizontal flow, allowing use of a coarser and computationally efficient grid. The alternative methods were tested and evaluated on the basis of hypothetical test problems and a field case involving tetrachloroethylene (PCE) contamination at a Superfund site in New Hampshire. For all cases, advective transport across the barrier was negligible, but preexisting numerical approaches to calculate dispersion yielded dispersive fluxes that were greater than expected. A transport model (MODFLOW-GWT) was modified to (1) allow different dispersive and diffusive properties to be assigned to the barrier than the adjacent aquifer and (2) more accurately calculate dispersion from concentration gradients and solute fluxes near barriers. The new approach yields reasonable and accurate concentrations for the test cases. ?? 2006.

Effect of the δ-potential on spin-dependent electron tunneling in double barrier semiconductor heterostructure

NASA Astrophysics Data System (ADS)

Chandrasekar, L. Bruno; Gnanasekar, K.; Karunakaran, M.

2018-06-01

The effect of δ-potential was studied in GaAs/Ga0.6Al0·4As double barrier heterostructure with Dresselhaus spin-orbit interaction. The role of barrier height and position of the δ- potential in the well region was analysed on spin-dependent electron tunneling using transfer matrix method. The spin-separation between spin-resonances on energy scale depends on both height and position of the δ- potential, whereas the tunneling life time of electrons highly influenced by the position of the δ- potential and not on the height. These results might be helpful for the fabrication of spin-filters.

Systematic planning of disconnection to enhance conservation success in a modified world.

PubMed

Hermoso, Virgilio; Januchowski-Hartley, Stephanie R; Linke, Simon

2015-12-01

Maintaining spatial-temporal connectivity for conservation is necessary to allow the persistence of ecological processes and the biodiversity they sustain. However, conservation practice in human-modified environments can also benefit from prescribed disconnection through the implementation of barriers. Barriers, such as fences or dams, and buffer zones can be a cost-effective way of addressing threats caused by a globally connected world, such as the propagation of invasive species and diseases, creating refuge areas for native biodiversity and helping reduce economic losses caused by native wildlife or invasive species. Despite the global attention that disconnection has received, no clear framework exists to guide the allocation of barriers for conservation management. Here we propose that the implementation of barriers for conservation should be systematically planned, considering ecological trade-offs for multiple species (easing threats vs. interruption of ecosystem processes) and socio-economic cost-benefits (implementation cost vs. reduced human-wildlife conflicts), rather than using ad-hoc opportunistic criteria or accommodating conservation needs for individual species. Such a systematic approach is necessary to ensure both socially acceptable and ecologically effective use of disconnections as a conservation tool and ideally planned across different realms so co-benefits or trade-offs can be accounted for. However, any implementation of disconnection for conservation should be cautiously considered if uncertainty in effectiveness of the barrier and ecological impacts to other species are high. We also suggest the need for improved approaches to monitoring to learn from previous successes and failures. Our recommendations should guide the systematic evaluation and allocation of barriers to help enhance the value of this conservation tool in the face of increasing propagation of threats worldwide. However, new tools and collaborative frameworks across different realms are needed to help stakeholders make better informed decision. Copyright © 2015 Elsevier B.V. All rights reserved.

Effect of perfluorodecyltrichlorosilane on the surface properties and anti-corrosion behavior of poly(dimethylsiloxane)-ZnO coatings

NASA Astrophysics Data System (ADS)

Arukalam, Innocent O.; Meng, Meijiang; Xiao, Haigang; Ma, Yuantai; Oguzie, Emeka E.; Li, Ying

2018-03-01

Poly(dimethylsiloxane)-ZnO coatings modified with different amounts of perfluorodecyltrichlorosilane (FDTS) were prepared using sol-gel technique. The results of field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) examinations showed that the surface structures and roughness of the coatings were respectively influenced by the increasing addition of FDTS. The water contact angle measurements showed maximum value of 130.52° with the 0.10 g FDTS-modified coating sample. The X-ray photoelectron spectroscopy (XPS) results indicated the coatings' hydrophobicity was also influenced by surface chemistry. The FTIR-ATR characterization results showed there was remarkable increase in the crystallinity of 0.10 g FDTS-modified coating after modification, and was confirmed by differential scanning calorimetry (DSC) analysis of crystallization temperature and the X-ray diffraction (XRD) results with an estimation of 71.29% percent crystallinity. The mechanical properties of the coatings were also conducted. The EIS measurements for anti-corrosion behavior showed that 0.10 g FDTS-modified coating had the highest barrier performance and lowest rate of degradation. Indeed, the obtained data have demonstrated that 0.10 g (≈ 0.18%) FDTS produced the most significantly effect on the surface and barrier properties of the coatings and thus, can effectively be used for anti-corrosion application in the marine environments.

Antibacterial Activity of a Novel Peptide-Modified Lysin Against Acinetobacter baumannii and Pseudomonas aeruginosa

PubMed Central

Yang, Hang; Wang, Mengyue; Yu, Junping; Wei, Hongping

2015-01-01

The global emergence of multidrug-resistant (MDR) bacteria is a growing threat to public health worldwide. Natural bacteriophage lysins are promising alternatives in the treatment of infections caused by Gram-positive pathogens, but not Gram-negative ones, like Acinetobacter baumannii and Pseudomonas aeruginosa, due to the barriers posed by their outer membranes. Recently, modifying a natural lysin with an antimicrobial peptide was found able to break the barriers, and to kill Gram-negative pathogens. Herein, a new peptide-modified lysin (PlyA) was constructed by fusing the cecropin A peptide residues 1–8 (KWKLFKKI) with the OBPgp279 lysin and its antibacterial activity was studied. PlyA showed good and broad antibacterial activities against logarithmic phase A. baumannii and P. aeruginosa, but much reduced activities against the cells in stationary phase. Addition of outer membrane permeabilizers (EDTA and citric acid) could enhance the antibacterial activity of PlyA against stationary phase cells. Finally, no antibacterial activity of PlyA could be observed in some bio-matrices, such as culture media, milk, and sera. In conclusion, we reported here a novel peptide-modified lysin with significant antibacterial activity against both logarithmic (without OMPs) and stationary phase (with OMPs) A. baumannii and P. aeruginosa cells in buffer, but further optimization is needed to achieve broad activity in diverse bio-matrices. PMID:26733995

Access to Strong Opioid Analgesics in the Context of Legal and Regulatory Barriers in Eleven Central and Eastern European Countries.

PubMed

Vranken, Marjolein J M; Mantel-Teeuwisse, Aukje K; Schutjens, Marie-Hélène D B; Scholten, Willem K; Jünger, Saskia; Medic, Dr Rer; Leufkens, Hubert G M

2018-04-06

In 2011-2013, >95% of the global opioid analgesics consumption occurred in three regions, accounting for 15% of the world population. Despite abundant literature on barriers to access, little is known on the correlation between actual access to opioid analgesics and barriers to access, including legal and regulatory barriers. This study aimed to evaluate the correlation between access to strong opioid analgesics and barriers to access in national legislation and regulations in 11 central and eastern European countries that participated in the Access to Opioid Medication in Europe (ATOME) project. Two variables were contrasted to assess their correlation: the country level of access to strong opioid analgesics indicated by the Adequacy of Consumption Measure (ACM) and the number of potential legal and regulatory barriers identified by an external review of legislation and regulations. A linear correlation was evaluated using a squared linear correlation coefficient. Evaluation of the correlation between the ACM and the number of potential barriers produces an R 2 value of 0.023 and a correlation plot trend line gradient of -0.075, indicating no correlation between access to strong opioid analgesics and the number of potential barriers in national legislation and regulations in the countries studied. No correlation was found, which indicates that other factors besides potential legal and regulatory barriers play a critical role in withholding prescribers and patients essential pain medication in the studied countries. More research is needed toward better understanding of the complex interplay of factors that determine access to strong opioid analgesics.

The proton permeability of self-assembled polymersomes and their neuroprotection by enhancing a neuroprotective peptide across the blood-brain barrier after modification with lactoferrin.

PubMed

Yu, Yuan; Jiang, Xinguo; Gong, Shuyu; Feng, Liang; Zhong, Yanqiang; Pang, Zhiqing

2014-03-21

Biotherapeutics such as peptides possess strong potential for the treatment of intractable neurological disorders. However, because of their low stability and the impermeability of the blood-brain barrier (BBB), biotherapeutics are difficult to transport into brain parenchyma via intravenous injection. Herein, we present a novel poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) polymersome-based nanomedicine with self-assembled bilayers, which was functionalized with lactoferrin (Lf-POS) to facilitate the transport of a neuroprotective peptide into the brain. The apparent diffusion coefficient (D*) of H(+) through the polymersome membrane was 5.659 × 10(-26) cm(2) s(-1), while that of liposomes was 1.017 × 10(-24) cm(2) s(-1). The stability of the polymersome membrane was much higher than that of liposomes. The uptake of polymersomes by mouse brain capillary endothelial cells proved that the optimal density of lactoferrin was 101 molecules per polymersome. Fluorescence imaging indicated that Lf101-POS was effectively transferred into the brain. In pharmacokinetics, compared with transferrin-modified polymersomes and cationic bovine serum albumin-modified polymersomes, Lf-POS obtained the greatest BBB permeability surface area and percentage of injected dose per gram (%ID per g). Furthermore, Lf-POS holding S14G-humanin protected against learning and memory impairment induced by amyloid-β25-35 in rats. Western blotting revealed that the nanomedicine provided neuroprotection against over-expression of apoptotic proteins exhibiting neurofibrillary tangle pathology in neurons. The results indicated that polymersomes can be exploited as a promising non-invasive nanomedicine capable of mediating peptide therapeutic delivery and controlling the release of drugs to the central nervous system.

Ductile all-cellulose nanocomposite films fabricated from core-shell structured cellulose nanofibrils.

PubMed

Larsson, Per A; Berglund, Lars A; Wågberg, Lars

2014-06-09

Cellulosic materials have many desirable properties such as high mechanical strength and low oxygen permeability and will be an important component in a sustainable biomaterial-based society, but unfortunately they often lack the ductility and formability offered by petroleum-based materials. This paper describes the fabrication and characterization of nanocomposite films made of core-shell modified cellulose nanofibrils (CNFs) surrounded by a shell of ductile dialcohol cellulose, created by heterogeneous periodate oxidation followed by borohydride reduction of the native cellulose in the external parts of the individual fibrils. The oxidation with periodate selectively produces dialdehyde cellulose, and the process does not increase the charge density of the material. Yet the modified cellulose fibers could easily be homogenized to CNFs. Prior to film fabrication, the CNF was shown by atomic force microscopy to be 0.5-2 μm long and 4-10 nm wide. The films were fabricated by filtration, and besides uniaxial tensile testing at different relative humidities, they were characterized by scanning electron microscopy and oxygen permeability. The strength-at-break at 23 °C and 50% RH was 175 MPa, and the films could, before rupture, be strained, mainly by plastic deformation, to about 15% and 37% at 50% RH and 90% RH, respectively. This moisture plasticization was further utilized to form a demonstrator consisting of a double-curved structure with a nominal strain of 24% over the curvature. At a relative humidity of 80%, the films still acted as a good oxygen barrier, having an oxygen permeability of 5.5 mL·μL/(m(2)·24 h·kPa). These properties indicate that this new material has a potential for use as a barrier in complex-shaped structures and hence ultimately reduce the need for petroleum-based plastics.

The proton permeability of self-assembled polymersomes and their neuroprotection by enhancing a neuroprotective peptide across the blood-brain barrier after modification with lactoferrin

NASA Astrophysics Data System (ADS)

Yu, Yuan; Jiang, Xinguo; Gong, Shuyu; Feng, Liang; Zhong, Yanqiang; Pang, Zhiqing

2014-02-01

Biotherapeutics such as peptides possess strong potential for the treatment of intractable neurological disorders. However, because of their low stability and the impermeability of the blood-brain barrier (BBB), biotherapeutics are difficult to transport into brain parenchyma via intravenous injection. Herein, we present a novel poly(ethylene glycol)-poly(d,l-lactic-co-glycolic acid) polymersome-based nanomedicine with self-assembled bilayers, which was functionalized with lactoferrin (Lf-POS) to facilitate the transport of a neuroprotective peptide into the brain. The apparent diffusion coefficient (D*) of H+ through the polymersome membrane was 5.659 × 10-26 cm2 s-1, while that of liposomes was 1.017 × 10-24 cm2 s-1. The stability of the polymersome membrane was much higher than that of liposomes. The uptake of polymersomes by mouse brain capillary endothelial cells proved that the optimal density of lactoferrin was 101 molecules per polymersome. Fluorescence imaging indicated that Lf101-POS was effectively transferred into the brain. In pharmacokinetics, compared with transferrin-modified polymersomes and cationic bovine serum albumin-modified polymersomes, Lf-POS obtained the greatest BBB permeability surface area and percentage of injected dose per gram (%ID per g). Furthermore, Lf-POS holding S14G-humanin protected against learning and memory impairment induced by amyloid-β25-35 in rats. Western blotting revealed that the nanomedicine provided neuroprotection against over-expression of apoptotic proteins exhibiting neurofibrillary tangle pathology in neurons. The results indicated that polymersomes can be exploited as a promising non-invasive nanomedicine capable of mediating peptide therapeutic delivery and controlling the release of drugs to the central nervous system.

Classification of the alterations of beaver dams to headwater streams in northeastern Connecticut, U.S.A.

NASA Astrophysics Data System (ADS)

Burchsted, Denise; Daniels, Melinda D.

2014-01-01

Of the many types of barriers to water flow, beaver dams are among the smallest, typically lasting less than a decade and rarely exceeding 1.5 m in height. They are also among the most frequent and common obstructions in rivers, with a density often exceeding ten dams per km, a frequency of construction within a given network on a time scale of years, and a historic extent covering most of North America. Past quantification of the geomorphologic impact of beaver dams has primarily been limited to local impacts within individual impoundments and is of limited geographic scope. To assess the impact of beaver dams at larger scales, this study examines channel shape and sediment distribution in thirty river reaches in northeastern Connecticut, U.S.A. The study reaches fall within the broader categories of impounded and free-flowing segments, leaving a third segment class of beaver meadows requiring additional study. Each of the study reaches were classified at the reach scale as free-flowing, valley-wide beaver pond, in-channel beaver pond, and downstream of beaver dam. The bankfull channel width to depth ratios and channel widths normalized by watershed area vary significantly across the study reach classes. Additionally, reaches modified by beaver dams have finer sediment distributions. This paper provides the first quantitative geomorphic descriptions of the in-channel beaver pond and reaches downstream of beaver dams. Given the different channel shapes and sediment distributions, we infer that geomorphic processes are longitudinally decoupled by these frequent barriers that control local base level. These barriers generate heterogeneity within a river network by greatly increasing the range of channel morphology and by generating patches controlled by different processes. Therefore, in spite of the small size of individual beaver dams, the cumulative effect of multiple dams has the potential to modify processes at larger spatial scales. To improve assessment of the larger-scale impacts, we propose a hierarchical classification scheme based on discontinuities, place the reach classes of this study within that scheme, and suggest that further research should continue investigation of discontinuity at the network scale and quantification of the cumulative impacts.

Applications and societal benefits of plastics.

PubMed

Andrady, Anthony L; Neal, Mike A

2009-07-27

This article explains the history, from 1600 BC to 2008, of materials that are today termed 'plastics'. It includes production volumes and current consumption patterns of five main commodity plastics: polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate. The use of additives to modify the properties of these plastics and any associated safety, in use, issues for the resulting polymeric materials are described. A comparison is made with the thermal and barrier properties of other materials to demonstrate the versatility of plastics. Societal benefits for health, safety, energy saving and material conservation are described, and the particular advantages of plastics in society are outlined. Concerns relating to littering and trends in recycling of plastics are also described. Finally, we give predictions for some of the potential applications of plastic over the next 20 years.

Applications and societal benefits of plastics

PubMed Central

Andrady, Anthony L.; Neal, Mike A.

2009-01-01

This article explains the history, from 1600 BC to 2008, of materials that are today termed ‘plastics’. It includes production volumes and current consumption patterns of five main commodity plastics: polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate. The use of additives to modify the properties of these plastics and any associated safety, in use, issues for the resulting polymeric materials are described. A comparison is made with the thermal and barrier properties of other materials to demonstrate the versatility of plastics. Societal benefits for health, safety, energy saving and material conservation are described, and the particular advantages of plastics in society are outlined. Concerns relating to littering and trends in recycling of plastics are also described. Finally, we give predictions for some of the potential applications of plastic over the next 20 years. PMID:19528050

Development of Protective Coatings for Chromium-Base Alloys

NASA Technical Reports Server (NTRS)

English, J. J.; MacMillan, C. A.; Williams, D. N.; Bartlett, E. S.

1966-01-01

Chromium alloy sheet was clad with 5 to 10-mil-thick oxidation-resistant nickel-base alloy foils. Specimens also contained 1/2 to 1-mil-thick intermediate layers of platinum, tungsten, and/or W-25Re. Cladding was done by the isostatic hot gas-pressure bonding,.process. The clad chromium-alloy specimens were cyclic oxidation tested at 2100 F and 2300 F for up to 200 hours to determine the effectiveness of these metal claddings in protecting the chromium alloy Cr-5W from oxidation and contamination. Cladding systems consisting of 5-mil-thick Ni-20Cr-20W modified with 3 to 5 weight percent aluminum and containing a 1 /2-mil tungsten diffusion barrier demonstrated potential for long-time service at temperatures as high as 2300 F.

Degradable Organically-Derivatized Polyoxometalate with Enhanced Activity against Glioblastoma Cell Line

NASA Astrophysics Data System (ADS)

She, Shan; Bian, Shengtai; Huo, Ruichao; Chen, Kun; Huang, Zehuan; Zhang, Jiangwei; Hao, Jian; Wei, Yongge

2016-09-01

High efficacy and low toxicity are critical for cancer treatment. Polyoxometalates (POMs) have been reported as potential candidates for cancer therapy. On accounts of the slow clearance of POMs, leading to long-term toxicity, the clinical application of POMs in cancer treatment is restricted. To address this problem, a degradable organoimido derivative of hexamolybdate is developed by modifying it with a cleavable organic group, leading to its degradation. Of note, this derivative exhibits favourable pharmacodynamics towards human malignant glioma cell (U251), the ability to penetrate across blood brain barrier and low toxicity towards rat pheochromocytoma cell (PC12). This line of research develops an effective POM-based agent for glioblastoma inhibition and will pave a new way to construct degradable anticancer agents for clinical cancer therapy.

Homeostasis and Gauss statistics: barriers to understanding natural variability.

PubMed

West, Bruce J

2010-06-01

In this paper, the concept of knowledge is argued to be the top of a three-tiered system of science. The first tier is that of measurement and data, followed by information consisting of the patterns within the data, and ending with theory that interprets the patterns and yields knowledge. Thus, when a scientific theory ceases to be consistent with the database the knowledge based on that theory must be re-examined and potentially modified. Consequently, all knowledge, like glory, is transient. Herein we focus on the non-normal statistics of physiologic time series and conclude that the empirical inverse power-law statistics and long-time correlations are inconsistent with the theoretical notion of homeostasis. We suggest replacing the notion of homeostasis with that of Fractal Physiology.

Radiation-tolerant imaging device

DOEpatents

Colella, N.J.; Kimbrough, J.R.

1996-11-19

A barrier at a uniform depth for an entire wafer is used to produce imaging devices less susceptible to noise pulses produced by the passage of ionizing radiation. The barrier prevents charge created in the bulk silicon of a CCD detector or a semiconductor logic or memory device from entering the collection volume of each pixel in the imaging device. The charge barrier is a physical barrier, a potential barrier, or a combination of both. The physical barrier is formed by an SiO{sub 2} insulator. The potential barrier is formed by increasing the concentration of majority carriers (holes) to combine with the electron`s generated by the ionizing radiation. A manufacturer of CCD imaging devices can produce radiation-tolerant devices by merely changing the wafer type fed into his process stream from a standard wafer to one possessing a barrier beneath its surface, thus introducing a very small added cost to his production cost. An effective barrier type is an SiO{sub 2} layer. 7 figs.

Radiation-tolerant imaging device

DOEpatents

Colella, Nicholas J.; Kimbrough, Joseph R.

1996-01-01

A barrier at a uniform depth for an entire wafer is used to produce imaging devices less susceptible to noise pulses produced by the passage of ionizing radiation. The barrier prevents charge created in the bulk silicon of a CCD detector or a semiconductor logic or memory device from entering the collection volume of each pixel in the imaging device. The charge barrier is a physical barrier, a potential barrier, or a combination of both. The physical barrier is formed by an SiO.sub.2 insulator. The potential barrier is formed by increasing the concentration of majority carriers (holes) to combine with the electron's generated by the ionizing radiation. A manufacturer of CCD imaging devices can produce radiation-tolerant devices by merely changing the wafer type fed into his process stream from a standard wafer to one possessing a barrier beneath its surface, thus introducing a very small added cost to his production cost. An effective barrier type is an SiO.sub.2 layer.

Lymphocyte Electrotaxis in vitro and in vivo

PubMed Central

Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D.; Santiago, Juan G.; Butcher, Eugene C.

2008-01-01

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e. electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified transwell assay and a simple microfluidic device, we show that human peripheral blood lymphocytes migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well. PMID:18684937

Lymphocyte electrotaxis in vitro and in vivo.

PubMed

Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D; Santiago, Juan G; Butcher, Eugene C

2008-08-15

Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e., electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified Transwell assay and a simple microfluidic device, we show that human PBLs migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well.

Low-dose penicillin in early life induces long-term changes in murine gut microbiota, brain cytokines and behavior

PubMed Central

Leclercq, Sophie; Mian, Firoz M.; Stanisz, Andrew M.; Bindels, Laure B.; Cambier, Emmanuel; Ben-Amram, Hila; Koren, Omry; Forsythe, Paul; Bienenstock, John

2017-01-01

There is increasing concern about potential long-term effects of antibiotics on children's health. Epidemiological studies have revealed that early-life antibiotic exposure can increase the risk of developing immune and metabolic diseases, and rodent studies have shown that administration of high doses of antibiotics has long-term effects on brain neurochemistry and behaviour. Here we investigate whether low-dose penicillin in late pregnancy and early postnatal life induces long-term effects in the offspring of mice. We find that penicillin has lasting effects in both sexes on gut microbiota, increases cytokine expression in frontal cortex, modifies blood–brain barrier integrity and alters behaviour. The antibiotic-treated mice exhibit impaired anxiety-like and social behaviours, and display aggression. Concurrent supplementation with Lactobacillus rhamnosus JB-1 prevents some of these alterations. These results warrant further studies on the potential role of early-life antibiotic use in the development of neuropsychiatric disorders, and the possible attenuation of these by beneficial bacteria. PMID:28375200

PEGylated Polyamidoamine dendrimer conjugated with tumor homing peptide as a potential targeted delivery system for glioma.

PubMed

Jiang, Yan; Lv, Lingyan; Shi, Huihui; Hua, Yabing; Lv, Wei; Wang, Xiuzhen; Xin, Hongliang; Xu, Qunwei

2016-11-01

Glioblastoma multiforme (GBM) is the most common and aggressive primary central nervous system (CNS) tumor with a short survival time. The failure of chemotherapy is ascribed to the low transport of chemotherapeutics across the Blood Brain Tumor Barrier (BBTB) and poor penetration into tumor tissue. In order to overcome the two barriers, small nanoparticles with active targeted capability are urgently needed for GBM drug delivery. In this study, we proposed PEGylated Polyamidoamine (PAMAM) dendrimer nanoparticles conjugated with glioma homing peptides (Pep-1) as potential glioma targeting delivery system (Pep-PEG-PAMAM), where PEGylated PAMAM dendrimer nanoparticle was utilized as carrier due to its small size and perfect penetration into tumor and Pep-1 was used to overcome BBTB via interleukin 13 receptor α2 (IL-13Rα2) mediated endocytosis. The preliminary availability and safety of Pep-PEG-PAMAM as a nanocarrier for glioma was evaluated. In vitro results indicated that a significantly higher amount of Pep-PEG-PAMAM was endocytosed by U87 MG cells. In vivo fluorescence imaging of U87MG tumor-bearing mice confirmed that the fluorescence intensity at glioma site of targeted group was 2.02 folds higher than that of untargeted group (**p<0.01), and glioma distribution experiment further revealed that Pep-PEG-PAMAM exhibited a significantly enhanced accumulation and improved penetration at tumor site. In conclusion, Pep-1 modified PAMAM was a promising nanocarrier for targeted delivery of brain glioma. Copyright © 2016 Elsevier B.V. All rights reserved.

Lower hybrid current drive in experiments for transport barriers at high βN of JET (Joint European Torus)

NASA Astrophysics Data System (ADS)

Cesario, R. C.; Castaldo, C.; Fonseca, A.; De Angelis, R.; Parail, V.; Smeulders, P.; Beurskens, M.; Brix, M.; Calabrò, G.; De Vries, P.; Mailloux, J.; Pericoli, V.; Ravera, G.; Zagorski, R.

2007-09-01

LHCD has been used in JET experiments aimed at producing internal transport barriers (ITBs) in highly triangular plasmas (δ≈0.4) at high βN (up to 3) for steady-state application. The LHCD is a potentially valuable tool for (i) modifying the target q-profile, which can help avoid deleterious MHD modes and favour the formation of ITBs, and (ii) contributing to the non-inductive current drive required to prolong such plasma regimes. The q-profile evolution has been simulated during the current ramp-up phase for such a discharge (B0 = 2.3 T, IP = 1.5 MA) where 2 MW of LHCD has been coupled. The JETTO code was used taking measured plasma profiles, and the LHCD profile modeled by the LHstar code. The results are in agreement with MSE measurements and indicate the importance of the elevated electron temperature due to LHCD, as well as the driven current. During main heating with 18 MW of NBI and 3 MW of ICRH the bootstrap current density at the edge also becomes large, consistently with the observed reduction of the local turbulence and of the MHD activity. JETTO modelling suggests that the bootstrap current can reduce the magnetic shear (sh) at large radius, potentially affecting the MHD stability and turbulence behaviour in this region. Keywords: lower hybrid current drive (LHCD), bootstrap current, q (safety factor) and shear (sh) profile evolutions.

The diffusion dynamics of PEGylated liposomes in the intact vitreous of the ex vivo porcine eye: A fluorescence correlation spectroscopy and biodistribution study.

PubMed

Eriksen, Anne Z; Brewer, Jonathan; Andresen, Thomas L; Urquhart, Andrew J

2017-04-30

The diffusion dynamics of nanocarriers in the vitreous and the influence of nanocarrier physicochemical properties on these dynamics is an important aspect of the efficacy of intravitreal administered nanomedicines for the treatment of posterior segment eye diseases. Here we use fluorescence correlation spectroscopy (FCS) to determine liposome diffusion coefficients in the intact vitreous (D Vit ) of ex vivo porcine eyes using a modified Miyake-Apple technique to minimize the disruption of the vitreous fine structure. We chose to investigate whether the zeta potential of polyethylene glycol functionalized (i.e. PEGylated) liposomes altered liposome in situ diffusion dynamics in the vitreous. Non-PEGylated cationic nanocarriers have previously shown little to no diffusion in the vitreous, whilst neutral and anionic have shown diffusion. The liposomes investigated had diameters below 150nm and zeta potentials ranging from -20 to +12mV. We observed that PEGylated cationic liposomes had significantly lower D Vit values (1.14μm 2 s -1 ) than PEGylated neutral and anionic liposomes (2.78 and 2.87μm 2 s -1 ). However, PEGylated cationic liposomes had a similar biodistribution profile across the vitreous to the other systems. These results show that PEGylated cationic liposomes with limited cationic charge can diffuse across the vitreous and indicate that the vitreous as a barrier to nanocarriers (Ø<500nm) is more complicated than simply an electrostatic barrier as previously suggested. Copyright © 2017 Elsevier B.V. All rights reserved.

Insilico direct folding of thrombin-binding aptamer G-quadruplex at all-atom level.

PubMed

Yang, Changwon; Kulkarni, Mandar; Lim, Manho; Pak, Youngshang

2017-12-15

The reversible folding of the thrombin-binding DNA aptamer G-quadruplexes (GQs) (TBA-15) starting from fully unfolded states was demonstrated using a prolonged time scale (10-12 μs) parallel tempering metadynamics (PTMetaD) simulation method in conjunction with a modified version of the AMBER bsc1 force field. For unbiased descriptions of the folding free energy landscape of TBA-15, this force field was minimally modified. From this direct folding simulation using the modified bsc1 force field, reasonably converged free energy landscapes were obtained in K+-rich aqueous solution (150 mM), providing detailed atomistic pictures of GQ folding mechanisms for TBA-15. This study found that the TBA folding occurred via multiple folding pathways with two major free energy barriers of 13 and 15 kcal/mol in the presence of several intermediate states of G-triplex variants. The early formation of these intermediates was associated with a single K+ ion capturing. Interestingly, these intermediate states appear to undergo facile transitions among themselves through relatively small energy barriers. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

Barriers to Implementation of Optimal Laboratory Biosafety Practices in Pakistan

PubMed Central

Shafaq, Humaira; Hasan, Rumina; Qureshi, Shahida M.; Dojki, Maqboola; Hughes, Molly A.; Zaidi, Anita K. M.; Khan, Erum

2016-01-01

The primary goal of biosafety education is to ensure safe practices among workers in biomedical laboratories. Despite several educational workshops by the Pakistan Biological Safety Association (PBSA), compliance with safe practices among laboratory workers remains low. To determine barriers to implementation of recommended biosafety practices among biomedical laboratory workers in Pakistan, we conducted a questionnaire-based survey of participants attending 2 workshops focusing on biosafety practices in Karachi and Lahore in February 2015. Questionnaires were developed by modifying the BARRIERS scale in which respondents are required to rate barriers on a 1-4 scale. Nineteen of the original 29 barriers were included and subcategorized into 4 groups: awareness, material quality, presentation, and workplace barriers. Workshops were attended by 64 participants. Among barriers that were rated as moderate to great barriers by at least 50% of respondents were: lack of time to read biosafety guidelines (workplace subscale), lack of staff authorization to change/improve practice (workplace subscale), no career or self-improvement advantages to the staff for implementing optimal practices (workplace subscale), and unclear practice implications (presentation subscale). A lack of recognition for employees' rights and benefits in the workplace was found to be a predominant reason for a lack of compliance. Based on perceived barriers, substantial improvement in work environment, worker facilitation, and enabling are needed for achieving improved or optimal biosafety practices in Pakistan. PMID:27400192

Perceived Barriers to Smoking Cessation among Adults with Substance Use Disorders

PubMed Central

McHugh, R. Kathryn; Votaw, Victoria R.; Fulciniti, Francesca; Connery, Hilary S.; Griffin, Margaret L.; Monti, Peter M.; Weiss, Roger D.

2017-01-01

The majority of adults seeking substance use disorder treatment also smoke. Smoking is associated with greater substance use disorder severity, poorer treatment outcome, and increased mortality among those with substance use disorders. Yet, engaging this population in smoking cessation treatment is a significant challenge. The aim of this study was to examine perceived barriers to smoking cessation among treatment-seeking adults with alcohol or opioid use disorder. Additionally, we examined whether anxiety sensitivity--a known risk factor for barriers to smoking cessation in the general population--was associated with more barriers to smoking cessation in this sample. A sample of 208 adults was recruited for a one-time study and completed self-report measures of anxiety sensitivity and perceived barriers to smoking cessation. Results indicated that the most common barriers were anxiety (82% of the sample), tension/irritability (76%), and concerns about the ability to maintain sobriety from their primary substance of abuse (64%). Those who reported more barriers also reported lower confidence in the ability to change their smoking behavior. Higher anxiety sensitivity was associated with more perceived barriers to smoking cessation, even when controlling for nicotine dependence severity. These results suggest that there are several perceived barriers to smoking cessation among treatment-seeking adults with substance use disorders. In addition to psychoeducational interventions aimed to modify negative beliefs about smoking cessation, anxiety sensitivity may be a promising therapeutic target in this population. PMID:28132700

Analytical investigation of thermal barrier coatings for advanced power generation combustion turbines

NASA Technical Reports Server (NTRS)

Amos, D. J.

1977-01-01

An analytical evaluation was conducted to determine quantitatively the improvement potential in cycle efficiency and cost of electricity made possible by the introduction of thermal barrier coatings to power generation combustion turbine systems. The thermal barrier system, a metallic bond coat and yttria stabilized zirconia outer layer applied by plasma spray techniques, acts as a heat insulator to provide substantial metal temperature reductions below that of the exposed thermal barrier surface. The study results show the thermal barrier to be a potentially attractive means for improving performance and reducing cost of electricity for the simple, recuperated, and combined cycles evaluated.

Partial hydrophilic modification of biaxially oriented polypropylene film by an atmospheric pressure plasma jet with the allylamine monomer

NASA Astrophysics Data System (ADS)

Chen, W. X.; Yu, J. S.; Hu, W.; Chen, G. L.

2016-11-01

In this paper, the partial modification of the biaxially oriented polypropylene (BOPP) film for potential biological and packaging applications was achieved via hydrophilic modification using atmospheric pressure plasma jet (APPJ). In the APPJ system, the allylamine (ALA) monomer was polymerized on the BOPP surface by either the Ar/O2 or the He/O2 plasma. The results showed that plasmatic modification created many micro/nano sized holes on the BOPP film, which increased the surface roughness dramatically and the increased roughness enhanced the combining intensity between the BOPP film and the ALA polymer. However, such a plasmatic modification increased the water vapor permeability. The FTIR and XPS characterizations showed that the amine groups were grafted onto the BOPP film, and the contact angle of the BOPP film decreases from 98.5° to 8°. Compared with the BOPP films treated by the Ar or He plasma, the barrier property of the modified BOPP film increased significantly when the ALA polymer was incorporated. The bio-affinity/toxicity of ALA polymer was illustrated by the attachment of the cultured SMMC-7721 hepatoma cells on the modified BOPP film. The significant enhancement in the cell density indicated that modified BOPP film was highly bio-compatible and non-toxic, especially treated with the Ar/O2/ALA plasma.

Coordination-based gold nanoparticle layers.

PubMed

Wanunu, Meni; Popovitz-Biro, Ronit; Cohen, Hagai; Vaskevich, Alexander; Rubinstein, Israel

2005-06-29

Gold nanoparticle (NP) mono- and multilayers were constructed on gold surfaces using coordination chemistry. Hydrophilic Au NPs (6.4 nm average core diameter), capped with a monolayer of 6-mercaptohexanol, were modified by partial substitution of bishydroxamic acid disulfide ligand molecules into their capping layer. A monolayer of the ligand-modified Au NPs was assembled via coordination with Zr4+ ions onto a semitransparent Au substrate (15 nm Au, evaporated on silanized glass and annealed) precoated with a self-assembled monolayer of the bishydroxamate disulfide ligand. Layer-by-layer construction of NP multilayers was achieved by alternate binding of Zr4+ ions and ligand-modified NPs onto the first NP layer. Characterization by atomic force microscopy (AFM), ellipsometry, wettability, transmission UV-vis spectroscopy, and cross-sectional transmission electron microscopy showed regular growth of NP layers, with a similar NP density in successive layers and gradually increased roughness. The use of coordination chemistry enables convenient step-by-step assembly of different ligand-possessing components to obtain elaborate structures. This is demonstrated by introducing nanometer-scale vertical spacing between a NP layer and the gold surface, using a coordination-based organic multilayer. Electrical characterization of the NP films was carried out using conductive AFM, emphasizing the barrier properties of the organic spacer multilayer. The results exhibit the potential of coordination self-assembly in achieving highly controlled composite nanostructures comprising molecules, NPs, and other ligand-derivatized components.

Accurate representation of B-DNA double helical structure with implicit solvent and counterions.

PubMed Central

Wang, Lihua; Hingerty, Brian E; Srinivasan, A R; Olson, Wilma K; Broyde, Suse

2002-01-01

High-resolution nuclear magnetic resonance (NMR) and crystallographic data have been taken to refine the force field used in the torsion angle space nucleic acids molecular mechanics program DUPLEX. The population balance deduced from NMR studies of two carcinogen-modified DNA conformers in equilibrium was used to fine tune a sigmoidal, distance-dependent dielectric function so that reasonable relative energies could be obtained. In addition, the base-pair and backbone geometry from high-resolution crystal structures of the Dickerson-Drew dodecamer was used to re-evaluate the deoxyribose pseudorotation profile and the Lennard-Jones nonbonded energy terms. With a modified dielectric function that assumes a very steep distance-dependent form, a deoxyribose pseudorotation profile with reduced energy barriers between C2'- and C3'-endo minima, and a shift of the Lennard-Jones potential energy minimum to a distance approximately 0.4 A greater than the sum of the van der Waals' radii, the sequence-dependent conformational features of the Dickerson-Drew dodecamer in both the solid state and the aqueous liquid crystalline phase are well reproduced. The robust performance of the revised force field, in conjunction with its efficiency through implicit treatment of solvent and counterions, provides a valuable tool for elucidating conformations and structure-function relationships of DNA, including those of molecules modified by carcinogens and other ligands. PMID:12080128

The effects of interfacial recombination and injection barrier on the electrical characteristics of perovskite solar cells

NASA Astrophysics Data System (ADS)

Shi, Lin Xing; Wang, Zi Shuai; Huang, Zengguang; Sha, Wei E. I.; Wang, Haoran; Zhou, Zhen

2018-02-01

Charge carrier recombination in the perovskite solar cells (PSCs) has a deep influence on the electrical performance, such as open circuit voltage, short circuit current, fill factor and ultimately power conversion efficiency. The impacts of injection barrier, recombination channels, doping properties of carrier transport layers and light intensity on the performance of PSCs are theoretically investigated by drift-diffusion model in this work. The results indicate that due to the injection barrier at the interfaces of perovskite and carrier transport layer, the accumulated carriers modify the electric field distribution throughout the PSCs. Thus, a zero electric field is generated at a specific applied voltage, with greatly increases the interfacial recombination, resulting in a local kink of current density-voltage (J-V) curve. This work provides an effective strategy to improve the efficiency of PSCs by pertinently reducing both the injection barrier and interfacial recombination.

Complementary Barrier Infrared Detector (CBIRD) with Double Tunnel Junction Contact and Quantum Dot Barrier Infrared Detector (QD-BIRD)

NASA Technical Reports Server (NTRS)

Ting, David Z.-Y; Soibel, Alexander; Khoshakhlagh, Arezou; Keo, Sam A.; Nguyen, Jean; Hoglund, Linda; Mumolo, Jason M.; Liu, John K.; Rafol, Sir B.; Hill, Cory J.;

Thick thermal barrier coatings for diesel components

NASA Technical Reports Server (NTRS)

Yonushonis, T. M.

1991-01-01

An engineered thick thermal barrier coating consisting of multiple layers of zirconia and CoCrAlY with a zirconia top layer and having a system thermal conductance less than 410 w/m(exp 2)K exceeded the 100 hour engine durability goals set forth in this program. The thermal barrier coatings were intact at the test conclusion. Back to back single cylinder research engine tests were conducted with watercooled, metal hardware and oil-cooled, thermal barrier coating insulated hardware to determine apparent heat release and fuel economy. Apparent heat release data revealed that the insulated engine had a shorter ignition delay and a longer combustion duration than the metal engine. The insulated engine fuel economy was approximately two percent worse on average for this series of tests. There was no attempt to optimize engine efficiency of the insulated engine by modifying the engine timing, coating, or other techniques.

Diffusion barriers in modified air brazes

DOEpatents

Weil, Kenneth Scott; Hardy, John S; Kim, Jin Yong; Choi, Jung-Pyung

2013-04-23

A method for joining two ceramic parts, or a ceramic part and a metal part, and the joint formed thereby. The method provides two or more parts, a braze consisting of a mixture of copper oxide and silver, a diffusion barrier, and then heats the braze for a time and at a temperature sufficient to form the braze into a bond holding the two or more parts together. The diffusion barrier is an oxidizable metal that forms either a homogeneous component of the braze, a heterogeneous component of the braze, a separate layer bordering the braze, or combinations thereof. The oxidizable metal is selected from the group Al, Mg, Cr, Si, Ni, Co, Mn, Ti, Zr, Hf, Pt, Pd, Au, lanthanides, and combinations thereof.

Diffusion barriers in modified air brazes

DOEpatents

Weil, Kenneth Scott [Richland, WA; Hardy, John S [Richland, WA; Kim, Jin Yong [Richland, WA; Choi, Jung-Pyung [Richland, WA

2010-04-06

A method for joining two ceramic parts, or a ceramic part and a metal part, and the joint formed thereby. The method provides two or more parts, a braze consisting of a mixture of copper oxide and silver, a diffusion barrier, and then heats the braze for a time and at a temperature sufficient to form the braze into a bond holding the two or more parts together. The diffusion barrier is an oxidizable metal that forms either a homogeneous component of the braze, a heterogeneous component of the braze, a separate layer bordering the braze, or combinations thereof. The oxidizable metal is selected from the group Al, Mg, Cr, Si, Ni, Co, Mn, Ti, Zr, Hf, Pt, Pd, Au, lanthanides, and combinations thereof.

Chemistry and microbiology of permeable reactive barriers for in situ groundwater clean up.

PubMed

Scherer, M M; Richter, S; Valentine, R L; Alvarez, P J

2000-01-01

Permeable reactive barriers (PRBs) are receiving a great deal of attention as an innovative, cost-effective technology for in situ clean up of groundwater contamination. A wide variety of materials are being proposed for use in PRBs, including zero-valent metals (e.g., iron metal), humic materials, oxides, surfactant-modified zeolites (SMZs), and oxygen- and nitrate-releasing compounds. PRB materials remove dissolved groundwater contaminants by immobilization within the barrier or transformation to less harmful products. The primary removal processes include: (1) sorption and precipitation, (2) chemical reaction, and (3) biologically mediated reactions. This article presents an overview of the mechanisms and factors controlling these individual processes and discusses the implications for the feasibility and long-term effectiveness of PRB technologies.

Building lipid barriers: biosynthesis of cutin and suberin.

PubMed

Pollard, Mike; Beisson, Fred; Li, Yonghua; Ohlrogge, John B

2008-05-01

Cutin and suberin are the polymer matrices for lipophilic cell wall barriers. These barriers control the fluxes of gases, water and solutes, and also play roles in protecting plants from biotic and abiotic stresses and in controlling plant morphology. Although they are ubiquitous, cutin and suberin are the least understood of the major plant extracellular polymers. The use of forward and reverse genetic approaches in Arabidopsis has led to the identification of oxidoreductase and acyltransferase genes involved in the biosynthesis of these polymers. However, major questions about the underlying polymer structure, biochemistry, and intracellular versus extracellular assembly remain to be resolved. The analysis of plant lines with modified cutins and suberins has begun to reveal the inter-relationships between the composition and function of these polymers.

Barriers to hydroxyurea adherence and health-related quality of life in adolescents and young adults with sickle cell disease.

PubMed

Badawy, Sherif M; Thompson, Alexis A; Penedo, Frank J; Lai, Jin-Shei; Rychlik, Karen; Liem, Robert I

2017-06-01

To identify barriers to hydroxyurea adherence (negative beliefs, access, and/or recall barriers), and their relationship to adherence rates and health-related quality of life (HRQOL) among adolescents and young adults (AYA) with sickle cell disease (SCD). A cross-sectional survey was administered to 34 AYAs (12-22 years old) in SCD clinics from January to December 2015. Study measures included Brief Medication Questionnaire, Modified Morisky Adherence Scale 8-items, visual analog scale, and Patient Reported Outcomes Measurement Information System. Participants (59% male; 91% Black) had a median age of 13.5 years (IQR 12-18). Participants reported negative beliefs (32%), recall barriers (44%), and access barriers (32%). Participants with recall barriers reported worse pain (P=.02), fatigue (P=.05), and depression (P=.05). The number of adherence barriers inversely correlated with adherence level using ©MMAS-8 (r s =-.38, P=.02) and VAS dose (r s =-.25, P=.14) as well as MCV (r s =-.45, P=.01) and HbF% (r s =-.36, P=.05), suggesting higher hydroxyurea adherence in patients with fewer barriers. Patients with fewer barriers to hydroxyurea adherence were more likely to have higher adherence rates and better HRQOL scores. Routine assessment of hydroxyurea adherence and its related barriers could provide actionable information to improve adherence rates, HRQOL, and other clinical outcomes. © 2017 The Authors. European Journal of Haematology Published by John Wiley & Sons Ltd.

Healthcare Access for Iraqi Refugee Children in Texas: Persistent Barriers, Potential Solutions, and Policy Implications.

PubMed

Vermette, David; Shetgiri, Rashmi; Al Zuheiri, Haidar; Flores, Glenn

2015-10-01

To identify access barriers to healthcare and potential interventions to improve access for Iraqi refugee children. Four focus groups were conducted using consecutive sampling of Iraqi refugee parents residing in the US for 8 months to 5 years. Eight key-informant interviews also were conducted with employees of organizations serving Iraqi refugee families, recruited using snowball sampling. Focus groups and interviews were audiotaped, transcribed, and analyzed using margin coding and grounded theory. Iraqi refugees identified provider availability, Medicaid maintenance and renewal, language issues, and inadequate recognition of post-traumatic stress disorder as barriers to care for their children. Interviewees cited loss of case-management services and difficulties in understanding the Medicaid renewal process as barriers. Potential interventions to improve access include community-oriented efforts to educate parents on Medicaid renewal, obtaining services, and accessing specialists. Given the enduring nature of language and Medicaid renewal barriers, policies addressing eligibility alone are insufficient.

Agent based modeling of the effects of potential treatments over the blood-brain barrier in multiple sclerosis.

PubMed

Pennisi, Marzio; Russo, Giulia; Motta, Santo; Pappalardo, Francesco

2015-12-01

Multiple sclerosis is a disease of the central nervous system that involves the destruction of the insulating sheath of axons, causing severe disabilities. Since the etiology of the disease is not yet fully understood, the use of novel techniques that may help to understand the disease, to suggest potential therapies and to test the effects of candidate treatments is highly advisable. To this end we developed an agent based model that demonstrated its ability to reproduce the typical oscillatory behavior observed in the most common form of multiple sclerosis, relapsing-remitting multiple sclerosis. The model has then been used to test the potential beneficial effects of vitamin D over the disease. Many scientific studies underlined the importance of the blood-brain barrier and of the mechanisms that influence its permeability on the development of the disease. In the present paper we further extend our previously developed model with a mechanism that mimics the blood-brain barrier behavior. The goal of our work is to suggest the best strategies to follow for developing new potential treatments that intervene in the blood-brain barrier. Results suggest that the best treatments should potentially prevent the opening of the blood-brain barrier, as treatments that help in recovering the blood-brain barrier functionality could be less effective. Copyright © 2015 Elsevier B.V. All rights reserved.

Resonances for Symmetric Two-Barrier Potentials

ERIC Educational Resources Information Center

Fernandez, Francisco M.

2011-01-01

We describe a method for the accurate calculation of bound-state and resonance energies for one-dimensional potentials. We calculate the shape resonances for symmetric two-barrier potentials and compare them with those coming from the Siegert approximation, the complex scaling method and the box-stabilization method. A comparison of the…

Effect of deformation and orientation on spin orbit density dependent nuclear potential

NASA Astrophysics Data System (ADS)

Mittal, Rajni; Kumar, Raj; Sharma, Manoj K.

2017-11-01

Role of deformation and orientation is investigated on spin-orbit density dependent part VJ of nuclear potential (VN=VP+VJ) obtained within semi-classical Thomas Fermi approach of Skyrme energy density formalism. Calculations are performed for 24-54Si+30Si reactions, with spherical target 30Si and projectiles 24-54Si having prolate and oblate shapes. The quadrupole deformation β2 is varying within range of 0.023 ≤ β2 ≤0.531 for prolate and -0.242 ≤ β2 ≤ -0.592 for oblate projectiles. The spin-orbit dependent potential gets influenced significantly with inclusion of deformation and orientation effect. The spin-orbit barrier and position gets significantly influenced by both the sign and magnitude of β2-deformation. Si-nuclei with β22<0 have higher spin-orbit barrier (compact spin-orbit configuration) in comparison to systems with β2>0. The possible role of spin-orbit potential on barrier characteristics such as barrier height, barrier curvature and on the fusion pocket is also probed. In reference to prolate and oblate systems, the angular dependence of spin-orbit potential is further studied on fusion cross-sections.

Perceived barriers to care and provider gender preferences among veteran men who have experienced military sexual trauma: a qualitative analysis.

PubMed

Turchik, Jessica A; McLean, Caitlin; Rafie, Samantha; Hoyt, Tim; Rosen, Craig S; Kimerling, Rachel

2013-05-01

Research suggests that there may be unique barriers to accessing care among men who have experienced sexual trauma. The primary goal of the current research was to elucidate potential barriers to accessing military sexual trauma (MST)-related care for male veterans. A secondary goal was to explore whether veterans have preferences regarding the gender of clinicians providing MST-related care. Qualitative analyses were used to examine data collected from semistructured interviews conducted with 20 male veterans enrolled in Veterans Health Administration care who reported MST but who had not received any MST-related mental health care. Veterans identified a number of potential barriers, with the majority of reported barriers relating to issues of stigma and gender. Regarding provider gender preferences, veterans were mixed, with 50% preferring a female provider, 25% a male provider, and 25% reporting no gender preference. These preliminary data suggest that stigma, gender, and knowledge-related barriers may exist for men regarding seeking MST-related care. Interventions to address potential barriers, such as outreach interventions and providing gender-specific psychoeducation, may increase access to care for male veterans who report MST. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Comparative Analysis: Potential Barriers to Career Participation by North American Physicians in Global Health

PubMed Central

Rhee, Daniel S.; Heckman, Jennifer E.

2014-01-01

Physician interest in global health, particularly among family physicians, is reflected by an increasing proliferation of field training and service experiences. However, translating initial training involvement into a defined and sustainable global health career remains difficult and beset by numerous barriers. Existing global health literature has largely examined training experiences and related ethical considerations while neglecting the role of career development in global health. To explore this, this paper extrapolates potential barriers to global health career involvement from existing literature and compares these to salary and skills requirements for archetypal physician positions in global health, presenting a framework of possible barriers to sustained physician participation in global health work. Notable barriers identified include financial limitations, scheduling conflicts, security/family concerns, skills limitations, limited awareness of opportunities, and specialty choice, with family practice often closely aligned with global health experience. Proposed solutions include financial support, protected time, family relocation support, and additional training. This framework delineates barriers to career involvement in global health by physicians. Further research regarding these barriers as well as potential solutions may help direct policy and initiatives to better utilize physicians, particularly family physicians, as a valuable global health human resource. PMID:25405030

Modeling connectivity to identify current and future anthropogenic barriers to movement of large carnivores: A case study in the American Southwest.

PubMed

McClure, Meredith L; Dickson, Brett G; Nicholson, Kerry L

2017-06-01

This study sought to identify critical areas for puma ( Puma concolor ) movement across the state of Arizona in the American Southwest and to identify those most likely to be impacted by current and future human land uses, particularly expanding urban development and associated increases in traffic volume. Human populations in this region are expanding rapidly, with the potential for urban centers and busy roads to increasingly act as barriers to demographic and genetic connectivity of large-bodied, wide-ranging carnivores such as pumas, whose long-distance movements are likely to bring them into contact with human land uses and whose low tolerance both for and from humans may put them at risk unless opportunities for safe passage through or around human-modified landscapes are present. Brownian bridge movement models based on global positioning system collar data collected during bouts of active movement and linear mixed models were used to model habitat quality for puma movement; then, a wall-to-wall application of circuit theory models was used to produce a continuous statewide estimate of connectivity for puma movement and to identify pinch points, or bottlenecks, that may be most at risk of impacts from current and future traffic volume and expanding development. Rugged, shrub- and scrub-dominated regions were highlighted as those offering high quality movement habitat for pumas, and pinch points with the greatest potential impacts from expanding development and traffic, although widely distributed, were particularly prominent to the north and east of the city of Phoenix and along interstate highways in the western portion of the state. These pinch points likely constitute important conservation opportunities, where barriers to movement may cause disproportionate loss of connectivity, but also where actions such as placement of wildlife crossing structures or conservation easements could enhance connectivity and prevent detrimental impacts before they occur.

Neuroscience: viable applications in education?

PubMed

Devonshire, Ian M; Dommett, Eleanor J

2010-08-01

As a relatively young science, neuroscience is still finding its feet in potential collaborations with other disciplines. One such discipline is education, with the field of neuroeducation being on the horizon since the 1960s. However, although its achievements are now growing, the partnership has not been as successful as first hopes suggested it should be. Here the authors discuss the theoretical barriers and potential solutions to this, which have been suggested previously, with particular focus on levels of research in neuroscience and their applicability to education. Moreover, they propose that these theoretical barriers are driven and maintained by practical barriers surrounding common language and research literacy. They propose that by overcoming these practical barriers through appropriate training and shared experience, neuroeducation can reach its full potential.

Ultrashort dark solitons interactions and nonlinear tunneling in the modified nonlinear Schrödinger equation with variable coefficient

NASA Astrophysics Data System (ADS)

Musammil, N. M.; Porsezian, K.; Nithyanandan, K.; Subha, P. A.; Tchofo Dinda, P.

2017-09-01

We present the study of the dark soliton dynamics in an inhomogeneous fiber by means of a variable coefficient modified nonlinear Schrödinger equation (Vc-MNLSE) with distributed dispersion, self-phase modulation, self-steepening and linear gain/loss. The ultrashort dark soliton pulse evolution and interaction is studied by using the Hirota bilinear (HB) method. In particular, we give much insight into the effect of self-steepening (SS) on the dark soliton dynamics. The study reveals a shock wave formation, as a major effect of SS. Numerically, we study the dark soliton propagation in the continuous wave background, and the stability of the soliton solution is tested in the presence of photon noise. The elastic collision behaviors of the dark solitons are discussed by the asymptotic analysis. On the other hand, considering the nonlinear tunneling of dark soliton through barrier/well, we find that the tunneling of the dark soliton depends on the height of the barrier and the amplitude of the soliton. The intensity of the tunneling soliton either forms a peak or valley and retains its shape after the tunneling. For the case of exponential background, the soliton tends to compress after tunneling through the barrier/well.

Brain delivery of proteins via their fatty acid and block copolymer modifications

PubMed Central

Yi, Xiang; Kabanov, Alexander V.

2014-01-01

It is well known that hydrophobic small molecules penetrate cell membranes better than hydrophilic molecules. Amphiphilic molecules that dissolve both in lipid and aqueous phases are best suited for membrane transport. Transport of biomacromolecules across physiological barriers, e.g. the blood-brain barrier, is greatly complicated by the unique structure and function of such barriers. Two decades ago we adopted a simple philosophy that to increase protein delivery to the brain one needs to modify this protein with hydrophobic moieties. With this general idea we began modifying proteins (antibodies, enzymes, hormones, etc.) with either hydrophobic fatty acid residues or amphiphilic block copolymer moieties, such as poy(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (pluronics or poloxamers) and more recently, poly(2-oxasolines). This simple approach has resulted in impressive successes in CNS drug delivery. We present a retrospective overview of these works initiated in the Soviet Union in 1980s, and then continued in the United States and other countries. Notably some of the early findings were later corroborated by brain pharmacokinetic data. Industrial development of several drug candidates employing these strategies has followed. Overall modification by hydrophobic fatty acids residues or amphiphilic block copolymers represents a promising and relatively safe strategy to deliver proteins to the brain. PMID:24160902

Review of potential subsurface permeable barrier emplacement and monitoring technologies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riggsbee, W.H.; Treat, R.L.; Stansfield, H.J.

1994-02-01

This report focuses on subsurface permeable barrier technologies potentially applicable to existing waste disposal sites. This report describes candidate subsurface permeable barriers, methods for emplacing these barriers, and methods used to monitor the barrier performance. Two types of subsurface barrier systems are described: those that apply to contamination.in the unsaturated zone, and those that apply to groundwater and to mobile contamination near the groundwater table. These barriers may be emplaced either horizontally or vertically depending on waste and site characteristics. Materials for creating permeable subsurface barriers are emplaced using one of three basic methods: injection, in situ mechanical mixing, ormore » excavation-insertion. Injection is the emplacement of dissolved reagents or colloidal suspensions into the soil at elevated pressures. In situ mechanical mixing is the physical blending of the soil and the barrier material underground. Excavation-insertion is the removal of a soil volume and adding barrier materials to the space created. Major vertical barrier emplacement technologies include trenching-backfilling; slurry trenching; and vertical drilling and injection, including boring (earth augering), cable tool drilling, rotary drilling, sonic drilling, jetting methods, injection-mixing in drilled holes, and deep soil mixing. Major horizontal barrier emplacement technologies include horizontal drilling, microtunneling, compaction boring, horizontal emplacement, longwall mining, hydraulic fracturing, and jetting methods.« less

Barriers to access to opioid medicines for patients with opioid dependence: a review of legislation and regulations in eleven central and eastern European countries.

PubMed

Vranken, Marjolein J M; Mantel-Teeuwisse, Aukje K; Jünger, Saskia; Radbruch, Lukas; Scholten, Willem; Lisman, John A; Subataite, Marija; Schutjens, Marie-Hélène D B

2017-06-01

Barriers linked to drug control systems are considered to contribute to inequitable access to controlled medicines, leaving millions of people in pain and suffering. Most studies focus on access to opioids for the treatment of severe (cancer) pain. This study aims to identify specific access barriers for patients with opioid dependence in legislation and regulations of 11 central and eastern European countries. This study builds on a previous analysis of legislation and regulations as part of the EU 7th Framework Access To Opioid Medication in Europe (ATOME) project. An in-depth analysis was undertaken to determine specific barriers for patients with opioid dependence in need of opioid analgesics or opioid agonist therapy (OAT). For each country, the number and nature of specific potential barriers for these patients were assessed according to eight categories: prescribing; dispensing; manufacturing; usage; trade and distribution; affordability; penalties; and other. An additional keyword search was conducted to minimize the omission of barriers. Barriers in an additional category, language, were recorded qualitatively. Countries included Bulgaria, Cyprus, Estonia, Greece, Hungary, Latvia, Lithuania, Serbia, Slovakia, Slovenia and Turkey. Ten of the 11 countries (all except Estonia) showed specific potential barriers in their legislation and regulations. The total number of barriers varied from two (Slovenia) to 46 (Lithuania); the number of categories varied from one (Slovenia) to five (Lithuania). Most specific potential barriers were shown in the categories 'prescribing', 'usage' and 'other'. The total number in a single category varied from one to 18 (Lithuania, prescribing). Individual differences between countries in the same specific potential barrier were shown; for example, variation in minimum age criteria for admission to OAT ranging from 15 (Lithuania, in special cases) to 20 years (Greece). All countries had stigmatizing language in their legislation. Patients with opioid dependence are likely to experience specific barriers to accessing opioids in addition to those experienced by other non-dependent patients. © 2017 Society for the Study of Addiction.

Influences of modified bacterial cellulose nanofibers (BCNs) on structural, thermophysical, optical, and barrier properties of poly ethylene-co-vinyl acetate (EVA) nanocomposite.

PubMed

Ghadikolaei, Shila Shirdel; Omrani, Abdollah; Ehsani, Morteza

2018-04-14

The BCNs were chemically modified using acetic anhydride with the aim of improving its dispersion and interfacial adhesion. Acetylation of BCNs was confirmed by FT-IR spectroscopy. Morphology studies using TEM and SEM revealed that a reasonable dispersion of the modified BCNs in the EVA matrix was accomplished. The DSC data displayed a little shift in the T g to higher temperatures with the incorporation of both modified and unmodified BCNs. Increased thermal stability of the nanocomposites consisting acetylated BCNs was confirmed by TGA technique. DMA measurements highlighted that the storage modulus increased and the damping properties decreased for the nanocomposites with regard to the neat EVA. Copyright © 2018 Elsevier B.V. All rights reserved.

The role of perceived barriers and objectively measured physical activity in adults aged 65-100.

PubMed

Gellert, Paul; Witham, Miles D; Crombie, Iain K; Donnan, Peter T; McMurdo, Marion E T; Sniehotta, Falko F

2015-05-01

to test the predictive utility of perceived barriers to objectively measured physical activity levels in a stratified sample of older adults when accounting for social-cognitive determinants proposed by the Theory of Planned Behaviour (TPB), and economic and demographic factors. data were analysed from the Physical Activity Cohort Scotland survey, a representative and stratified (65-80 and 80+ years; deprived and affluent) sample of 584 community-dwelling older people, resident in Tayside, Scotland. Physical activity was measured objectively by accelerometry. perceived barriers clustered around the areas of poor health, lack of interest, lack of safety and lack of access. Perceived poor health and lack of interest, but not lack of access or concerns about personal safety, predicted physical activity after controlling for demographic, economic and TPB variables. perceived person-related barriers (poor health and lack of interest) seem to be more strongly associated with physical activity levels than perceived environmental barriers (safety and access) in a large sample of older adults. Perceived barriers are modifiable and may be a target for future interventions. © The Author 2015. Published by Oxford University Press on behalf of the British Geriatrics Society. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Delay time in a single barrier for a movable quantum shutter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hernandez, Alberto

2010-05-15

The transient solution and delay time for a {delta} potential scatterer with a movable quantum shutter is calculated by solving analytically the time-dependent Schroedinger equation. The delay time is analyzed as a function of the distance between the shutter and the potential barrier and also as a function of the distance between the potential barrier and the detector. In both cases, it is found that the delay time exhibits a dynamical behavior and that it tends to a saturation value {Delta}t{sub sat} in the limit of very short distances, which represents the maximum delay produced by the potential barrier nearmore » the interaction region. The phase time {tau}{sub {theta},} on the other hand, is not an appropriate time scale for measuring the time delay near the interaction region, except if the shutter is moved far away from the potential. The role played by the antibound state of the system on the behavior of the delay time is also discussed.« less

Tunneling of heat: Beyond linear response regime

NASA Astrophysics Data System (ADS)

Walczak, Kamil; Saroka, David

2018-02-01

We examine nanoscale processes of heat (energy) transfer as carried by electrons tunneling via potential barriers and molecular interconnects between two heat reservoirs (thermal baths). For that purpose, we use Landauer-type formulas to calculate thermal conductance and quadratic correction to heat flux flowing via quantum systems. As an input, we implement analytical expressions for transmission functions related to simple potential barriers and atomic bridges. Our results are discussed with respect to energy of tunneling electrons, temperature, the presence of resonant states, and specific parameters characterizing potential barriers as well as heat carriers. The simplicity of semi-analytical models developed by us allows to fit experimental data and extract crucial information about the values of model parameters. Further investigations are expected for more realistic transmission functions, while time-dependent aspects of nanoscale heat transfer may be addressed by using the concept of wave packets scattered on potential barriers and point-like defects within regular (periodic) nanostructures.

MATCON MODIFIED ASPHALT CONTAINMENT SYSTEM FOR MULTI-USE BROWNFIELDS

EPA Science Inventory

The concept of putting brownfield real estate back into safe and practical use is very appealing o both the owner and the neighborhood. Environmental regulations often preclude multi-use alterantives because traditional containment solutions rely on water barrier covers. These ar...

Impact test of a crash-energy management passenger rail car

DOT National Transportation Integrated Search

2004-04-06

On December 3, 2003, a single-car impact test was : conducted to assess the crashworthiness performance of a : modified passenger rail car. A coach car retrofitted with a : Crash Energy Management (CEM) end structure impacted a : fixed barrier at app...

Effects of Post Annealing on I-V-T Characteristics of (Ni/Au)/Al0.09Ga0.91N Schottky Barrier Diodes

NASA Astrophysics Data System (ADS)

Akkaya, Abdullah; Ayyıldız, Enise

2016-04-01

Post annealing is a simple, effective and suitable method for improving the diode parameters, especially when the used chemically stable substrates like Si, III-N and ternary alloys. In our work, we were applied this method to (Ni/Au)/Al0.09Ga0.91N Schottky Barrier Diodes (SBDs) and investigated by temperature-dependent current-voltage (I-V-T) characteristics at optimum conditions. Optimum annealing temperature was 600°C, which it’s determined with respect to have a highest barrier height value. The temperature-dependent electrical characteristics of the annealed at 600°C (Ni/Au)/Al0.09Ga0.91N SBDs were investigated in the wide temperature range of 95-315K. The diode parameters such as ideality factor (n) and Schottky barrier height (Vb0) were obtained to be strongly temperature dependent. The observed variation in Vb0 and n can be attributed to the spatial barrier inhomogeneities in Schottky barrier height by assuming a triple Gaussian distribution (TGD) of barrier heights (BHs) at 95-145K, 145-230K and 230-315K. The modified Richardson plots and T0 analysis was performed to provide an experimental Richardson constants and bias coefficients of the mean barrier height. Furthermore, the chemical composition of the contacts was examined by the XPS depth profile analysis.

Plasma membrane translocation of a protein needle based on a triple-stranded β-helix motif.

PubMed

Sanghamitra, Nusrat J M; Inaba, Hiroshi; Arisaka, Fumio; Ohtan Wang, Dan; Kanamaru, Shuji; Kitagawa, Susumu; Ueno, Takafumi

2014-10-01

Plasma membrane translocation is challenging due to the barrier of the cell membrane. Contrary to the synthetic cell-penetrating materials, tailed bacteriophages use cell-puncturing protein needles to puncture the cell membranes as an initial step of the DNA injection process. Cell-puncturing protein needles are thought to remain functional in the native phages. In this paper, we found that a bacteriophage T4 derived protein needle of 16 nm length spontaneously translocates through the living cell membrane. The β-helical protein needle (β-PN) internalizes into human red blood cells that lack endocytic machinery. By comparing the cellular uptake of β-PNs with modified surface charge, it is shown that the uptake efficiency is maximum when it has a negative charge corresponding to a zeta potential value of -16 mV. In HeLa cells, uptake of β-PN incorporates endocytosis independent mechanisms with partial macropinocytosis dependence. The endocytosis dependence of the uptake increases when the surface charges of β-PNs are modified to positive or negative. Thus, these results suggest that natural DNA injecting machinery can serve as an inspiration to design new class of cell-penetrating materials with a tailored mechanism.

Ion Implantation-Modified Fluorine-Doped Tin Oxide by Zirconium with Continuously Tunable Work Function and Its Application in Perovskite Solar Cells.

PubMed

Han, Dong; Wu, Cuncun; Zhao, Yunbiao; Chen, Yi; Xiao, Lixin; Zhao, Ziqiang

2017-12-06

In recent years, perovskite solar cells have drawn a widespread attention. As an electrode material, fluorine-doped tin oxide (FTO) is widely used in various kinds of solar cells. However, the relatively low work function (WF) (∼4.6 eV) limits its application. The potential barrier between the transparent conductive oxide electrode and the hole transport layer (HTL) in inverted perovskite solar cells results in a decrease in device performance. In this paper, we propose a method to adjust WF of FTO by implanting zirconium ions into the FTO surface. The WF of FTO can be precisely and continuously tuned between 4.59 and 5.55 eV through different dopant concentration of zirconium. In the meantime, the modified FTO, which had a WF of 5.1 eV to match well the highest occupied molecular orbital energy level of poly(3,4-ethylenedioxylenethiophene):polystyrene sulfonate, was used as the HTL in inverted planar perovskite solar cells. Compared with the pristine FTO electrode-based device, the open circuit voltage increased from 0.82 to 0.91 V, and the power conversion efficiency increased from 11.6 to 14.0%.

Recent innovations in edible and/or biodegradable packaging materials.

PubMed

Guilbert, S; Cuq, B; Gontard, N

1997-01-01

Certain newly discovered characteristics of natural biopolymers should make them a choice material to be used for different types of wrappings and films. Edible and/or biodegradable packagings produced from agricultural origin macromolecules provide a supplementary and sometimes essential means to control physiological, microbiological, and physicochemical changes in food products. This is accomplished (i) by controlling mass transfers between food product and ambient atmosphere or between components in heterogeneous food product, and (iii) by modifying and controlling food surface conditions (pH, level of specific functional agents, slow release of flavour compounds), it should be stressed that the material characteristics (polysaccharide, protein, or lipid, plasticized or not, chemically modified or not, used alone or in combination) and the fabrication procedures (casting of a film-forming solution, thermoforming) must be adapted to each specific food product and usage condition (relative humidity, temperature). Some potential uses of these materials (e.g. wrapping of various fabricated foods; protection of fruits and vegetables by control of maturation; protection of meat and fish; control of internal moisture transfer in pizzas), which are hinged on film properties (e.g. organoleptic, mechanical, gas and solute barrier) are described with examples.

Asthma Morbidity, Comorbidities, and Modifiable Factors Among Older Adults.

PubMed

Hsu, Joy; Chen, Jessica; Mirabelli, Maria C

Asthma morbidity is increased among older adults, especially older adult women. Interventions to improve asthma control in this population are not well described. The objective of this study was to identify risk factors (including modifiable factors) associated with asthma-related hospitalizations and emergency department or urgent care center visits (ED/UCV) among older adults. A secondary objective was to investigate sex differences in variables relevant to asthma control. Data were obtained from 14,076 older adults ≥65 years with active asthma participating in the 2006-2010 Behavioral Risk Factor Surveillance System Asthma Call-back Survey (a random-digit dialed survey) in 40 US states, the District of Columbia, and Puerto Rico, representative of >2.6 million persons. Weighted, adjusted logistic regression was conducted. One or more asthma-related hospitalizations in the past year were reported by 5.7% (95% confidence interval [95% CI] = 5.0% to 6.4%) of participants; 10.6% (95% CI = 9.7% to 11.5%) reported ≥1 asthma-related ED/UCV. Compared with older adults without asthma-related hospitalizations, adjusted odds were higher among those with ≥1 asthma-related hospitalization for chronic obstructive pulmonary disease (COPD), coronary artery disease, depression, cockroaches or mold in the home, and cost barriers to asthma-related health care or medication. All these factors, except for cockroaches, were associated with asthma-related ED/UCV. Compared with males, adjusted odds were higher among females for COPD, depression, obesity, and cost barriers to asthma-related health care or medication. Among older adults, asthma-related hospitalizations and ED/UCV were associated with clinical comorbidities, mold in the home, and financial barriers to asthma-related health care. Interventions addressing modifiable factors could reduce asthma morbidity among older adults. Published by Elsevier Inc.

Planning and Implementing Immunization Billing Programs at State and Local Health Departments: Barriers and Possible Solutions.

PubMed

Corriero, Rosemary; Redmon, Ginger

Before participating in a project funded by the Centers for Disease Control and Prevention, most state and local health departments (LHDs) were not seeking reimbursement or being fully reimbursed by insurance plans for the cost of immunization services (including vaccine costs and administration fees) they provided to insured patients. Centers for Disease Control and Prevention's Billables Project was designed to enable state and LHDs to bill public and private insurance plans for immunization services provided to insured patients. Identify and describe key barriers state and LHDs may encounter while planning and implementing a billing program, as well as possible solutions for overcoming those barriers. This study used reports from Billables Project participants to explore barriers they encountered when planning and implementing a billing program and steps taken to address those barriers. Thirty-eight state immunization programs. Based on project participants' reports, barriers were noted in 7 categories: (1) funding and costs, (2) staff, (3) health department characteristics, (4) third-party payers and insurance plans, (5) software, (6) patient insurance status, and (7) other barriers. Possible solutions for overcoming those barriers included hiring or seeking external help, creating billing guides and training modules, streamlining workflows, and modifying existing software systems. Overcoming barriers during planning and implementation of a billing program can be challenging for state and LHDs, but the experiences and suggestions of past Billables Project participants can help guide future billing program efforts.

Wave trapping by dual porous barriers near a wall in the presence of bottom undulation

NASA Astrophysics Data System (ADS)

Kaligatla, R. B.; Manisha; Sahoo, T.

2017-09-01

Trapping of oblique surface gravity waves by dual porous barriers near a wall is studied in the presence of step type varying bottom bed that is connected on both sides by water of uniform depths. The porous barriers are assumed to be fixed at a certain distance in front of a vertical rigid wall. Using linear water wave theory and Darcy's law for flow past porous structure, the physical problem is converted into a boundary value problem. Using eigenfunction expansion in the uniform bottom bed region and modified mild-slope equation in the varying bottom bed region, the mathematical problem is handled for solution. Moreover, certain jump conditions are used to account for mass conservation at slope discontinuities in the bottom bed profile. To understand the effect of dual porous barriers in creating tranquility zone and minimum load on the sea wall, reflection coefficient, wave forces acting on the barrier and the wall, and surface wave elevation are computed and analyzed for different values of depth ratio, porous-effect parameter, incident wave angle, gap between the barriers and wall and slope length of undulated bottom. The study reveals that with moderate porosity and suitable gap between barriers and sea wall, using dual barriers an effective wave trapping system can be developed which will exert less wave force on the barriers and the rigid wall. The proposed wave trapping system is likely to be of immense help for protecting various facilities/ infrastructures in coastal environment.

Identifying Barriers That Hinder Onsite Parental Involvement in a School-Based Health Promotion Program

PubMed Central

Garcia-Dominic, Oralia; Wray, Linda A.; Treviño, Roberto P.; Hernandez, Arthur E.; Yin, Zenong; Ulbrecht, Jan S.

2009-01-01

We investigated whether barriers to onsite parental involvement in the Bienestar Health Program Parent Component could be identified and whether participation rates could be increased by addressing these barriers. All nonparticipating parents of fourth-grade students of San Antonio Independent School District from 4 schools, which were selected randomly from 20 intervention schools in Bienestar, were invited to take part in this study. A total of 47 of 223 (21%) parents engaged in one of four focus groups offered. Parents identified barriers to their involvement in Bienestar that fit into five descriptive categories: (a) low value, (b) high cost, (c) competing family demands, (d) concerns about the program design, and (e) social role norms. The Bienestar Parent Component was then modified according to the focus group findings, which resulted in a marked increase in parental involvement from 17% to 37% overall. These findings suggest that even when parents are involved in the initial design of parent-friendly and culturally sensitive programs, as was the case for Bienestar, maximizing parental involvement may require additional assessment, identification, and remediation of barriers. PMID:19339644

Characterization of WB/SiC Schottky Barrier Diodes Using I-V-T Method

NASA Astrophysics Data System (ADS)

Aldridge, James; Oder, Tom

2009-04-01

The importance of silicon carbide (SiC) semiconductor for high temperature and high power microelectronic device applications has long been established. We have fabricated SiC Schottky barrier diodes using tungsten boride (WB) as the Schottky contact. The diodes were characterized using the current-voltage-temperature method. The sample was mounted on a heated stage and the temperature varied from about 25 ^oC to 300 ^oC at intervals of 25 ^oC. From the Richardson's plot, we obtained an energy barrier height of 0.96 eV and a Richardson's constant of 71.2 AK-1cm-2. Using the modified Richardson's plot, we obtained a barrier height of 1.01 eV. From the variation of the ideality factor and the temperature, we determined a characteristic energy of 0.02 eV to 0.04 eV across the range of the measurement temperature. This implies that thermionic emission is dominant in the low measurement temperature range. Our results confirm the excellent thermal stability of WB/SiC Schottky barrier diodes.

Potential barriers to electric vehicle commercialization : A. insurance B. vehicle recharging

DOT National Transportation Integrated Search

1981-03-01

An assessment of the potential barriers to the commercialization of electric and hybrid vehicles due to insurance considerations and the absence of a range extension infrastructure was performed. Availability of operator and manufacturers liability i...

Barriers, motivators and enablers for dispensing multifocal contact lenses in Mumbai, India

PubMed Central

Thite, Nilesh; Shah, Ukti; Mehta, Jasmin; Jurkus, Janice

2015-01-01

Purpose To understand the potential barriers, motivators and enablers in dispensing multifocal contact lenses (MFCL). Method Two focus group discussions were conducted to design questionnaires regarding the prescribing habits for multifocal contact lenses (MFCL). Questions on potential barriers and motivators were included. The questionnaires were distributed among 133 eye care practitioners across Mumbai, India. Practitioners fitting one or less patient per month with MFCL completed the survey describing potential barriers, while those who prescribed more MFCL's per month completed the survey describing enablers and motivators. Results Responses from 102 practitioners were received. Most common potential barriers in prescribing MFCL were increased chair time (75%), lack of readily available trials (69%) and limitation in power range (63%). Lack of awareness among patients (90%) was the most common barrier from patients’ outlook. Professional satisfaction (88%) and better business proposition (82%) were observed as main motivators while availability of the trials (84%) and correct patient selection (82%) were the major enablers. Graduate Optometrists felt dispensing MFCL did not offer a good business proposition (p = 0.02). Experienced practitioners were observed to be least motivated (p = 0.01) and believed that their patients found these lenses expensive (p = 0.02). Conclusion To enhance the MFCL practice, barriers like lack of awareness and limitations in power range must be addressed. Trial lens availability may motivate practitioners to prescribe MFCL. Further probing is required to understand lack of motivation among experienced practitioners. PMID:25563404

Barriers, motivators and enablers for dispensing multifocal contact lenses in Mumbai, India.

PubMed

Thite, Nilesh; Shah, Ukti; Mehta, Jasmin; Jurkus, Janice

2015-01-01

To understand the potential barriers, motivators and enablers in dispensing multifocal contact lenses (MFCL). Two focus group discussions were conducted to design questionnaires regarding the prescribing habits for multifocal contact lenses (MFCL). Questions on potential barriers and motivators were included. The questionnaires were distributed among 133 eye care practitioners across Mumbai, India. Practitioners fitting one or less patient per month with MFCL completed the survey describing potential barriers, while those who prescribed more MFCL's per month completed the survey describing enablers and motivators. Responses from 102 practitioners were received. Most common potential barriers in prescribing MFCL were increased chair time (75%), lack of readily available trials (69%) and limitation in power range (63%). Lack of awareness among patients (90%) was the most common barrier from patients' outlook. Professional satisfaction (88%) and better business proposition (82%) were observed as main motivators while availability of the trials (84%) and correct patient selection (82%) were the major enablers. Graduate Optometrists felt dispensing MFCL did not offer a good business proposition (p=0.02). Experienced practitioners were observed to be least motivated (p=0.01) and believed that their patients found these lenses expensive (p=0.02). To enhance the MFCL practice, barriers like lack of awareness and limitations in power range must be addressed. Trial lens availability may motivate practitioners to prescribe MFCL. Further probing is required to understand lack of motivation among experienced practitioners. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Access barriers to and unmet needs for home- and community-based services among older Korean Americans.

PubMed

Casado, Banghwa Lee; Lee, Sang E

2012-01-01

This cross-sectional survey study of 146 caregivers of older Korean Americans explored access barriers to and unmet needs for home- and community-based services (HCBS) programs (respite care, adult day care, personal care, home health, housekeeping, and transportation). Most often reported access barriers were lack of awareness and care recipient refusal. Predictors of unmet needs varied depending on the type of service, but included caregiver gender, relationship, education, caregiving duration, Medicaid coverage, English proficiency, caregiver self-efficacy, care recipient functional dependency, cognitive impairment, and caregiving hours. This study highlighted unmet needs for HCBS in Korean American communities, pointing to the pressing need for a collaborative effort to develop plans that modify and expand HCBS programs for older Korean Americans.

Clinical Applications Involving CNS Gene Transfer

PubMed Central

Kantor, Boris; McCown, Thomas; Leone, Paola; Gray, Steven J.

2015-01-01

Diseases of the central nervous system (CNS) have traditionally been the most difficult to treat by traditional pharmacological methods, due mostly to the blood–brain barrier and the difficulties associated with repeated drug administration targeting the CNS. Viral vector gene transfer represents a way to permanently provide a therapeutic protein within the nervous system after a single administration, whether this be a gene replacement strategy for an inherited disorder or a disease-modifying protein for a disease such as Parkinson's. Gene therapy approaches for CNS disorders has evolved considerably over the last two decades. Although a breakthrough treatment has remained elusive, current strategies are now considerably safer and potentially much more effective. This chapter will explore the past, current, and future status of CNS gene therapy, focusing on clinical trials utilizing adeno-associated virus and lentiviral vectors. PMID:25311921

Turning theory into practice: the development of modern transdermal drug delivery systems and future trends.

PubMed

Perumal, O; Murthy, S N; Kalia, Y N

2013-01-01

Despite its remarkable barrier function, the skin remains an attractive site for systemic drug delivery given its easy accessibility, large surface area and the possibility to bypass the gastrointestinal tract and the liver and so modify drug absorption kinetics. The pioneering work of Scheuplein, Higuchi and others in the 1960s helped to explain the processes involved in passive percutaneous absorption and led to the development of mathematical models to describe transdermal drug delivery. The intervening years have seen these theories turned to practice and a significant number of transdermal systems are now available including some that employ active drug delivery. This review briefly discusses the evolution of transdermal therapeutic systems over the years and the potential of newer transdermal technologies to deliver hydrophilic drugs and macromolecules through the skin. © 2013 S. Karger AG, Basel.

Damage Detection and Mitigation in Open Collaboration Applications

ERIC Educational Resources Information Center

West, Andrew G.

2013-01-01

Collaborative functionality is changing the way information is amassed, refined, and disseminated in online environments. A subclass of these systems characterized by "open collaboration" uniquely allow participants to "modify" content with low barriers-to-entry. A prominent example and our case study, English Wikipedia,…

Finding resiliency in the face of financial barriers: Development of a conceptual framework for people with cardiovascular-related chronic disease.

PubMed

Campbell, David J T; Manns, Braden J; Leblanc, Pamela; Hemmelgarn, Brenda R; Sanmartin, Claudia; King-Shier, Kathryn

2016-12-01

Patients with chronic diseases often face financial barriers to optimize their health. These financial barriers may be related to direct healthcare costs such as medications or self-monitoring supplies, or indirect costs such as transportation to medical appointments. No known framework exists to understand how financial barriers impact patients' lives or their health outcomes.We undertook a grounded theory study to develop such a framework. We used semistructured interviews with a purposive sample of participants with cardiovascular-related chronic disease (hypertension, diabetes, heart disease, or stroke) from Alberta, Canada. Interview transcripts were analyzed in triplicate, and interviews continued until saturation was reached.We interviewed 34 participants. We found that the confluence of 2 events contributed to the perception of having a financial barrier-onset of chronic disease and lack of income or health benefits. The impact of having a perceived financial barrier varied considerably. Protective, predisposing, or modifying of factors determined how impactful a financial barrier would be. An individual's particular set of factors is then shaped by their worldview. This combination of factors and lens determines one's degree of resiliency, which ultimately impacts how well they cope with their disease.The role of financial barriers is complex. How well an individual copes with their financial barriers is intimately tied to resiliency, which is related to the composite of a personal circumstances and their worldview. Our framework for understanding the experience of financial barriers can be used by both researchers and clinicians to better understand patient behavior.

[Blood-nerve barrier and peripheral nerve regeneration].

PubMed

Kanda, Takashi

2013-01-01

Blood-nerve barrier (BNB) restricts the movement of soluble mediators and leukocytes from the blood contents to the peripheral nervous system (PNS) parenchyma and thus maintains the endoneurial homeostasis. However, it interferes the supply of various neurotrophic factors from the blood constituents and stops the drainage of toxic substances out of the PNS parenchyma, resulting in the inhibition of peripheral nerve regeneration. If the manipulation of BNB function is possible, regeneration of peripheral nerve may be facilitated via the alteration of peripheral nerve microenvironment and ample supply of neurotrophic substances. A possible method to manipulate the BNB for therapeutic purposes is to modify the endothelial function using siRNAs, oligonucleotides and virus vectors. Another possible method is to modify BNB pericytes: small hydrophobic substances that can reach the pericyte membrane through the endothelial monolayer and strengthen the pericytic activity, including the release of various cytokines/chemokines that influence endothelial function, may also be useful as drug candidates to control the BNB function.

Viscoelastic subdiffusion: from anomalous to normal.

PubMed

Goychuk, Igor

2009-10-01

We study viscoelastic subdiffusion in bistable and periodic potentials within the generalized Langevin equation approach. Our results justify the (ultra)slow fluctuating rate view of the corresponding bistable non-Markovian dynamics which displays bursting and anticorrelation of the residence times in two potential wells. The transition kinetics is asymptotically stretched exponential when the potential barrier V0 several times exceeds thermal energy k(B)T [V(0) approximately (2-10)k(B)T] and it cannot be described by the non-Markovian rate theory (NMRT). The well-known NMRT result approximates, however, ever better with the increasing barrier height, the most probable logarithm of the residence times. Moreover, the rate description is gradually restored when the barrier height exceeds a fuzzy borderline which depends on the power-law exponent of free subdiffusion alpha . Such a potential-free subdiffusion is ergodic. Surprisingly, in periodic potentials it is not sensitive to the barrier height in the long time asymptotic limit. However, the transient to this asymptotic regime is extremally slow and it does profoundly depend on the barrier height. The time scale of such subdiffusion can exceed the mean residence time in a potential well or in a finite spatial domain by many orders of magnitude. All these features are in sharp contrast with an alternative subdiffusion mechanism involving jumps among traps with the divergent mean residence time in these traps.

Fission Meter Information Barrier Attribute Measurement System - NA-243 FNI/UKC FY2017 Task 1-2 Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kerr, P. L.; Decman, D.; Prasad, M.

An SNM attribute Information Barrier (IB) system was developed for a 2011 US/UK Exercise. The system was modified and extensively tested in a 2013-2014 US-UK Measurement Campaign. This work demonstrated rapid deployment of an IB system for potential treaty use. The system utilizes an Ortec Fission Meter neutron multiplicity counter and custom computer code. The system demonstrates a proof-of-principle automated Pu-240 mass determination with an information barrier. After a software start command is issued, the system automatically acquires and downloads data, performs an analysis, and displays the results. This system conveys the results of a Pu mass threshold measurements inmore » a way the does not reveal sensitive information. In full IB mode, only the pass/fail result is displayed as a “Mass <= Threshold Amount” or “Mass >= Threshold Amount” as shown in Figure 4. This can easily be adapted to a red/green “lights” display similar to the Detective IB system for Pu isotopics as shown in Figure 6. In test mode, more detailed information is displayed. The code can also read in, analyze, and display results from previously acquired or simulated data. Because the equipment is commercial-off-the-shelf (COTS), the system demonstrates a low-cost short-lead-time technology for treaty SNM attribute measurements. A deployed system will likely require integration of additional authentication and tamper-indicating technologies. This will be discussed for the project in this and future progress reports.« less

Oral health activities of early head start teachers directed toward children and parents.

PubMed

Kranz, Ashley M; Rozier, R Gary; Zeldin, Leslie P; Preisser, John S

2011-01-01

This cross-sectional study examined Early Head Start (EHS) teachers' oral health program activities and their association with teacher and program characteristics. Self-completed questionnaires were distributed to the staff in all EHS programs in North Carolina. Variables for dental health activities for parents (four items) and children (four items) were constructed as the sum of responses to a 0-4 Likert-type scale (never to very frequently). Ordinary least squares regression models examined the association between teachers' oral health program activities and modifiable teacher (oral health knowledge, values, self-efficacy, dental health training, perceived barriers to dental activities) and program (director and health coordinator knowledge and perceived barriers to dental activities) characteristics. Teachers in the parent (n=260) and child (n=231) analyses were a subset of the 485 staff respondents (98 percent response rate). Teachers engaged in child oral health activities (range = 0-16; mean = 9.0) more frequently than parent activities (range = 0-16; mean = 6.9). Teachers' oral health values, perceived oral health self-efficacy, dental training, and director and health coordinator knowledge were positively associated with oral health activities (P < 0.05). Perceived barriers were negatively associated with child activities (P < 0.05). The level of oral health activity in EHS programs is less than optimal. Several characteristics of EHS staff were identified that can be targeted with education interventions. Evidence for effectiveness of EHS interventions needs to be strengthened, but results of this survey provide encouraging findings about the potential effects of teacher training on their oral health practices.

Perspectives on family planning services among adolescents at a Boston community health center.

PubMed

Johnson, Katherine M; Dodge, Laura E; Hacker, Michele R; Ricciotti, Hope A

2015-04-01

The aim of this project was to investigate adolescent perspectives on family planning services at a community-health center, with the intent to inform health center programs aimed at stemming the adolescent pregnancy rate. This project was cross-sectional and employed mixed methods, including surveys and interviews, for the purposes of quality improvement. The project was conducted in the obstetrics and gynecology clinic at an urban community health center in Boston. Twenty adolescent females (age 16-20) who used services at the health center. Participants were individually interviewed to assess perspectives on family planning services and to identify major influences on methods of pregnancy prevention. Major themes were categorized into contraceptive usage, reproductive health knowledge, adult influence and communication, barriers to contraceptive care and expectations of a family planning clinic. All participants were sexually active and 80% had experienced pregnancy. Reproductive health knowledge was variable and in many cases limited. Concern about disapproval was a prominent barrier to going to a clinician for contraception or advice and parents were not often involved in the initial contraception discussion. Other barriers to use of contraception included forgetting to use the methods and fear of side effects. We identified several potentially modifiable factors, including lack of knowledge, concern for provider disapproval and fear of side effects that may limit effective use of family planning services by adolescents. Further attention should be paid to these factors in designing and improving youth-friendly services in ob-gyn clinics. Copyright © 2015 North American Society for Pediatric and Adolescent Gynecology. Published by Elsevier Inc. All rights reserved.

2-Hydroxypropyl-β-cyclodextrins and the Blood-Brain Barrier: Considerations for Niemann-Pick Disease Type C1

PubMed Central

Calias, Pericles

2017-01-01

The rare, chronic, autosomal-recessive lysosomal storage disease Niemann-Pick disease type C1 (NPC1) is characterized by progressively debilitating and ultimately fatal neurological manifestations. There is an urgent need for disease-modifying therapies that address NPC1 neurological pathophysiology, and passage through the blood-brain barrier represents an important consideration for novel NPC1 drugs. Animal investigations of 2-hydroxypropyl-β-cyclodextrins (HPβCD) in NPC1 in mice demonstrated that HPβCD does not cross the blood-brain barrier in significant amounts but suggested a potential for these complex oligosaccharides to moderately impact CNS manifestations when administered subcutaneously or intraperitoneally at very high doses; however, safety concerns regarding pulmonary toxicity were raised. Subsequent NPC1 investigations in cats demonstrated far greater HPβCD efficacy at much lower doses when the drug was administered directly to the CNS. Based on this, a phase 1/2a clinical trial was initiated with intrathecal administration of a specific, well-characterized mixture of HPβCD, with a tightly controlled molar substitution specification and a defined molecular “fingerprint” of the different species. The findings were very encouraging and a phase 2b/3 clinical trial has completed enrollment and is underway. In addition, phase 1 clinical studies utilizing high-dose intravenous administration of a different HPβCD are currently recruiting. Independent studies are needed for each product to satisfactorily address questions of safety, efficacy, dosing, and route of administration. The outcomes cannot be assumed to be translatable between HPβCD products and/or routes of administration. PMID:29065825

Blood-brain barrier structure and function and the challenges for CNS drug delivery.

PubMed

Abbott, N Joan

2013-05-01

The neurons of the central nervous system (CNS) require precise control of their bathing microenvironment for optimal function, and an important element in this control is the blood-brain barrier (BBB). The BBB is formed by the endothelial cells lining the brain microvessels, under the inductive influence of neighbouring cell types within the 'neurovascular unit' (NVU) including astrocytes and pericytes. The endothelium forms the major interface between the blood and the CNS, and by a combination of low passive permeability and presence of specific transport systems, enzymes and receptors regulates molecular and cellular traffic across the barrier layer. A number of methods and models are available for examining BBB permeation in vivo and in vitro, and can give valuable information on the mechanisms by which therapeutic agents and constructs permeate, ways to optimize permeation, and implications for drug discovery, delivery and toxicity. For treating lysosomal storage diseases (LSDs), models can be included that mimic aspects of the disease, including genetically-modified animals, and in vitro models can be used to examine the effects of cells of the NVU on the BBB under pathological conditions. For testing CNS drug delivery, several in vitro models now provide reliable prediction of penetration of drugs including large molecules and artificial constructs with promising potential in treating LSDs. For many of these diseases it is still not clear how best to deliver appropriate drugs to the CNS, and a concerted approach using a variety of models and methods can give critical insights and indicate practical solutions.

Significant improvement in the electrical characteristics of Schottky barrier diodes on molecularly modified Gallium Nitride surfaces

NASA Astrophysics Data System (ADS)

Garg, Manjari; Naik, Tejas R.; Pathak, C. S.; Nagarajan, S.; Rao, V. Ramgopal; Singh, R.

2018-04-01

III-Nitride semiconductors face the issue of localized surface states, which causes fermi level pinning and large leakage current at the metal semiconductor interface, thereby degrading the device performance. In this work, we have demonstrated the use of a Self-Assembled Monolayer (SAM) of organic molecules to improve the electrical characteristics of Schottky barrier diodes (SBDs) on n-type Gallium Nitride (n-GaN) epitaxial films. The electrical characteristics of diodes were improved by adsorption of SAM of hydroxyl-phenyl metallated porphyrin organic molecules (Zn-TPPOH) onto the surface of n-GaN. SAM-semiconductor bonding via native oxide on the n-GaN surface was confirmed using X-ray photoelectron spectroscopy measurements. Surface morphology and surface electronic properties were characterized using atomic force microscopy and Kelvin probe force microscopy. Current-voltage characteristics of different metal (Cu, Ni) SBDs on bare n-GaN were compared with those of Cu/Zn-TPPOH/n-GaN and Ni/Zn-TPPOH/n-GaN SBDs. It was found that due to the molecular monolayer, the surface potential of n-GaN was decreased by ˜350 mV. This caused an increase in the Schottky barrier height of Cu and Ni SBDs from 1.13 eV to 1.38 eV and 1.07 eV to 1.22 eV, respectively. In addition to this, the reverse bias leakage current was reduced by 3-4 orders of magnitude for both Cu and Ni SBDs. Such a significant improvement in the electrical performance of the diodes can be very useful for better device functioning.

Unplanned extubations in an intensive care unit: Findings from a critical incident technique.

PubMed

Danielis, Matteo; Chiaruttini, Simona; Palese, Alvisa

2018-05-15

Patients on mechanical ventilation are at risk of experiencing a potentially life-threatening unplanned extubation in the intensive care unit, which can lead to arrhythmias, bronchial aspiration, difficulty in reintubation or even sudden cardiac arrest. Although incidence and outcomes of the phenomenon have been documented in several quantitative studies, no studies have investigated the antecedents as experienced by critical care nurses. To gain a greater understanding of the antecedents of unplanned extubations. A qualitative study design involving the critical-incident technique. A total of 10 registered nurses who reported one or more episodes of unplanned extubations were involved in an in-depth interview. According to the nurses' experience, episodes of unplanned extubations are determined by predisposing, precipitating and mediating factors. The predisposing factors have been recognised in the (a) weaning programme (expected/unexpected decreased sedation) and in the (b) patient factors (increased needs due to discomfort, restlessness and desire to communicate). The precipitating factors have been divided into (a) organisational (failures in multi-professional communication), (b) environmental (excessive environmental chaos and barriers preventing direct surveillance) and (c) nursing care factors (ensuring privacy by creating barriers, avoiding disturbing other patients and poor nurse-to-patient ratio). Among the mediating factors, which are affected by the precipitating factors, decreased surveillance and mechanical restraints' use have been identified. Identifying risk factors of unplanned extubation, specifically those that are modifiable, such as increasing interprofessional communication, reducing excessive environment chaos, implementing strategies aimed at overcoming barriers threatening direct surveillance and ensuring appropriate nurse-to-patient ratio, can prevent the occurrence of these events. Copyright © 2018 Elsevier Ltd. All rights reserved.

Influence of tumors on protective anti-tumor immunity and the effects of irradiation

PubMed Central

Foulds, Gemma A.; Radons, Jürgen; Kreuzer, Mira; Multhoff, Gabriele; Pockley, Alan G.

2012-01-01

Innate and adaptive immunity plays important roles in the development and progression of cancer and it is becoming apparent that tumors can influence the induction of potentially protective responses in a number of ways. The prevalence of immunoregulatory T cell populations in the circulation and tumors of patients with cancer is increased and the presence of these cells appears to present a major barrier to the induction of tumor immunity. One aspect of tumor-mediated immunoregulation which has received comparatively little attention is that which is directed toward natural killer (NK) cells, although evidence that the phenotype and function of NK cell populations are modified in patients with cancer is accumulating. Although the precise mechanisms underlying these localized and systemic immunoregulatory effects remain unclear, tumor-derived factors appear, in part at least, to be involved. The effects could be manifested by an altered function and/or via an influence on the migratory properties of individual cell subsets. A better insight into endogenous immunoregulatory mechanisms and the capacity of tumors to modify the phenotype and function of innate and adaptive immune cells might assist the development of new immunotherapeutic approaches and improve the management of patients with cancer. This article reviews current knowledge relating to the influence of tumors on protective anti-tumor immunity and considers the potential influence that radiation-induced effects might have on the prevalence, phenotype, and function of innate and adaptive immune cells in patients with cancer. PMID:23378947

The BARRIERS scale -- the barriers to research utilization scale: A systematic review

PubMed Central

2010-01-01

Background A commonly recommended strategy for increasing research use in clinical practice is to identify barriers to change and then tailor interventions to overcome the identified barriers. In nursing, the BARRIERS scale has been used extensively to identify barriers to research utilization. Aim and objectives The aim of this systematic review was to examine the state of knowledge resulting from use of the BARRIERS scale and to make recommendations about future use of the scale. The following objectives were addressed: To examine how the scale has been modified, to examine its psychometric properties, to determine the main barriers (and whether they varied over time and geographic locations), and to identify associations between nurses' reported barriers and reported research use. Methods Medline (1991 to September 2009) and CINHAL (1991 to September 2009) were searched for published research, and ProQuest® digital dissertations were searched for unpublished dissertations using the BARRIERS scale. Inclusion criteria were: studies using the BARRIERS scale in its entirety and where the sample was nurses. Two authors independently assessed the study quality and extracted the data. Descriptive and inferential statistics were used. Results Sixty-three studies were included, with most using a cross-sectional design. Not one study used the scale for tailoring interventions to overcome identified barriers. The main barriers reported were related to the setting, and the presentation of research findings. Overall, identified barriers were consistent over time and across geographic locations, despite varying sample size, response rate, study setting, and assessment of study quality. Few studies reported associations between reported research use and perceptions of barriers to research utilization. Conclusions The BARRIERS scale is a nonspecific tool for identifying general barriers to research utilization. The scale is reliable as reflected in assessments of internal consistency. The validity of the scale, however, is doubtful. There is no evidence that it is a useful tool for planning implementation interventions. We recommend that no further descriptive studies using the BARRIERS scale be undertaken. Barriers need to be measured specific to the particular context of implementation and the intended evidence to be implemented. PMID:20420696

Identification of potential barriers to nurse-sensitive outcome demonstration.

PubMed

Beckel, Jean; Wolf, Gail; Wilson, Roxanne; Hoolahan, Susan

2013-12-01

The objective of this study was to determine differences in chief nursing officer, Magnet(®) program director, nurse leader, and direct care RN perspectives of potential barriers to demonstration of nurse-sensitive outcomes. The Magnet Recognition Program(®) and other designations are focusing on patient outcomes. No evidence is available addressing barriers to demonstration of nursing outcomes at multiple levels of practice. A Likert scale tool was developed and administered to 526 attendees at the 2012 national Magnet conference. Questions related to available resources, benchmarks, outcome demonstration process understanding, perception of value, and competing priorities. Significant perception differences by role were demonstrated related to available resources, competing priorities, and process understanding supporting demonstration of nurse-sensitive outcomes. No significant differences were identified related to benchmarks or perception of process value to the organization. This study provides new information demonstrating potential barriers to demonstration of nurse-sensitive outcomes differing by role. Opportunity exists to develop systems and processes to reduce perceived barriers among the nursing workforce.

Calculation of multidimensional potential energy surfaces for even-even transuranium nuclei: systematic investigation of the triaxiality effect on the fission barrier

NASA Astrophysics Data System (ADS)

Chai, Qing-Zhen; Zhao, Wei-Juan; Liu, Min-Liang; Wang, Hua-Lei

2018-05-01

Static fission barriers for 95 even-even transuranium nuclei with charge number Z = 94–118 have been systematically investigated by means of pairing self-consistent Woods-Saxon-Strutinsky calculations using the potential energy surface approach in multidimensional (β 2, γ, β 4) deformation space. Taking the heavier 252Cf nucleus (with the available fission barrier from experiment) as an example, the formation of the fission barrier and the influence of macroscopic, shell and pairing correction energies on it are analyzed. The results of the present calculated β 2 values and barrier heights are compared with previous calculations and available experiments. The role of triaxiality in the region of the first saddle is discussed. It is found that the second fission barrier is also considerably affected by the triaxial deformation degree of freedom in some nuclei (e.g., the Z=112–118 isotopes). Based on the potential energy curves, general trends of the evolution of the fission barrier heights and widths as a function of the nucleon numbers are investigated. In addition, the effects of Woods-Saxon potential parameter modifications (e.g., the strength of the spin-orbit coupling and the nuclear surface diffuseness) on the fission barrier are briefly discussed. Supported by National Natural Science Foundation of China (11675148, 11505157), the Project of Youth Backbone Teachers of Colleges and Universities of Henan Province (2017GGJS008), the Foundation and Advanced Technology Research Program of Henan Province (162300410222), the Outstanding Young Talent Research Fund of Zhengzhou University (1521317002) and the Physics Research and Development Program of Zhengzhou University (32410017)

Electron transport through triangular potential barriers with doping-induced disorder

NASA Astrophysics Data System (ADS)

Elpelt, R.; Wolst, O.; Willenberg, H.; Malzer, S.; Döhler, G. H.

2004-05-01

Electron transport through single-, double-, and triple-barrier structures created by the insertion of suitably δ-doped layers in GaAs is investigated. The results are compared with experiments on barriers of similar shape, but obtained by linear grading of the Al fraction x in AlxGa1-xAs structures. In the case of the doping-induced space-charge potential it is found that the effective barrier height for transport is much lower than expected from a simple model, in which uniform distribution of the doping charge within the doped layers is assumed. This reduction is quantitatively explained by taking into account the random distribution of the acceptor atoms within the δp-doped layers, which results in large spatial fluctuations of the barrier potential. The transport turns out to be dominated by small regions around the energetically lowest saddle points of the random space-charge potential. Additionally, independent on the dimensionality of the transport [three-dimensional (3D) to 3D in the single barrier, from 3D through 2D to 3D in the double barrier, and from 3D through 2D through 2D to 3D in the triple-barrier structure], fingerprints of 2D subband resonances are neither experimentally observed nor theoretically expected in the doping-induced structures. This is attributed to the disorder-induced random spatial fluctuations of the subband energies in the n layers which are uncorrelated for neighboring layers. Our interpretations of the temperature-dependent current-voltage characteristics are corroborated by comparison with the experimental and theoretical results obtained from the corresponding fluctuation-free AlxGa1-xAs structures. Quantitative agreement between theory and experiment is observed in both cases.

Epigenetic regulation of cell fate reprogramming in aging and disease: A predictive computational model.

PubMed

Folguera-Blasco, Núria; Cuyàs, Elisabet; Menéndez, Javier A; Alarcón, Tomás

2018-03-01

Understanding the control of epigenetic regulation is key to explain and modify the aging process. Because histone-modifying enzymes are sensitive to shifts in availability of cofactors (e.g. metabolites), cellular epigenetic states may be tied to changing conditions associated with cofactor variability. The aim of this study is to analyse the relationships between cofactor fluctuations, epigenetic landscapes, and cell state transitions. Using Approximate Bayesian Computation, we generate an ensemble of epigenetic regulation (ER) systems whose heterogeneity reflects variability in cofactor pools used by histone modifiers. The heterogeneity of epigenetic metabolites, which operates as regulator of the kinetic parameters promoting/preventing histone modifications, stochastically drives phenotypic variability. The ensemble of ER configurations reveals the occurrence of distinct epi-states within the ensemble. Whereas resilient states maintain large epigenetic barriers refractory to reprogramming cellular identity, plastic states lower these barriers, and increase the sensitivity to reprogramming. Moreover, fine-tuning of cofactor levels redirects plastic epigenetic states to re-enter epigenetic resilience, and vice versa. Our ensemble model agrees with a model of metabolism-responsive loss of epigenetic resilience as a cellular aging mechanism. Our findings support the notion that cellular aging, and its reversal, might result from stochastic translation of metabolic inputs into resilient/plastic cell states via ER systems.

Effects of group status and victim sex on female bystanders' responses to a potential party rape.

PubMed

Katz, Jennifer; Colbert, Samuel; Colangelo, Liane

2015-01-01

This research examined bystander responses to 1 of 4 potential party rape scenarios. Undergraduate women (N = 249) imagined attending a party either alone or with three friends where a sober man led an intoxicated potential victim (either male or female) into a bedroom. After random assignment to conditions, participants reported on intent to help and barriers to helping the potential victim. In contrast to the classic bystander effect, bystanders in groups intended to offer more help than lone bystanders. Bystanders also intended to offer more help to potential female than male victims and experienced more barriers to helping male victims. Two of these barriers (lack of personal responsibility to help and identifying risk) explained the lower intentions to help potential male victims. Potential male victims were more likely than female victims to be perceived as gay, and bystanders reported the least intentions to help presumably gay men at risk.

Plasma Surface Modification of Polymer Backsheets: Origins of Future Interfacial Barrier/Backsheet Failure (Poster)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pankow, J. W.; Glick, S. H.

2006-05-01

Flexible polymer substrates coated with inorganic oxide moisture barriers are a potential replacement for glass backsheets in thin-film PV (photovoltaic) modules. Silicon oxynitride (SiO{sub x}N{sub y}) deposited by plasma enhanced chemical vapor deposition (PECVD) on polyethylene terephthalate (PET) represents one potential new backsheet candidate. Barrier deposition runs at NREL have included a nitrogen-rich plasma pretreatment prior to barrier deposition with the intention of cleaning the PET surface and enhancing adhesion of the SiO{sub x}N{sub y} barrier film to PET; however, test coupons of PET/barrier/EVA/TPE failed after damp-heat exposure. (EVA is ethylene vinyl acetate and TPE is Tedlar{reg_sign}-PET-EVA). PET substrates exposedmore » to plasma conditions similar to those used in pretreatment were examined by X-ray photoelectron spectroscopy (XPS) to reveal that new low molecular weight PET fragments were created at the PET surface. These fragments are responsible for barrier/PET interfacial failure and barrier transfer to the EVA encapsulant side following damp heat exposure.« less

Three-cable barrier makes I-5 safer.

DOT National Transportation Integrated Search

1998-08-01

The cable median barrier system has been effective in preventing crossover accidents at the selected location, from December 1996 through March 1998. Of the 53 barrier impacts, 21 potential crossovers were restrained from entering the opposing traffi...

Leveraging technology: creating and sustaining changes for health.

PubMed

Teyhen, Deydre S; Aldag, Matt; Edinborough, Elton; Ghannadian, Jason D; Haught, Andrea; Kinn, Julie; Kunkler, Kevin J; Levine, Betty; McClain, James; Neal, David; Stewart, Tiffany; Thorndike, Frances P; Trabosh, Valerie; Wesensten, Nancy; Parramore, David J

2014-09-01

The rapid growth and evolution of health-related technology capabilities are driving an established presence in the marketplace and are opening up tremendous potential to minimize and/or mitigate barriers associated with achieving optimal health, performance, and readiness. This article summarizes technology-based strategies that promote healthy habits related to physical activity, nutrition, and sleep. The Telemedicine and Advanced Technology Research Center convened a workshop titled "Leveraging Technology: Creating & Sustaining Changes for Health" (May 29-30, 2013, Fort Detrick, MD). Participants included experts from academia (n=3), government (n=33), and industry (n=16). A modified Delphi method was used to establish expert consensus in six topic areas: (1) physical activity, (2) nutrition, (3) sleep, (4) incentives for behavior change, (5) usability/interoperability, and (6) mobile health/open platform. Overall, 162 technology features, constructs, and best practices were reviewed and prioritized for physical activity monitors (n=29), nutrition monitors (n=35), sleep monitors (n=24), incentives for change (n=36), usability and interoperability (n=25), and open data (n=13). Leading practices, gaps, and research needs for technology-based strategies were identified and prioritized. This information can be used to provide a research and development road map for (1) leveraging technology to minimize barriers to enhancing health and (2) facilitating evidence-based techniques to create and sustain healthy behaviors.

Extracellular microvesicle microRNAs in children with sickle cell anaemia with divergent clinical phenotypes.

PubMed

Khalyfa, Abdelnaby; Khalyfa, Ahamed A; Akbarpour, Mahzad; Connes, Phillippe; Romana, Marc; Lapping-Carr, Gabrielle; Zhang, Chunling; Andrade, Jorge; Gozal, David

2016-09-01

Sickle cell anaemia (SCA) is the most frequent genetic haemoglobinopathy, which exhibits a highly variable clinical course characterized by hyper-coagulable and pro-inflammatory states, as well as endothelial dysfunction. Extracellular microvesicles are released into biological fluids and play a role in modifying the functional phenotype of target cells. We hypothesized that potential differences in plasma-derived extracellular microvesicles (EV) function and cargo from SCA patients may underlie divergent clinical trajectories. Plasma EV from SCA patients with mild, intermediate and severe clinical disease course were isolated, and primary endothelial cell cultures were exposed. Endothelial cell activation, monocyte adhesion, barrier disruption and exosome cargo (microRNA microarrays) were assessed. EV disrupted the endothelial barrier and induced expression of adhesion molecules and monocyte adhesion in a SCA severity-dependent manner compared to healthy children. Microarray approaches identified a restricted signature of exosomal microRNAs that readily distinguished severe from mild SCA, as well as from healthy children. The microRNA candidates were further validated using quantitative real time polymerase chain reaction assays, and revealed putative gene targets. Circulating exosomal microRNAs may play important roles in predicting the clinical course of SCA, and in delineation of individually tailored, mechanistically-based clinical treatment approaches of SCA patients in the near future. © 2016 John Wiley & Sons Ltd.

TRIPS, the Doha Declaration and increasing access to medicines: policy options for Ghana

PubMed Central

Cohen, JC; Gyansa-Lutterodt, M; Torpey, K; Esmail, LC; Kurokawa, G

2005-01-01

There are acute disparities in pharmaceutical access between developing and industrialized countries. Developing countries make up approximately 80% of the world's population but only represent approximately 20% of global pharmaceutical consumption. Among the many barriers to drug access are the potential consequences of the Trade Related Aspects of Intellectual Property Rights (TRIPS) Agreement. Many developing countries have recently modified their patent laws to conform to the TRIPS standards, given the 2005 deadline for developing countries. Safeguards to protect public health have been incorporated into the TRIPS Agreement; however, in practice governments may be reluctant to exercise such rights given concern about the international trade and political ramifications. The Doha Declaration and the recent Decision on the Implementation of Paragraph 6 of the Doha Declaration on the TRIPS Agreement and Public Health may provide more freedom for developing countries in using these safeguards. This paper focuses on Ghana, a developing country that recently changed its patent laws to conform to TRIPS standards. We examine Ghana's patent law changes in the context of the Doha Declaration and assess their meaning for access to drugs of its population. We discuss new and existing barriers, as well as possible solutions, to provide policy-makers with lessons learned from the Ghanaian experience. PMID:16336685

Atmospheric-pressure diffuse dielectric barrier discharges in Ar/O2 gas mixture using 200 kHz/13.56 MHz dual frequency excitation

NASA Astrophysics Data System (ADS)

Liu, Y.; Starostin, S. A.; Peeters, F. J. J.; van de Sanden, M. C. M.; de Vries, H. W.

2018-03-01

Atmospheric-pressure diffuse dielectric barrier discharges (DBDs) were obtained in Ar/O2 gas mixture using dual-frequency (DF) excitation at 200 kHz low frequency (LF) and 13.56 MHz radio frequency (RF). The excitation dynamics and the plasma generation mechanism were studied by means of electrical characterization and phase resolved optical emission spectroscopy (PROES). The DF excitation results in a time-varying electric field which is determined by the total LF and RF gas voltage and the spatial ion distribution which only responds to the LF component. By tuning the amplitude ratio of the superimposed LF and RF signals, the effect of each frequency component on the DF discharge mechanism was analysed. The LF excitation results in a transient plasma with the formation of an electrode sheath and therefore a pronounced excitation near the substrate. The RF oscillation allows the electron trapping in the gas gap and helps to improve the plasma uniformity by contributing to the pre-ionization and by controlling the discharge development. The possibility of temporally modifying the electric field and thus the plasma generation mechanism in the DF discharge exhibits potential applications in plasma-assisted surface processing and plasma-assisted gas phase chemical conversion.

The functional curcumin liposomes induce apoptosis in C6 glioblastoma cells and C6 glioblastoma stem cells in vitro and in animals.

PubMed

Wang, Yahua; Ying, Xue; Xu, Haolun; Yan, Helu; Li, Xia; Tang, Hui

2017-01-01

Glioblastoma is a kind of malignant gliomas that is almost impossible to cure due to the poor drug transportation across the blood-brain barrier and the existence of glioma stem cells. We prepared a new kind of targeted liposomes in order to improve the drug delivery system onto the glioma cells and induce the apoptosis of glioma stem cells afterward. In this experiment, curcumin was chosen to kill gliomas, while quinacrine was used to induce apoptosis of the glioma stem cells. Also, p -aminophenyl-α-D-mannopyranoside could facilitate the transport of liposomes across the blood-brain barrier and finally target the brain glioma cells. The cell experiments in vitro indicated that the targeted liposomes could significantly improve the anti-tumor effects of the drugs, while enhancing the uptake effects, apoptosis effects, and endocytic effects of C6 glioma cells and C6 glioma stem cells. Given the animal experiments in vivo, we discovered that the targeted liposomes could obviously increase the survival period of brain glioma-bearing mice and inhibit the growth of gliomas. In summary, curcumin and quinacrine liposomes modified with p -aminophenyl-α-D-mannopyranoside is a potential preparation to treat brain glioma cells and brain glioma stem cells.

Cervical Cancer Stigma in Rural Kenya: What Does HIV Have to Do with It?

PubMed

Rosser, Joelle I; Njoroge, Betty; Huchko, Megan J

2016-06-01

Cervical cancer is a leading cause of cancer-related death amongst women in sub-Saharan Africa, largely due to the lack of early screening and treatment. In addition to poor access to screening services, inadequate uptake of available services is a barrier to early identification of precancerous lesions. Given that cervical cancer is caused by a sexually transmitted virus and is associated with HIV positivity, stigma is one of the potential barriers to the utilization of cervical cancer programs in sub-Saharan Africa. We conducted a cross-sectional survey of 419 women attending health facilities in rural western Kenya to measure levels of cervical cancer and HIV stigma and to measure the associations between cervical cancer stigma, HIV stigma, and HIV status. Women who qualified for cervical cancer screening were asked to complete an oral questionnaire using a modified 9-point HIV stigma scale. Low cervical cancer stigma was reported in this study, with only 85/419 (20.3 %) of respondents answering yes to at least one cervical cancer stigma question. However, cervical cancer stigma was highly correlated with HIV stigma (correlation coefficient 0.72) and was significantly lower in HIV-positive women (p < 0.001). Reducing cervical cancer stigma in the general population is an important part of promoting screening in sub-Saharan Africa.

Manipulating nanoparticle transport within blood flow through external forces: an exemplar of mechanics in nanomedicine

PubMed Central

Ye, Huilin; Shen, Zhiqiang; Wei, Mei; Li, Ying

2018-01-01

A large number of nanoparticles (NPs) have been raised for diverse biomedical applications and some of them have shown great potential in treatment and imaging of diseases. Design of NPs is essential for delivery efficacy due to a number of biophysical barriers, which prevents the circulation of NPs in vascular flow and their accumulation at tumour sites. The physiochemical properties of NPs, so-called ‘4S’ parameters, such as size, shape, stiffness and surface functionalization, play crucial roles in their life journey to be delivered to tumour sites. NPs can be modified in various ways to extend their blood circulation time and avoid their clearance by phagocytosis, and efficiently diffuse into tumour cells. However, it is difficult to overcome these barriers simultaneously by a simple combination of ‘4S’ parameters for NPs. At this moment, external triggerings are necessary to guide the movement of NPs, which include light, ultrasound, magnetic field, electrical field and chemical interaction. The delivery system can be constructed to be sensitive to these external stimuli which can reduce the non-specific toxicity and improve the efficacy of the drug-delivery system. From a mechanics point of view, we discuss how different forces play their roles in the margination of NPs in blood flow and tumour microvasculature. PMID:29662344

Prevention of work disability due to musculoskeletal disorders: the challenge of implementing evidence.

PubMed

Loisel, Patrick; Buchbinder, Rachelle; Hazard, Rowland; Keller, Robert; Scheel, Inger; van Tulder, Maurits; Webster, Barbara

2005-12-01

The process of returning disabled workers to work presents numerous challenges. In spite of the growing evidence regarding work disability prevention, little uptake of this evidence has been observed. One reason for limited dissemination of evidence is the complexity of the problem, as it is subject to multiple legal, administrative, social, political, and cultural challenges. A literature review and collection of experts' opinion is presented, on the current evidence for work disability prevention, and barriers to evidence implementation. Recommendations are presented for enhancing implementation of research results. The current evidence regarding work disability prevention shows that some clinical interventions (advice to return to modified work and graded activity programs) and some non-clinical interventions (at a service and policy/community level but not at a practice level) are effective in reducing work absenteeism. Implementation of evidence in work disability is a major challenge because intervention recommendations are often imprecise and not yet practical for immediate use, many barriers exist, and many stakeholders are involved. Future studies should involve all relevant stakeholders and aim at developing new strategies that are effective, efficient, and have a potential for successful implementation. These studies should be based upon a clearer conceptualization of the broader context and inter-relationships that determine return to work outcomes.

Manipulating nanoparticle transport within blood flow through external forces: an exemplar of mechanics in nanomedicine

NASA Astrophysics Data System (ADS)

Ye, Huilin; Shen, Zhiqiang; Yu, Le; Wei, Mei; Li, Ying

2018-03-01

A large number of nanoparticles (NPs) have been raised for diverse biomedical applications and some of them have shown great potential in treatment and imaging of diseases. Design of NPs is essential for delivery efficacy due to a number of biophysical barriers, which prevents the circulation of NPs in vascular flow and their accumulation at tumour sites. The physiochemical properties of NPs, so-called `4S' parameters, such as size, shape, stiffness and surface functionalization, play crucial roles in their life journey to be delivered to tumour sites. NPs can be modified in various ways to extend their blood circulation time and avoid their clearance by phagocytosis, and efficiently diffuse into tumour cells. However, it is difficult to overcome these barriers simultaneously by a simple combination of `4S' parameters for NPs. At this moment, external triggerings are necessary to guide the movement of NPs, which include light, ultrasound, magnetic field, electrical field and chemical interaction. The delivery system can be constructed to be sensitive to these external stimuli which can reduce the non-specific toxicity and improve the efficacy of the drug-delivery system. From a mechanics point of view, we discuss how different forces play their roles in the margination of NPs in blood flow and tumour microvasculature.

Temperature and frequency response of conductivity in Ag2S doped chalcogenide glassy semiconductor

NASA Astrophysics Data System (ADS)

Ojha, Swarupa; Das, Anindya Sundar; Roy, Madhab; Bhattacharya, Sanjib

2018-06-01

The electric conductivity of chalcogenide glassy semiconductor xAg2S-(1-x)(0.5S-0.5Te) has been presented here as a function of temperature and frequency. Formation of different nanocrystallites has been confirmed from X-ray diffraction study. It is also noteworthy that average size of nanocrystallites decreases with the increase of dislocation density. Dc conductivity data have been interpreted using Mott's model and Greaves's model in low and high temperature regions respectively. Ac conductivity above the room temperature has been analyzed using Meyer-Neldel (MN) conduction rule. It is interestingly noted that Correlated Barrier Hopping (CBH) model is the most appropriate conduction mechanism for x = 0.35, where pairs of charge carrier are considered to hop over the potential barrier between the sites via thermal activation. To interpret experimental data for x = 0.45, modified non-overlapping small polaron tunnelling (NSPT) model is supposed to be appropriate model due to tunnelling through grain boundary. The conductivity spectra at various temperatures have been analyzed using Almond-West Formalism (power law model). Scaling of conductivity spectra reveals that electrical relaxation process of charge carriers (polaron) is temperature independent but depends upon the composition of the present chalcogenide glassy system.

The functional curcumin liposomes induce apoptosis in C6 glioblastoma cells and C6 glioblastoma stem cells in vitro and in animals

PubMed Central

Wang, Yahua; Ying, Xue; Xu, Haolun; Yan, Helu; Li, Xia; Tang, Hui

2017-01-01

Glioblastoma is a kind of malignant gliomas that is almost impossible to cure due to the poor drug transportation across the blood–brain barrier and the existence of glioma stem cells. We prepared a new kind of targeted liposomes in order to improve the drug delivery system onto the glioma cells and induce the apoptosis of glioma stem cells afterward. In this experiment, curcumin was chosen to kill gliomas, while quinacrine was used to induce apoptosis of the glioma stem cells. Also, p-aminophenyl-α-D-mannopyranoside could facilitate the transport of liposomes across the blood–brain barrier and finally target the brain glioma cells. The cell experiments in vitro indicated that the targeted liposomes could significantly improve the anti-tumor effects of the drugs, while enhancing the uptake effects, apoptosis effects, and endocytic effects of C6 glioma cells and C6 glioma stem cells. Given the animal experiments in vivo, we discovered that the targeted liposomes could obviously increase the survival period of brain glioma-bearing mice and inhibit the growth of gliomas. In summary, curcumin and quinacrine liposomes modified with p-aminophenyl-α-D-mannopyranoside is a potential preparation to treat brain glioma cells and brain glioma stem cells. PMID:28260885

A C-terminal cyclic 8-13 neurotensin fragment analog appears less exposed to neprilysin when it crosses the blood-brain barrier than the cerebrospinal fluid-brain barrier in mice.

PubMed

Van Kemmel, F M; Dubuc, I; Bourdel, E; Fehrentz, J A; Martinez, J; Costentin, J

1996-10-11

A C-terminal cyclic 8-13 neurotensin fragment analog. JMV 1193, a direct agonist of central neurotensin receptors, is able to cross both the cerebrospinal fluid-brain barrier and the blood-brain barrier. When administered intracerebroventricularly (i.c.v.), its hypothermic effect was potentiated by the enkephalinase inhibition induced either by thiorphan (simultaneous intracerebroventricular administration of 10 micrograms) or by the thiorphan prodrug. acetorphan (intravenous (i.v.) administration of 10 mg/kg). Such a potentiation was not observed when both JMV 1193 and acetorphan were administered intravenously. Therefore it appears that the sensitivity of JMV 1193 to enkephalinase depends on its route of administration. It is exposed to this peptidase after i.c.v. injection (when crossing the cerebrospinal fluid-brain barrier), while it is not after i.v. administration (when crossing the blood-brain barrier).

Barriers to treatment adherence among African American and white women with systemic lupus erythematosus.

PubMed

Mosley-Williams, Angelia; Lumley, Mark A; Gillis, Mazy; Leisen, James; Guice, Deena

2002-12-15

To determine whether African Americans with systemic lupus erythematosus (SLE) have poorer treatment adherence than whites, and to determine ethnic group differences in barriers to adherence, and how barriers affect adherence. We compared 68 African American and 54 white women with SLE on 19 potential barriers, on 2 adherence behaviors during the past year, and on how the potential barriers relate to each nonadherence behavior. African Americans and whites were similar on most barriers, although African Americans were more likely to rely on religion and were more concerned about long-term medication effects. The 2 ethnic groups were comparable on medication nonadherence, but whites tended to have poorer clinic appointment adherence than African Americans. Finally, we found that barriers related to negative affect (depression, medication concerns, physical symptoms) as well as short-term memory problems and the need for child or elder care were associated with nonadherence among African Americans, whereas perceived treatment inefficacy and lacking trust in physicians were associated with nonadherence among whites. Relationships between adherence barriers and nonadherence may be ethnicity specific, suggesting that interventions to address barriers should be targeted to specific groups.

Ultra short laser pulse modification of wave guides

NASA Astrophysics Data System (ADS)

Rosenfeld, Arkadi; Ashkenasi, David

2003-11-01

The high peak powers of ultra short (ps and sub-ps) pulsed lasers available at relatively low single pulse energies potentially allow for a precise localization of photon energy, either on the surface or inside (transparent) materials. Three dimensional micro structuring of bulk transparent media without any sign of mechanical cracking has shown the potential of ultra short laser processing. In this study, the micro structuring of bulk transparent media was used to modify fused silica and especially the cladding-core interface in normal fused silica wave guides. The idea behind this technique is to enforce a local mismatch for total reflection at the interface at minimal mechanic stress to overcome the barrier for enhanced optical out-coupling. The laser-induced modifications were studied in dependence of pulse width, focal alignment, single pulse energy and pulse overlap. Micro traces with a thickness between 3 and 8 μm were generated with a spacing of 10 μm in the subsurface region using sub-ps and ps laser pulses at a wavelength of 800 nm. The optical leakage enforced by a micro spiral pattern is significant and can be utilized for medical applications or potentially also for telecommunications and fiber laser technology.

How does the urothelium affect bladder function in health and disease?

PubMed Central

Birder, L.A.; Ruggieri, M.; Takeda, M.; van Koeveringe, G.; Veltkamp, S.A.; Korstanje, C.; Parsons, B.A.; Fry, C.H.

2011-01-01

The urothelium is a multifunctional tissue that not only acts as a barrier between the vesical contents of the lower urinary tract and the underlying tissues but also acts as a sensory organ by transducing physical and chemical stresses to the attendant afferent nervous system and underlying smooth muscle. This review will consider the nature of the stresses that the urothelium can transduce; the transmitters that mediate the transduction process; and how lower urinary pathologies, including overactive bladder syndrome, painful bladder syndrome and bacterial infections, are associated with alterations to this sensory system. In particular, the role of muscarinic receptors and the TRPV channels system will be discussed in this context. The urothelium also influences the contractile state of detrusor smooth muscle, both through modifying its contractility and the extent of spontaneous activity; potential pathways are discussed. The potential role that the urothelium may play in bladder underactivity is introduced, as well as potential biomarkers for the condition that may cross the urothelium to the urine. Finally consideration is given to vesical administration of therapeutic agents that influence urinary tract function and how the properties of the urothelium may determine the effectiveness of this mode of delivery. PMID:22275289

Multistate metadynamics for automatic exploration of conical intersections

NASA Astrophysics Data System (ADS)

Lindner, Joachim O.; Röhr, Merle I. S.; Mitrić, Roland

2018-05-01

We introduce multistate metadynamics for automatic exploration of conical intersection seams between adiabatic Born-Oppenheimer potential energy surfaces in molecular systems. By choosing the energy gap between the electronic states as a collective variable the metadynamics drives the system from an arbitrary ground-state configuration toward the intersection seam. Upon reaching the seam, the multistate electronic Hamiltonian is extended by introducing biasing potentials into the off-diagonal elements, and the molecular dynamics is continued on a modified potential energy surface obtained by diagonalization of the latter. The off-diagonal bias serves to locally open the energy gap and push the system to the next intersection point. In this way, the conical intersection energy landscape can be explored, identifying minimum energy crossing points and the barriers separating them. We illustrate the method on the example of furan, a prototype organic molecule exhibiting rich photophysics. The multistate metadynamics reveals plateaus on the conical intersection energy landscape from which the minimum energy crossing points with characteristic geometries can be extracted. The method can be combined with the broad spectrum of electronic structure methods and represents a generally applicable tool for the exploration of photophysics and photochemistry in complex molecules and materials.

A survey of the barriers associated with academic-based cancer research commercialization.

PubMed

Vanderford, Nathan L; Weiss, L Todd; Weiss, Heidi L

2013-01-01

Commercialization within the academic setting is associated with many challenges and barriers. Previous studies investigating these challenges/barriers have, in general, broadly focused on multiple disciplines and, oftentimes, several institutions simultaneously. The goal of the study presented here was to analyze a range of barriers that may be broadly associated with commercializing academic-based cancer research. This goal was addressed via a study of the barriers associated with cancer research commercialization at the University of Kentucky (UK). To this end, a research instrument in the form of an electronic survey was developed. General demographic information was collected on study participants and two research questions were addressed: 1) What are the general barriers inhibiting cancer research commercialization at UK? and 2) Would mitigation of the barriers potentially enhance faculty engagement in commercialization activities? Descriptive and statistical analysis of the data reveal that multiple barriers likely inhibit cancer research commercialization at UK with expense, time, infrastructure, and lack of industry partnerships being among the most commonly cited factors. The potential alleviation of these factors in addition to revised University policies/procedures, risk mitigation, more emphasis on commercialization by academia research field, and increased information on how to commercialize significantly correlated with the potential for increased commercialization activity. Furthermore, multivariate logistic regression modeling demonstrated that research commercialization would incrementally increase as barriers to the process are removed and that PhD-holding respondents and respondents in commercialization-supportive research fields would be more likely to commercialize their research upon barrier removal. Overall, as with other disciplines, these data suggest that for innovations derived from academic cancer-research to move more effectively and efficiently into the marketplace, university administrators and external agents, such as policymakers, need to address what are well-documented and defined issues.

A Survey of the Barriers Associated with Academic-based Cancer Research Commercialization

PubMed Central

Vanderford, Nathan L.; Weiss, L. Todd; Weiss, Heidi L.

2013-01-01

Commercialization within the academic setting is associated with many challenges and barriers. Previous studies investigating these challenges/barriers have, in general, broadly focused on multiple disciplines and, oftentimes, several institutions simultaneously. The goal of the study presented here was to analyze a range of barriers that may be broadly associated with commercializing academic-based cancer research. This goal was addressed via a study of the barriers associated with cancer research commercialization at the University of Kentucky (UK). To this end, a research instrument in the form of an electronic survey was developed. General demographic information was collected on study participants and two research questions were addressed: 1) What are the general barriers inhibiting cancer research commercialization at UK? and 2) Would mitigation of the barriers potentially enhance faculty engagement in commercialization activities? Descriptive and statistical analysis of the data reveal that multiple barriers likely inhibit cancer research commercialization at UK with expense, time, infrastructure, and lack of industry partnerships being among the most commonly cited factors. The potential alleviation of these factors in addition to revised University policies/procedures, risk mitigation, more emphasis on commercialization by academia research field, and increased information on how to commercialize significantly correlated with the potential for increased commercialization activity. Furthermore, multivariate logistic regression modeling demonstrated that research commercialization would incrementally increase as barriers to the process are removed and that PhD-holding respondents and respondents in commercialization-supportive research fields would be more likely to commercialize their research upon barrier removal. Overall, as with other disciplines, these data suggest that for innovations derived from academic cancer-research to move more effectively and efficiently into the marketplace, university administrators and external agents, such as policymakers, need to address what are well-documented and defined issues. PMID:23991077

Electromagnetic Saturation of Angstrom-Sized Quantum Barriers at Terahertz Frequencies

NASA Astrophysics Data System (ADS)

Bahk, Young-Mi; Kang, Bong Joo; Kim, Yong Seung; Kim, Joon-Yeon; Kim, Won Tae; Kim, Tae Yun; Kang, Taehee; Rhie, Jiyeah; Han, Sanghoon; Park, Cheol-Hwan; Rotermund, Fabian; Kim, Dai-Sik

2015-09-01

Metal-graphene-metal hybrid structures allow angstrom-scale van der Waals gaps, across which electron tunneling occurs. We squeeze terahertz electromagnetic waves through these λ /10 000 000 gaps, accompanied by giant field enhancements. Unprecedented transmission reduction of 97% is achieved with the transient voltage across the gap saturating at 5 V. Electron tunneling facilitated by the transient electric field strongly modifies the gap index, starting a self-limiting process related to the barrier height. Our work enables greater interplay between classical optics and quantum tunneling, and provides optical indices to the van der Waals gaps.

Electromagnetic Saturation of Angstrom-Sized Quantum Barriers at Terahertz Frequencies.

PubMed

Bahk, Young-Mi; Kang, Bong Joo; Kim, Yong Seung; Kim, Joon-Yeon; Kim, Won Tae; Kim, Tae Yun; Kang, Taehee; Rhie, Jiyeah; Han, Sanghoon; Park, Cheol-Hwan; Rotermund, Fabian; Kim, Dai-Sik

2015-09-18

Metal-graphene-metal hybrid structures allow angstrom-scale van der Waals gaps, across which electron tunneling occurs. We squeeze terahertz electromagnetic waves through these λ/10 000 000 gaps, accompanied by giant field enhancements. Unprecedented transmission reduction of 97% is achieved with the transient voltage across the gap saturating at 5 V. Electron tunneling facilitated by the transient electric field strongly modifies the gap index, starting a self-limiting process related to the barrier height. Our work enables greater interplay between classical optics and quantum tunneling, and provides optical indices to the van der Waals gaps.

Entrainment, retention, and transport of freely swimming fish in junction gaps between commercial barges operating on the Illinois Waterway

USGS Publications Warehouse

Davis, Jeremiah J.; Jackson, P. Ryan; Engel, Frank; LeRoy, Jessica Z.; Neeley, Rebecca N.; Finney, Samuel T.; Murphy, Elizabeth A.

2016-01-01

Large Electric Dispersal Barriers were constructed in the Chicago Sanitary and Ship Canal (CSSC) to prevent the transfer of invasive fish species between the Mississippi River Basin and the Great Lakes Basin while simultaneously allowing the passage of commercial barge traffic. We investigated the potential for entrainment, retention, and transport of freely swimming fish within large gaps (> 50 m3) created at junction points between barges. Modified mark and capture trials were employed to assess fish entrainment, retention, and transport by barge tows. A multi-beam sonar system enabled estimation of fish abundance within barge junction gaps. Barges were also instrumented with acoustic Doppler velocity meters to map the velocity distribution in the water surrounding the barge and in the gap formed at the junction of two barges. Results indicate that the water inside the gap can move upstream with a barge tow at speeds near the barge tow travel speed. Water within 1 m to the side of the barge junction gaps was observed to move upstream with the barge tow. Observed transverse and vertical water velocities suggest pathways by which fish may potentially be entrained into barge junction gaps. Results of mark and capture trials provide direct evidence that small fish can become entrained by barges, retained within junction gaps, and transported over distances of at least 15.5 km. Fish entrained within the barge junction gap were retained in that space as the barge tow transited through locks and the Electric Dispersal Barriers, which would be expected to impede fish movement upstream.

Relevance of nanocomposite packaging on the stability of vacuum-packed dry cured ham.

PubMed

Lloret, Elsa; Fernandez, Avelina; Trbojevich, Raul; Arnau, Jacint; Picouet, Pierre A

2016-08-01

In this study effects of a novel high barrier multilayer polyamide film containing dispersed nanoclays (PAN) on the stability of vacuum packed dry-cured ham were investigated during 90days refrigerated storage in comparison with non-modified multilayer polyamide (PA) and a commercial high barrier film. Characteristic bands of the mineral in FT-IR spectra confirmed the presence of nanoclays in PAN, enhancing oxygen transmission barrier properties and UV protection. Packaging in PAN films did not originate significant changes on colour or lipid oxidation during prolonged storage of vacuum-packed dry-cured ham. Larger oxygen transmission rates in PA films caused changes in CIE b* during refrigerated storage. Ham quality was not affected by light exposition during 90days and only curing had a significant benefit on colour and TBARS, being cured samples more stable during storage in all the packages used. Packaging of dry-cured ham in PAN was equivalent to commercial high barrier films. Copyright © 2016 Elsevier Ltd. All rights reserved.

EMSC program manager survey on education of prehospital providers.

PubMed

Ngo, Thuy L; Belli, Karen; Shah, Manish I

2014-01-01

Although pediatric-specific objectives for the initial education of prehospital providers have been established, uniform implementation of these objectives and guidelines for hours of required pediatric continuing education (CE) for prehospital providers have not been established. To examine the content and number of hours of pediatric-specific education that prehospital providers receive during initial certification and recertification. Second, to identify barriers to implementing specific requirements for pediatric education of prehospital providers. Electronic surveys were sent to 55 EMS for Children (EMSC) State Partnership grantee program managers inquiring about the certification and recertification processes of prehospital providers and barriers to receiving pediatric training in each jurisdiction. We had a 91% response rate for our survey. Specified pediatric education hours exist in more states and territories for recertification (63-67%) than initial certification (41%). Limitations in funding, time, instructors, and accessibility are barriers to enhancing pediatric education. Modifying statewide policies on prehospital education and increasing hands-on training may overcome identified barriers.

Military Sexual Trauma Among US Servicewomen During Deployment: A Qualitative Study

PubMed Central

Grindlay, Kate; Holt, Kelsey; Manski, Ruth; Grossman, Daniel

2014-01-01

Objectives. We explored qualitatively US servicewomen’s experiences with and perceptions of military sexual trauma (MST), reporting, and related services. Methods. From May 2011 to January 2012, we conducted 22 telephone interviews with US servicewomen deployed overseas between 2002 and 2011. We analyzed data thematically with modified grounded theory methods. Results. Factors identified as contributing to MST included deployment dynamics, military culture, and lack of consequences for perpetrators. Participants attributed low MST reporting to negative reactions and blame from peers and supervisors, concerns about confidentiality, and stigma. Unit cohesion was cited as both a facilitator and a barrier to reporting. Availability and awareness of MST services during deployment varied. Barriers to care seeking were similar to reporting barriers and included confidentiality concerns and stigma. We identified several avenues to address MST, including strengthening consequences for perpetrators. Conclusions. We identified barriers to MST reporting and services. Better understanding of these issues will allow policymakers to improve MST prevention and services. PMID:24328617

MASH test 3-21 on TL-3 thrie beam transition without curb.

DOT National Transportation Integrated Search

2013-01-01

This project evaluated the impact performance of a modified TxDOT thrie beam transition to rigid : concrete barrier without a curb element below the transition rail. In a previous test described in TxDOT : Research Report 0-4564, a thrie beam transit...

Implementation of a cystic fibrosis lung transplant referral patient decision aid in routine clinical practice: an observational study.

PubMed

Stacey, Dawn; Vandemheen, Katherine L; Hennessey, Rosamund; Gooyers, Tracy; Gaudet, Ena; Mallick, Ranjeeta; Salgado, Josette; Freitag, Andreas; Berthiaume, Yves; Brown, Neil; Aaron, Shawn D

2015-02-07

The decision to have lung transplantation as treatment for end-stage lung disease from cystic fibrosis (CF) has benefits and serious risks. Although patient decision aids are effective interventions for helping patients reach a quality decision, little is known about implementing them in clinical practice. Our study evaluated a sustainable approach for implementing a patient decision aid for adults with CF considering referral for lung transplantation. A prospective pragmatic observational study was guided by the Knowledge-to-Action Framework. Healthcare professionals in all 23 Canadian CF clinics were eligible. We surveyed participants regarding perceived barriers and facilitators to patient decision aid use. Interventions tailored to address modifiable identified barriers included training, access to decision aids, and conference calls. The primary outcome was >80% use of the decision aid in year 2. Of 23 adult CF clinics, 18 participated (78.2%) and 13 had healthcare professionals attend training. Baseline barriers were healthcare professionals' inadequate knowledge for supporting patients making decisions (55%), clarifying patients' values for outcomes of options (58%), and helping patients handle conflicting views of others (71%). Other barriers were lack of time (52%) and needing to change how transplantation is discussed (42%). Baseline facilitators were healthcare professionals feeling comfortable discussing bad transplantation outcomes (74%), agreeing the decision aid would be easy to experiment with (71%) and use in the CF clinic (87%), and agreeing that using the decision aid would not require reorganization of the CF clinic (90%). After implementing the decision aid with interventions tailored to the barriers, decision aid use increased from 29% at baseline to 85% during year 1 and 92% in year 2 (p < 0.001). Compared to baseline, more healthcare professionals at the end of the study were confident in supporting decision-making (p = 0.03) but continued to feel inadequate ability with supporting patients to handle conflicting views (p = 0.01). Most Canadian CF clinics agreed to participate in the study. Interventions were used to target identified modifiable barriers to using the patient decision aid in routine CF clinical practice. CF clinics reported using it with almost all patients in the second year.

The Modified Hartmann Potential Effects on γ-rigid Bohr Hamiltonian

NASA Astrophysics Data System (ADS)

Suparmi, A.; Cari, C.; Nur Pratiwi, Beta

2018-04-01

In this paper, we present the solution of Bohr Hamiltonian in the case of γ-rigid for the modified Hartmann potential. The modified Hartmann potential was formed from the original Hartmann potential, consists of β function and θ function. By using the separation method, the three-dimensional Bohr Hamiltonian equation was reduced into three one-dimensional Schrodinger-like equation which was solved analytically. The results for the wavefunction were shown in mathematically, while for the binding energy was solved numerically. The numerical binding energy for the presence of the modified Hartmann potential is lower than the binding energy value in the absence of modified Hartmann potential effect.

DNA barcoding simplifies environmental risk assessment of genetically modified crops in biodiverse regions.

PubMed

Nzeduru, Chinyere V; Ronca, Sandra; Wilkinson, Mike J

2012-01-01

Transgenes encoding for insecticidal crystal (Cry) proteins from the soil-dwelling bacterium Bacillus Thuringiensis have been widely introduced into Genetically Modified (GM) crops to confer protection against insect pests. Concern that these transgenes may also harm beneficial or otherwise valued insects (so-called Non Target Organisms, NTOs) represents a major element of the Environmental Risk Assessments (ERAs) used by all countries prior to commercial release. Compiling a comprehensive list of potentially susceptible NTOs is therefore a necessary part of an ERA for any Cry toxin-containing GM crop. In partly-characterised and biodiverse countries, NTO identification is slowed by the need for taxonomic expertise and time to enable morphological identifications. This limitation represents a potentially serious barrier to timely adoption of GM technology in some developing countries. We consider Bt Cry1A cowpea (Vigna unguiculata) in Nigeria as an exemplar to demonstrate how COI barcoding can provide a simple and cost-effective means of addressing this problem. Over a period of eight weeks, we collected 163 insects from cowpea flowers across the agroecological and geographic range of the crop in Nigeria. These individuals included 32 Operational Taxonomic Units (OTUs) spanning four Orders and that could mostly be assigned to genus or species level. They included 12 Lepidopterans and two Coleopterans (both potentially sensitive to different groups of Cry proteins). Thus, barcode-assisted diagnoses were highly harmonised across groups (typically to genus or species level) and so were insensitive to expertise or knowledge gaps. Decisively, the entire study was completed within four months at a cost of less than 10,000 US$. The broader implications of the findings for food security and the capacity for safe adoption of GM technology are briefly explored.

Crossing the Barriers: An Analysis of Market Barriers to Geothermal Development and Potential Improvement Scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Katherine R; Levine, Aaron L; Cook, Jeffrey J

Developers have identified many non-technical barriers to geothermal power development, including market barriers. Understanding the challenges to market deployment of geothermal power is important since obtaining power purchase agreements is often cited as one of the largest barriers to geothermal development. This paper discusses the impacts to deployment caused by market challenges, including market demand, price of electricity, policies and incentives.

Optimized surface topography of thermoplastics blends modified by graphene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, Girish M., E-mail: varadgm@gmail.com, E-mail: girish.joshi@vit.ac.in; Sharma, Ajay; Pandey, Mayank

2016-05-23

Polyacrilonitrile (PAN)/ Polyvinylfloride (PVDF) blends were modified by loading the graphene (0.5 to 1.5 wt %). The presence of graphene reveals the interesting surface properties. The decrease in surface roughness as function of graphene loading was confirmed by the topographic method of recording (two and three dimensional images) with atomic force microscope (AFM). The blends become smoother in nature due to occupied smaller surface area of graphene. This property may be useful for several applications in the marine, naval, nuclear domain and engineering applications as barrier medium.

Single ricin detection by atomic force microscopy chemomechanical mapping

NASA Astrophysics Data System (ADS)

Chen, Guojun; Zhou, Jianfeng; Park, Bosoon; Xu, Bingqian

2009-07-01

The authors report on a study of detecting ricin molecules immobilized on chemically modified Au (111) surface by chemomechanically mapping the molecular interactions with a chemically modified atomic force microscopy (AFM) tip. AFM images resolved the different fold-up conformations of single ricin molecule as well as their intramolecule structure of A- and B-chains. AFM force spectroscopy study of the interaction indicates that the unbinding force has a linear relation with the logarithmic force loading rate, which agrees well with calculations using one-barrier bond dissociation model.

Assessing Controls on the Geometry and Dimensions of Modern Barrier Islands

NASA Astrophysics Data System (ADS)

Mulhern, J.; Johnson, C. L.; Martin, J. M.

2015-12-01

Barrier islands are highly ephemeral features, shaped by wave, tide, and storm energy. The processes that govern the size, shape, and motion of barrier islands are not well constrained, yet central to coastal dynamics. While the global distribution of barrier islands has been mapped and assessed, there is little consensus on the forces controlling barrier island formation, motion, or preservation. This study presents a new semi-global database of modern barrier islands to better understand their morphology and spatial distribution. We have mapped, in Google Earth, the subaerial extent of >350 barrier islands and spits, measuring spatial characteristic such as exposed area, perimeter, length, and width. These objects are cross-referenced with parameters that potentially control morphology, including tidal range, wave height, climate, distance from the continental shelf, proximity to fluvial output, and tectonic setting. This approach provides a more optimal framework to assess controls on coastal features, including barrier island morphology, and to investigate potential geometric scaling relationships. Preliminary analysis shows trends in the spatial characteristics of barrier islands. There is a strong linear relationship between the perimeter and length (y= -0.59 + 0.42x, R2=0.95). Linear trends also relate length to area when the data are separated by tidal range to wave height ratio. Assessment of barrier island shape supports the hypothesis of Hayes (1979) that barrier islands in wave-dominated settings are long and linear while those in mixed energy setting are more rounded. The barrier islands of the Texas Gulf of Mexico are larger than the global average for the database, with distinctly longer length values (41.16 km vs. 15.77 km respectively) and larger areas (103.81 km2 vs. 42.14 km2 respectively). Initial assessment shows that tidal range and wave height are primary controls barrier island dimensions. Future work will consider climate, latitude, fluvial input, and tectonic regime as additional factors. Assessing modern barrier islands will lend insight into potential paleomorphodynamic relationships and help determine how islands are transferred into the rock record, with implications for sequence stratigraphy, subsurface reservoirs, etc.

Transmittance and Tunneling Current through a Trapezoidal Barrier under Spin Polarization Consideration

NASA Astrophysics Data System (ADS)

Noor, F. A.; Nabila, E.; Mardianti, H.; Ariani, T. I.; Khairurrijal

2018-04-01

The transmittance and tunneling current in heterostructures under spin polarization consideration were studied by employing a zinc-blended structure for the heterostructures. An electron tunnels through a potential barrier by applying a bias voltage to the barrier, which is called the trapezoidal potential barrier. In order to study the transmittance, an Airy wave function approach was employed to find the transmittance. The obtained transmittance was then utilized to compute the tunneling current by using a Gauss quadrature method. It was shown that the transmittances were asymmetric with the incident angle of the electron. It was also shown that the tunneling currents increased as the bias voltage increased.

Limited effectiveness of heat acclimation to soldiers wearing US Army and US Air Force chemical protective clothing. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, S.K.; Gonzalez, R.R.

1995-11-01

Heat acclilmation-induced sweating responses have the potential of reducing heat strain for soldiers wearing chemical protective garment. However, this potential benefit is strongly affected by the properties of the garment. If the clothing ensemble permits sufficient evaporative heat dissipation, then heat acclimation becomes helpful in reducing heat strain. On the other hand, if the garment creates an impenetrable barrier to moisture, no benefit can be gained from heat acclimation as the additional sweating cannot be evaporated. We studied 10 subjects exercising on a treadmill while wearing two different U.S. military chemical protective ensembles. Skin heat flux, skin temperature, core temperature,more » metabolic heat production, and heart rate were measured. We found that the benefit of heat acclimation is strongly dependent on an unimpeded ability of evaporative heat loss from skin areas. The evaporative potential (EP), a measure of thermal insulation modified by moisture permeability, of the clothing ensemble offers a quantitative index useful to determine whether heat acclimation is helpful while protective clothing system. Our data show that when EP is less than 15%, heat acclimation affords no benefit. An evaporative potential graph is created to aid in this determination.« less

Super-giant magnetoresistance at room-temperature in copper nanowires due to magnetic field modulation of potential barrier heights at nanowire-contact interfaces

NASA Astrophysics Data System (ADS)

Hossain, Md I.; Maksud, M.; Palapati, N. K. R.; Subramanian, A.; Atulasimha, J.; Bandyopadhyay, S.

2016-07-01

We have observed a super-giant (∼10 000 000%) negative magnetoresistance at 39 mT field in Cu nanowires contacted with Au contact pads. In these nanowires, potential barriers form at the two Cu/Au interfaces because of Cu oxidation that results in an ultrathin copper oxide layer forming between Cu and Au. Current flows when electrons tunnel through, and/or thermionically emit over, these barriers. A magnetic field applied transverse to the direction of current flow along the wire deflects electrons toward one edge of the wire because of the Lorentz force, causing electron accumulation at that edge and depletion at the other. This lowers the potential barrier at the accumulated edge and raises it at the depleted edge, causing a super-giant magnetoresistance at room temperature.

Super-giant magnetoresistance at room-temperature in copper nanowires due to magnetic field modulation of potential barrier heights at nanowire-contact interfaces.

PubMed

Hossain, Md I; Maksud, M; Palapati, N K R; Subramanian, A; Atulasimha, J; Bandyopadhyay, S

2016-07-29

We have observed a super-giant (∼10 000 000%) negative magnetoresistance at 39 mT field in Cu nanowires contacted with Au contact pads. In these nanowires, potential barriers form at the two Cu/Au interfaces because of Cu oxidation that results in an ultrathin copper oxide layer forming between Cu and Au. Current flows when electrons tunnel through, and/or thermionically emit over, these barriers. A magnetic field applied transverse to the direction of current flow along the wire deflects electrons toward one edge of the wire because of the Lorentz force, causing electron accumulation at that edge and depletion at the other. This lowers the potential barrier at the accumulated edge and raises it at the depleted edge, causing a super-giant magnetoresistance at room temperature.

Influence of solid noise barriers on near-road and on-road air quality

NASA Astrophysics Data System (ADS)

Baldauf, Richard W.; Isakov, Vlad; Deshmukh, Parikshit; Venkatram, Akula; Yang, Bo; Zhang, K. Max

2016-03-01

Public health concerns regarding adverse health effects for populations spending significant amounts of time near high traffic roadways has increased substantially in recent years. Roadside features, including solid noise barriers, have been investigated as potential methods that can be implemented in a relatively short time period to reduce air pollution exposures from nearby traffic. A field study was conducted to determine the influence of noise barriers on both on-road and downwind pollutant concentrations near a large highway in Phoenix, Arizona, USA. Concentrations of nitrogen dioxide, carbon monoxide, ultrafine particles, and black carbon were measured using a mobile platform and fixed sites along two limited-access stretches of highway that contained a section of noise barrier and a section with no noise barrier at-grade with the surrounding terrain. Results of the study showed that pollutant concentrations behind the roadside barriers were significantly lower relative to those measured in the absence of barriers. The reductions ranged from 50% within 50 m from the barrier to about 30% as far as 300 m from the barrier. Reductions in pollutant concentrations generally began within the first 50 m of the barrier edge; however, concentrations were highly variable due to vehicle activity behind the barrier and along nearby urban arterial roadways. The concentrations on the highway, upwind of the barrier, varied depending on wind direction. Overall, the on-road concentrations in front of the noise barrier were similar to those measured in the absence of the barrier, contradicting previous modeling results that suggested roadside barriers increase pollutant levels on the road. Thus, this study suggests that noise barriers do reduce potential pollutant exposures for populations downwind of the road, and do not likely increase exposures to traffic-related pollutants for vehicle passengers on the highway.

Measuring the barriers against seeking consultation for urinary incontinence among Middle Eastern women

PubMed Central

2010-01-01

Background Existing questionnaires to assess barriers against consultation for urinary incontinence (UI) are not appropriate for use in the Middle East culture. The aim of this study was to explore barriers against seeking help for UI and introducing a questionnaire that assess these barriers among those women. This is important before proceeding to any educational programs or having interval clinical audits to help incontinent women. Methods 1- Screening for UI. Women - aged 20 years and older, attending the outpatient Urology and Gynaecology clinics were invited to participate and interviewed by a research nurse. The UDI-6 was administered to assess the presence and type of UI. Women with UI as their chief complaint were excluded. 2- Interviewing study subjects for possible barriers. Subjects who had UI - as determined by the UDI-6-were first asked an open question "what prevented you from seeking medical consultation for urine leakage?"." They were then asked the proposed questions to assess possible barriers. We developed a preliminary questionnaire based on a review of reasons for not seeking incontinence care from the literature and the response of UI sufferers to the open question in this study. The questionnaire was modified many times to reach this final form. 3- Pilot Study to assess characteristics of the questionnaire. Validity and reliability of the final version of the questionnaire were assessed in a small pilot study including 36 women who completed questionnaire at initial visit and again after 2 weeks. Results Of the 1231 subjects who agreed to participate in the study, 348 reported having UI. About 80% of incontinent women have never sought medical advice. Factors significantly associated with seeking help were husband encouragement, prayer affection and having severe UI. Common barriers were embarrassment and assuming UI as a normal part of aging. A pilot study included 36 women to assess the psychometric properties of the questionnaire after modifying it. The number of missing or not interpretable responses per item ranged from 2.2% to 8.7%. Internal consistency of the items was good. The test-retest reliability of individual items of the questionnaire was variable, with weighted kappa statistics ranging from 0.32 to 0.94 (median, 0.76, p 0.000). Conclusions Preliminary data on our proposed questionnaire show that it is an easy to administer, stable and suits the Middle Eastern culture. PMID:20105307

Measuring the barriers against seeking consultation for urinary incontinence among Middle Eastern women.

PubMed

El-Azab, Ahmed S; Shaaban, Omar M

2010-01-27

Existing questionnaires to assess barriers against consultation for urinary incontinence (UI) are not appropriate for use in the Middle East culture. The aim of this study was to explore barriers against seeking help for UI and introducing a questionnaire that assess these barriers among those women. This is important before proceeding to any educational programs or having interval clinical audits to help incontinent women. 1- Screening for UI. Women - aged 20 years and older, attending the outpatient Urology and Gynaecology clinics were invited to participate and interviewed by a research nurse. The UDI-6 was administered to assess the presence and type of UI. Women with UI as their chief complaint were excluded. 2- Interviewing study subjects for possible barriers. Subjects who had UI - as determined by the UDI-6-were first asked an open question "what prevented you from seeking medical consultation for urine leakage?"." They were then asked the proposed questions to assess possible barriers. We developed a preliminary questionnaire based on a review of reasons for not seeking incontinence care from the literature and the response of UI sufferers to the open question in this study. The questionnaire was modified many times to reach this final form. 3- Pilot Study to assess characteristics of the questionnaire. Validity and reliability of the final version of the questionnaire were assessed in a small pilot study including 36 women who completed questionnaire at initial visit and again after 2 weeks. Of the 1231 subjects who agreed to participate in the study, 348 reported having UI. About 80% of incontinent women have never sought medical advice. Factors significantly associated with seeking help were husband encouragement, prayer affection and having severe UI. Common barriers were embarrassment and assuming UI as a normal part of aging. A pilot study included 36 women to assess the psychometric properties of the questionnaire after modifying it. The number of missing or not interpretable responses per item ranged from 2.2% to 8.7%. Internal consistency of the items was good. The test-retest reliability of individual items of the questionnaire was variable, with weighted kappa statistics ranging from 0.32 to 0.94 (median, 0.76, p 0.000). Preliminary data on our proposed questionnaire show that it is an easy to administer, stable and suits the Middle Eastern culture.

Combined acoustical and visual performance of noise barriers in mitigating the environmental impact of motorways.

PubMed

Jiang, Like; Kang, Jian

2016-02-01

This study investigated the overall performance of noise barriers in mitigating environmental impact of motorways, taking into consideration their effects on reducing noise and visual intrusions of moving traffic, but also potentially inducing visual impact themselves. A laboratory experiment was carried out, using computer-visualised video scenes and motorway traffic noise recordings to present experimental scenarios covering two traffic levels, two distances of receiver to road, two types of background landscape, and five barrier conditions including motorway only, motorway with tree belt, motorways with 3 m timber barrier, 5m timber barrier, and 5m transparent barrier. Responses from 30 participants of university students were gathered and perceived barrier performance analysed. The results show that noise barriers were always beneficial in mitigating environmental impact of motorways, or made no significant changes in environmental quality when the impact of motorways was low. Overall, barriers only offered similar mitigation effect as compared to tree belt, but showed some potential to be more advantageous when traffic level went high. 5m timber barrier tended to perform better than the 3m one at the distance of 300 m but not at 100 m possibly due to its negative visual effect when getting closer. The transparent barrier did not perform much differently from the timber barriers but tended to be the least effective in most scenarios. Some low positive correlations were found between aesthetic preference for barriers and environmental impact reduction by the barriers. Copyright © 2015 Elsevier B.V. All rights reserved.

Fingolimod promotes blood-nerve barrier properties in vitro.

PubMed

Nishihara, Hideaki; Maeda, Toshihiko; Sano, Yasuteru; Ueno, Maho; Okamoto, Nana; Takeshita, Yukio; Shimizu, Fumitaka; Koga, Michiaki; Kanda, Takashi

2018-04-01

The main effect of fingolimod is thought to be functional antagonism of lymphocytic S1P1 receptors and the prevention of lymphocyte egress from lymphoid tissues, thereby reducing lymphocyte infiltration into the nervous system. However, a growing number of reports suggest that fingolimod also has a direct effect on several cell types in the nervous system. Although we previously reported that fingolimod enhances blood-brain barrier (BBB) functions, there have been no investigations regarding the blood-nerve barrier (BNB). In this study, we examine how fingolimod affects the BNB. An immortalized human peripheral nerve microvascular endothelial cell line (HPnMEC) was used to evaluate BNB barrier properties. We examined tight junction proteins and barrier functions of HPnMECs in conditioned medium with or without fingolimod-phosphate and blood sera from patients with typical chronic inflammatory demyelinating polyneuropathy (CIDP). Incubation with fingolimod-phosphate increased levels of claudin-5 mRNA and protein as well as TEER values in HPnMECs. Conversely, typical CIDP sera decreased claudin-5 mRNA/protein levels and TEER values in HPnMECs; however, pretreatment with fingolimod-phosphate inhibited the effects of the typical CIDP sera. Fingolimod-phosphate directly modifies the BNB and enhances barrier properties. This mechanism may be a viable therapeutic target for CIDP, and fingolimod may be useful in patients with typical CIDP who have severe barrier disruption.

Identifying barriers to the provision of bystander cardiopulmonary resuscitation (CPR) in high-risk regions: a qualitative review of emergency calls.

PubMed

Case, Rosalind; Cartledge, Susie; Siedenburg, Josine; Smith, Karen; Straney, Lahn; Barger, Bill; Finn, Judith; Bray, Janet E

2018-06-01

Understanding regional variation in bystander cardiopulmonary resuscitation (CPR) is important to improving out-of-hospital cardiac arrest (OHCA) survival. In this study we aimed to identify barriers to providing bystander CPR in regions with low rates of bystander CPR and where OHCA was recognised in the emergency call. We retrospectively reviewed emergency calls for adults in regions of low bystander CPR in the Australian state of Victoria. Included calls were those where OHCA was identified during the call but no bystander CPR was given. A thematic content analysis was independently conducted by two investigators. Saturation of themes was reached after listening to 139 calls. Calls progressed to the point of compression instructions before EMS arrival in only 26 (18.7%) of cases. Three types of barriers were identified: procedural barriers (time lost due to language barriers and communication issues; telephone problems), CPR knowledge (skill deficits; perceived benefit) and personal factors (physical frailty or disability; patient position; emotional factors). A range of factors are associated with barriers to delivering bystander CPR even in the presence of dispatcher instructions -some of which are modifiable. To overcome these barriers in high-risk regions, targeted public education needs to provide information about what occurs in an emergency call, how to recognise an OHCA and to improve CPR knowledge and skills. Copyright © 2018. Published by Elsevier B.V.

Barriers to Treatment Among African Americans with Obsessive-Compulsive Disorder

PubMed Central

Williams, M.T.; Domanico, J.; Marques, L.; Leblanc, N.J.; Turkheimer, E.

2012-01-01

African Americans are underrepresented in OCD treatment centers and less likely to experience a remission of symptoms. This study examines the barriers that prevent African Americans with OCD from receiving treatment. Seventy-one adult African Americans with OCD were recruited and administered the modified Barriers to Treatment Participation Scale (BTPS) and the Barriers to Treatment Questionnaire (BTQ). Comparing the BTQ between a European American Internet sample (N=108) and the African American OCD sample (N=71) revealed barriers unique to African Americans, including not knowing where to find help and concerns about discrimination. A Mokken Scale Analysis of the BTPS in the African American participants identified seven major barriers, including the cost of treatment, stigma, fears of therapy, believing that the clinician will be unable to help, feeling no need for treatment, and treatment logistics (being too busy or treatment being too inconvenient). Pearson and point-biserial correlations of the scales and demographic and psychological variables were conducted. Significant relationships emerged between age, gender, income, education, insurance status, and ethnic affirmation/belonging among several of the Mokken scales. A one-way ANOVA demonstrated that concerns about cost were significantly greater for those without insurance, versus those with public or private plans. Suggestions for overcoming barriers are presented, including community education, affordable treatment options, and increasing cultural competence among mental health providers. PMID:22410094

Gender-Related Barriers and Delays in Accessing Tuberculosis Diagnostic and Treatment Services: A Systematic Review of Qualitative Studies

PubMed Central

Akande, Tokunbo; Shankar, Anita V.; McIntire, Katherine N.; Gounder, Celine R.; Gupta, Amita; Yang, Wei-Teng

2014-01-01

Background. Tuberculosis (TB) remains a significant global public health problem with known gender-related (male versus female) disparities. We reviewed the qualitative evidence (written/spoken narrative) for gender-related differences limiting TB service access from symptom onset to treatment initiation. Methods. Following a systematic process, we searched 12 electronic databases, included qualitative studies that assessed gender differences in accessing TB diagnostic and treatment services, abstracted data, and assessed study validity. Using a modified “inductive coding” system, we synthesized emergent themes within defined barriers and delays limiting access at the individual and provider/system levels and examined gender-related differences. Results. Among 13,448 studies, 28 studies were included. All were conducted in developing countries and assessed individual-level barriers; 11 (39%) assessed provider/system-level barriers, 18 (64%) surveyed persons with suspected or diagnosed TB, and 7 (25%) exclusively surveyed randomly sampled community members or health care workers. Each barrier affected both genders but had gender-variable nature and impact reflecting sociodemographic themes. Women experienced financial and physical dependence, lower general literacy, and household stigma, whereas men faced work-related financial and physical barriers and community-based stigma. Conclusions. In developing countries, barriers limiting access to TB care have context-specific gender-related differences that can inform integrated interventions to optimize TB services. PMID:24900921

Temperature dependent current-voltage characteristics of Au/n-Si Schottky barrier diodes and the effect of transition metal oxides as an interface layer

NASA Astrophysics Data System (ADS)

Mahato, Somnath; Puigdollers, Joaquim

2018-02-01

Temperature dependent current-voltage (I‒V) characteristics of Au/n-type silicon (n-Si) Schottky barrier diodes have been investigated. Three transition metal oxides (TMO) are used as an interface layer between gold and silicon. The basic Schottky diode parameters such as ideality factor (n), barrier height (ϕb 0) and series resistance (Rs) are calculated and successfully explained by the thermionic emission (TE) theory. It has been found that ideality factor decreased and barrier height increased with increased of temperature. The conventional Richardson plot of ln(I0/T2) vs. 1000/T is determined the activation energy (Ea) and Richardson constant (A*). Whereas value of 'A*' is much smaller than the known theoretical value of n-type Si. The temperature dependent I-V characteristics obtained the mean value of barrier height (ϕb 0 bar) and standard deviation (σs) from the linear plot of ϕap vs. 1000/T. From the modified Richardson plot of ln(I0/T2) ˗ (qσ)2/2(kT)2 vs. 1000/T gives Richardson constant and homogeneous barrier height of Schottky diodes. Main observation in this present work is the barrier height and ideality factor shows a considerable change but the series resistance value exhibits negligible change due to TMO as an interface layer.

Surfactants have multi-fold effects on skin barrier function.

PubMed

Lemery, Emmanuelle; Briançon, Stéphanie; Chevalier, Yves; Oddos, Thierry; Gohier, Annie; Boyron, Olivier; Bolzinger, Marie-Alexandrine

2015-01-01

The stratum corneum (SC) is responsible for the barrier properties of the skin and the role of intercorneocyte skin lipids, particularly their structural organization, in controlling SC permeability is acknowledged. Upon contacting the skin, surfactants interact with the SC components leading to barrier damage. To improve knowledge of the effect of several classes of surfactant on skin barrier function at three different levels. The influence of treatments of human skin explants with six non-ionic and four ionic surfactant solutions on the physicochemical properties of skin was investigated. Skin surface wettability and polarity were assessed through contact angle measurements. Infrared spectroscopy allowed monitoring the SC lipid organization. The lipid extraction potency of surfactants was evaluated thanks to HPLC-ELSD assays. One anionic and one cationic surfactant increased the skin polarity by removing the sebaceous and epidermal lipids and by disturbing the organization of the lipid matrix. Another cationic surfactant displayed a detergency effect without disturbing the skin barrier. Several non-ionic surfactants disturbed the lipid matrix organization and modified the skin wettability without any extraction of the skin lipids. Finally two non-ionic surfactants did not show any effect on the investigated parameters or on the skin barrier. The polarity, the organization of the lipid matrix and the lipid composition of the skin allowed describing finely how surfactants can interact with the skin and disturb the skin barrier function.

Identification of a barrier height threshold where brook trout population genetic diversity, differentiation, and relatedness are affected

Treesearch

Anne Timm; Eric Hallerman; Andy Dolloff; Mark Hudy; Randall Kolka

2016-01-01

The overall goal of the study was to evaluate effects of landscape features, barriers, on Brook Trout Salvelinus fontinalis population genetics and to identify a potential barrier height threshold where genetic diversity was reduced upstream of the barrier and differentiation and relatedness increase. We screened variation at eight...

Perceived barriers to the regionalization of adult critical care in the United States: a qualitative preliminary study

PubMed Central

Kahn, Jeremy M; Asch, Rebecca J; Iwashyna, Theodore J; Rubenfeld, Gordon D; Angus, Derek C; Asch, David A

2008-01-01

Background Regionalization of adult critical care services may improve outcomes for critically ill patients. We sought to develop a framework for understanding clinician attitudes toward regionalization and potential barriers to developing a tiered, regionalized system of care in the United States. Methods We performed a qualitative study using semi-structured interviews of critical care stakeholders in the United States, including physicians, nurses and hospital administrators. Stakeholders were identified from a stratified-random sample of United States general medical and surgical hospitals. Key barriers and potential solutions were identified by performing content analysis of the interview transcriptions. Results We interviewed 30 stakeholders from 24 different hospitals, representing a broad range of hospital locations and sizes. Key barriers to regionalization included personal and economic strain on families, loss of autonomy on the part of referring physicians and hospitals, loss of revenue on the part of referring physicians and hospitals, the potential to worsen outcomes at small hospitals by limiting services, and the potential to overwhelm large hospitals. Improving communication between destination and source hospitals, provider education, instituting voluntary objective criteria to become a designated referral center, and mechanisms to feed back patients and revenue to source hospitals were identified as potential solutions to some of these barriers. Conclusion Regionalization efforts will be met with significant conceptual and structural barriers. These data provide a foundation for future research and can be used to inform policy decisions regarding the design and implementation of a regionalized system of critical care. PMID:19014704

Knowledge, barriers and facilitators of exercise in dialysis patients: a qualitative study of patients, staff and nephrologists.

PubMed

Jhamb, Manisha; McNulty, Mary L; Ingalsbe, Gerald; Childers, Julie W; Schell, Jane; Conroy, Molly B; Forman, Daniel E; Hergenroeder, Andrea; Dew, Mary Amanda

2016-11-24

Despite growing evidence on benefits of increased physical activity in hemodialysis (HD) patients and safety of intra-dialytic exercise, it is not part of standard clinical care, resulting in a missed opportunity to improve clinical outcomes in these patients. To develop a successful exercise program for HD patients, it is critical to understand patients', staff and nephrologists' knowledge, barriers, motivators and preferences for patient exercise. In-depth interviews were conducted with a purposive sample of HD patients, staff and nephrologists from 4 dialysis units. The data collection, analysis and interpretation followed Criteria for Reporting Qualitative Research guidelines. Using grounded theory, emergent themes were identified, discussed and organized into major themes and subthemes. We interviewed 16 in-center HD patients (mean age 60 years, 50% females, 63% blacks), 14 dialysis staff members (6 nurses, 3 technicians, 2 dietitians, 1 social worker, 2 unit administrators) and 6 nephrologists (50% females, 50% in private practice). Although majority of the participants viewed exercise as beneficial for overall health, most patients failed to recognize potential mental health benefits. Most commonly reported barriers to exercise were dialysis-related fatigue, comorbid health conditions and lack of motivation. Specifically for intra-dialytic exercise, participants expressed concern over safety and type of exercise, impact on staff workload and resistance to changing dialysis routine. One of the most important motivators identified was support from friends, family and health care providers. Specific recommendations for an intra-dialytic exercise program included building a culture of exercise in the dialysis unit, and providing an individualized engaging program that incorporates education and incentives for exercising. Patients, staff and nephrologists perceive a number of barriers to exercise, some of which may be modifiable. Participants desired an individualized intra-dialytic exercise program which incorporates education and motivation, and they provided a number of recommendations that should be considered when implementing such a program.

Temperature dependent current transport of Pd/ZnO nanowire Schottky diodes

NASA Astrophysics Data System (ADS)

Gayen, R. N.; Bhattacharyya, S. R.; Jana, P.

2014-09-01

Zinc oxide (ZnO) nanowire based Schottky barrier diodes are fabricated by depositing Pd metal contact on top of vertically well-aligned ZnO nanowire arrays. A vertical array of ZnO nanowires on indium tin oxide (ITO) coated glass substrates is synthesized by hybrid wet chemical route. Scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) measurement confirm the formation of stoichiometric well-aligned hexagonal (h-ZnO) nanowire arrays with wurtzite structure. Temperature dependent current-voltage (I-V) measurements on palladium-ZnO (Pd/ZnO) nanowire Schottky junctions in the temperature range 303-383 K exhibit excellent rectifying character. From these nonlinear I-V plots, different electrical parameters of diode-like reverse saturation current, barrier height and ideality factor are determined as a function of temperature assuming pure thermionic emission model. The ideality factor is found to decrease while the barrier height increases with the increase in temperature. The series resistance values calculated from Cheung’s functions also show temperature dependency. Such behavior can be attributed to the presence of defects that traps carriers, and barrier height inhomogeneity at the interface of the barrier junction. After barrier height inhomogeneity correction, considering a Gaussian distributed barrier height fluctuation across the Pd/ZnO interface, the estimated values of mean barrier height and modified Richardson constant are more closely matched to the theoretically predicted value for Pd/ZnO Schottky barrier diodes. The variation of density of interface states as a function of interface state energy is also calculated.

Barriers, Benefits, and Behaviors Related to Breakfast Consumption Among Rural Adolescents.

PubMed

Hearst, Mary O; Shanafelt, Amy; Wang, Qi; Leduc, Robert; Nanney, Marilyn S

2016-03-01

We sought to determine if perceived barriers, benefits, and modifiable behaviors support or interfere with breakfast consumption in a racially and economically diverse rural high school population. The participants were 832 Minnesota adolescents from 16 rural high schools. We used baseline data from a group randomized trial aimed at increasing school breakfast participation through policy and environmental-level school changes. Students completed an online survey asking about demographics, breakfast eating behaviors, and the barriers and benefits of eating as it relates to school performance. Bivariate and multivariate logistic regression, accounting for clustering by school, was performed using SAS. Each scale was modeled independently. Participants were 9th and 10th grade students, 36% free/reduced-price lunch (FRL), 30% non-White, and 55% female. Breakfast skippers compared to nonbreakfast skippers reported fewer school related benefits and beliefs and more barriers to eating breakfast (p < .01). Adjusted models revealed students reported more positive beliefs (OR = 0.78, 95% CI = 0.73-0.83), more benefits (OR = 0.95, 95% CI = 0.93-0.97) and fewer barriers (OR = 0.85, 95% CI = 0.82-0.87) and were less likely to skip breakfast. Future intervention research should focus on alleviating barriers and enhancing education around the school related benefits of eating breakfast. © 2016, American School Health Association.

Factors predicting barriers to exercise in midlife Australian women.

PubMed

McGuire, Amanda; Seib, Charrlotte; Anderson, Debra

2016-05-01

Chronic diseases are the leading cause of death and disability worldwide. They are, though, largely attributable to modifiable lifestyle risk factors, including lack of exercise. This study aims to investigate what factors predict perceptions of barriers to exercise in midlife women. This cross-sectional descriptive study collected data from midlife Australian women by online questionnaire. Volunteers aged between 40 and 65 years were recruited following media publicity about the study. The primary outcome measure was perceived exercise barriers (EBBS Barriers sub-scale). Other self-report data included: exercise, smoking, alcohol, fruit and vegetable consumption, body mass index, physical and mental health and well-being (MOS SF-12v2) and exercise self-efficacy. On average, the 225 participants were aged 50.9 years (SD=5.9). The significant predictors of perceived barriers to exercise were perceived benefits of exercise, exercise self-efficacy, physical well-being and mental well-being. These variables explained 41% of the variance in the final model (F (8219)=20.1, p<.01) CONCLUSIONS: In midlife women, perceptions of barriers to exercise correlate with beliefs about the health benefits of exercise, exercise self-efficacy, physical and mental well-being. These findings have application to health promotion interventions targeting exercise behaviour change in midlife women. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Barriers, benefits and behaviors related to breakfast consumption among rural adolescents

PubMed Central

Shanafelt, Amy; Wang, Qi; Leduc, Robert; Nanney, Marilyn S.

2015-01-01

Background We sought to determine if perceived barriers, benefits, and modifiable behaviors support or interfere with breakfast consumption in a racially and economically diverse rural high school population. Methods The participants were 832 Minnesota adolescents from 16 rural high schools. We used baseline data from a group randomized trial aimed at increasing school breakfast participation through policy and environmental-level school changes. Students completed an online survey asking about demographics, breakfast eating behaviors, and the barriers and benefits of eating as it relates to school performance. Bivariate and multivariate logistic regression, accounting for clustering by school, was performed using SAS. Each scale was modeled independently. Results Participants were 9th and 10th grade students, 36% free/reduced price lunch (FRL), 30% non-white and 55% female. Breakfast skippers compared to non-breakfast skippers reported fewer school related benefits and beliefs and more barriers to eating breakfast (p < .01). Adjusted models revealed students reported more positive beliefs (OR= 0.78, 95%CI=0.73-0.83), more benefits (OR=0.95, 95% CI=0.93-0.97) and fewer barriers (OR=0.85, 95%CI=0.82-0.87) and were less likely to skip breakfast. Conclusions Future intervention research should focus on alleviating barriers and enhancing education around the school related benefits of eating breakfast. PMID:26830505

Barriers and Facilitators to Exercise Participation in People with Hip and/or Knee Osteoarthritis: Synthesis of the Literature Using Behavior Change Theory.

PubMed

Dobson, Fiona; Bennell, Kim L; French, Simon D; Nicolson, Philippa J A; Klaasman, Remco N; Holden, Melanie A; Atkins, Lou; Hinman, Rana S

2016-05-01

Exercise is recommended for hip and knee osteoarthritis (OA). Patient initiation of, and adherence to, exercise is key to the success of managing symptoms. This study aimed to (1) identify modifiable barriers and facilitators to participation in intentional exercise in hip and/or knee OA, and (2) synthesize findings using behavior change theory. A scoping review with systematic searches was conducted through March 2015. Two reviewers screened studies for eligibility. Barriers and facilitators were extracted and synthesized according to the Theoretical Domains Framework (TDF) by two independent reviewers. Twenty-three studies (total of 4633 participants) were included. The greatest number of unique barriers and facilitators mapped to the Environmental Context and Resources domain. Many barriers were related to Beliefs about Consequences and Beliefs about Capabilities, whereas many facilitators were related to Reinforcement. Clinicians should take a proactive role in facilitating exercise uptake and adherence, rather than trusting patients to independently overcome barriers to exercise. Strategies that may be useful include a personalized approach to exercise prescription, considering environmental context and available resources, personalized education about beneficial consequences of exercise and reassurance about exercise capability, and use of reinforcement strategies. Future research should investigate the effectiveness of behavior change interventions that specifically target these factors.

Sialic acid (SA)-modified selenium nanoparticles coated with a high blood-brain barrier permeability peptide-B6 peptide for potential use in Alzheimer's disease.

PubMed

Yin, Tiantian; Yang, Licong; Liu, Yanan; Zhou, Xianbo; Sun, Jing; Liu, Jie

2015-10-01

The blood-brain barrier (BBB) is a formidable gatekeeper toward exogenous substances, playing an important role in brain homeostasis and maintaining a healthy microenvironment for complex neuronal activities. However, it also greatly hinders drug permeability into the brain and limits the management of brain diseases. The development of new drugs that show improved transport across the BBB represents a promising strategy for Alzheimer's disease (AD) intervention. Whereas, previous study of receptor-mediated endogenous BBB transport systems has focused on a strategy of using transferrin to facilitate brain drug delivery system, a system that still suffers from limitations including synthesis procedure, stability and immunological response. In the present study, we synthetised sialic acid (SA)-modified selenium (Se) nanoparticles conjugated with an alternative peptide-B6 peptide (B6-SA-SeNPs, a synthetic selenoprotein analogue), which shows high permeability across the BBB and has the potential to serve as a novel nanomedicine for disease modification in AD. Laser-scanning confocal microscopy, flow cytometry analysis and inductively coupled plasma-atomic emission spectroscopy ICP-AES revealed high cellular uptake of B6-SA-SeNPs by cerebral endothelial cells (bEnd.3). The transport efficiency of B6-SA-SeNPs was evaluated in a Transwell experiment based on in vitro BBB model. It provided direct evidence for B6-SA-SeNPs crossing the BBB and being absorbed by PC12 cells. Moreover, inhibitory effects of B6-SA-SeNPs on amyloid-β peptide (Aβ) fibrillation could be demonstrated in PC12 cells and bEnd3 cells. B6-SA-SeNPs could not only effectively inhibit Aβ aggregation but could disaggregate preformed Aβ fibrils into non-toxic amorphous oligomers. These results suggested that B6-SA-SeNPs may provide a promising platform, particularly for the application of nanoparticles in the treatment of brain diseases. Alzheimer's disease (AD) is the world's most common form of dementia characterized by intracellular neurofibrillary tangles in the brain. Over the past decades, the blood-brain barrier (BBB) limits access of therapeutic or diagnostic agents into the brain, which greatly hinders the development of new drugs for treating AD. In this work, we evaluated the efficiency of B6-SA-SeNPs across BBB and investigated the interactions between B6-SA-SeNPs and amyloid-β peptide (Aβ). We confirm that B6-SA-SeNPs could provide a promising platform because of its high brain delivery efficiency, anti-amyloid properties and anti-oxidant properties, which may serve as a novel nanomedicine for the application in the treatment of brain diseases. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Anomalously high potentials observed on ISEE

NASA Technical Reports Server (NTRS)

Whipple, E. C.; Krinsky, I. S.; Torbert, R. B.; Olsen, R. C.

1985-01-01

Data from two electric field experiments and from the plasma composition experiment on ISEE-1 are used to show that the spacecraft charged to close to -70 V in sunlight at 0700 UT on March 17, 1978. Data from the electron spectrometer experiment show that there was a potential barrier of -10 to -20 V about the spacecraft during this event. The potential barrier was effective in turning back emitted photoelectrons to the spacecraft. The stringent electrostatic cleanliness specifications imposed on ISEE make the presence of differential charging unlikely. Modeling of this event is required to determine if the barrier was produced by the presence of space charge.

Interferometry of Klein tunnelling electrons in graphene quantum rings

NASA Astrophysics Data System (ADS)

de Sousa, D. J. P.; Chaves, Andrey; Pereira, J. M.; Farias, G. A.

2017-01-01

We theoretically study a current switch that exploits the phase acquired by a charge carrier as it tunnels through a potential barrier in graphene. The system acts as an interferometer based on an armchair graphene quantum ring, where the phase difference between interfering electronic wave functions for each path can be controlled by tuning either the height or the width of a potential barrier in the ring arms. By varying the parameters of the potential barriers, the interference can become completely destructive. We demonstrate how this interference effect can be used for developing a simple graphene-based logic gate with a high on/off ratio.

Modeling the dynamics of a phreatic eruption based on a tilt observation: Barrier breakage leading to the 2014 eruption of Mount Ontake, Japan

NASA Astrophysics Data System (ADS)

Maeda, Yuta; Kato, Aitaro; Yamanaka, Yoshiko

2017-02-01

Although phreatic eruptions are common volcanic phenomena that sometimes result in significant disasters, their dynamics are poorly understood. In this study, we address the dynamics of the phreatic eruption of Mount Ontake, Japan, in 2014 based on analyses of a tilt change observed immediately (450 s) before the eruption onset. We conducted two sets of analysis: a waveform inversion and a modified phase-space analysis. Our waveform inversion of the tilt signal points to a vertical tensile crack at a depth of 1100 m. Our modified phase-space analysis suggests that the tilt change was at first a linear function in time that then switched to exponential growth. We constructed simple analytical models to explain these temporal functions. The linear function was explained by the boiling of underground water controlled by a constant heat supply from a greater depth. The exponential function was explained by the decompression-induced boiling of water and the upward Darcy flow of the water vapor through a permeable region of small cracks that were newly created in response to ongoing boiling. We interpret that this region was intact prior to the start of the tilt change, and thus, it has acted as a permeability barrier for the upward migration of fluids; it was a breakage of this barrier that led to the eruption.

Role of the supersymmetric semiclassical approach in barrier penetration and heavy-ion fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sil, T.; Dutt, R.; Varshni, Y.P.

1994-11-01

The problem of heavy-ion fusion reactions in the one-dimensional barrier penetration model (BPM) has been reexamined in light of supersymmetry-inspired WKB (SWKB) method. Motivated by our recent work [Phys. Lett. A 184, 209 (1994)] describing the SWKB method for the computation of the transmission coefficient [ital T]([ital E]), we have performed similar calculations for a potential barrier that mimics the proximity potential obtained by fitting experimentally measured fusion cross section [sigma][sub [ital F

Barriers Keep Drops Of Water Out Of Infrared Gas Sensors

NASA Technical Reports Server (NTRS)

Murray, Sean K.

1996-01-01

Infrared-sensor cells used for measuring partial pressures of CO(2) and other breathable gases modified to prevent entry of liquid water into sensory optical paths of cells. Hydrophobic membrane prevents drops of water entrained in flow from entering optical path from lamp to infrared detectors.

Modifying lignin to improve bioenergy feedstocks: strengthening the barrier against pathogens?

USDA-ARS?s Scientific Manuscript database

Lignin is a ubiquitous polymer present in cell walls of all vascular plants, where it rigidifies and strengthens the cell wall structure through covalent cross-linkages to cell wall polysaccharides. The presence of lignin makes the cell wall recalcitrant to conversion into fermentable sugars for bi...

Financial Literacy Curriculum: The Effect on Offender Money Management Skills

ERIC Educational Resources Information Center

Koenig, Lori A.

2007-01-01

Offenders involved in this study lacked basic financial knowledge which presented a barrier to their success upon release. The researcher modified existing curriculum and created a course in financial literacy for offenders within a medium security correctional facility based upon their personal experiences. The offenders gained financial…

Modifying Dialectical Behavior Therapy for Deaf Individuals

ERIC Educational Resources Information Center

O'Hearn, Amanda; Pollard, Robert Q., Jr.

2008-01-01

Therapies that rely on written materials, information, or procedures involving familiarity with the dominant culture (e.g., colloquialisms, history) often pose barriers to people who use another language, have low English literacy, or are less familiar with the dominant culture. All this applies deaf individuals. One of the most well-validated…

Modifying the Existing Campus Building for Accessibility: Accessible Products Catalog.

ERIC Educational Resources Information Center

Cotler, Stephen Richard

This catalog is intended to assist architects and college administrators to select products that help physically handicapped people lead lives free of architectural barriers. The product information, obtained directly from the manufacturers, is listed on comparative matrix sheets, that can be used to achieve the design recommendations. Products of…

Unique Educational Needs of Learners with Physical and Other Health Impairments.

ERIC Educational Resources Information Center

Kendall, Robbie M.

This monograph addresses the educational needs of learners who have physical and health impairments that adversely interfere with their educational performance and who thus require special training, related services, adaptive equipment, modified materials, and/or barrier free facilities. The first section discusses the identification of learners…

46 CFR 56.07-5 - Definitions (modifies 100.2).

Code of Federal Regulations, 2010 CFR

2010-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND... similar fittings which form part of the pressure barrier of any system are included under this heading.... “Nonstandard fitting” means a component of a piping system which is not fabricated under an adopted industry...

Engineering species-like barriers to sexual reproduction.

PubMed

Maselko, Maciej; Heinsch, Stephen C; Chacón, Jeremy M; Harcombe, William R; Smanski, Michael J

2017-10-12

Controlling the exchange of genetic information between sexually reproducing populations has applications in agriculture, eradication of disease vectors, control of invasive species, and the safe study of emerging biotechnology applications. Here we introduce an approach to engineer a genetic barrier to sexual reproduction between otherwise compatible populations. Programmable transcription factors drive lethal gene expression in hybrid offspring following undesired mating events. As a proof of concept, we target the ACT1 promoter of the model organism Saccharomyces cerevisiae using a dCas9-based transcriptional activator. Lethal overexpression of actin results from mating this engineered strain with a strain containing the wild-type ACT1 promoter.Genetic isolation of a genetically modified organism represents a useful strategy for biocontainment. Here the authors use dCas9-VP64-driven gene expression to construct a 'species-like' barrier to reproduction between two otherwise compatible populations.

Temperature dependence of electrical characteristics of Pt/GaN Schottky diode fabricated by UHV e-beam evaporation.

PubMed

Kumar, Ashish; Arafin, Shamsul; Amann, Markus Christian; Singh, Rajendra

2013-11-15

Temperature-dependent electrical characterization of Pt/n-GaN Schottky barrier diodes prepared by ultra high vacuum evaporation has been done. Analysis has been made to determine the origin of the anomalous temperature dependence of the Schottky barrier height, the ideality factor, and the Richardson constant calculated from the I-V-T characteristics. Variable-temperature Hall effect measurements have been carried out to understand charge transport at low temperature. The modified activation energy plot from the barrier inhomogeneity model has given the value of 32.2 A/(cm2 K2) for the Richardson constant A** in the temperature range 200 to 380 K which is close to the known value of 26.4A/(cm2 K2) for n-type GaN.

Modulators of IgG penetration through the blood-brain barrier: Implications for Alzheimer's disease immunotherapy.

PubMed

Finke, John M; Banks, William A

2017-01-01

This review serves to highlight approaches that may improve the access of antibody drugs to regions of the brain affected by Alzheimer's Disease. While previous antibody drugs have been unsuccessful in treating Alzheimer's disease, recent work demonstrates that Alzheimer's pathology can be modified if these drugs can penetrate the brain parenchyma with greater efficacy. Research in antibody blood-brain barrier drug delivery predominantly follows one of three distinct directions: (1) enhancing influx with reduced antibody size, addition of Trojan horse modules, or blood-brain barrier disruption; (2) modulating trancytotic equilibrium and/or kinetics of the neonatal Fc Receptor; and (3) manipulation of antibody glycan carbohydrate composition. In addition to these topics, recent studies are discussed that reveal a role of glycan sialic acid in suppressing antibody efflux from the brain.

Multiple Ligands Targeting Cholinesterases and β-Amyloid: Synthesis, Biological Evaluation of Heterodimeric Compounds with Benzylamine Pharmacophore.

PubMed

Szałaj, Natalia; Bajda, Marek; Dudek, Katarzyna; Brus, Boris; Gobec, Stanislav; Malawska, Barbara

2015-08-01

Alzheimer's disease (AD) is a fatal and complex neurodegenerative disorder for which effective treatment remains the unmet challenge. Using donepezil as a starting point, we aimed to develop novel potential anti-AD agents with a multidirectional biological profile. We designed the target compounds as dual binding site acetylcholinesterase inhibitors, where the N-benzylamine pharmacophore is responsible for interactions with the catalytic anionic site of the enzyme. The heteroaromatic fragment responsible for interactions with the peripheral anionic site was modified and three different heterocycles were introduced: isoindoline, isoindolin-1-one, and saccharine. Based on the results of the pharmacological evaluation, we identified compound 8b with a saccharine moiety as the most potent and selective human acetylcholinesterase inhibitor (IC50  = 33 nM) and beta amyloid aggregation inhibitor. It acts as a non-competitive acetylcholinesterase inhibitor and is able to cross the blood-brain barrier in vitro. We believe that compound 8b represents an important lead compound for further development as potential anti-AD agent. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Accessibility of mHealth Self-Care Apps for Individuals with Spina Bifida

PubMed Central

Yu, Daihua X.; Parmanto, Bambang; Dicianno, Brad E.; Pramana, Gede

2015-01-01

As the smartphone becomes ubiquitous, mobile health is becoming a viable technology to empower individuals to engage in preventive self-care. An innovative mobile health system called iMHere (Internet Mobile Health and Rehabilitation) has been developed at the University of Pittsburgh to support self-care and adherence to self-care regimens for individuals with spina bifida and other complex conditions who are vulnerable to secondary complications. The goal of this study was to explore the accessibility of iMHere apps for individuals with spina bifida. Six participants were asked to perform tasks in a lab environment. Though all of the participants were satisfied with the iMHere apps and would use them again in the future, their needs and preferences to access and use iMHere apps differed. Personalization that provides the ability for a participant to modify the appearance of content, such as the size of the icons and the color of text, could be an ideal solution to address potential issues and barriers to accessibility. The importance of personalization—and potential strategies—for accessibility are discussed. PMID:26755902

Morphological Plant Modeling: Unleashing Geometric and Topological Potential within the Plant Sciences

PubMed Central

Bucksch, Alexander; Atta-Boateng, Acheampong; Azihou, Akomian F.; Battogtokh, Dorjsuren; Baumgartner, Aly; Binder, Brad M.; Braybrook, Siobhan A.; Chang, Cynthia; Coneva, Viktoirya; DeWitt, Thomas J.; Fletcher, Alexander G.; Gehan, Malia A.; Diaz-Martinez, Diego Hernan; Hong, Lilan; Iyer-Pascuzzi, Anjali S.; Klein, Laura L.; Leiboff, Samuel; Li, Mao; Lynch, Jonathan P.; Maizel, Alexis; Maloof, Julin N.; Markelz, R. J. Cody; Martinez, Ciera C.; Miller, Laura A.; Mio, Washington; Palubicki, Wojtek; Poorter, Hendrik; Pradal, Christophe; Price, Charles A.; Puttonen, Eetu; Reese, John B.; Rellán-Álvarez, Rubén; Spalding, Edgar P.; Sparks, Erin E.; Topp, Christopher N.; Williams, Joseph H.; Chitwood, Daniel H.

2017-01-01

The geometries and topologies of leaves, flowers, roots, shoots, and their arrangements have fascinated plant biologists and mathematicians alike. As such, plant morphology is inherently mathematical in that it describes plant form and architecture with geometrical and topological techniques. Gaining an understanding of how to modify plant morphology, through molecular biology and breeding, aided by a mathematical perspective, is critical to improving agriculture, and the monitoring of ecosystems is vital to modeling a future with fewer natural resources. In this white paper, we begin with an overview in quantifying the form of plants and mathematical models of patterning in plants. We then explore the fundamental challenges that remain unanswered concerning plant morphology, from the barriers preventing the prediction of phenotype from genotype to modeling the movement of leaves in air streams. We end with a discussion concerning the education of plant morphology synthesizing biological and mathematical approaches and ways to facilitate research advances through outreach, cross-disciplinary training, and open science. Unleashing the potential of geometric and topological approaches in the plant sciences promises to transform our understanding of both plants and mathematics. PMID:28659934

Design and characterisation of a polyethylene oxide matrix with the potential use as a teat insert for prevention/treatment of bovine mastitis.

PubMed

Bhattarai, Sushila; Alany, Raid G; Bunt, Craig R; Abdelkader, Hamdy; Rathbone, Michael J

2015-01-01

This manuscript reports (for the first time) on antibiotic-free polymeric inserts for the prevention and/or treatment of bovine mastitis. Polyethylene oxide (PEO)-based inserts were prepared using different concentrations of various hydrophilic polymers and water-soluble and water-insoluble drug-release-modifying excipients. A simple and scalable melt-extrusion method was employed to prepare the inserts. The prepared inserts were characterised for their dimension, rheological and mechanical properties. The in vitro release of a model bacteriostatic drug (salicylic acid) from the prepared inserts was studied to demonstrate the effectiveness and reproducibility of the melt-extrusion manufacturing method. Further, the in vitro stability of the inserts was evaluated using gel permeation chromatography (GPC) to monitor any change in molecular weight under real-time and accelerated storage conditions. The investigated inserts were stable at accelerated storage conditions over a period of 6 months. PEO inserts have the potential to serve a dual purpose, act as a physical barrier against pathogens invading the teat canal of cows and possibly control the release of a drug.

Isolated Rat Hepatocyte Couplets: A Primary Secretory Unit for Electrophysiologic Studies of Bile Secretory Function

NASA Astrophysics Data System (ADS)

Graf, J.; Gautam, A.; Boyer, J. L.

1984-10-01

Hepatocyte couplets were isolated by collagenase perfusion from rat liver. Between adjacent cells, the bile canaliculus forma a closed space into which secretion occurs. As in intact liver, Mg2+-ATPase is localized at the canalicular lumen, the organic anion fluorescein is excreted, and secretion is modified by osmotic gradients. By passing a microelectrode through one cell into the canalicular vacuole, a transepithelial potential profile was obtained. In 27 cell couplets the steady-state intracellular (-26.3 ± 5.3 mV) and intracanalicular (-5.9 ± 3.3 mV) potentials were recorded at 37 degrees C with reference to the external medium. Input resistances were determined within the cell (86 ± 23 MΩ ) and in the bile canalicular lumen (32 ± 17 MΩ ) by passing current pulses through the microelectrode. These data define electrical driving forces for ion transport across the sinusoidal, canalicular, and paracellular barriers and indicate ion permeation across a leaky paracellular junctional pathway. These findings indicate that the isolated hepatocyte couplet is an effective model for electrophysiologic studies of bile secretory function.

Experimental investigation of flow induced dust acoustic shock waves in a complex plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jaiswal, S., E-mail: surabhijaiswal73@gmail.com; Bandyopadhyay, P.; Sen, A.

2016-08-15

We report on experimental observations of flow induced large amplitude dust-acoustic shock waves in a complex plasma. The experiments have been carried out in a Π shaped direct current glow discharge experimental device using kaolin particles as the dust component in a background of Argon plasma. A strong supersonic flow of the dust fluid is induced by adjusting the pumping speed and neutral gas flow into the device. An isolated copper wire mounted on the cathode acts as a potential barrier to the flow of dust particles. A sudden change in the gas flow rate is used to trigger themore » onset of high velocity dust acoustic shocks whose dynamics are captured by fast video pictures of the evolving structures. The physical characteristics of these shocks are delineated through a parametric scan of their dynamical properties over a range of flow speeds and potential hill heights. The observed evolution of the shock waves and their propagation characteristics are found to compare well with model numerical results based on a modified Korteweg-de-Vries-Burgers type equation.« less

Effect of irradiation, active and modified atmosphere packaging, container oxygen barrier and storage conditions on the physicochemical and sensory properties of raw unpeeled almond kernels (Prunus dulcis).

PubMed

Mexis, Stamatios F; Riganakos, Kyriakos A; Kontominas, Michael G

2011-03-15

The present study investigated the effect of irradiation, active and modified atmosphere packaging, and storage conditions on quality retention of raw, whole, unpeeled almonds. Almond kernels were packaged in barrier and high-barrier pouches, under N(2) or with an O(2) absorber and stored either under fluorescent lighting or in the dark at 20 °C for 12 months. Quality parameters monitored were peroxide value, hexanal content, colour, fatty acid composition and volatile compounds. Of the sensory attributes colour, texture, odour and taste were evaluated. Peroxide value and hexanal increased with dose of irradiation and storage time. Irradiation resulted in a decrease of polyunsaturated and monounsaturated fatty acids during storage with a parallel increase of saturated fatty acids. Volatile compounds were not affected by irradiation but increased with storage time indicating enhanced lipid oxidation. Colour parameters of samples remained unaffected immediately after irradiation. For samples packaged under a N(2) , atmosphere L and b values decreased during storage with a parallel increase of value a resulting to gradual product darkening especially in irradiated samples. Non-irradiated almonds retained acceptable quality for ca. 12 months stored at 20 °C with the O(2) absorber irrespective of lighting conditions and packaging material oxygen barrier. The respective shelf life for samples irradiated at 1.0 kGy was 12 months packaged in PET-SiOx//LDPE irrespective of lighting conditions and 12 months for samples irradiated at 3 kGy packaged in PET-SiOx//LDPE stored in the dark. Copyright © 2010 Society of Chemical Industry.

76 FR 38655 - Agency Information Collection Activities: Proposed Collection; Comment Request

Federal Register 2010, 2011, 2012, 2013, 2014

2011-07-01

... Request: New collection; Title of Information Collection: Analysis of Transportation Barriers to... of the proposed study is to identify and analyze transportation barriers associated with the... analyze the health outcomes resulting from those barriers, and ultimately to identify potential solutions...

Financial Strain and Regional Unemployment as Barriers to Job Search Self-Efficacy: A Test of Social Cognitive Career Theory

ERIC Educational Resources Information Center

Dahling, Jason J.; Melloy, Robert; Thompson, Mindi N.

2013-01-01

Social cognitive career theory (SCCT) emphasizes the potential impact of contextual barriers on vocational self-efficacy, interests, and goals. However, most tests of SCCT to date have focused exclusively on person-level, perceptual barriers rather than objective, macroeconomic barriers that may influence large groups of people. In this study, we…

Electronic tunneling through a potential barrier on the surface of a topological insulator

NASA Astrophysics Data System (ADS)

Zhou, Benliang; Zhou, Benhu; Zhou, Guanghui

2016-12-01

We investigate the tunneling transport for electrons on the surface of a topological insulator (TI) through an electrostatic potential barrier. By using the Dirac equation with the continuity conditions for all segments of wave functions at the interfaces between regions inside and outside the barrier, we calculate analytically the transmission probability and conductance for the system. It is demonstrated that, the Klein paradox can also been observed in the system same as in graphene system. Interestingly, the conductance reaches the minimum value when the incident electron energy is equal to the barrier strength. Moreover, with increasing barrier width, the conductance turns up some tunneling oscillation peaks, and larger barrier strength can cause lower conductance, shorter period but larger oscillation amplitude. The oscillation amplitude decreases as the barrier width increases, which is similar as that of the system consisting of the compressive uniaxial strain applied on a TI, but somewhat different from that of graphene system where the oscillation amplitude is a constant. The findings here imply that an electrostatic barrier can greatly influence the electron tunneling transport of the system, and may provide a new way to realize directional filtering of electrons.

Effects of different sterilization methods on the physico-chemical and bioresponsive properties of plasma-treated polycaprolactone films.

PubMed

Ghobeira, Rouba; Philips, Charlot; Declercq, Heidi; Cools, Pieter; De Geyter, Nathalie; Cornelissen, Ria; Morent, Rino

2017-01-24

For most tissue engineering applications, surface modification and sterilization of polymers are critical aspects determining the implant success. The first part of this study is thus dedicated to modifying polycaprolactone (PCL) surfaces via plasma treatment using a medium pressure dielectric barrier discharge, while the second part focuses on the sterilization of plasma-modified PCL. Chemical and physical surface changes are examined making use of water contact angle goniometry (WCA), x-ray photoelectron spectroscopy and atomic force microscopy. Bioresponsive properties are evaluated by performing cell culture tests. The results show that air and argon plasmas decrease the WCA significantly due to the incorporation of oxygen-containing functionalities onto the PCL surface, without modifying its morphology. Extended treatment times lead to PCL degradation, especially in the case of air plasma. In addition to surface modification, the plasma potential to sterilize PCL is studied with appropriate treatment times, but sterility has not been achieved so far. Therefore, plasma-modified films are subjected to UV, H 2 O 2 plasma (HP) and ethylene oxide (EtO) sterilizations. UV exposure of 3 h does not alter the PCL physico-chemical properties. A decreased wettability is observed after EtO sterilization, attributable to the modification of PCL chain ends reacting with EtO molecules. HP sterilization increases the WCA of the plasma-treated samples, presumably due to the scission of the hydrophilic bonds generated during the prior plasma treatments. Moreover, HP modifies the PCL surface morphology. For all the sterilizations, an improved cell adhesion and proliferation is observed on plasma-treated films compared to untreated ones. EtO shows the lowest proliferation rate compared to HP and UV. Overall, of the three sterilizations, UV is the most effective, since the physical alterations provoked by HP might interfere with the structural integrity when it comes to 3D scaffolds, and the chemical modifications caused by EtO, in addition to its toxicity, interfere with PCL bioactivity.

Implementation Intentions as a Strategy to Increase the Notification Rate of Potential Ocular Tissue Donors by Nurses: A Clustered Randomized Trial in Hospital Settings

PubMed Central

2014-01-01

Aim. The purpose of this study is to evaluate the impact, among nurses in hospital settings, of a questionnaire-based implementation intentions intervention on notification of potential ocular tissue donors to donation stakeholders. Methods. This randomized intervention was clustered at the level of hospital departments with two study arms: questionnaire-based implementation intentions intervention and control. In the intervention group, nurses were asked to plan specific actions if faced with a number of barriers when reporting potential ocular donors. The primary outcome was the potential ocular tissue donors' notification rate before and after the intervention. Analysis was based on a generalized linear model with an identity link and a binomial distribution. Results. We compared outcomes in 26 departments from 5 hospitals, 13 departments per condition. The implementation intentions intervention did not significantly increase the notification rate of ocular tissue donors (intervention: 23.1% versus control: 21.1%; χ 2 = 1.14, 2; P = 0.56). Conclusion. A single and brief implementation intentions intervention among nurses did not modify the notification rate of potential ocular tissue donors to donation stakeholders. Low exposure to the intervention was a major challenge in this study. Further studies should carefully consider a multicomponent intervention to increase exposure to this type of intervention. PMID:25132990

Conducting Research with LGB People of Color: Methodological Challenges and Strategies

ERIC Educational Resources Information Center

DeBlaere, Cirleen; Brewster, Melanie E.; Sarkees, Anthony; Moradi, Bonnie

2010-01-01

Methodological barriers have been highlighted as a primary reason for the limited research with lesbian, gay, and bisexual (LGB) people of color. Thus, strategies for anticipating and addressing potential methodological barriers are needed. To address this need, this article discusses potential challenges associated with conducting research with…

The potential oral health impact of cost barriers to dental care: findings from a Canadian population-based study

PubMed Central

2014-01-01

Background Prior to the 2007/09 Canadian Health Measures Survey, there was no nationally representative clinical data on the oral health of Canadians experiencing cost barriers to dental care. The aim of this study was to determine the oral health status and dental treatment needs of Canadians reporting cost barriers to dental care. Methods A secondary data analysis of the 2007/09 Canadian Health Measures Survey was undertaken using a sample of 5,586 Canadians aged 6 to 79. Chi square tests were conducted to test the association between reporting cost barriers to care and oral health outcomes. Logistic regressions were conducted to identify predictors of reporting cost barriers. Results Individuals who reported cost barriers to dental care had poorer oral health and more treatment needs compared to their counterparts. Conclusions Avoiding dental care and/or foregoing recommended treatment because of cost may contribute to poor oral health. This study substantiates the potential likelihood of progressive dental problems caused by an inability to treat existing conditions due to financial barriers. PMID:24962622

Novel delivery methods bypassing the blood-brain and blood-tumor barriers.

PubMed

Hendricks, Benjamin K; Cohen-Gadol, Aaron A; Miller, James C

2015-03-01

Glioblastoma (GBM) is the most common primary brain tumor and carries a grave prognosis. Despite years of research investigating potentially new therapies for GBM, the median survival rate of individuals with this disease has remained fairly stagnant. Delivery of drugs to the tumor site is hampered by various barriers posed by the GBM pathological process and by the complex physiology of the blood-brain and blood-cerebrospinal fluid barriers. These anatomical and physiological barriers serve as a natural protection for the brain and preserve brain homeostasis, but they also have significantly limited the reach of intraparenchymal treatments in patients with GBM. In this article, the authors review the functional capabilities of the physical and physiological barriers that impede chemotherapy for GBM, with a specific focus on the pathological alterations of the blood-brain barrier (BBB) in this disease. They also provide an overview of current and future methods for circumventing these barriers in therapeutic interventions. Although ongoing research has yielded some potential options for future GBM therapies, delivery of chemotherapy medications across the BBB remains elusive and has limited the efficacy of these medications.

Numerical simulation of tunneling through arbitrary potential barriers applied on MIM and MIIM rectenna diodes

NASA Astrophysics Data System (ADS)

Abdolkader, Tarek M.; Shaker, Ahmed; Alahmadi, A. N. M.

2018-07-01

With the continuous miniaturization of electronic devices, quantum-mechanical effects such as tunneling become more effective in many device applications. In this paper, a numerical simulation tool is developed under a MATLAB environment to calculate the tunneling probability and current through an arbitrary potential barrier comparing three different numerical techniques: the finite difference method, transfer matrix method, and transmission line method. For benchmarking, the tool is applied to many case studies such as the rectangular single barrier, rectangular double barrier, and continuous bell-shaped potential barrier, each compared to analytical solutions and giving the dependence of the error on the number of mesh points. In addition, a thorough study of the J ‑ V characteristics of MIM and MIIM diodes, used as rectifiers for rectenna solar cells, is presented and simulations are compared to experimental results showing satisfactory agreement. On the undergraduate level, the tool provides a deeper insight for students to compare numerical techniques used to solve various tunneling problems and helps students to choose a suitable technique for a certain application.

Adaptive management in the context of barriers in European freshwater ecosystems.

PubMed

Birnie-Gauvin, Kim; Tummers, Jeroen S; Lucas, Martyn C; Aarestrup, Kim

2017-12-15

Many natural habitats have been modified to accommodate for the presence of humans and their needs. Infrastructures - such as hydroelectric dams, weirs, culverts and bridges - are now a common occurrence in streams and rivers across the world. As a result, freshwater ecosystems have been altered extensively, affecting both biological and geomorphological components of the habitats. Many fish species rely on these freshwater ecosystems to complete their lifecycles, and the presence of barriers has been shown to reduce their ability to migrate and sustain healthy populations. In the long run, barriers may have severe repercussions on population densities and dynamics of aquatic animal species. There is currently an urgent need to address these issues with adequate conservation approaches. Adaptive management provides a relevant approach to managing barriers in freshwater ecosystems as it addresses the uncertainties of dealing with natural systems, and accommodates for future unexpected events, though this approach may not be suitable in all instances. A literature search on this subject yielded virtually no output. Hence, we propose a step-by-step guide for implementing adaptive management, which could be used to manage freshwater barriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

Involvement of specific macrophage-lineage cells surrounding arterioles in barrier and scavenger function in brain cortex.

PubMed Central

Mato, M; Ookawara, S; Sakamoto, A; Aikawa, E; Ogawa, T; Mitsuhashi, U; Masuzawa, T; Suzuki, H; Honda, M; Yazaki, Y; Watanabe, E; Luoma, J; Yla-Herttuala, S; Fraser, I; Gordon, S; Kodama, T

1996-01-01

The transport of solutes between blood and brain is regulated by a specific barrier. Capillary endothelial cells of brain are known to mediate barrier function and facilitate transport. Here we report that specific cells surrounding arterioles, known as Mato's fluorescent granular perithelial (FGP) cells or perivascular microglial cells, contribute to the barrier function. Immunohistochemical and in situ hybridization studies indicate that, in normal brain cortex, type I and type II macrophage scavenger receptors are expressed only in FGP/perivascular microglial cells, and surface markers of macrophage lineage are also detected on them. These cells mediate the uptake of macromolecules, including modified low density lipoprotein, horseradish peroxidase, and ferritin injected either into the blood or into the cerebral ventricles. Accumulation of scavenged materials with aging or after the administration of a high-fat diet results in the formation of honeycomb-like foam cells and the narrowing of the lumen of arterioles in the brain cortex. These results indicate involvement of FGP/perivascular microglial cells in the barrier and scavenger functions in the central nervous system. Images Fig. 1 Fig. 2 Fig. 4 Fig. 5 Fig. 6 PMID:8622926

Theory of chaos regularization of tunneling in chaotic quantum dots.

PubMed

Lee, Ming-Jer; Antonsen, Thomas M; Ott, Edward; Pecora, Louis M

2012-11-01

Recent numerical experiments of Pecora et al. [Phys. Rev. E 83, 065201 (2011)] have investigated tunneling between two-dimensional symmetric double wells separated by a tunneling barrier. The wells were bounded by hard walls and by the potential barrier which was created by a step increase from the zero potential within a well to a uniform barrier potential within the barrier region, which is a situation potentially realizable in the context of quantum dots. Numerical results for the splitting of energy levels between symmetric and antisymmetric eigenstates were calculated. It was found that the splittings vary erratically from state to state, and the statistics of these variations were studied for different well shapes with the fluctuation levels being much less in chaotic wells than in comparable nonchaotic wells. Here we develop a quantitative theory for the statistics of the energy level splittings for chaotic wells. Our theory is based on the random plane wave hypothesis of Berry. While the fluctuation statistics are very different for chaotic and nonchaotic well dynamics, we show that the mean splittings of differently shaped wells, including integrable and chaotic wells, are the same if their well areas and barrier parameters are the same. We also consider the case of tunneling from a single well into a region with outgoing quantum waves.

Soliton tunneling in the nonlinear Schrödinger equation with variable coefficients and an external harmonic potential.

PubMed

Zhong, Wei-Ping; Belić, Milivoj R

2010-05-01

We report on the nonlinear tunneling effects of spatial solitons of the generalized nonlinear Schrödinger equation with distributed coefficients in an external harmonic potential. By using the homogeneous balance principle and the F-expansion technique we find the spatial bright and dark soliton solutions. We then display tunneling effects of such solutions occurring under special conditions; specifically when the spatial solitons pass unchanged through the potential barriers and wells affected by special choices of the diffraction and/or the nonlinearity coefficients. Our results show that the solitons display tunneling effects not only when passing through the nonlinear potential barriers or wells but also when passing through the diffractive barriers or wells. During tunneling the solitons may also undergo a controllable compression.

Novel treatment strategies for brain tumors and metastases

PubMed Central

El-Habashy, Salma E.; Nazief, Alaa M.; Adkins, Chris E.; Wen, Ming Ming; El-Kamel, Amal H.; Hamdan, Ahmed M.; Hanafy, Amira S.; Terrell, Tori O.; Mohammad, Afroz S.; Lockman, Paul R.; Nounou, Mohamed Ismail

2015-01-01

This review summarizes patent applications in the past 5 years for the management of brain tumors and metastases. Most of the recent patents discuss one of the following strategies: the development of new drug entities that specifically target the brain cells, the blood–brain barrier and the tumor cells, tailor-designing a novel carrier system that is able to perform multitasks and multifunction as a drug carrier, targeting vehicle and even as a diagnostic tool, direct conjugation of a US FDA approved drug with a targeting moiety, diagnostic moiety or PK modifying moiety, or the use of innovative nontraditional approaches such as genetic engineering, stem cells and vaccinations. Until now, there has been no optimal strategy to deliver therapeutic agents to the CNS for the treatment of brain tumors and metastases. Intensive research efforts are actively ongoing to take brain tumor targeting, and novel and targeted CNS delivery systems to potential clinical application. PMID:24998288

Communication of alcohol and smoking lifestyle advice to the gastroenterological patient.

PubMed

Spence, Andrew D; Khasawneh, Mais; Allen, Patrick B; Addley, Jennifer

2017-10-01

Effective communication between healthcare staff and patients is central to development of the patient-professional relationship. Many barriers influence this communication, often resulting in patients' lack of understanding and retention of information, particularly affecting advice regarding lifestyle habits, such as alcohol consumption and smoking. Alcohol and smoking misuse are potentially modifiable risk factors known to adversely affect a variety of gastroenterological conditions and improvements in communication with patients regarding this is an important management component. This review discusses the clinical impact of these factors and how healthcare professionals can improve communication. We discuss how enhancing verbal communication skills through medical training leads to greater outcomes in patient satisfaction and adherence to treatment and advice. In addition, with the rapid digitalisation of society, platforms such as social media and smartphone applications may be considered as adjuncts to traditional forms of communication. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and properties of graphene oxide/graphene nanostructures

NASA Astrophysics Data System (ADS)

Kapitanova, O. O.; Panin, G. N.; Baranov, A. N.; Kang, T. W.

2012-05-01

We report preparation of graphene oxide (GO)/graphene (G) nanostructures and their structural, optical and electrical properties. GO was synthesized through oxidation of graphite by using the modified Hummer's method, in which a long oxidation time was combined with a highly effective method for purifying the reaction products. The obtained GO was partially reduced (r-GO) by adding ascorbic acid and thermal annealing. An electrical reduction/oxidation process in r-GO under an electric field was used to form and control the GO/G nanostructures and the potential barrier at the interface. After the treatment, the ratio of the intensity of peak G (1578 cm-1) to that of peak D (1357 cm-1) in Raman spectra of the samples is increased, which is attributed to an increase in the ratio between the sp2 and sp3 regions. The electrical and the luminescence characteristics of the GO/G nanostructures were investigated.

Superconducting spin valves controlled by spiral re-orientation in B20-family magnets

NASA Astrophysics Data System (ADS)

Pugach, N. G.; Safonchik, M.; Champel, T.; Zhitomirsky, M. E.; Lähderanta, E.; Eschrig, M.; Lacroix, C.

2017-10-01

We propose a superconducting spin-triplet valve, which consists of a superconductor and an itinerant magnetic material, with the magnet showing an intrinsic non-collinear order characterized by a wave vector that may be aligned in a few equivalent preferred directions under the control of a weak external magnetic field. Re-orienting the spiral direction allows one to controllably modify long-range spin-triplet superconducting correlations, leading to spin-valve switching behavior. Our results indicate that the spin-valve effect may be noticeable. This bilayer may be used as a magnetic memory element for cryogenic nanoelectronics. It has the following advantages in comparison to superconducting spin valves proposed previously: (i) it contains only one magnetic layer, which may be more easily fabricated and controlled; (ii) its ground states are separated by a potential barrier, which solves the "half-select" problem of the addressed switch of memory elements.

Cell-free synthetic biology for environmental sensing and remediation.

PubMed

Karig, David K

2017-06-01

The fields of biosensing and bioremediation leverage the phenomenal array of sensing and metabolic capabilities offered by natural microbes. Synthetic biology provides tools for transforming these fields through complex integration of natural and novel biological components to achieve sophisticated sensing, regulation, and metabolic function. However, the majority of synthetic biology efforts are conducted in living cells, and concerns over releasing genetically modified organisms constitute a key barrier to environmental applications. Cell-free protein expression systems offer a path towards leveraging synthetic biology, while preventing the spread of engineered organisms in nature. Recent efforts in the areas of cell-free approaches for sensing, regulation, and metabolic pathway implementation, as well as for preserving and deploying cell-free expression components, embody key steps towards realizing the potential of cell-free systems for environmental sensing and remediation. Copyright © 2017 The Author. Published by Elsevier Ltd.. All rights reserved.

A Facile Pathway to Modify Cellulose Composite Film by Reducing Wettability and Improving Barrier towards Moisture.

PubMed

Hu, Xiaorong; Chen, Lin; Tao, Dandan; Ma, Zhaocheng; Liu, Shilin

2017-01-05

The hydrophilic property of cellulose is a key limiting factor for its wide application. Here, a novel solution impregnation pathway was developed to increase the hydrophobic properties of cellulose. When compared with the regenerated cellulose (RC), the composite films showed a decrease in water uptake ability towards water vapor, and an increase of the water contact angle from 29° to 65° with increasing resin content in the composites, with only a slight change in the transmittance. Furthermore, the Young's modulus value increased from 3.2 GPa (RC film) to 5.1 GPa (RCBEA50 film). The results indicated that the composites had combined the advantages of cellulose and biphenyl A epoxy acrylate prepolymer (BEA) resin. The presented method has great potential for the preparation of biocomposites with improved properties. The overall results suggest that composite films can be used as high-performance packaging materials.

Neuropeptides, Microbiota, and Behavior.

PubMed

Holzer, P

2016-01-01

The gut microbiota and the brain interact with each other through multiple bidirectional signaling pathways in which neuropeptides and neuroactive peptide messengers play potentially important mediator roles. Currently, six particular modes of a neuropeptide link are emerging. (i) Neuropeptides and neurotransmitters contribute to the mutual microbiota-host interaction. (ii) The synthesis of neuroactive peptides is influenced by microbial control of the availability of amino acids. (iii) The activity of neuropeptides is tempered by microbiota-dependent autoantibodies. (iv) Peptide signaling between periphery and brain is modified by a regulatory action of the gut microbiota on the blood-brain barrier. (v) Within the brain, gut hormones released under the influence of the gut microbiota turn into neuropeptides that regulate multiple aspects of brain activity. (vi) Cerebral neuropeptides participate in the molecular, behavioral, and autonomic alterations which the brain undergoes in response to signals from the gut microbiota. © 2016 Elsevier Inc. All rights reserved.

A Facile Pathway to Modify Cellulose Composite Film by Reducing Wettability and Improving Barrier towards Moisture

PubMed Central

Hu, Xiaorong; Chen, Lin; Tao, Dandan; Ma, Zhaocheng; Liu, Shilin

2017-01-01

The hydrophilic property of cellulose is a key limiting factor for its wide application. Here, a novel solution impregnation pathway was developed to increase the hydrophobic properties of cellulose. When compared with the regenerated cellulose (RC), the composite films showed a decrease in water uptake ability towards water vapor, and an increase of the water contact angle from 29° to 65° with increasing resin content in the composites, with only a slight change in the transmittance. Furthermore, the Young’s modulus value increased from 3.2 GPa (RC film) to 5.1 GPa (RCBEA50 film). The results indicated that the composites had combined the advantages of cellulose and biphenyl A epoxy acrylate prepolymer (BEA) resin. The presented method has great potential for the preparation of biocomposites with improved properties. The overall results suggest that composite films can be used as high-performance packaging materials. PMID:28772399

Electronic health records: what are the most important barriers?

PubMed

Ayatollahi, Haleh; Mirani, Nader; Haghani, Hamid

2014-01-01

The process of design and adoption of electronic health records may face a number of barriers. This study aimed to compare the importance of the main barriers from the experts' point of views in Iran. This survey study was completed in 2011. The potential participants (62 experts) included faculty members who worked in departments of health information technology and individuals who worked in the Ministry of Health in Iran and were in charge of the development and adoption of electronic health records. No sampling method was used in this study. Data were collected using a Likert-scale questionnaire ranging from 1 to 5. The validity of the questionnaire was established using content and face validity methods, and the reliability was calculated using Cronbach's alpha coefficient. The response rate was 51.6 percent. The participants' perspectives showed that the most important barriers in the process of design and adoption of electronic health records were technical barriers (mean = 3.84). Financial and ethical-legal barriers, with the mean value of 3.80 were other important barriers, and individual and organizational barriers, with the mean values of 3.59 and 3.50 were found to be less important than other barriers from the experts' perspectives. Strategic planning for the creation and adoption of electronic health records in the country, creating a team of experts to assess the potential barriers and develop strategies to eliminate them, and allocating financial resources can help to overcome most important barriers to the adoption of electronic health records.

Classical vs. non-classical pathways of mineral formation (Invited)

NASA Astrophysics Data System (ADS)

De Yoreo, J. J.

2013-12-01

Recent chemical analyses, microscopy studies and computer simulations suggest many minerals nucleate through aggregation of pre-nucleation clusters and grow by particle-mediated processes that involve amorphous or disordered precursors. Still other analyses, both experimental and computational, conclude that even simple mineral systems like calcium carbonate form via a barrier-free process of liquid-liquid separation, which is followed by dehydration of the ion-rich phase to form the solid products. However, careful measurements of calcite nucleation rates on a variety of ionized surfaces give results that are in complete agreement with the expectations of classical nucleation theory, in which clusters growing through ion-by-ion addition overcome a free energy barrier through the natural microscopic density fluctuations of the system. Here the challenge of integrating these seemingly disparate observations and analyses into a coherent picture of mineral formation is addressed by considering the energy barriers to calcite formation predicted by the classical theory and the changes in those barriers brought about by the introduction of interfaces and clusters, both stable and metastable. Results from a suite of in situ TEM, AFM, and optical experiments combined with simulations are used to illustrate the conclusions. The analyses show that the expected barrier to homogeneous calcite nucleation is prohibitive even at concentrations exceeding the solubility limit of amorphous calcium carbonate. However, as demonstrated by experiments on self-assembled monolayers, the introduction of surfaces that moderately decrease the interfacial energy associated with the forming nucleus can reduce the magnitude of the barrier to a level that is easily surmounted under typical laboratory conditions. In the absence of such surfaces, experiments that proceed by continually increasing supersaturation with time can easily by-pass direct nucleation of calcite and open up pathways through all other solid phases, as well as dense liquid phases associated with a spinodal. Simulations predict that this phase boundary lies within the region of the calcium carbonate - water phase diagram accessible at room temperature. AFM and TEM analyses of other mineral systems, particularly calcium phosphate, suggest cluster aggregation can play important roles both in modifying barriers and in biasing pathways towards or away from amorphous phases. Most importantly, analysis of the energetic changes shows that barriers are only reduced if the clusters are metastable relative to the free ions and that the reduction is naturally accompanied by a bias towards formation of amorphous precursors. Finally, results from in situ TEM observations of nanoparticle interactions are used to understand the mechanisms controlling particle-mediated growth following formation of primary nuclei of either crystalline phases or disordered precursors. Measurements of the particle speeds and accelerations are used to estimate the magnitude of the attractive potential that drives particle-particle aggregation.

Along the speciation continuum: Quantifying intrinsic and extrinsic isolating barriers across five million years of evolutionary divergence in California jewelflowers.

PubMed

Christie, Kyle; Strauss, Sharon Y

2018-05-01

Understanding the relative roles of intrinsic and extrinsic reproductive barriers, and their interplay within the geographic context of diverging taxa, remains an outstanding challenge in the study of speciation. We conducted a comparative analysis of reproductive isolation in California Jewelflowers (Streptanthus, s.l., Brassicaceae) by quantifying potential barriers to gene flow at multiple life history stages in 39 species pairs spanning five million years of evolutionary divergence. We quantified nine potential pre- and postzygotic barriers and explored patterns of reproductive isolation in relation to genetic distance. Intrinsic postzygotic isolation was initially weak, increased at intermediate genetic distances, and reached a threshold characterized by complete genetic incompatibility. Climatic niche differences were strong at shallow genetic distances, and species pairs with overlapping ranges showed slight but appreciable phenological isolation, highlighting the potential for ecological barriers to contribute to speciation. Geographic analyses suggest that speciation is not regionally allopatric in the California Jewelflowers, as recently diverged taxa occur in relatively close proximity and display substantial range overlap. Young pairs are characterized by incomplete intrinsic postzygotic isolation, suggesting that extrinsic barriers or fine-scale spatial segregation are more important early in the divergence process than genetic incompatibilities. © 2018 The Author(s). Evolution © 2018 The Society for the Study of Evolution.

Tunneling effect on double potential barriers GaAs and PbS

NASA Astrophysics Data System (ADS)

Prastowo, S. H. B.; Supriadi, B.; Ridlo, Z. R.; Prihandono, T.

2018-04-01

A simple model of transport phenomenon tunnelling effect through double barrier structure was developed. In this research we concentrate on the variation of electron energy which entering double potential barriers to transmission coefficient. The barriers using semiconductor materials GaAs (Galium Arsenide) with band-gap energy 1.424 eV, distance of lattice 0.565 nm, and PbS (Lead Sulphide) with band gap energy 0.41 eV distance of lattice is 18 nm. The Analysisof tunnelling effect on double potentials GaAs and PbS using Schrodinger’s equation, continuity, and matrix propagation to get transmission coefficient. The maximum energy of electron that we use is 1.0 eV, and observable from 0.0025 eV- 1.0 eV. The shows the highest transmission coefficient is0.9982 from electron energy 0.5123eV means electron can pass the barriers with probability 99.82%. Semiconductor from materials GaAs and PbS is one of selected material to design semiconductor device because of transmission coefficient directly proportional to bias the voltage of semiconductor device. Application of the theoretical analysis of resonant tunnelling effect on double barriers was used to design and develop new structure and combination of materials for semiconductor device (diode, transistor, and integrated circuit).

Surface modified PLGA nanoparticles for brain targeting of Bacoside-A.

PubMed

Jose, S; Sowmya, S; Cinu, T A; Aleykutty, N A; Thomas, S; Souto, E B

2014-10-15

The present paper focuses on the development and in vitro/in vivo characterization of nanoparticles composed of poly-(D,L)-Lactide-co-Glycolide (PLGA) loading Bacoside-A, as a new approach for the brain delivery of the neuroprotective drug for the treatment of neurodegenerative disorders (e.g. Alzheimer Disease). Bacoside-A-loaded PLGA nanoparticles were prepared via o/w emulsion solvent evaporation technique. Surface of the nanoparticles were modified by coating with polysorbate 80 to facilitate the crossing of the blood brain barrier (BBB), and the processing parameters (i.e. sonication time, the concentration of polymer (PLGA) and surfactant (polysorbate 80), and drug-polymer ratio) were optimized with the aim to achieve a high production yield. Brain targeting potential of the nanoparticles was evaluated by in vivo studies using Wistar albino rats. The nanoparticles produced by optimal formulation were within the nanosized range (70-200 nm) with relatively low polydispersity index (0.391 ± 1.2). The encapsulation efficiency of Bacoside-A in PLGA nanoparticles was 57.11 ± 7.11%, with a drug loading capacity of 20.5 ± 1.98%. SEM images showed the spherical shape of the PLGA nanoparticles, whereas their low crystallinity was demonstrated by X-ray studies, which also confirmed no chemical interactions between the drug and polymer molecules. The in vitro release of Bacoside-A from the PLGA nanoparticles followed a sustained release pattern with a maximum release of up to 83.04 ± 2.55% in 48 h. When compared to pure drug solution (2.56 ± 1.23 μg/g tissue), in vivo study demonstrated higher brain concentration of Bacoside-A (23.94 ± 1.74 μg/g tissue) suggesting a significant role of surface coated nanoparticles on brain targeting. The results indicate the potential of surface modified PLGA nanoparticles for the delivery of Bacoside-A to the brain. Copyright © 2014 Elsevier B.V. All rights reserved.

Assessment of DInSAR Potential in Simulating Geological Subsurface Structure

NASA Astrophysics Data System (ADS)

Fouladi Moghaddam, N.; Rudiger, C.; Samsonov, S. V.; Hall, M.; Walker, J. P.; Camporese, M.

2013-12-01

High resolution geophysical surveys, including seismic, gravity, magnetic, etc., provide valuable information about subsurface structuring but they are very costly and time consuming with non-unique and sometimes conflicting interpretations. Several recent studies have examined the application of DInSAR to estimate surface deformation, monitor possible fault reactivation and constrain reservoir dynamic behaviour in geothermal and groundwater fields. The main focus of these studies was to generate an elevation map, which represents the reservoir extraction induced deformation. This research study, however, will focus on developing methods to simulate subsurface structuring and identify hidden faults/hydraulic barriers using DInSAR surface observations, as an innovative and cost-effective reconnaissance exploration tool for planning of seismic acquisition surveys in geothermal and Carbon Capture and Sequestration regions. By direct integration of various DInSAR datasets with overlapping temporal and spatial coverage we produce multi-temporal ground deformation maps with high resolution and precision to evaluate the potential of a new multidimensional MSBAS technique (Samsonov & d'Oreye, 2012). The technique is based on the Small Baseline Subset Algorithm (SBAS) that is modified to account for variation in sensor parameters. It allows integration of data from sensors with different wave-band, azimuth and incidence angles, different spatial and temporal sampling and resolutions. These deformation maps then will be used as an input for inverse modelling to simulate strain history and shallow depth structure. To achieve the main objective of our research, i.e. developing a method for coupled InSAR and geophysical observations and better understanding of subsurface structuring, comparing DInSAR inverse modelling results with previously provided static structural model will result in iteratively modified DInSAR structural model for adequate match with in situ observations. The newly developed and modified algorithm will then be applied in another part of the region where subsurface information is limited.

Anti-collimation of ballistic electrons by a potential barrier

NASA Astrophysics Data System (ADS)

Coleridge, P. T.; Taylor, R. P.; Sachrajda, A. S.; Adams, J. A.

1994-03-01

A pair of Quantum Point Contacts separated by a continuous barrier have been fabricated using the surface gate technique. Transport measurements for each component of this system and for various combinations have shown both additive and non-additive behaviour. The results are explained by a combination of reflection by the barrier of electrons collimated by the Quantum Point Contacts and transport by diffusion across the barrier.

Method and tool to reverse the charges in anti-reflection films used for solar cell applications

DOEpatents

Sharma, Vivek; Tracy, Clarence

2017-01-31

A method is provided for making a solar cell. The method includes providing a stack including a substrate, a barrier layer disposed on the substrate, and an anti-reflective layer disposed on the barrier layer, where the anti-reflective layer has charge centers. The method also includes generating a corona with a charging tool and contacting the anti-reflective layer with the corona thereby injecting charge into at least some of the charge centers in the anti-reflective layer. Ultra-violet illumination and temperature-based annealing may be used to modify the charge of the anti-reflective layer.

Highway median impacts on wildlife movement and mortality : state of the practice survey and gap analysis.

DOT National Transportation Integrated Search

2006-10-01

Highway median barriers are used to separate lanes of traffic and enhance motorist safety on freeways and multi-lane interstate highways. : Median barriers of all types have the potential to impede animal movements across highways. Barriers may also ...

MOSFET Replacement Devices for Energy-Efficient Digital Integrated Circuits

DTIC Science & Technology

2009-12-17

MOSFET is limited by the thermal voltage kBT/q; it is greater than or equal to 60mV/dec at room temperature. Fig. 1.4 The potential barrier for...60mV/dec can be explained by the electron energy band profile of a MOSFET, which is shown in Fig. 1.4. As Vgs increases, the channel potential is...channel potential (φs) reduces the potential barrier for electron injection, and hence the electron energy (E) increases. According to the Boltzmann

A role for long chain myosin light chain kinase (MLCK-210) in microvascular hyperpermeability during severe burns.

PubMed

Reynoso, Rashell; Perrin, Rachel M; Breslin, Jerome W; Daines, Dayle A; Watson, Katherine D; Watterson, D Martin; Wu, Mack H; Yuan, Sarah

2007-11-01

Microvascular leakage has been implicated in the pathogenesis of multiple organ dysfunction during trauma. Previous studies suggest the involvement of myosin light chain (MLC) phosphorylation-triggered endothelial contraction in the development of microvascular hyperpermeability. Myosin light chain kinase (MLCK) plays a key role in the control of MLC-phosphorylation status; thus, it is thought to modulate barrier function through its regulation of intracellular contractile machinery. The aim of this study was to further investigate the endothelial mechanism of MLC-dependent barrier injury in burns, focusing on the long isoform of MLCK (MLCK-210) that has recently been identified as the predominant isoform expressed in vascular endothelial cells. An MLCK-210 knockout mouse model was subjected to third-degree scald burn covering 25% total body surface area. The mesenteric microcirculation was observed using intravital microscopy, and the microvascular permeability was assessed by measuring the transvenular flux of fluorescein isothiocyanate-albumin. In a separate experiment, in vivo mesenteric hydraulic conductivity (Lp) was measured using the modified Landis technique. The injury caused a profound microvascular leakage, as indicated by a 2-fold increase in albumin flux and 4-fold increase in Lp at the early stages, which was associated with a high mortality within the 24-h period. Compared with wild-type control, the MLCK-210-deficient mice displayed a significantly improved survival with a greatly attenuated microvascular hyperpermeability response to albumin and fluid. These results provide direct evidence for a role of MLCK-210 in mediating burn-induced microvascular barrier injury and validate MLCK-210 as a potential therapeutic target in the treatment of burn edema.

How personal and standardized coordination impact implementation of integrated care.

PubMed

Benzer, Justin K; Cramer, Irene E; Burgess, James F; Mohr, David C; Sullivan, Jennifer L; Charns, Martin P

2015-10-02

Integrating health care across specialized work units has the potential to lower costs and increase quality and access to mental health care. However, a key challenge for healthcare managers is how to develop policies, procedures, and practices that coordinate care across specialized units. The purpose of this study was to identify how organizational factors impacted coordination, and how to facilitate implementation of integrated care. Semi-structured interviews were conducted in August 2009 with 30 clinic leaders and 35 frontline staff who were recruited from a convenience sample of 16 primary care and mental health clinics across eight medical centers. Data were drawn from a management evaluation of primary care-mental health integration in the US Department of Veterans Affairs. To protect informant confidentiality, the institutional review board did not allow quotations. Interviews identified antecedents of organizational coordination processes, and highlighted how these antecedents can impact the implementation of integrated care. Overall, implementing new workflow practices were reported to create conflicts with pre-existing standardized coordination processes. Personal coordination (i.e., interpersonal communication processes) between primary care leaders and staff was reported to be effective in overcoming these barriers both by working around standardized coordination barriers and modifying standardized procedures. This study identifies challenges to integrated care that might be solved with attention to personal and standardized coordination. A key finding was that personal coordination both between primary care and mental health leaders and between frontline staff is important for resolving barriers related to integrated care implementation. Integrated care interventions can involve both new standardized procedures and adjustments to existing procedures. Aligning and integrating procedures between primary care and specialty care requires personal coordination amongst leaders. Interpersonal relationships should be strengthened between staff when personal connections are important for coordinating patient care across clinical settings.

Progressive multiple sclerosis: from pathogenic mechanisms to treatment.

PubMed

Correale, Jorge; Gaitán, María I; Ysrraelit, María C; Fiol, Marcela P

2017-03-01

During the past decades, better understanding of relapsing-remitting multiple sclerosis disease mechanisms have led to the development of several disease-modifying therapies, reducing relapse rates and severity, through immune system modulation or suppression. In contrast, current therapeutic options for progressive multiple sclerosis remain comparatively disappointing and challenging. One possible explanation is a lack of understanding of pathogenic mechanisms driving progressive multiple sclerosis. Furthermore, diagnosis is usually retrospective, based on history of gradual neurological worsening with or without occasional relapses, minor remissions or plateaus. In addition, imaging methods as well as biomarkers are not well established. Magnetic resonance imaging studies in progressive multiple sclerosis show decreased blood-brain barrier permeability, probably reflecting compartmentalization of inflammation behind a relatively intact blood-brain barrier. Interestingly, a spectrum of inflammatory cell types infiltrates the leptomeninges during subpial cortical demyelination. Indeed, recent magnetic resonance imaging studies show leptomeningeal contrast enhancement in subjects with progressive multiple sclerosis, possibly representing an in vivo marker of inflammation associated to subpial demyelination. Treatments for progressive disease depend on underlying mechanisms causing central nervous system damage. Immunity sheltered behind an intact blood-brain barrier, energy failure, and membrane channel dysfunction may be key processes in progressive disease. Interfering with these mechanisms may provide neuroprotection and prevent disability progression, while potentially restoring activity and conduction along damaged axons by repairing myelin. Although most previous clinical trials in progressive multiple sclerosis have yielded disappointing results, important lessons have been learnt, improving the design of novel ones. This review discusses mechanisms involved in progressive multiple sclerosis, correlations between histopathology and magnetic resonance imaging studies, along with possible new therapeutic approaches. © The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Charter School Barriers: Do Enrollment Requirements Limit Student Access to Charter Schools?

ERIC Educational Resources Information Center

Weiler, Spencer C.; Vogel, Linda R.

2015-01-01

The potential of the charter school movement to positively influence traditional public education lies in the ability of charter school officials to provide all students access to the curriculum. The aim of this study was to document potential registration and enrollment barriers incorporated into the practices of Colorado charter schools. The…

Transport of Zn(OH)4(-2) ions across a polyolefin microporous membrane

NASA Astrophysics Data System (ADS)

Krejci, Ivan; Vanysek, Peter; Trojanek, Antonin

1993-04-01

Transport of ZN(OH)4(2-) ions through modified microporous polypropylene membranes (Celgard 3401, 350140) was studied using polarography and conductometry. Soluble Nafion as an ion exchange modifying agent was applied to the membrane by several techniques. The influence of Nafion and a surfactant on transport of zinc ions through the membrane was studied. A relationship between membrane impedance and the rate of Zn(OH)4(2-) transport was found. The found correlation between conductivity, ion permeability and Nafion coverage suggests a suitable technique of membrane preparation to obtain desired zinc ion barrier properties.

Improvement of Uveal and Capsular Biocompatibility of Hydrophobic Acrylic Intraocular Lens by Surface Grafting with 2-Methacryloyloxyethyl Phosphorylcholine-Methacrylic Acid Copolymer

PubMed Central

Tan, Xuhua; Zhan, Jiezhao; Zhu, Yi; Cao, Ji; Wang, Lin; Liu, Sa; Wang, Yingjun; Liu, Zhenzhen; Qin, Yingyan; Wu, Mingxing; Liu, Yizhi; Ren, Li

2017-01-01

Biocompatibility of intraocular lens (IOL) is critical to vision reconstruction after cataract surgery. Foldable hydrophobic acrylic IOL is vulnerable to the adhesion of extracellular matrix proteins and cells, leading to increased incidence of postoperative inflammation and capsule opacification. To increase IOL biocompatibility, we synthesized a hydrophilic copolymer P(MPC-MAA) and grafted the copolymer onto the surface of IOL through air plasma treatment. X-ray photoelectron spectroscopy, atomic force microscopy and static water contact angle were used to characterize chemical changes, topography and hydrophilicity of the IOL surface, respectively. Quartz crystal microbalance with dissipation (QCM-D) showed that P(MPC-MAA) modified IOLs were resistant to protein adsorption. Moreover, P(MPC-MAA) modification inhibited adhesion and proliferation of lens epithelial cells (LECs) in vitro. To analyze uveal and capsular biocompatibility in vivo, we implanted the P(MPC-MAA) modified IOLs into rabbits after phacoemulsification. P(MPC-MAA) modification significantly reduced postoperative inflammation and anterior capsule opacification (ACO), and did not affect posterior capsule opacification (PCO). Collectively, our study suggests that surface modification by P(MPC-MAA) can significantly improve uveal and capsular biocompatibility of hydrophobic acrylic IOL, which could potentially benefit patients with blood-aqueous barrier damage. PMID:28084469

Barrier height inhomogeneity in electrical transport characteristics of InGaN/GaN heterostructure interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roul, Basanta; Central Research Laboratory, Bharat Electronics, Bangalore 560013; Mukundan, Shruti

2015-03-15

We have grown InGaN/GaN heterostructures using plasma-assisted molecular beam epitaxy and studied the temperature dependent electrical transport characteristics. The barrier height (φ{sub b}) and the ideally factor (η) estimated using thermionic emission model were found to be temperature dependent. The conventional Richardson plot of ln(J{sub s}/T{sup 2}) versus 1/kT showed two temperature regions (region-I: 400–500 K and region-II: 200–350 K) and it provides Richardson constants (A{sup ∗}) which are much lower than the theoretical value of GaN. The observed variation in the barrier height and the presence of two temperature regions were attributed to spatial barrier inhomogeneities at the heterojunctionmore » interface and was explained by assuming a double Gaussian distribution of barrier heights with mean barrier height values 1.61 and 1.21 eV with standard deviation (σ{sub s}{sup 2}) of 0.044 and 0.022 V, respectively. The modified Richardson plot of ln(J{sub s}/T{sup 2}) − (q{sup 2}σ{sub s}{sup 2}/2k{sup 2}T{sup 2}) versus 1/kT for two temperature regions gave mean barrier height values as 1.61 eV and 1.22 eV with Richardson constants (A{sup ∗}) values 25.5 Acm{sup −2}K{sup −2} and 43.9 Acm{sup −2}K{sup −2}, respectively, which are very close to the theoretical value. The observed barrier height inhomogeneities were interpreted on the basis of the existence of a double Gaussian distribution of barrier heights at the interface.« less

Barriers to Beta-Blocker Use and Up-Titration Among Patients with Heart Failure with Reduced Ejection Fraction.

PubMed

Levitan, Emily B; Van Dyke, Melissa K; Loop, Matthew Shane; O'Beirne, Ronan; Safford, Monika M

2017-12-01

For patients with heart failure with reduced ejection fraction (HFrEF), guidelines recommend use of beta-blockers with gradual up-titration. However, many patients with HFrEF do not use beta-blockers and up-titration is rare. Our purpose was to identify and rank barriers to beta-blocker use and up-titration from the perspective of primary care physicians. We conducted 4 moderated, structured group discussions among 19 primary care physicians using the nominal group technique; 16 participants also completed a survey. Participants generated lists of barriers to beta-blocker use and up-titration among patients with HFrEF. Each participant had six votes with three votes assigned to the item ranked most important, two to the second most important item, and one to the third most important item. Investigators characterized items into themes. The percentage of available votes was calculated for each theme. Fifteen of 16 participating primary care physicians who completed the survey reported that management of beta-blockers was their responsibility. Treatment/side effects, particularly hypotension, were identified as the most important barrier for beta-blocker use (72% of available votes) followed by polypharmacy (11%), healthcare system barriers (10%), and comorbidities (6%). Barriers to up-titration included treatment/side effects (49% of available votes), patient communication/buy-in (21%), polypharmacy (13%), and healthcare system barriers (8%). Many barriers to guideline concordant use of beta-blockers among patients with HFrEF identified by primary care providers are not readily modifiable. Addressing these barriers may require development, testing, and dissemination of protocols for beta-blocker initiation and up-titration that are safe and appropriate in primary care.

Geographically weighted regression as a generalized Wombling to detect barriers to gene flow.

PubMed

Diniz-Filho, José Alexandre Felizola; Soares, Thannya Nascimento; de Campos Telles, Mariana Pires

2016-08-01

Barriers to gene flow play an important role in structuring populations, especially in human-modified landscapes, and several methods have been proposed to detect such barriers. However, most applications of these methods require a relative large number of individuals or populations distributed in space, connected by vertices from Delaunay or Gabriel networks. Here we show, using both simulated and empirical data, a new application of geographically weighted regression (GWR) to detect such barriers, modeling the genetic variation as a "local" linear function of geographic coordinates (latitude and longitude). In the GWR, standard regression statistics, such as R(2) and slopes, are estimated for each sampling unit and thus are mapped. Peaks in these local statistics are then expected close to the barriers if genetic discontinuities exist, capturing a higher rate of population differentiation among neighboring populations. Isolation-by-Distance simulations on a longitudinally warped lattice revealed that higher local slopes from GWR coincide with the barrier detected with Monmonier algorithm. Even with a relatively small effect of the barrier, the power of local GWR in detecting the east-west barriers was higher than 95 %. We also analyzed empirical data of genetic differentiation among tree populations of Dipteryx alata and Eugenia dysenterica Brazilian Cerrado. GWR was applied to the principal coordinate of the pairwise FST matrix based on microsatellite loci. In both simulated and empirical data, the GWR results were consistent with discontinuities detected by Monmonier algorithm, as well as with previous explanations for the spatial patterns of genetic differentiation for the two species. Our analyses reveal how this new application of GWR can viewed as a generalized Wombling in a continuous space and be a useful approach to detect barriers and discontinuities to gene flow.

Effect of Hydrothermal Treatment on the Physicochemical, Rheological, and Oil-Resistant Properties of Rice Flour

USDA-ARS?s Scientific Manuscript database

Rice flour was thermo-mechanically modified by steam jet-cooking and the physico-chemical and rheological properties of the resulting product were characterized. Then, its performance in frying batters was evaluated as an oil barrier. Compared to native rice flour, the steam jet-cooked rice flour ...

Moisture sorption properties of composite boards from esterified aspen fiber

Treesearch

C. Clemons; R. A. Young; R. M. Rowell

1992-01-01

One barrier to producing wood-plastic composites with wood fiber is the poor thermoplasticity of wood fiber. The objective of our study was to determine the plasticization of chemically modified wood fiber through tests on unmodified and esterified fiberboards. Attrition-milled aspen fiber was esterified with neat acetic, maleic, or succinic anhydride. Fourier...

FROM NEEDS ASSESSMENT TO PARTICIPATORY RESEARCH: A COMMUNITY VISION OF HEALTH PROMOTION PROGRAMS IN ONE NATIVE AMERICAN COMMUNITY

USDA-ARS?s Scientific Manuscript database

OBJECTIVE: Identify unique cultural needs, priorities, program delivery preferences and barriers to achieving a healthy diet and lifestyle in one Native American community. DESIGN: A novel modified nominal group technique (NGT) conducted in four districts and three age groups (Elders, adults and...

Perspectives of Mexican-Origin Smokers on Healthy Eating and Physical Activity

ERIC Educational Resources Information Center

Strong, Larkin L.; Hoover, Diana S.; Heredia, Natalia I.; Krasny, Sarah; Spears, Claire A.; Correa-Fernández, Virmarie; Wetter, David W.; Fernandez, Maria E.

2016-01-01

Key modifiable risk behaviors such as smoking, poor diet and physical inactivity often cluster and may have multiplicative adverse effects on health. This study investigated barriers and facilitators to healthy eating and physical activity (PA) in overweight Mexican-origin smokers to inform the adaptation of an evidence-based smoking cessation…

Preparation of chitosan-based multifunctional nanocarriers overcoming multiple barriers for oral delivery of insulin.

PubMed

Li, Lei; Jiang, Guohua; Yu, Weijiang; Liu, Depeng; Chen, Hua; Liu, Yongkun; Tong, Zaizai; Kong, Xiangdong; Yao, Juming

2017-01-01

To overcome multiple barriers for oral delivery of insulin, the chitosan-based multifunctional nanocarriers modified by L-valine (LV, used as a target ligand to facilitate the absorption of the small intestine) and phenylboronic acid (PBA, used as a glucose-responsive unit) have been designed and evaluated in this study. The resultant nanocarriers exhibited low cytotoxicity against HT-29 cells and excellent stability against protein solution. The insulin release behaviors were evaluated triggered by pH and glucose in vitro. The chemical stability of loaded insulin against digestive enzyme were established in presence of simulated gastric fluid (SGF) containing pepsin and simulated intestinal fluid (SIF) containing pancreatin, respectively. The uptake behavior of HT-29 cells was evaluated by confocal laser scanning microscope. After oral administration to the diabetic rats, an effective hypoglycemic effect was obtained compared with subcutaneous injection of insulin. This work suggests that L-valine modified chitosan-based multifunctional nanocarriers may be a promising drug delivery carrier for oral administration of insulin. Copyright © 2016 Elsevier B.V. All rights reserved.

Blend-modification of soy protein/lauric acid edible films using polysaccharides.

PubMed

Pan, Hongyang; Jiang, Bo; Chen, Jie; Jin, Zhengyu

2014-05-15

Different types of polysaccharides (propyleneglycol alginate (PGA), pectin, carrageenan and aloe polysaccharide) were incorporated into soy protein isolate (SPI)/lauric acid (La) films using a co-drying process or by direct addition to form biodegradable composite films with modified water vapour permeability (WVP) and mechanical properties. The WVP of SPI/La/polysaccharide films decreased when polysaccharides were added using the co-drying process, regardless of the type of polysaccharide. The tensile strength of SPI/La film was increased by the addition of polysaccharides, and the percentage elongation at break was increased by incorporating PGA using the co-drying process. Regarding oxygen-barrier performance, no notable differences were observed between the SPI/La and SPI/La/polysaccharide films. The most significant improvement was observed by blending PGA, with the co-dried preparation exhibiting better properties than the direct-addition preparation. Scanning electron microscopy (SEM) revealed that the microstructures of the films are the basis for the differences in the barrier and mechanical properties of the modified blends of SPI, polysaccharides and La. Copyright © 2013 Elsevier Ltd. All rights reserved.

The myth of natural barriers. Is transgene introgression by genetically modified crops an environmental risk?

PubMed

Guarnieri, Vincenzo; Benessia, Alice; Camino, Elena; Barbiero, Giuseppe

2008-01-01

Genetically modified (GM) crops under open field conditions are a complex and controversial issue. Ecologists are discussing about the possibility that a transgene belonging to GM plants could spread to native populations through a process known as introgression the stable incorporation of a gene in the host genome able to generate a differentiated population. The ecological consequences of a transgene introgression in plants or bacteria are not yet well understood, but could be significant. In this critical review we consider vertical and horizontal introgression. We analyse the biochemical and genetic constraints, and environmental factors that limit the possibility of transgene spread; meanwhile we show cases in which the natural barriers are overcome. Then we discuss the overall management of GM crops, noting the shortcomings and approximations of risk assessment based on linear thinking typical of the biomolecular approach. Finally we suggest to explicitly weight facts together with values and we encourage the undertaking of an ecological perspective, encompassing the complexity of (non-linear) relations between organisms and the environment.

Cardiovascular and Antiobesity Effects of Resveratrol Mediated through the Gut Microbiota.

PubMed

Bird, Julia K; Raederstorff, Daniel; Weber, Peter; Steinert, Robert E

2017-11-01

Encouraging scientific research into the health effects of dietary bioactive resveratrol has been confounded by its rapid first-pass metabolism, which leads to low in vivo bioavailability. Preliminary studies have shown that resveratrol can modulate gut microbiota composition, undergo biotransformation to active metabolites via the intestinal microbiota, or affect gut barrier function. In rodents, resveratrol can modify the relative Bacteroidetes:Firmicutes ratio and reverse the gut microbial dysbiosis caused by a high-fat diet. By upregulating the expression of genes involved in maintaining tight junctions between intestinal cells, resveratrol contributes to gut barrier integrity. The composition of the gut microbiome and rapid metabolism of resveratrol determines the production of resveratrol metabolites, which are found at greater concentrations in humans after ingestion than their parent molecule and can have similar biological effects. Resveratrol may affect cardiovascular risk factors such as elevated blood cholesterol or trimethylamine N -oxide concentrations. Modulating the composition of the gut microbiota by resveratrol may affect central energy metabolism and modify concentrations of satiety hormones to produce antiobesity effects. Encouraging research from animal models could be tested in humans. © 2017 American Society for Nutrition.

Barriers to cancer screening in Hmong Americans: the influence of health care accessibility, culture, and cancer literacy.

PubMed

Lee, Hee Yun; Vang, Suzanne

2010-06-01

Hmong Americans face high cancer mortality rates even in comparison to their Asian American counterparts, and report low utilization of cancer screenings. To date, no study has been conducted on the cultural barriers this population faces in undergoing cancer screenings. A systematic review of the literature was conducted to examine the existing knowledge regarding the barriers to cancer screening for Hmong Americans. Potential barriers were identified from this examination to include: health access factors (type of health insurance, ethnicity of provider, low English proficiency, and years spent in the U.S.); cultural factors (belief in the spiritual etiology of diseases, patriarchal values, modesty, and mistrust of the western medical system); and cancer literacy factors (cancer and prevention illiteracy). Based on this review, potential cultural and ethnic group-specific prevention strategies and cancer health policies are discussed to address these barriers and enhance screening behavior among the Hmong.

Characterization of the inhomogeneous barrier distribution in a Pt/(100)β-Ga2O3 Schottky diode via its temperature-dependent electrical properties

NASA Astrophysics Data System (ADS)

Jian, Guangzhong; He, Qiming; Mu, Wenxiang; Fu, Bo; Dong, Hang; Qin, Yuan; Zhang, Ying; Xue, Huiwen; Long, Shibing; Jia, Zhitai; Lv, Hangbing; Liu, Qi; Tao, Xutang; Liu, Ming

2018-01-01

β-Ga2O3 is an ultra-wide bandgap semiconductor with applications in power electronic devices. Revealing the transport characteristics of β-Ga2O3 devices at various temperatures is important for improving device performance and reliability. In this study, we fabricated a Pt/β-Ga2O3 Schottky barrier diode with good performance characteristics, such as a low ON-resistance, high forward current, and a large rectification ratio. Its temperature-dependent current-voltage and capacitance-voltage characteristics were measured at various temperatures. The characteristic diode parameters were derived using thermionic emission theory. The ideality factor n was found to decrease from 2.57 to 1.16 while the zero-bias barrier height Φb0 increased from 0.47 V to 1.00 V when the temperature was increased from 125 K to 350 K. This was explained by the Gaussian distribution of barrier height inhomogeneity. The mean barrier height Φ ¯ b0 = 1.27 V and zero-bias standard deviation σ0 = 0.13 V were obtained. A modified Richardson plot gave a Richardson constant A* of 36.02 A.cm-2.K-2, which is close to the theoretical value of 41.11 A.cm-2.K-2. The differences between the barrier heights determined using the capacitance-voltage and current-voltage curves were also in line with the Gaussian distribution of barrier height inhomogeneity.

Self-efficacy toward physical activity and the physical activity behavior of children with and without Developmental Coordination Disorder.

PubMed

Batey, C A; Missiuna, C A; Timmons, B W; Hay, J A; Faught, B E; Cairney, J

2014-08-01

Affecting 5-6% of children, Developmental Coordination Disorder (DCD) is a prevalent chronic condition. The nature of the disorder - impaired motor coordination - makes avoidance of physical activity (PA) common. The purpose of this study was to examine the effect of barrier and task self-efficacy on PA behavior in children with DCD and a group of typically developing (TD) children. Children were compared on their perceived ability to complete different intensities and duration of PA (task efficacy) and their confidence in completing PA when faced with everyday barriers (barrier efficacy). An accelerometer was used to record their activity over the subsequent week. Children with DCD were found to have significantly lower task efficacy and barrier efficacy. They also spent significantly less time in moderate to vigorous physical activity (MVPA). Multivariate analyses revealed that gender modified the relationship for both groups. Separate multivariate regressions, were therefore conducted by gender. A direct effect of DCD on PA was observed for boys, but not for girls. Further analyses showed that neither task efficacy nor barrier efficacy influenced the relationship between DCD and PA. Results from this study confirm that children with DCD have lower task and barrier self-efficacy than TD children and that males have lower PA levels than their TD peers; however neither task or barrier self-efficacy mediated the relationship between DCD and PA. Copyright © 2013. Published by Elsevier B.V.

Preparation of an injectable doxorubicin surface modified cellulose nanofiber gel and evaluation of its anti-tumor and anti-metastasis activity in melanoma.

PubMed

Alizadeh, Najmeh; Akbari, Vajihe; Nurani, Maryam; Taheri, Azade

2018-03-01

Cellulose nanofibers (Cel-NFs) gel can be considered as a useful drug carrier because of its biocompatibility, high specific surface area, and high loading capacity of drugs. Injectable Cel-NFs gel could deliver doxorubicin (DOX) for localized chemotherapy of melanoma and suppress melanoma cells migration because of the physical barrier property of Cel-NFs. We prepared DOX surface modified Cel-NFs (DOX-Cel-NFs) gel by the electrostatic attachment of DOX molecules on the surface of Cel-NFs. The increase in the zeta potential of nanofibers and the changes in the FTIR spectra of DOX-Cel-NFs compared to Cel-NFs proved this attachment. DOX-Cel-NFs showed nano-fibrous structure with an average diameter of 22.32 ± 10.66 nm after analyzing using field emission scanning electron microscopy. The suitable injectability of DOX-Cel-NFs gel verified its promising application for the localized chemotherapy. DOX-Cel-NFs gel exhibited a sustained drug release manner. The cytotoxicity results showed that DOX-Cel-NFs were more cytotoxic against melanoma cancer cells than the free DOX during 48 h incubation period. Moreover, DOX-Cel-NFs gel can suppress the melanoma cancer cells migration efficiently. Thus our results emphasize the potential of DOX-Cel-NFs gel as a chemotherapeutic agent for local delivery of DOX in order to treat melanoma and prevent its metastasis. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:537-545, 2018. © 2018 American Institute of Chemical Engineers.

A comparative study of wood highway sound barriers

Treesearch

Stefan Grgurevich; Thomas Boothby; Harvey Manbeck; Courtney Burroughs; Stephen Cegelka; Craig Bernecker; Michael A. Ritter

2002-01-01

Prototype designs for wood highway sound barriers meeting the multiple criteria of structural integrity, acoustic effectiveness, durability, and potential for public acceptance have been developed. Existing installations of wood sound barriers were reviewed and measurements conducted in the field to estimate acoustic insertion losses. A complete matrix of design...