| 1. |
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Haddad, Noël, et al.
(författare)
-
Dielectric properties of Ti2AlC and Ti2AlN MAX phases : The conductivity anisotropy
- 2008
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 104:2
-
Tidskriftsartikel (refereegranskat)abstract
- The optical properties of Ti2AlN and Ti2AlC were determined in the 2-80 eV energy range by electron energy loss spectroscopy and in the visible-ultraviolet range, from 1.6 to 5.5 eV, by spectroscopic ellipsometry. Both experimental techniques are angular resolved and in very good agreement over their overlapping energy range. We observe a dependence of the dielectric function as a function of the crystallographic orientation of the crystals. In particular, we notice a shift of the energy position of the plasmon absorption of Ti2AlC with respect to Ti2AlN. Moreover, a drastic change is also observed in the shape of the dielectric function as a function of the composition (or valence electron concentration). The dielectric functions are fitted to an empirical semiclassic Drude-Lorentz model to obtain physical parameters such as the relaxation times. These microscopic parameters are then used in a macroscopic model to yield the transport properties such as the static conductivity as function of the crystal orientation. Ti 2AlN is found to be a better conductor than Ti2AlC in all orientations, which is consistent with experimental measurements. A comparison of the electrical and optical properties of these two compounds is made in terms of different electronic properties and interband-intraband transitions deduced from our model. © 2008 American Institute of Physics.
|
|
| 5. |
- Hug, H., et al.
(författare)
-
Rhodamine 110-linked amino acids and peptides as substrates to measure caspase activity upon apoptosis induction in intact cells
- 1999
-
Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 38:42, s. 13906-13911
-
Tidskriftsartikel (refereegranskat)abstract
- Caspases (cysteine aspartate-specific proteases) are a structurally related group of cysteine proteases that cleave peptide bonds following specific recognition sequences. They play a central role in activating apoptosis of vertebrate cells. To measure apoptosis induced by various stimuli and at an early apoptotic stage, caspases are an ideal target. This is especially the case when apoptotic cells have to be analyzed ex vivo before phagocytes remove them. A new and sensitive caspase assay is based on a substrate that contains only aspartate residues linked to rhodamine 110. With this and similar substrates, we are able to detect intracellular caspase activation by flow cytometry after apoptosis induction in intact hematopoetic cell lines.
|
|
| 6. |
- Lane, Nina J, et al.
(författare)
-
First-order Raman scattering of the MAX phases Ta4AlC3, Nb4AlC3, Ti4AlN3, and Ta2AlC
- 2012
-
Ingår i: Journal of Raman Spectroscopy. - : John Wiley and Sons. - 0377-0486 .- 1097-4555. ; 43:7, s. 954-958
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, we report on the Raman spectra of the following ternary hexagonal carbides and nitrides (MAX phases): Ta4AlC3, Ta2AlC and Ti4AlN3. We also present the Raman-active modes of a- and beta-Ta4AlC3, Nb4AlC3 and Ti4AlN3, also referred to as the 413 MAX phases as predicted from first principles calculations using density functional theory. We compare the obtained experimental and calculated results with previous studies on Ta2AlC and Ti4AlN3. The vibrational behavior associated with the Raman-active modes for the 413 phases has been identified for the first time. In general, the agreement is good between theory and experiment. The experimental and calculated results indicate that the modes at low wavenumbers - dominated by the Al atoms - are a weak function of chemistry and the differences in energy can be traced to variations in the reduced mass. The modes at higher wavenumbers are dominated by the C and N atoms and show a strong dependence on the unit cell chemistry, with the TaC bond being stiffer than the NbC bond, which is in turn stiffer than TiN.
|
|
| 7. |
- Lane, Nina J., et al.
(författare)
-
Neutron diffraction measurements and first-principles study of thermal motion of atoms in select M(n+1)AX(n) and binary MX transition-metal carbide phases
- 2012
-
Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 86:21
-
Tidskriftsartikel (refereegranskat)abstract
- Herein, we compare the thermal vibrations of atoms in select ternary carbides with the formula M(n+1)AX(n) ("MAX phases," M = Ti, Cr; A = Al, Si, Ge; X = C, N) as determined from first-principles phonon calculations to those obtained from high-temperature neutron powder diffraction studies. The transition metal carbides TiC, TaC, and WC are also studied to test our methodology on simpler carbides. Good qualitative and quantitative agreement is found between predicted and experimental values for the binary carbides. For all the MAX phases studied-Ti3SiC2, Ti3GeC2, Ti2AlN, Cr2GeC and Ti4AlN3-density functional theory calculations predict that the A element vibrates with the highest amplitude and does so anisotropically with a higher amplitude within the basal plane, which is in line with earlier results from high-temperature neutron diffraction studies. In some cases, there are quantitative differences in the absolute values between the theoretical and experimental atomic displacement parameters (ADPs), such as reversal of anisotropy or a systematic offset of temperature-dependent ADPs. The mode-dependent Gruneisen parameters are also computed to explore the anharmonicity in the system.
|
|
| 8. |
- Pecquet, C, et al.
(författare)
-
Calreticulin mutants as oncogenic rogue chaperones for TpoR and traffic-defective pathogenic TpoR mutants
- 2019
-
Ingår i: Blood. - : American Society of Hematology. - 1528-0020 .- 0006-4971. ; 133:25, s. 2669-2681
-
Tidskriftsartikel (refereegranskat)abstract
- Calreticulin (CALR) +1 frameshift mutations in exon 9 are prevalent in myeloproliferative neoplasms. Mutant CALRs possess a new C-terminal sequence rich in positively charged amino acids, leading to activation of the thrombopoietin receptor (TpoR/MPL). We show that the new sequence endows the mutant CALR with rogue chaperone activity, stabilizing a dimeric state and transporting TpoR and mutants thereof to the cell surface in states that would not pass quality control; this function is absolutely required for oncogenic transformation. Mutant CALRs determine traffic via the secretory pathway of partially immature TpoR, as they protect N117-linked glycans from further processing in the Golgi apparatus. A number of engineered or disease-associated TpoRs such as TpoR/MPL R102P, which causes congenital thrombocytopenia, are rescued for traffic and function by mutant CALRs, which can also overcome endoplasmic reticulum retention signals on TpoR. In addition to requiring N-glycosylation of TpoR, mutant CALRs require a hydrophobic patch located in the extracellular domain of TpoR to induce TpoR thermal stability and initial intracellular activation, whereas full activation requires cell surface localization of TpoR. Thus, mutant CALRs are rogue chaperones for TpoR and traffic-defective TpoR mutants, a function required for the oncogenic effects.
|
|
| 9. |
- Sadlej, J., et al.
(författare)
-
Properties and Spectroscopies
- 2007
-
Ingår i: Continuum Solvation Models in Chemical Physics: From Theory to Applications. - Chichester, UK : John Wiley & Sons. - 9780470029381 ; , s. 125-312
-
Bokkapitel (refereegranskat)
|
|
| 10. |
- Sadowski-Debbing, K., et al.
(författare)
-
Caspases - Their role in apoptosis and other physiological processes as revealed by knock-out studies
- 2002
-
Ingår i: Archivum Immunologiae et Therapiae Experimentalis. - 0004-069X .- 1661-4917. ; 50:1, s. 19-34
-
Forskningsöversikt (refereegranskat)abstract
- Caspases are crucial mediators of apoptosis, a form of physiological cell death. Their activation is carefully controlled by a philogenetically conserved death program, which is indispensable for the homeostasis and development of higher organisms. Dysregulation of apoptosis contributes to the pathogenesis of many human diseases. As effectors of the apoptotic machinery, caspases are considered potential therapeutic targets. In vitro studies have demonstrated the requirement of caspase activity for both the triggering phase as well as the execution of apoptosis, thus providing a molecular base for the time-tuning of this process by pharmacological agents. The precise roles of the individual caspases in vivo and their functional relation to each other have been best demonstrated in genetically modified animals. The generation of single caspase-deficient mice have confirmed most of the data obtained in vitro and exposed some new aspects previously undetected in the cell culture system. Interestingly, inactivation of many caspases revealed not only their expected participation in apoptotic events as well as in the maturation of cytokines, but also provided hints about the role of at least some caspases in cell differentiation and stimulatory responses. In this review we will discuss what these studies have unveiled about the role of individual caspases in development, apoptosis, and inflammation, with particular focus on their role beyond the apoptotic process.
|
|
