Multiphonon Raman Scattering in Graphene

We report multiphonon Raman scattering in graphene samples. Higher order combination modes involving 3 phonons and 4 phonons are observed in single-layer (SLG), bi-layer (BLG), and few layer (FLG) graphene samples prepared by mechanical exfoliation. The intensity of the higher order phonon modes (relative to the G peak) is highest in SLG and decreases with increasing layers. In addition, all higher order modes are observed to upshift in frequency almost linearly with increasing graphene layers, betraying the underlying interlayer van der Waals interactions.Comment: Accepted for publication in Phys. Rev.

All-order evaluation of weak measurements: --- The cases of an operator A{\bf A} which satisfies the property A2=1{\bf A}^{2}=1 ---

Some exact formulae of the expectation values and probability densities in a weak measurement for an operator ${\bf A}$ which satisfies the property ${\bf A}^{2}=1$ are derived. These formulae include all-order effects of the unitary evolution due to the von-Neumann interaction. These are valid not only in the weak measurement regime but also in the strong measurement regime and tell us the connection between these two regime. Using these formulae, arguments of the optimization of the signal amplification and the signal to noise ratio are developed in two typical experimental setups.Comment: 17 pages, 10 figures (v1); Fig.3 and some typos are corrected (v2); Comments and references are added and some typos are corrected (v3

The Effects Of Social Media Influencer Attributes On Collaborating Brand Credibility And Advocacy

This thesis investigates different characteristics and dimensions related to social media influencers that might affect some brand outcomes after being endorsed by /collaborating with the influencer in brand communications. This study specifically examines the impact of three dimensions—social media influencer credibility, attractiveness, and endorsement content quality—on the collaborating brand’s credibility. It also examines the influence of brand credibility on brand advocacy. The study also explores the mediating role of brand credibility and the moderating role of digital experience. To achieve these aims, the researcher employed the premises of two theories: the stimulus–organism–response theory and the social learning theory. The data were collected using an online questionnaire from 281 respondents. The findings reveal that social media influencer credibility significantly influences the credibility of the collaborating brand which in turn exert significant impact on brand advocacy. A mediating effect of collaborating brand credibility is identified between social media influencer credibility and brand advocacy. The findings have essential managerial implications that assist managers in choosing the most effective social media influencer for their brand

Gene therapy for lipid disorders

Lipid disorders are associated with atherosclerotic vascular disease, and therapy is associated with a substantial reduction in cardiovascular events. Current approaches to the treatment of lipid disorders are ineffective in a substantial number of patients. New therapies for refractory hypercholesterolemia, severe hypertriglyceridemia, and low levels of high-density lipoprotein cholesterol are needed: somatic gene therapy is one viable approach. The molecular etiology and pathophysiology of most of the candidate diseases are well understood. Animal models exist for the diseases and in many cases preclinical proof-of-principle studies have already been performed. There has been progress in the development of vectors that provide long-term gene expression. New clinical gene therapy trials for lipid disorders are likely to be initiated within the next few years

What Controls Activity Trends of Electrocatalytic Hydrogen Evolution Reaction?-Activation Energy Versus Frequency Factor

Renewable energy storage via water electrolysis strongly depends on the design of electrified electrode–electrolyte interfaces at which electricity is converted into chemical energy. At the core of the hydrogen evolution reaction (HER) and the oxygen evolution reaction conversion efficiency are interfacial processes with complex dynamic mechanisms, whose further acceleration is practically impossible without a thorough fundamental understanding of electrocatalysis. Here, we communicate new experimental insights into HER, which will potentially further deepen our general understanding of electrocatalysis. Of special note is the very surprising observation that the most active metals (i.e., noble metals) for HER, which exhibit the lowest overpotentials at a defined current density, exhibit the highest activation energies in comparison to the other metals from the d-block. This suggests a major, if not dominant, impact of the frequency factor on activity trends and the need for deeper reconsideration of the origins of electrocatalytic activity

The Effect of Iron Impurities on Transition Metal Catalysts for the Oxygen Evolution Reaction in Alkaline Environment: Activity Mediators or Active Sites?

There is an ongoing debate on elucidating the actual role of Fe impurities in alkaline water electrolysis, acting either as reactivity mediators or as co-catalysts through synergistic interaction with the main catalyst material. This perspective summarizes the most prominent oxygen evolution reaction (OER) mechanisms mostly for Ni-based oxides as model transition metal catalysts and highlights the effect of Fe incorporation on the catalyst surface in the form of impurities originating from the electrolyte or co-precipitated in the catalyst lattice, in modulating the OER reaction kinetics, mechanism and stabilit

Study of the genetic homogeneity of Albarino (Vitis vinifera L.) growing in Galicia (Spain) using isozyme and RAPD markers

Research NoteAn evaluation of the genetic diversity of cv. Albarino (Vitis vinifera L.) was carried out. Centenarian and young plants were selected from vineyards, some of them showing slight ampelographic differences. Using ELISA tests 5 out of 24 plants were found to be infected with grapevine leafroll-associated virus 3 (GLRaV-3). In order to evaluate genetic polymorphism, 10 enzyme systems and 42 RAPD primers were used. The 73 isozyme and 308 RAPD markers were common in the samples tested. The results show the existence of a genetic homogeneity within Albarino cultivated in Galicia. Minor ampelographic differences among samples could be due to external factors rather than to genetic differences

Influence of elevation and slope exposure on must volatiles of mencía cultivar from Ribeira Sacra (NW Spain)

Ribeira Sacra is a Spanish Denomination of Origen (D.O.) that produces young red wines from Mencía cultivar (Galicia, NW). The orography of the Ribeira Sacra D.O. is very characteristic and renders a wide variety of situations that combine elevation, orientation, slope exposure and slope inclination. Indeed, in this area all have terraced vineyards are very close to just one meter wide, where it is only a single row of vines and spread over the slopes which normally have a large inclination (70 to 80 ° slope). With a south-southwest direction, the vineyards are protected from cold winds from the north and the sun bathes the terraces throughout the day. The stone warmed by the sun during the day blunted the lower night temperatures avoiding frost. During the year 2009 we have studied the volatile composition of Mencía cultivar in six different situations (orientation and altitude) of Amandi subzone (Ribeira Sacra D.O.) and the relationship with the altitude and exposition. The results showed the influence climatic and topographic conditions on the volatile composition of Mencía grape grown along Amandi site from Ribeira Sacra D.O. Six different situations were studied and the data were analysed by analysis of variance and mean differences between situations were calculated using the LSD Fishers’ test. Biplot principal component analysis (PCA) was performed with mean of volatile compounds identified and quantified. The results showed significant differences among the different situations studied, showed different ripening states in the vineyard

Correlation between instrumental and sensory analysis for the characterization of Vitis vinifera wines

In this work, sensory analysis of was used to evaluate the wine aroma character with different aroma attributes according to Norm ISO 11035.1 In parallel wine volatiles were identified and quantified by gas chromatography according the methodology proposed by Oliveira et al. (2006).2 The objective of this work was to study the correlation between instrumental analysis and sensory perception of wine constituents. Thirty-five Albariño white young wines from 2006 vintage were evaluated by GC-FID and sensory analysis by trained and native panel composed by 10 wine tasters from Appellation of Origin Rias Baixas (Galicia, Spain). Forty volatile compounds were identified and quantified by Gas Chromatography and forty-seven aroma descriptors were developed using quantitative descriptive analysis and evaluated with line scaling method. Principal component analysis showed the distribution of the wines in basis to chemical and sensory characteristics. The correlation coefficients of the flavour scores between sensory evaluation and instrumental analysis (R2 > 0.50) were found for methanollacticvanilla, guaiacolhoney, 3-methyl-1-propanolgreen-pepper, 1-butanolliquorice, ethyl lactategreenpepper liquorice. These correlations linking chemical compounds and sensory descriptors may be attributed to possible relations between them, to the presence of other produced compounds which were not analysed or, to some associations among the analysed compounds

Electrocatalysis in confined space

The complex interplay of restricted mass transport leading to local accumulation or depletion of educts, intermediates, products, counterions and co-ions influences the reactions at the active sites of electrocatalysts when electrodes are rough, three-dimensionally mesoporous or nanoporous. This influence is important with regard to activity, and even more to selectivity, of electrocatalytic reactions. The underlying principles are discussed based on the growing awareness of these considerations over recent years