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- Brauer, H.E., et al.
(author)
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Na intercalation of VSe2 studied by photoemission and scanning tunneling microscopy
- 1997
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 55:15, s. 10022-10026
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Journal article (peer-reviewed)abstract
- In situ Na intercalation of the layered compound VSe2 has been studied with photoemission and scanning tunneling microscopy. Core-level spectroscopy proves that Na deposited in UHV onto the VSe2 surface rapidly intercalates, leaving only small amounts at the surface. The scanning tunneling microscopy measurements show that the intercalated Na is not uniformly distributed between the VSe2 layers, but preferentially in two-dimensional islands. Thus the surface region is divided into intercalated and nonintercalated areas. Hole-like features in the intercalated areas are interpreted as locally missing Na.
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| 4. |
- Cetinic, I., et al.
(author)
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Ultrasound Shear Wave Elastography, Shear Wave Dispersion and Attenuation Imaging of Pediatric Liver Disease with Histological Correlation
- 2022
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In: Children. - : MDPI AG. - 2227-9067. ; 9:5
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Journal article (peer-reviewed)abstract
- Aim: To evaluate the feasibility of multiple ultrasound markers for the non-invasive characterization of fibrosis, inflammation and steatosis in the liver in pediatric patients. Materials and methods: The quantitative ultrasound measures shear wave elastography (SWE), shear wave dispersion (SWD) and attenuation imaging (ATI) were compared and correlated with percutaneous liver biopsies and corresponding measures in a control cohort. Results: The median age of the 32 patients was 12.1 years (range 0.1-17.9), and that of the 15 controls was 11.8 years (range: 2.6-16.6). Results: There was a significant difference in SWE values between histologic grades of fibrosis (p = 0.003), with a positive correlation according to the grade (r = 0.7; p < 0.0001). Overall, a difference in SWD values between grades of inflammation was found (p = 0.009) but with a lack of correlation (r = 0.1; p = 0.67). Comparing inflammation grades 0-1 (median:13.6 m/s kHz [min; max; 8.4; 17.5]) versus grades 2-3 (16.3 m/s kHz [14.6; 24.2]) showed significant differences between the groups (p = 0.003). In the 30 individuals with a steatosis score of 0, ATI was measured in 23 cases with a median value of 0.56 dB/cm/MHz. Conclusion: Comprehensive ultrasound analysis was feasible to apply in children and has the potential to reflect the various components of liver affection non-invasively. Larger studies are necessary to conclude to what extent these image-based markers can classify the grade of fibrosis, inflammation and steatosis.
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| 5. |
- Choudhury, Maidul I., et al.
(author)
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Charophytes collapse beyond a critical warming and brownification threshold in shallow lake systems
- 2019
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 661, s. 148-154
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Journal article (peer-reviewed)abstract
- Charophytes play a critical role for the functioning of shallow lake ecosystems. Although growth of charophytes can be limited by many factors, such as temperature, nutrients and light availability, our understanding about concomitant effects of climate warming and other large-scale environmental perturbations, e.g. increases in humic matter content (‘brownification’) is still limited. Here we conducted an outdoor mesocosm experiment during 71 days with a common charophyte species, Chara vulgaris, along an increasing gradient of temperature and brownification. We hypothesized the growth of C. vulgaris to increase with temperature, but to level off along the combined temperature and brownification gradient when reaching a critical threshold for light limitation via brownification. We show that C. vulgaris increases the relative growth rate (RGR), main and total shoot elongation, as well as number of lateral shoots when temperature and brownification increased by +2 °C and + 100%, respectively above today's levels. However, the RGR, shoot elongation and number of lateral shoots declined at further increment of temperature and brownification. Macrophyte weight-length ratio decreased with increased temperature and brownification, indicating that C. vulgaris allocate more resources or energy for shoot elongation instead of biomass increase at warmer temperatures and higher brownification. Our study shows that C. vulgaris will initially benefit from warming and brownification but will then decline as a future scenario of increased warming and brownification reaches a certain threshold level, in case of our experiment at +4 °C and a 2-fold increase in brownification above today's levels.
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| 9. |
- Ekvall, I, et al.
(author)
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Preparation and characterization of electrochemically etched W tips for STM
- 1999
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In: MEASUREMENT SCIENCE & TECHNOLOGY. - : IOP PUBLISHING LTD. - 0957-0233. ; 10:1, s. 11-18
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Journal article (other academic/artistic)abstract
- We have investigated methods for cleaning de-etched polycrystalline tungsten tips for scanning tunnelling microscopy (STM). The cleaning methods include Ar-ion sputtering, heating, chemical treatments and Ne-ion self-sputtering. We correlate transmission
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| 10. |
- Kim, J J, et al.
(author)
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Temperature-dependent scanning tunneling spectroscopy of 1T-TaS2
- 1996
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In: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 54, s. 2244-2248
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Journal article (peer-reviewed)abstract
- We have studied temperature-dependent tunneling spectroscopy of 1T-TaS2 from room temperature down to about 40 K. The spectra indicated an abrupt transition from the charge-density-wave-induced broad depletion to an opening of a deep pseudogap within 1 K of the nearly commensurate to commensurate transition temperature. The measured pseudogap was deep enough to form localized states at the Fermi level. In contrast to an inverse photoelectron spectroscopy study, our tunneling results indicate gap structures of two Hubbard subbands resulting from the band splitting of the Ta 5d band due to the electron correlation effect. We have also found an abrupt increase of thermoelectric voltage developing between the tip and sample at the transition temperature.
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