| 1. |
- Andreasson, Jakob, 1975, et al.
(author)
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Electron-phonon interactions in perovskites containing Fe and Cr studied by Raman scattering using oxygen-isotope and cation substitution
- 2008
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X .- 2469-9950 .- 2469-9969. ; 78:23, s. 235103-
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Journal article (peer-reviewed)abstract
- We use temperature-dependent inelastic light scattering to study the origin of the strong multiphonon scattering of a local oxygen breathing mode present in the mixed B-site orthorhombic (space group Pnma) perovskite LaFe0.5Cr0.5O3 but absent in isostructural LaFeO3 and LaCrO3. It is seen that the multiphonon scattering is critically sensitive to the presence of both Fe and Cr ions on the B site. These results support our interpretation that the multiphonon scattering is activated by local electron-phonon interactions according to the Franck-Condon picture following an Fe-Cr charge transfer. Further, O-18 substitution is performed on the x=0, 0.04, and 0.5 compounds and clearly shows that all modes appearing above the first-order phonon-scattering region in these compounds originate from higher-order oxygen stretching vibrations. In particular this is the case for the strong second-order scattering dominating the scattering response in LaFeO3. Accordingly we propose that these modes are generated by infrared-active longitudinal optical (IR LO) two-phonon and combination scattering activated by Frohlich interaction. For x=0.02 and 0.04 the characteristic IR LO two-phonon and Franck-Condon multiphonon-scattering profiles mix. We also study the influence of isovalent cation substitution and Sr doping in AFe(0.5)Cr(0.5)O(3) (A=La, Nd, and Gd) and La1-ySryFe0.5Cr0.5O3-delta (y=0, 0.16, and 0.5) on the strong electron-phonon coupling present in LaFe0.5Cr0.5O3. The Franck-Condon effect in LaFe0.5Cr0.5O3, is not significantly affected by isovalent A-site substitution, despite the increasing orthorhombic distortion associated with decreasing A-site ionic radii. On the contrary, aliovalent Sr doping causes a rapid decrease in the Franck-Condon scattering. This shows that the strong electron-phonon coupling in these compounds is highly sensitive to local lattice and electronic decoherence but insensitive to global lattice distortions. Finally, a preliminary assignment of the A(g) and B-2g phonon modes in AFe(0.5)Cr(0.5)O(3) (A=La, Nd, and Gd) is made based on the present observations and published results for LaCrO3 and AMnO(3). The modes associated with oxygen octahedral tilt and bending vibrations are heavily influenced by the magnitude of the orthorhombic distortion.
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| 2. |
- Andreasson, Jakob, 1975, et al.
(author)
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Franck-Condon higher order lattice excitations in the LaFe(1-x)Cr(x)O3 (x=0, 0.1, 0.5, 0.9, 1.0) perovskites due to Fe-Cr charge transfer effects
- 2007
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In: Physical Review B. ; 75, s. 104302-
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Journal article (peer-reviewed)abstract
- First and higher order lattice excitiations in the B-site disordered perovskites LaFe(1-x)Cr(x)O3 (x = 0, 0.1, 0.5, 0.9, 1) and La(0.835)Sr(0.165)Fe(0.5)Cr(0.5)O(3-d) are investigated using temperature dependent and polarised inelastic light scattering [lambda = 515 nm (2.41 eV) and 676 nm (1.83 eV)] on oriented crystallites.A peak at approximately 2.4 eV in the imaginary part of the dielectric function of LaFe(0.5)Cr(0.5)O3 is assigned to a charge transfer from Fe 3+ (d5) to Cr 3+ (d3) ions and coupled the appearance of an intense Ag-like mode at approximately 700 cm-1 in the Raman data. This excitation is identified as a symmetric oxygen breathing mode activated by the Fe-Cr charge transfer through an orbital coupling mechanism. Higher order scattering (up to 7th order) of the intrinsic Raman active symmetric breathing mode is also explained by an orbital mediated, electron-phonon coupling, similar to the Franck-Condon effect observed in the Jahn-Teller active perovskite structured manganite LaMnO3. These results show that the Franck-Condon mechanism is a more common mechanism for resonant higher order scattering in solids than previously believed and propose the LaFe(1-x)Cr(x)O(3) system as a model system for electron-phonon coupling and higher order Raman scattering in solids.
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| 3. |
- Andreasson, Jakob, et al.
(author)
-
Franck-Condon higher order lattice excitations in the LaFe1-xCrxO3 (x=0, 0.1, 0.5, 0.9, 1.0) perovskites due to Fe-Cr charge transfer effects
- 2007
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75
-
Journal article (peer-reviewed)abstract
- First and higher order lattice excitations in the B-site disordered perovskites LaFe1-xCrxO3 (x=0, 0.1, 0.5, 0.9, and 1) and La0.835Sr0.165Fe0.5Cr0.5O3-delta are investigated using temperature dependent and polarized inelastic light scattering [lambda=515 nm (2.41 eV) and 676 nm (1.83 eV)] on oriented crystallites. A peak at approximately 2.4 eV in the imaginary part of the dielectric function of LaFe0.5Cr0.5O3 is assigned to a charge transfer from Fe3+ (d(5)) to Cr3+ (d(3)) ions, coupled with the appearance of an intense A(g)-like mode at approximately 700 cm(-1) in the Raman data. This excitation is identified as a symmetric oxygen breathing mode activated by the Fe-Cr charge transfer through an orbital coupling mechanism. Higher order scattering (up to seventh order) of the intrinsic Raman active symmetric breathing mode is also explained by an orbital-mediated electron-phonon coupling, similar to the Franck-Condon effect observed in the Jahn-Teller active-perovskite-structured manganite LaMaO(3). These results show that the Franck-Condon mechanism is a more common mechanism for resonant higher order scattering in solids than previously believed and propose the LaFe1-xCrxO3 system as a model system for electron-phonon coupling and higher order Raman scattering in solids.
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| 4. |
- Eriksson, Joakim, 1977-
(author)
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Coping with decisions on deviations in complex product development projects
- 2012
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Doctoral thesis (other academic/artistic)abstract
- A strong need for resource efficiency within manufacturing companies have been driven extensively through pro-active planning and methods which have naturally resulted in an increased amount of strong couplings between product development projects, their activities, and resources. These strong couplings mean a high level of complexity where deviations are likely to occur on a regular basis which can spread quickly and have far reaching consequences. Praxis related to treatment of such deviations in product development projects has not been widely discussed. The subsequent question is therefore How are decisions on managing deviations made in practice?A Practice approach has been adopted in this research and led on to the use of context sensitive research methods in order to collect relevant data. The main amount of data has been gathered through one year of participant observations and document retrieval in a product development project. Also, a large amount of interviews have been used as a method for collecting data.38 deviations have been analysed through the identification of praxis which has been primarily analysed by three theories. The first theory, decision roles, has been used to clarify the different types of uncertainties people within complex product development projects need to manage in practice. The second theory, loosely coupled systems, shows how temporary organizing by loose couplings enables parallel management of both planned and unplanned activities when deviations occur. The third theory, Sensemaking, have been used to characterise processes related to different types of uncertainties.Conclusions are drawn regarding how people acts related to deviations are directly dependent on the types of uncertainties of the context as well as the situation itself. Uncertainties regarding choices, responsibilities, mobilization, and legitimization combined with the temporary organization leads to certain praxis patterns. The patterns can be used by project managers and other decision makers as a way of discussing temporary organization and how process emerge within the organization today, and how they would like resulting processes to be managed when deviations occur.
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| 5. |
- Eriksson, Joakim, 1977-, et al.
(author)
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Decisions on managing project deviations in practice
- 2024
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In: International Journal of Project Organisation and Management. - : Inderscience Publishers. - 1740-2891 .- 1740-2905.
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Journal article (peer-reviewed)abstract
- This paper presents the results of a case study aimed at investigating how decisions are made on managing deviations in complex product development projects. The results are based on the analysis of data collected from participant observations, as well as interviews with project managers from seven large manufacturing companies. The data is analysed according to four types of sensemaking processes. This research examines why these processes are used in different situations and further explore their characteristics and at their relationship with the different roles decisions play in organizations. The factors driving controlled and uncontrolled sensemaking are also examined. This research contributes to knowledge of how project managers use different praxes to manage deviations in complex, socially and politically sensitive environments. The results can be used by decision makers within complex product development in order to assist them in managing deviations, proactively as well as reactively.
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| 6. |
- Jämbeck, Joakim P. M., 1986-, et al.
(author)
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Molecular Dynamics Studies of Liposomes as Carriers for Photosensitizing Drugs : Development, Validation, and Simulations with a Coarse-Grained Model
- 2014
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In: Journal of Chemical Theory and Computation. - : American Chemical Society (ACS). - 1549-9618 .- 1549-9626. ; 10:1, s. 5-13
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Journal article (peer-reviewed)abstract
- Liposomes are proposed as drug delivery systems and can in principle be designed so as to cohere with specific tissue types or local environments. However, little detail is known about the exact mechanisms for drug delivery and the distributions of drug molecules inside the lipid carrier. In the current work, a coarse-grained (CG) liposome model is developed, consisting of over 2500 lipids, with varying degrees of drug loading. For the drug molecule, we chose hypericin, a natural compound proposed for use in photodynamic therapy, for which a CG model was derived and benchmarked against corresponding atomistic membrane bilayer model simulations. Liposomes with 21-84 hypericin molecules were generated and subjected to 10 microsecond simulations. Distribution of the hypericins, their orientations within the lipid bilayer, and the potential of mean force for transferring a hypericin molecule from the interior aqueous droplet through the liposome bilayer are reported herein.
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| 7. |
- Kalm, Marie, 1981, et al.
(author)
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Serum concentrations of the axonal injury marker neurofilament light protein are not influenced by blood-brain barrier permeability
- 2017
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In: Brain Research. - : Elsevier BV. - 0006-8993. ; 1668, s. 12-19
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Journal article (peer-reviewed)abstract
- A blood biomarker to monitor individual susceptibility to neuronal injury from cranial radiotherapy could potentially help to individualize radiation treatment and thereby reduce the incidence and severity of late effects. An important feature of such a blood biomarker is that its concentration is not confounded by varying degrees of release from the brain into the blood across the blood-brain barrier (BBB). In this study, we investigated serum neurofilament light protein (NFL) concentrations in 21-day old mice following a single dose of cranial irradiation (8 Gy). Cranial irradiation resulted in acute cell injury measured as a 12.9-fold increase in caspase activity 6 h after irradiation; activation of inflammation measured by levels of CCL2 and increased BBB permeability measured by C-14-sucrose concentration ratios in brain and cerebrospinal fluid (CSF). Serum levels of NFL peaked at 6 h after both anesthesia and cranial irradiation, but no timely correlation of serum NFL concentration with BBB permeability was found. Further, three groups of patients with different degrees of BBB impairment (measured as the CSF/serum albumin ratio) were investigated. There was no correlation between serum NFL concentration and CSF/serum albumin ratio (r = 0.139, p = 0.3513), however a strong correlation was found for NFL concentration in serum and NFL concentration in CSF (r = 0.6303, p < 0.0001). In conclusion, serum NFL appears to be a reliable blood biomarker for neuronal injury, and its concentration is not confounded by BBB permeability. (C) 2017 Elsevier B.V. All rights reserved.
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| 8. |
- Lenka, Sambit, et al.
(author)
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Role conflicts in R&D units undergoing pss transition
- 2015
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In: IAMOT 2015 - 24th International Association for Management of Technology Conference. - : Graduate School of Technology Management, University of Pretoria. - 9781775921110 ; , s. 579-590
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Conference paper (peer-reviewed)abstract
- Recent trends in manufacturing industries, is the movement of firms towards providing industrial services or product-service systems (PSS). Importance of this phenomenon has been acknowledged as imperative for strategic differentiation, maintaining competitiveness, increase profitability and be environmentally sustainable. Although a lot of studies have focussed on the benefits of PSS provision, yet very less is know about the challenges of such transition, especially at the functional unit level within an organsiation. Our study focusses on the R&D unit and the various role conflicts that emerges as the function of the unit moves from being based on legal structure to that based on collegial authotiry in the PSS transition process. In a cross-case analysis of large manufacturing companies involved in PSS transition, we identified how role conflicts occur at the organisation, unit and intra-unit levels. Our findings contribute to role conflict literature and in the context of PSS and R&D units. We also observe that role conflict operates not just at the individual member level but at various levels within the organisation and the R&D unit, which has not been observed previously. We contribute by showing that an understanding of these challenges can be the differentiating factor for successful implementation and managing transition towards PSS that have been previously neglected in PSS and R&D literature as well.
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| 9. |
- Lenka, Sambit, et al.
(author)
-
Role conflicts in R&D units undergoing pss transition
- 2016
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In: IAMOT 2015. - Pretoria : Graduate School of Technology Management, University of Pretoria. - 9781775921110 ; , s. 579-590
-
Conference paper (peer-reviewed)abstract
- Recent trends in manufacturing industries, is the movement of firms towards providing industrial services or product-service systems (PSS). Importance of this phenomenon has been acknowledged as imperative for strategic differentiation, maintaining competitiveness, increase profitability and be environmentally sustainable. Although a lot of studies have focussed on the benefits of PSS provision, yet very less is know about the challenges of such transition, especially at the functional unit level within an organsiation. Our study focusses on the R&D unit and the various role conflicts that emerges as the function of the unit moves from being based on legal structure to that based on collegial authotiry in the PSS transition process. In a cross-case analysis of large manufacturing companies involved in PSS transition, we identified how role conflicts occur at the organisation, unit and intra-unit levels. Our findings contribute to role conflict literature and in the context of PSS and R&D units. We also observe that role conflict operates not just at the individual member level but at various levels within the organisation and the R&D unit, which has not been observed previously. We contribute by showing that an understanding of these challenges can be the differentiating factor for successful implementation and managing transition towards PSS that have been previously neglected in PSS and R&D literature as well.
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| 10. |
- Malmgren, Christine, et al.
(author)
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Nanocrystallinity in RuO2 coatings-Influence of precursor and preparation temperature
- 2010
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In: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 518:14, s. 3615-3618
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Journal article (peer-reviewed)abstract
- The effects of precursor and calcination temperature on the nano morphology of ruthenium dioxide on titanium, prepared from thermal decomposition of aqueous salt solutions were investigated. Transmission electron microscopy. X-ray diffraction, gas porosimetry and cyclic voltammetry showed that lower calcination temperature yielded smaller crystallites. The crystallites were between 6 and 22 nm in diameter. When using ruthenium nitrosyl nitrate the firing temperature had a large impact on the grain size, but for chloride there was only a minor effect in the temperature range 350-550 degrees C.
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