Transfer of Graphene with Protective Oxide Layers

Transfer of graphene, grown by Chemical Vapor Deposition (CVD), to a substrate of choice, typically involves deposition of a polymeric layer (typically, poly(methyl methacrylate, PMMA or polydimethylsiloxane, PDMS). These polymers are quite hard to remove without leaving some residues behind. Here we study a transfer of graphene with a protective thin oxide layer. The thin oxide layer is grown by Atomic Deposition Layer (ALD) on the graphene right after the growth stage on Cu foils. One can further aid the oxide-graphene transfer by depositing a very thin polymer layer on top of the composite (much thinner than the usual thickness) following by a more aggressive polymeric removal methods, thus leaving the graphene intact. We report on the nucleation growth process of alumina and hafnia films on the graphene, their resulting strain and on their optical transmission. We suggest that hafnia is a better oxide to coat the graphene than alumina in terms of uniformity and defects.Comment: 13 pgs, 13 figure

Seasonal Variation in Phenolic Content and Antioxidant Activity of Glechoma Hederacea L. Harvested from Six Hungarian Populations

Ground ivy (Glechoma hederacea L.) is one of the prosperous plants for the food-industry as natural antioxidant. This fact led us to examine the chemical diversity of six ground ivy populations situated in different natural habitats and to analyse the effect of the harvesting time. Total phenolic content, chlorogenic acid, and rutin content, as well as the antioxidant capacity showed significant differences due to the harvest time. The highest total phenol content (115 mg g–1 GAE) and the strongest antioxidant activity (53.3 mg g–1 AAE) were measured in the population originated from Budapest (GLE 6), harvested in July. The highest chlorogenic acid (357 mg/100 g) and rutin (950 mg/100 g) contents were detected in the July harvested samples from the Soroksár Botanical Garden population (GLE 1). According to our results, the collection time has significant effect on the total phenolic content – first of all on the chlorogenic acid and rutin accumulation levels of ground ivy, while the influence of the habitat seems to be less important

ミナミ タイヘイヨウ ヒカク チタイ ジョウヤク ケイセイ カテイ ニ オケル オーストタリア ノ カクグンシュク ガイコウ セイサク

Alternate bilayer structures of N,N'-bis(2,5-di-tert-butylphenyl)-3,4,9,10- perylene dicarboximide (PDI), freebase phthalocyanines (Pc), and double-linked free-base phthalocyanine-fullerene dyad (Pc-C 60) were prepared by the Langmuir-Schäfer method and studied using a range of optical spectroscopy methods including femtosecond pump-probe and up-conversion. An efficient quenching of the PDI fluorescence by Pc and Pc-C 60 dyad was observed in both steady-state and time-resolved fluorescence measurements. The quenching takes place in less than a few picoseconds, and is due to energy transfer from perylene dicarboximide to phthalocyanine chromophore in PDI|Pc and PDI|Pc-C 60 films. In the PDI|Pc-C 60 bilayer structure the energy transfer is followed by a charge separation in the Pc-C 60 layer, yielding a long-lived (a few microseconds) intermolecular charge separated state similar to that reported recently for Pc-C 60 Langmuir-Blodgett films (Lehtivuori, H.; et al. J. Phys. Chem. C 2008, 112, 9896-9902)

Comparative evaluation of chamomile (Matricaria recutita L.) populations from different origin

In our research project under cultivation we examined 4 cultivars ('Soroksári 40', 'Lutea , 'Goral', 'Bona') and 28 wild populations of chamomile assuring all of them the same environmental conditions. Plant height, flower-diameter, essential-oil content, and the main terpenoid and flavonoid composition were analysed. The aim of our study was to establish the genetic background of breeding a new cultivar as well as encircle those natural habitats that give chamomile drug with the best quality. In the case of plant height populations from the Great Hungarian Plain were lower than plants from Transdanubia and the control cultivars. Between the wild and the standard individuals we found significant differences with relevance to the flower-diameter. With regard to the essential oil content the populations were very heterogeneous even those, which came from the same habitat. Populations form Transdanubia and Nagyiván reached the essential oil level of the cultivars (0.721-0.931 gi100g), and 75% of the examined plants exceeded the minimum requirement of the PhHg VIII. According to the essential oil composition our previous statement was confirmed that in the populations of Transdanubia and Northern part of Danube—Tisza Mid Region the main component is bisabolol-oxide A (30-41.2%), while plants native to the territory cast of the river Tisza are mainly characterised by a-bisabolol (32.3-48.4). In some samples the ratio of bisabolol-oxide B was more than 10%. The chamazulene content was higher in the cultivars selected to this component (above 20%), than in the wild populations (varied between 1.22 and 17.2%). Populations originated from the central part of Hortobágy region had extremely high apigenin content (10-13 mg/g), but in the case of chlorogenic acid, hyperoside and quercitrin we did not find any differences affected by the origin