Search results for "Barrier"

A new class of ZnIIand CrIIIporphyrins incorporated into porous polymer matrices via an atmospheric pressure plasma enhanced CVD to form gas sensing …

2014

Designed ZnII and CrIII porphyrins (ZnIIP, CrIIIP(Cl)(H2O)) and conventional ZnIITPP and CrIIITPP(Cl)(H2O) are immobilized into porous polysiloxane films via chemical vapor deposition enhanced by an atmospheric pressure dielectric barrier discharge. UV/vis spectroscopy and mass spectrometry prove the integrity of the chromophores after the plasma treatment. The optical amine sensing capabilities of the films are investigated spectroscopically on exposure to triethylamine vapors. A series of coatings with different porphyrin loadings indicate influences of the deposition conditions on the growth of the sensing films and hence the device performance. Additionally, the synthesis and characteri…

Naphthothiete und ihre Anwendung in der Heterocyclen-Synthese

1995

Naphtothietes and Their Application to the Synthesis of Heterocycles The three isomeric naphthothietes 5, 11, and 16 were prepared according to the reaction sequences shown in Schemes 1–3. The final step was in each case a flash vacuum pyrolysis (FVP) of the corresponding mercaptonaphthalenemethanol 4, 9, and 15, respectively. The thiete rings in 5 and 11 can be opened by gentle heating; the ring opening of the isomer 16 possesses a much higher activation barrier. A MNDO calculation of the ΔHf values of 5, 11, and 16 and the open isomers 5′, 11′, and 16′ provides an explanation for the different behavior. Photochemical ring opening represents a useful alternative. The reaction Schemes 4, 6,…

How Glutamate Is Managed by the Blood-Brain Barrier

2016

A facilitative transport system exists on the blood brain barrier (BBB) that has been tacitly assumed to be a path for glutamate entry to brain. But glutamate is a non-essential amino acid whose brain content is much greater than plasma, and studies in vivo show that glutamate does not enter brain in material quantities except in those small regions with fenestrated capillaries (circumventricular organs). The situation became understandable when luminal (blood facing) and abluminal (brain facing) membranes were isolated and studied separately. Facilitative transport of glutamate and glutamine exist only on the luminal membranes whereas Na+-dependent transport systems for glutamate, glutamin…

Solid State Structures of Amide-Substituted 8-Hydroxyquinoline Derivatives

2000

Abstract The amide substituted 8-hydroxyquinoline derivatives 3 and 4 form, in the solid state, hydrogen bonded polymers. Polymeric 3 adopts a helical conformation while 4 forms a double-stranded ladder-type structure.

2013

Re-canalization of cerebral vessels in ischemic stroke is pivotal to rescue dysfunctional brain areas that are exposed to moderate hypoxia within the penumbra from irreversible cell death. Goal of the present study was to evaluate the effect of moderate hypoxia followed by reoxygenation (MHR) on the evolution of reactive oxygen species (ROS) and blood-brain barrier (BBB) integrity in brain endothelial cells (BEC). BBB integrity was assessed in BEC in vitro and in microvessels of the guinea pig whole brain in situ preparation. Probes were exposed to MHR (2 hours 67-70 mmHg O2, 3 hours reoxygenation, BEC) or towards occlusion of the arteria cerebri media (MCAO) with or without subsequent repe…

Amino acid transport across each side of the blood-brain barrier.

2011

Electrical tree growth in EVA-layered silicate nanocomposites

2006

This work deals with the growth of electrical treeing in different EVA-layered silicate nanostructured compounds. The experimental activity evidenced that the intercalated nanocomposites have longer lifetimes than pure EVA under the same constant AC stress conditions. A monitoring of the tree growth morphology allowed to evidence very interesting features of the intercalated nano-compounds showing a barrier effect to the treeing path. A preliminary investigation on the possible arrangement of the filler particles inside the matrix was also carried out.

Towards a converged barrier height for the entrance channel transition state of the N(2D)+CH4 reaction and its implication for the chemistry in Titan…

2011

Abstract The N( 2 D) + CH 4 reaction appears to be a key reaction for the chemistry of Titan’s atmosphere, opening the door to nitrile formation as recently observed by the Cassini–Huygens mission. Faced to the controversy concerning the existence or not of a potential barrier for this reaction, we have carried out accurate ab initio calculations by means of multi-state multi-reference configuration interaction (MS-MR-SDCI) method. These calculations have been partially corrected for the size-consistency errors (SCE) by Davidson, Pople or AQCC corrections. We suggest a barrier height of 3.86 ± 0.84 kJ/mol, including ZPE, for the entrance transition state, in good agreement with the experime…

Effect of Pulp Pigmentation Intensity on Consumer Acceptance of New Blood Mandarins: A Cross-Cultural Study in Spain and Italy

2022

One of the current objectives of different citrus breeding programmes is obtaining new pigmented mandarins. This study investigates to what extent consumer preferences, expectations and purchase intention are affected by the appearance of new mandarins, specifically pulp pigmentation intensity. Four hundred consumers from both Italy and Spain (800 in all) participated in the study. In each country, half were informed about the healthy properties of the anthocyanins responsible for red pulp colouration, while the other half were not. Italians more readily accepted new mandarin varieties than Spaniards, which was linked to them being more familiar with blood oranges. In Italy, both slight- an…

Support for culture via crowdfunding in question: beyond motivations, an analysis of the barriers to participate

2017

In a context of strong budgetary pressure for non-market cultural organizations and of relative slowdown of crowdfunding campaigns in this sector, this reflection aims to provide a critical analysis of these new forms of financial support for culture. After drawing up a state of the art on the levers and obstacles to participation in such financing operations, the results of a qualitative study based on 43 individuals (donors and non-donors, familiar or not with cultural practices) will be exposed to highlight the diversity of misgivings about crowdfunding, beyond the traditional barriers attached to cultural gift, and the paradoxes that these calls for generosity arouse.