Search results for " Barrier"

EPR, ENDOR and TRIPLE resonance of amino-substituted 9,10-anthraquinone radicals and the rotation of the amino groups in the solution phase

1996

EPR, ENDOR and TRIPLE resonance spectra were recorded for 1-amino-9,10-anthraquinone (1-aminoAQ), 2-aminoAQ, 1,2-diaminoAQ, 1.4-diaminoAQ, 1,5-diaminoAQ and 2,6-diaminoAQ anion radicals in the solution phase. The rotation of the amino groups is discussed with reference to the experimental data. Rotation barrier calculations were carried out using B3PW91/3-21G* density functional method. The amino groups at positions 1, 4, 5, 8 were found not to be in rotational movement up to the EPR time-scale.

Momentum-resolved photoelectron absorption in surface barrier scattering on Ir(111) and graphene/Ir(111)

2017

Physical review / B 96(15), 155108 (2017). doi:10.1103/PhysRevB.96.155108

Industrial Symbiosis: A Mechanism to Guarantee the Implementation of Circular Economy Practices

2022

There is a growing concern regarding the scarcity of natural resources. The levels of resource exploitation generated by the current system of production and consumption has led the European Commission to develop a set of guidelines that aim to reduce the pressure on natural resources. The set of guidelines proposed by the European Union is based on the transformation of the current linear economic system into a circular system in which resources and materials remain in the production system for longer. However, for this change to take effect, practical measures are required. This paper presents an industrial symbiosis approach as a practical application of a circular economy model. The aim…

Coulomb Effects on Few-Body Scattering States

1986

Modifications of stationary momentum space scattering theory, necessitated by the presence of Coulomb forces, are described, both in the formalism which uses unscreened Coulomb potentials and in the screening and renormalization approach. Thereby, emphasis is laid on exposing the conceptual differences, as well as the different, presently achieved status of applicability. Some of the unresolved problems in both methods are enumerated.

2014

In the pathogenesis of Alzheimer’s disease (AD) the homeostasis of amyloid precursor protein (APP) processing in the brain is impaired. The expression of the competing proteases ADAM10 (a disintegrin and metalloproteinase 10) and BACE-1 (beta site APP cleaving enzyme 1) is shifted in favor of the A-beta generating enzyme BACE-1. Acitretin–a synthetic retinoid–e.g., has been shown to increase ADAM10 gene expression, resulting in a decreased level of A-beta peptides within the brain of AD model mice and thus is of possible value for AD therapy. A striking challenge in evaluating novel therapeutically applicable drugs is the analysis of their potential to overcome the blood-brain barrier (BBB)…

2015

Transporters of the ATP-binding cassette (ABC) family such as MDR1 play a pivotal role in persistence of brain homeostasis by contributing to the strict permeability properties of the blood–brain barrier. This barrier on one hand compromises treatment of central nervous system diseases by restricting access of drugs; on the other hand, an impaired or altered function of barrier building cells has been described in neurological disorders. The latter might contribute to increased vulnerability of the brain under pathological conditions or even enforce pathogenesis. Here, we present a novel approach for a systematic examination of drug impact on Mdr1 gene expression by establishing a dual repo…

Strategic Analysis Tools Application at SMEs in Ecuador

2015

This article explores the nature and scope of Strategic Analysis Tools (SAT) application in SMEs located in emerging countries such as Ecuador (where there are no formal studies on the subject). It is intended to assess which of the instruments utilized by these firms may contribute to formulate strategic options and which of them create awareness of relevant risks or distress specifically about continuity concerning their operations. Through the application of a survey to an intentional sample-selection of SMEs in Quito-Ecuador we analyzed the consciousness over these instruments to facilitate the creation of strategic options, their contribution to assess their competitive position and th…

Gd-DTPA in blood-ocular barrier damage: a new diagnostic tool for future application in MRI?

1995

The blood-brain barrier is not the only neuroepithelial blood filter in the body: the eye too is supported by a highly specialised microvascular filter, the so-called blood-ocular barrier (BOB). The BOB is actually divided into a blood-aqueous (BAB) and a blood-retinal (BRB) barrier, filtering the aqueous fluid and biological supplies, respectively, to the retina. The authors’ purpose was to study the possibility of imaging BAB or BRB damage by contrast-enhanced MRI: they examined 21 patients with a 0.5 T system and surface coil. Despite the normal findings in the damaged eyes immediately after a Gd-DTPA bolus, delayed contrast-enhanced MRI was able to show focal or diffuse barrier damage.

Preclinical Retinal Neurodegeneration in a Model of Multiple Sclerosis

2012

Neurodegeneration plays a major role in multiple sclerosis (MS), in which it is thought to be the main determinant of permanent disability. However, the relationship between the immune response and the onset of neurodegeneration is still a matter of debate. Moreover, recent findings in MS patients raised the question of whether primary neurodegenerative changes can occur in the retina independent of optic nerve inflammation. Using a rat model of MS that frequently leads to optic neuritis, we have investigated the interconnection between neurodegenerative and inflammatory changes in the retina and the optic nerves with special focus on preclinical disease stages. We report that, before manif…

Scanning tunneling microscopy and spectroscopy of Mo clusters grown on TiO2(110).

2007

Molybdenum was deposited in two steps (3 eq. ML and 1 eq. ML) on the light blue rutile TiO2 10) (1 x 1) surface at room temperature, each Mo deposition cycle being followed by an annealing up to 950-1000 K. This procedure was found to lead to formation of separated clusters having a size in very wide range (1-20 nm). Scanning tunneling microscopy showed a dependence of the cluster morphology as a function of the size. The scanning tunneling spectra of Mo clusters was studied as a function of cluster dimensions and discussed in comparison with photoelectron spectroscopy results previously obtained for homogeneous Mo films. The dI/d V curves do not display the valence band structure of deposi…