| 1. |
- Okuyama, H, et al.
(author)
-
Modifying current-voltage characteristics of a single molecule junction by isotope substitution : OHOD dimer on Cu(110)
- 2012
-
In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 85:20
-
Journal article (peer-reviewed)abstract
- Vibrationally induced configurational change and nonlinear current-voltage (I-V) characteristics are investigated within the scanning tunneling microscope (STM) junction, including hydroxyl dimers on a Cu(110) surface. H-bonded hydroxyl dimers composed of OH and/or OD have a unique inclined geometry that can be switched back and forth by vibrational excitations via the inelastic electron tunneling process of the STM. The relative occupation change between the high-and low-conductance states as a function of bias voltage critically depends on the isotopic compositions, and thus the I-V characteristics can be modified to exhibit negative differential resistance by H/D substitution. The experimental results of the occupation change and I-V curves are nicely reproduced using a recently proposed analytical model combined with comprehensive density functional calculations for the input parameters (vibrational modes and their emission rates by tunneling electrons, conductance, and relative occupation change of high-and low-conductance states), and they underlines the different roles played by the free and shared O-H(D) stretch modes of the hydroxyl dimers on a Cu(110) surface.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Davidsson, Josef, et al.
(author)
-
Relapsed childhood high hyperdiploid acute lymphoblastic leukemia : presence of preleukemic ancestral clones and the secondary nature of microdeletions and RTK-RAS mutations.
- 2010
-
In: Leukemia. - : Springer Science and Business Media LLC. - 0887-6924 .- 1476-5551. ; 24:5, s. 924-31
-
Journal article (peer-reviewed)abstract
- Although childhood high hyperdiploid acute lymphoblastic leukemia is associated with a favorable outcome, 20% of patients still relapse. It is important to identify these patients already at diagnosis to ensure proper risk stratification. We have investigated 11 paired diagnostic and relapse samples with single nucleotide polymorphism array and mutation analyses of FLT3, KRAS, NRAS and PTPN11 in order to identify changes associated with relapse and to ascertain the genetic evolution patterns. Structural changes, mainly cryptic hemizygous deletions, were significantly more common at relapse (P<0.05). No single aberration was linked to relapse, but four deletions, involving IKZF1, PAX5, CDKN2A/B or AK3, were recurrent. On the basis of the genetic relationship between the paired samples, three groups were delineated: (1) identical genetic changes at diagnosis and relapse (2 of 11 cases), (2) clonal evolution with all changes at diagnosis being present at relapse (2 of 11) and (3) clonal evolution with some changes conserved, lost or gained (7 of 11), suggesting the presence of a preleukemic clone. This ancestral clone was characterized by numerical changes only, with structural changes and RTK-RAS mutations being secondary to the high hyperdiploid pattern.
|
|
| 5. |
- Frederiksen, T., et al.
(author)
-
Theory of action spectroscopy for single-molecule reactions induced by vibrational excitations with STM
- 2014
-
In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 89:3, s. 035427-
-
Journal article (peer-reviewed)abstract
- A theory of action spectroscopy, i.e., a reaction rate or yield as a function of bias voltage, is presented for single-molecule reactions induced by the inelastic tunneling current with a scanning tunneling microscope. A formula for the reaction yield is derived using the adsorbate resonance model, which provides a versatile tool to analyze vibrationally mediated reactions of single adsorbates on conductive surfaces. This allows us to determine the energy quantum of the excited vibrational mode, the effective broadening of the vibrational density of states (as described by Gaussian or Lorentzian functions), and a prefactor characterizing the elementary process behind the reaction. The underlying approximations are critically discussed. We point out that observation of reaction yields at both bias voltage polarities can provide additional insight into the adsorbate density of states near the Fermi level. As an example, we apply the theory to the case of flip motion of a hydroxyl dimer (OD)(2) on Cu(110) which was experimentally observed by Kumagai et al. [Phys. Rev. B 79, 035423 (2009)]. In combination with density functional theory calculations for the vibrational modes, the vibrational damping due to electron-hole pair generation, and the potential energy landscape for the flip motion, a detailed microscopic picture for the switching process is established. This picture reveals that the predominant mechanism is excitation of the OD stretch modes which couple anharmonically to the low-energy frustrated rotation mode.
|
|
| 6. |
- Glantz, Maria, et al.
(author)
-
Importance of casein micelle size and milk composition for milk gelation.
- 2010
-
In: Journal of Dairy Science. - : American Dairy Science Association. - 1525-3198 .- 0022-0302. ; 93:4, s. 1444-1451
-
Journal article (peer-reviewed)abstract
- The economic output of the dairy industry is to a great extent dependent on the processing of milk into other milk-based products such as cheese. The yield and quality of cheese are dependent on both the composition and technological properties of milk. The objective of this study was to evaluate the importance and effects of casein (CN) micelle size and milk composition on milk gelation characteristics in order to evaluate the possibilities for enhancing gelation properties through breeding. Milk was collected on 4 sampling occasions at the farm level in winter and summer from dairy cows with high genetic merit, classified as elite dairy cows, of the Swedish Red and Swedish Holstein breeds. Comparisons were made with milk from a Swedish Red herd, a Swedish Holstein herd, and a Swedish dairy processor. Properties of CN micelles, such as their native and rennet-induced CN micelle size and their zeta-potential, were analyzed by photon correlation spectroscopy, and rennet-induced gelation characteristics, including gel strength, gelation time, and frequency sweeps, were determined. Milk parameters of the protein, lipid, and carbohydrate profiles as well as minerals were used to obtain correlations with native CN micelle size and gelation characteristics. Milk pH and protein, CN, and lactose contents were found to affect milk gelation. Smaller native CN micelles were shown to form stronger gels when poorly coagulating milk was excluded from the correlation analysis. In addition, milk pH correlated positively, whereas Mg and K correlated negatively with native CN micellar size. The milk from the elite dairy cows was shown to have good gelation characteristics. Furthermore, genetic progress in relation to CN micelle size was found for these cows as a correlated response to selection for the Swedish breeding objective if optimizing for milk gelation characteristics. The results indicate that selection for smaller native CN micelles and lower milk pH through breeding would enhance gelation properties and may thus improve the initial step in the processing of cheese.
|
|
| 7. |
|
|
| 8. |
|
|
| 9. |
|
|
| 10. |
|
|
