2,068 research outputs found
Effect of electron-phonon interaction on the formation of one-dimensional electronic states in coupled Cl vacancies
The formation of extended electron states in one-dimensional nanostructures
is of key importance for the function of molecular electronics devices. Here we
study the effects of strong electron-phonon interaction on the formation of
extended electronic states in intentionally created Cl vacancy pairs and chains
in a NaCl bilayer on Cu(111). The interaction between the vacancies was
tailored by fabricating vacancy pairs and chains of different orientation and
separation with atomic precision using vertical manipulation. Small separation
of divacancies led to the formation of symmetric and antisymmetric vacancy
states and localized interface-states. By scanning tunneling spectroscopy (STS)
we measured their energy splitting and broadening as a function of the
inter-vacancy separation. Unexpectedly, the energy splitting between the
vacancy states is enlarged by level repulsion resulting from phonon dressing of
the electronic states, as evidenced by theory. Already for a few coupled
vacancies we observe an emerging band structure of the defect band.Comment: 9 pages, 4 figure
Snell's law for surface electrons: Refraction of an electron gas imaged in real space
On NaCl(100)/Cu(111) an interface state band is observed that descends from
the surface-state band of the clean copper surface. This band exhibits a
Moire-pattern-induced one-dimensional band gap, which is accompanied by strong
standing-wave patterns, as revealed in low-temperature scanning tunneling
microscopy images. At NaCl island step edges, one can directly see the
refraction of these standing waves, which obey Snell's refraction law.Comment: 4 pages, 4 figure
Comparative study of the growth of sputtered aluminum oxide films on organic and inorganic substrates
We present a comparative study of the growth of the technologically highly
relevant gate dielectric and encapsulation material aluminum oxide in inorganic
and also organic heterostructures. Atomic force microscopy studies indicate
strong similarities in the surface morphology of aluminum oxide films grown on
these chemically different substrates. In addition, from X-ray reflectivity
measurements we extract the roughness exponent \beta of aluminum oxide growth
on both substrates. By renormalising the aluminum oxide roughness by the
roughness of the underlying organic film we find good agreement with \beta as
obtained from the aluminum oxide on silicon oxide (\beta = 0.38 \pm 0.02),
suggesting a remarkable similarity of the aluminum oxide growth on the two
substrates under the conditions employed
Comparison of the Effects of Early Pregnancy with Human Interferon, Alpha 2 (IFNA2), on Gene Expression in Bovine Endometrium
Interferon tau (IFNT), a type I IFN similar to alpha IFNs (IFNA), is the pregnancy recognition signal produced by the ruminant conceptus. To elucidate specific effects of bovine IFNT and of other conceptus-derived factors, endometrial gene expression changes during early pregnancy were compared to gene expression changes after intrauterine application of human IFNA2. In experiment 1, endometrial tissue samples were obtained on Day (D) 12, D15, and D18 postmating from nonpregnant or pregnant heifers. In experiment 2, heifers were treated from D14 to D16 of the estrous cycle with an intrauterine device releasing IFNA2 or, as controls, placebo lipid extrudates or PBS only. Endometrial biopsies were performed after flushing the uterus. All samples from both experiments were analyzed with an Affymetrix Bovine Genome Array. Experiment 1 revealed differential gene expression between pregnant and nonpregnant endometria on D15 and D18. In experiment 2, IFNA2 treatment resulted in differential gene expression in the bovine endometrium. Comparison of the data sets from both studies identified genes that were differentially expressed in response to IFNA2 but not in response to pregnancy on D15 or D18. In addition, genes were found that were differentially expressed during pregnancy but not after IFNA2 treatment. In experiment 3, spatiotemporal alterations in expression of selected genes were determined in uteri from nonpregnant and early pregnant heifers using in situ hybridization. The overall findings of this study suggest differential effects of bovine IFNT compared to human IFNA2 and that some pregnancy-specific changes in the endometrium are elicited by conceptus-derived factors other than IFNT
Customer Communication of Regional Quality Efforts: A Case From the Grain Sector
Usually, marketing communication efforts in the agrifood sector address the end consumers and concentrate on products that are processed and ready for consumption, thus quality efforts often concentrate on the final product. Moreover, there’s a widespread view that agricultural commodities like wheat aren’t suitable neither for product focused marketing nor branding. However, recent developments in the in agrifood sector challenge this view. The increasing use of biotechnology, the globalisation of markets and changing consumer demands for quality, food safety and process attributes require improved communication concepts and information sharing along whole production chains. This paper considers the development of a quality communication system to support a regional wheat brand and prerequisites for quality management efforts
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