| 1. |
- Jakobsson, Sofie, 1968, et al.
(författare)
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Extended Support Within a Person-Centered Practice After Surgery for Patients With Pituitary Tumors: Protocol for a Quasiexperimental Study.
- 2020
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Ingår i: JMIR research protocols. - : JMIR Publications Inc.. - 1929-0748. ; 9:7
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Tidskriftsartikel (refereegranskat)abstract
- Patients with pituitary tumors often live with lifelong consequences of their disease. Treatment options include surgery, radiotherapy, and medical therapy. Symptoms associated with the tumor or its treatment affect several areas of life. Patients need to adhere to long-term contact with both specialist and general health care providers due to the disease, complex treatments, and associated morbidity. The first year after pituitary surgery constitutes an important time period, with medical evaluations after surgery and decisions on hormonal substitution. The development and evaluation of extended patient support during this time are limited.The aim of this study is to evaluate whether support within a person-centered care practice increases wellbeing for patients with pituitary tumors. Our main hypothesis is that the extended support will result in increased psychological wellbeing compared with the support given within standard of care. Secondary objectives are to evaluate whether the extended support, compared with standard care, will result in (1) better health status, (2) less fatigue, (3) higher satisfaction with care, (4) higher self-efficacy, (5) increased person-centered content in care documentation, and (6) sustained patient safety.Within a quasiexperimental design, patients diagnosed with a pituitary tumor planned for neurosurgery are consecutively included in a pretest-posttest study performed at a specialist endocrine clinic. The control group receives standard of care after surgery, and the interventional group receives structured patient support for 1 year after surgery based on person-centeredness covering self-management support, accessibility, and continuity. A total of 90 patients are targeted for each group.Recruitment into the control group was performed between Q3 2015 and Q4 2017. Recruitment into the intervention group started in Q4 2017 and is ongoing until Q4 2020. The study is conducted according to the Declaration of Helsinki, and the protocol has received approval from a regional ethical review board.This study entails an extensive intervention constructed in collaboration between clinicians, patients, and researchers that acknowledges accessibility, continuity, and self-management support within person-centeredness. The study has the potential to compare standard care to person-centered practice adapted specifically for patients with pituitary tumors and evaluated with a combination of patient-reported outcomes and patient-reported experience measures. Following the results, the person-centered practice may also become a useful model to further develop and explore person-centered care for patients with other rare, lifelong conditions.Researchweb.org. https://www.researchweb.org/is/sverige/project/161671.DERR1-10.2196/17697.
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| 2. |
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| 3. |
- Andersson, Agnes, et al.
(författare)
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Headache Before and After Endoscopic Transsphenoidal Pituitary Tumor Surgery: A Prospective Study
- 2022
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Ingår i: Journal of Neurological Surgery Part B-Skull Base. - : Georg Thieme Verlag KG. - 2193-6331 .- 2193-634X. ; 83:suppl. 2
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Tidskriftsartikel (refereegranskat)abstract
- Objective Headache is a common symptom among patients with pituitary tumors, as it is in the general population. The aim of the study was to investigate headache as a symptom in patients with pituitary tumors before and 6 months after endoscopic transsphenoidal surgery (TSS). Design This is a prospective observational cohort study. Setting This study was conducted at university tertiary referral hospital. Participants A total of 110 adult patients underwent endoscopic TSS for pituitary tumors. Main Outcome Measures The Migraine Disability Assessment (MIDAS) questionnaire was used before and 6 months after surgery for the assessment of headache. Clinical variables with potential influence on headache were analyzed. Results Sixty-eight (62%) patients experienced headaches at least once during the 3 months before surgery. Thirty (27%) patients reported disabling headache before surgery, with younger age being an independent associated factor ( p <0.001). In patients with disabling headache before surgery, the median (interquartile range) MIDAS score improved from 78 (27-168) to 16 (2-145; p =0.049), headache frequency decreased from 45 (20-81) to 14 (4-35) days ( p =0.009), and headache intensity decreased from 6 (5-8) to 5 (4-7) ( p =0.011) after surgery. In total, 16 of the 30 (53%) patients reported a clinically relevant improvement and five (17%) a clinically relevant worsening. Four (5%) patients developed new disabling headache. No predictor for postoperative improvement of headache was identified. Conclusion In this prospective study, the results show that disabling headache improves following endoscopic TSS in a subset of patients with pituitary tumors. However, no predictive factors for improvement could be identified.
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| 4. |
- Auvray, Xavier, 1986, et al.
(författare)
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The effect gas composition during thermal aging on the dispersion and NO oxidation activity over Pt/Al2O3 catalysts
- 2013
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Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 129, s. 517-527
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Tidskriftsartikel (refereegranskat)abstract
- The aging of a model 1 wt.% Pt/Al2O3 catalyst was performed stepwise under different reactive atmosphere to study the evolution of metal dispersion and NO oxidation activity. After each aging step the dispersion was evaluated by CO chemisorptions and the activity of the catalyst for NO oxidation was measured using 500 ppm NO and 8%O-2 diluted in Ar. After a degreening step at 500 degrees C, aging was performed at 600, 700,800 and 900 degrees C. Five wash-coated cordierite monoliths were aged in Ar, 10% O-2, 1% H-2 30 ppm SO2 and 30 ppm SO2 + 10% O-2, respectively. The general trend showed a linear decrease in dispersion when increasing the aging temperature for the lower aging temperatures and for the highest ones the dispersion levels off. When the platinum dispersion decreased the NO oxidation activity increased, due to that the reaction is structure sensitive. H-2 seemed to hinder sintering at low aging temperature. Interestingly, after aging in 10% oxygen at 600 degrees C the NO oxidation activity was significantly higher compared to the Ar aged sample, although the dispersions were similar. Aging in oxygen at higher temperatures resulted in a decrease of dispersion and a slightly decreasing NO oxidation activity. Moreover lower dispersion limit was reached with oxygen aging. Aging in SO2 provoked a severe dispersion drop at low aging temperature meanwhile the activity increased only moderately. However, activity kept increasing with further treatments at higher temperature. The combination of O-2 and SO2 enabled to decrease rapidly the dispersion and to greatly enhance the catalytic NO oxidation activity after the first aging step at only 600 degrees C. The best overall conversion was obtained for the catalyst treated with this mixture after aging at 800 degrees C. A 22-h aging at 250 degrees C in a mixture containing 500 ppm NO, 10% O-2 and 30 ppm SO2 led to a significant decrease of Pt dispersion, which shows the ability of SO2 to promote platinum sintering already 250 degrees C. The low temperature sintering was confirmed with STEM measurements. Several larger particles were observed, but also many small particles remained. Thus the SO2 + O-2 induced low temperature sintering results in a large variation of particle sizes. This treatment resulted in an increase of the maximum NO conversion (after reduction of the sample) from 45% to 76%. The different aging experiments show that it is beneficial to add SO2 during aging and the reason is the increased particle size, but also a clear chemical effect was observed.
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| 5. |
- Boström, Magnus, 1972-, et al.
(författare)
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Conditions for Transformative Learning for Sustainable Development : A Theoretical Review and Approach
- 2018
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Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 10:12
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Tidskriftsartikel (refereegranskat)abstract
- Continued unsustainability and surpassed planetary boundaries require not only scientific and technological advances, but deep and enduring social and cultural changes. The purpose of this article is to contribute a theoretical approach to understand conditions and constraints for societal change towards sustainable development. In order to break with unsustainable norms, habits, practices, and structures, there is a need for learning for transformation, not only adaption. Based on a critical literature review within the field of learning for sustainable development, our approach is a development of the concept of transformative learning, by integrating three additional dimensions—Institutional Structures, Social Practices, and Conflict Perspectives. This approach acknowledges conflicts on macro, meso, and micro levels, as well as structural and cultural constraints. It contends that transformative learning is processual, interactional, long-term, and cumbersome. It takes place within existing institutions and social practices, while also transcending them. The article adopts an interdisciplinary social science perspective that acknowledges the importance of transformative learning in order for communities, organizations, and individuals to be able to deal with global sustainability problems, acknowledging the societal and personal conflicts involved in such transformation.
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| 6. |
- Fager, Cecilia, 1990, et al.
(författare)
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3D high spatial resolution visualisation and quantification of interconnectivity in polymer films
- 2020
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Ingår i: International Journal of Pharmaceutics. - : Elsevier B.V.. - 0378-5173 .- 1873-3476. ; 587
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Tidskriftsartikel (refereegranskat)abstract
- A porous network acts as transport paths for drugs through films for controlled drug release. The interconnectivity of the network strongly influences the transport properties. It is therefore important to quantify the interconnectivity and correlate it to transport properties for control and design of new films. This work presents a novel method for 3D visualisation and analysis of interconnectivity. High spatial resolution 3D data on porous polymer films for controlled drug release has been acquired using a focused ion beam (FIB) combined with a scanning electron microscope (SEM). The data analysis method enables visualisation of pore paths starting at a chosen inlet pore, dividing them into groups by length, enabling a more detailed quantification and visualisation. The method also enables identification of central features of the porous network by quantification of channels where pore paths coincide. The method was applied to FIB-SEM data of three leached ethyl cellulose (EC)/hydroxypropyl cellulose (HPC) films with different weight percentages. The results from the analysis were consistent with the experimentally measured release properties of the films. The interconnectivity and porosity increase with increasing amount of HPC. The bottleneck effect was strong in the leached film with lowest porosity.
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| 7. |
- Fager, Cecilia, 1990, et al.
(författare)
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Correlating 3D porous structure in polymer films with mass transport properties using FIB-SEM tomography
- 2021
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Ingår i: Chemical Engineering Science: X. - : Elsevier BV. - 2590-1400. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Porous polymer coatings are used to control drug release from pharmaceutical products. The coating covers a drug core and depending on the porous structure, different drug release rates are obtained. This work presents mass transport simulations performed on porous ethyl cellulose films with different porosities. The simulations were performed on high spatial resolution 3D data obtained using a focused ion beam scanning electron microscope. The effective diffusion coefficient of water was determined using a diffusion chamber. Lattice Boltzmann simulations were used to simulate water diffusion in the 3D data. The simulated coefficient was in good agreement with the measured coefficient. From the results it was concluded that the tortuosity and constrictivity of the porous network increase with decreasing amount of added hydroxypropyl cellulose, resulting in a sharp decrease in effective diffusion. This work shows that high spatial resolution 3D data is necessary, and that 2D data is insufficient, in order to predict diffusion through the porous structure with high accuracy.
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| 8. |
- Fager, Cecilia, 1990, et al.
(författare)
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Optimization of FIB-SEM Tomography and Reconstruction for Soft, Porous, and Poorly Conducting Materials
- 2020
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Ingår i: Microscopy and Microanalysis. - 1431-9276 .- 1435-8115. ; 26:4, s. 837-845
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Tidskriftsartikel (refereegranskat)abstract
- Tomography using a focused ion beam (FIB) combined with a scanning electron microscope (SEM) is well-established for a wide range of conducting materials. However, performing FIB-SEM tomography on ion- and electron-beam-sensitive materials as well as poorly conducting soft materials remains challenging. Some common challenges include cross-sectioning artifacts, shadowing effects, and charging. Fully dense materials provide a planar cross section, whereas pores also expose subsurface areas of the planar cross-section surface. The image intensity of the subsurface areas gives rise to overlap between the grayscale intensity levels of the solid and pore areas, which complicates image processing and segmentation for three-dimensional (3D) reconstruction. To avoid the introduction of artifacts, the goal is to examine porous and poorly conducting soft materials as close as possible to their original state. This work presents a protocol for the optimization of FIB-SEM tomography parameters for porous and poorly conducting soft materials. The protocol reduces cross-sectioning artifacts, charging, and eliminates shadowing effects. In addition, it handles the subsurface and grayscale intensity overlap problems in image segmentation. The protocol was evaluated on porous polymer films which have both poor conductivity and pores. 3D reconstructions, with automated data segmentation, from three films with different porosities were successfully obtained.
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| 9. |
- Hallén, Tobias, et al.
(författare)
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Circulating brain injury biomarkers increase after endoscopic surgery for pituitary tumors.
- 2021
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Ingår i: Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia. - : Elsevier BV. - 1532-2653. ; 89, s. 113-121
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Tidskriftsartikel (refereegranskat)abstract
- Pituitary tumors and subsequent treatment with endoscopic transsphenoidal surgery (ETSS) may cause injury to suprasellar structures, causing long-term fatigue and neurocognitive impairment. A method to quantify brain injury after ETSS is not available. In this prospective, exploratory study of patients undergoing ETSS for pituitary tumors, a novel approach to detect possible neuronal damage is presented. Plasma concentrations of brain injury biomarkers (glial fibrillary acidic protein [GFAP], tau, and neurofilament light [NFL]) were measured the day before surgery, immediately after surgery, at day 1 and 5, and at 6 and 12months after surgery, using enzyme-linked immunosorbent assays. The association between the increase of biomarkers with preoperative tumor extension and postoperative patient-perceived fatigue was evaluated. Suprasellar tumor extension was assessed from MRI scans, and self-perceived fatigue was assessed using the Multidimensional Fatigue Inventory before and 6months after surgery. Thirty-five patients were included in the analysis. Compared to baseline, GFAP showed a maximal increase at day 1 after surgery (p=0.0005), tau peaked postoperatively on the day of surgery (p=0.019), and NFL reached its maximum at day 5 after surgery (p<0.0001). The increase in GFAP correlated with preoperative chiasmal compression (p=0.020). The increase in tau was correlated with preoperative chiasmal (p=0.011) and hypothalamus compression (p=0.016), and fatigue score 6months after surgery (p=0.016). In conclusion, the concentrations of brain injury biomarkers in blood increased after ETSS for pituitary tumors. The results indicate that postoperative plasma GFAP and tau might reflect astroglial and neuronal damage after ETSS.
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| 10. |
- Hallén, Tobias, et al.
(författare)
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Sinonasal Symptoms and Self-Reported Health before and after Endoscopic Pituitary Surgery-A Prospective Study
- 2022
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Ingår i: Journal of Neurological Surgery, Part B: Skull Base. - : Georg Thieme Verlag KG. - 2193-634X .- 2193-6331. ; 83:suppl. 2
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Tidskriftsartikel (refereegranskat)abstract
- © 2021 Thieme Medical Publishers, Inc.. All rights reserved. Objectives Despite the limited invasiveness of endoscopic transsphenoidal surgery (ETSS), some degree of nasal structure destruction is unavoidable. Our objective was to evaluate sinonasal morbidity and self-reported health before and 6 months after ETSS for pituitary tumors, and to identify possible predictive factors for deterioration in sinonasal health. Design Prospective observational cohort study. Setting University tertiary referral hospital. Participants Totally 109 consecutive adult patients undergoing ETSS for pituitary tumors between 2015 and 2019. Main Outcome Measures Sinonasal symptoms and self-reported health before and 6 months after ETSS, assessed by the Sinonasal Outcome Test (SNOT-22) and the EQ-5D questionnaire. Predictive factors for postoperative deterioration in sinonasal symptoms. Results The overall SNOT-22 score did not change, but the score of the rhinologic domain of SNOT-22 worsened from 6.0 ± 5.9 before to 8.0 ± 7.4 6 months after surgery (p = 0.011). The EQ-5D visual analog scale improved from 64.0 ± 22.9 before to 71.1 ± 18.7 6 months after surgery (p = 0.00088). Univariate and multivariable regression analyses showed that prior sinonasal surgery was associated with a significant worsening in rhinologic symptoms 6 months after surgery (p = 0.046 and p = 0.020, respectively). Conclusions Although self-reported overall health improved, significant deterioration of rhinologic symptoms was seen 6 months after ETSS. This information is important for preoperative patient counselling. Further refinement of the surgical technique and follow-up strategies to reduce postoperative sinonasal morbidity could be of value, especially in patients who have undergone prior sinonasal surgery.
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| 11. |
- Häbel, Henrike, 1987, et al.
(författare)
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Characterization of pore structure of polymer blended films used for controlled drug release
- 2016
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Ingår i: Journal of Controlled Release. - : Elsevier BV. - 0168-3659 .- 1873-4995. ; 222, s. 151-158
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Tidskriftsartikel (refereegranskat)abstract
- The characterization of the pore structure in pharmaceutical coatings is crucial for understanding and controlling mass transport properties and function in controlled drug release. Since the drug release rate can be associated with the film permeability, the effect of the pore structure on the permeability is important to study. In this paper, a new approach for characterizing the pore structure in polymer blended films was developed based on an image processing procedure for given two-dimensional scanning electron microscopy images of film cross-sections. The focus was on different measures for characterizing the complexity of the shape of a pore. The pore characterization developed was applied to ethyl cellulose (EC) and hydroxypropyl cellulose (HPC) blended films, often used as pharmaceutical coatings, where HPC acts as the pore former. It was studied how two different HPC viscosity grades influence the pore structure and, hence, mass transport through the respective films. The film with higher HPC viscosity grade had been observed to be more permeable than the other in a previous study; however, experiments had failed to show a difference between their pore structures. By instead characterizing the pore structures using tools from image analysis, statistically significant differences in pore area fraction and pore shape were identified. More specifically, it was found that the more permeable film with higher HPC viscosity grade seemed to have more extended and complex pore shapes than the film with lower HPC viscosity grade. This result indicates a greater degree of connectivity in the film with higher permeability and statistically confirms hypotheses on permeability from related experimental studies.
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| 12. |
- Jakobsson Ung, Eva, 1960, et al.
(författare)
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The pre- and postoperative illness trajectory in patients with pituitary tumours.
- 2019
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Ingår i: Endocrine connections. - 2049-3614. ; 8:7, s. 878-886
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Tidskriftsartikel (refereegranskat)abstract
- Experiences and need of support during surgery and start of replacement therapy in patients with pituitary tumours are highly unknown. This study therefore aimed at exploring patient experiences during pre- and postoperative care and recovery after pituitary surgery in patients with a pituitary tumour.Within a qualitative study design, 16 consecutive patients who underwent surgery for pituitary tumours were repeatedly interviewed. In total 42 interviews were performed before and after surgery. Analysis was performed using qualitative interpretation.Suffering a pituitary tumour was overwhelming for many patients and struggling with existential issues was common. Patients expressed loneliness and vulnerability before and after surgery. How professionals handled information in connection with diagnosis greatly affected the patients. Other patients with the same diagnosis were experienced as the greatest support. Normalisation of bodily symptoms and relationships with others were reported during postoperative recovery. However, a fear that the tumour would return was present.Patients with pituitary tumours need structured support, including peer support, which acknowledges physical, cognitive as well as emotional and existential concerns. Information related to diagnosis and surgery should be adapted in relation to the loneliness and the existential seriousness of the situation. Care and support for patients with pituitary tumours should preferably be organised based on continuity and an unbroken care pathway from the first pre-operative evaluation through to post-operative care and the start of a life-long endocrine treatment and tumour surveillance.
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| 13. |
- Jonsson, Rasmus, 1989, et al.
(författare)
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Chemical poisoning by zinc and phosphorous of Pt/Ba/Al2O3 NOx storage catalysts
- 2019
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Ingår i: Applied Catalysis A: General. - : Elsevier BV. - 1873-3875 .- 0926-860X. ; 571, s. 158-169
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Tidskriftsartikel (refereegranskat)abstract
- The effects of phosphorous and zinc on the performance of Pt/Ba/Al2O3 catalysts were investigated through wet impregnation of ammonium phosphate and zinc acetate aqueous solutions. Six different sample combinations were studied; 1 wt-% P, 1 wt-% Zn, 1 wt-% P with 1 wt-% Zn, 2 wt-% P, 2 wt-% Zn, 2 wt-% P with 2 wt-% Zn. NOx storage and reduction (NSR) activity and NO2 temperature programmed desorption (TPD) profiles were measured before and after impregnation of P and Zn. Samples containing P performed significantly worse than samples only containing Zn in both NSR activity and TPD measurements. The increased NOx slip during lean phase in activity measurements for P-poisoned samples is mainly related to an increased slip of NO2. This was found for both NO and NO2 in the gas feed during lean phase and suggests that it is mainly the storage component that is poisoned and not the noble metal. Furthermore, the combination (1 wt-% P and 1 wt-% Zn) proved to result in slightly worse performance than only 1 wt-% P, however this was not the case for samples containing 2 wt-%, where the addition of zinc reduced the negative effect of phosphorous. Measurements from NO2-TPD experiments showed that NOx release at low temperature was not affected by the addition of P, while desorption in the temperature range 425–475 °C was significantly reduced. It can therefore be concluded that the poisoning mainly is related to barium NOx storage sites and not to alumina sites. Moreover, X-ray diffraction measurements indicate that some of the barium species are affected by phosphorous. Images from scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX) mapping were in line with the results seen in both the activity tests and NO2-TPD experiments. Phosphorous was concentrated at the same position as barium in the observed images, whereas zinc was more evenly distributed over the surface. For the sample with both 2 wt-% P and 2 wt-% Zn, X-ray photoelectron spectroscopy measurements indicate that Zn and P have a low interaction and this suggests that most of the zinc and phosphorous are separated. However, STEM-EDX showed agglomerates of some zinc and phosphorous, which could be zinc phosphates. This is a plausible explanation of the decreased deactivation observed after introducing 2 wt-% Zn compared to the sample only containing 2 wt-% P.
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| 14. |
- Jonsson, Rasmus, 1989, et al.
(författare)
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Gas-phase phosphorous poisoning of a Pt/Ba/Al2O3 NOx storage catalyst
- 2018
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Ingår i: Catalysts. - : MDPI AG. - 2073-4344. ; 8:4
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Tidskriftsartikel (refereegranskat)abstract
- The effect of phosphorous exposure on the NO x storage capacity of a Pt/Ba/Al 2 O 3 catalyst coated on a ceramic monolith substrate has been studied. The catalyst was exposed to phosphorous by evaporating phosphoric acid in presence of H 2 O and O 2 . The NOx storage capacity was measured before and after the phosphorus exposure and a significant loss of the NO x storage capacity was detected after phosphorous exposure. The phosphorous poisoned samples were characterized by X-ray photoelectron spectroscopy (XPS), environmental scanning electron microscopy (ESEM), N 2 -physisorption and inductive coupled plasma atomic emission spectroscopy (ICP-AES). All characterization methods showed an axial distribution of phosphorous ranging from the inlet to the outlet of the coated monolith samples with a higher concentration at the inlet of the samples. Elemental analysis, using ICP-AES, confirmed this distribution of phosphorous on the catalyst surface. The specific surface area and pore volume were significantly lower at the inlet section of the monolith where the phosphorous concentration was higher, and higher at the outlet where the phosphorous concentration was lower. The results from the XPS and scanning electron microscopy (SEM)-energy dispersive X-ray (EDX) analyses showed higher accumulation of phosphorus towards the surface of the catalyst at the inlet of the monolith and the phosphorus was to a large extent present in the form of P 4 O 10 . However, in the middle section of the monolith, the XPS analysis revealed the presence of more metaphosphate (PO 3 – ). Moreover, the SEM-EDX analysis showed that the phosphorous to higher extent had diffused into the washcoat and was less accumulated at the surface close to the outlet of the sample
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| 15. |
- Mahmood, Zeid, et al.
(författare)
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The effect of acute exercise on interleukin-6 and hypothalamic-pituitary-adrenal axis responses in patients with coronary artery disease
- 2020
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Vulnerability to stress-induced inflammation has been linked to a dysfunctional hypothalamus–pituitary–adrenal (HPA) axis. In the present study, patients with known or suspected coronary artery disease (CAD) were assessed with respect to inflammatory and HPA axis response to acute physical exercise. An exercise stress test was combined with SPECT myocardial perfusion imaging. Plasma and saliva samples were collected before and 30 min after exercise. Interleukin (IL)-6 and adrenocorticotropic hormone (ACTH) were measured in plasma, while cortisol was measured in both plasma and saliva. In total, 124 patients were included of whom 29% had a prior history of CAD and/or a myocardial perfusion deficit. The levels of exercise intensity and duration were comparable in CAD and non-CAD patients. However, in CAD patients, IL-6 increased after exercise (p = 0.019) while no differences were seen in HPA axis variables. Conversely, patients without CAD exhibited increased levels of ACTH (p = 0.003) and cortisol (p = 0.004 in plasma, p = 0.006 in saliva), but no change in IL-6. We conclude that the IL-6 response to acute physical exercise is exaggerated in CAD patients and may be out of balance due to HPA axis hypoactivity. It remains to be further investigated whether this imbalance is a potential diagnostic and therapeutic target in CAD.
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| 16. |
- Matsakas, Leonidas, et al.
(författare)
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A novel hybrid organosolv: Steam explosion method for the efficient fractionation and pretreatment of birch biomass
- 2018
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834 .- 1754-6834. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: The main role of pretreatment is to reduce the natural biomass recalcitrance and thus enhance saccharification yield. A further prerequisite for efficient utilization of all biomass components is their efficient fractionation into well-defined process streams. Currently available pretreatment methods only partially fulfill these criteria. Steam explosion, for example, excels as a pretreatment method but has limited potential for fractionation, whereas organosolv is excellent for delignification but offers poor biomass deconstruction. Results: In this article, a hybrid method combining the cooking and fractionation of conventional organosolv pretreatment with the implementation of an explosive discharge of the cooking mixture at the end of pretreatment was developed. The effects of various pretreatment parameters (ethanol content, duration, and addition of sulfuric acid) were evaluated. Pretreatment of birch at 200 °C with 60% v/v ethanol and 1% w/wbiomassH2SO4was proven to be the most efficient pretreatment condition yielding pretreated solids with 77.9% w/w cellulose, 8.9% w/w hemicellulose, and 7.0 w/w lignin content. Under these conditions, high delignification of 86.2% was demonstrated. The recovered lignin was of high purity, with cellulose and hemicellulose contents not exceeding 0.31 and 3.25% w/w, respectively, and ash to be < 0.17% w/w in all cases, making it suitable for various applications. The pretreated solids presented high saccharification yields, reaching 68% at low enzyme load (6 FPU/g) and complete saccharification at high enzyme load (22.5 FPU/g). Finally, simultaneous saccharification and fermentation (SSF) at 20% w/w solids yielded an ethanol titer of 80 g/L after 192 h, corresponding to 90% of the theoretical maximum. Conclusions: The novel hybrid method developed in this study allowed for the efficient fractionation of birch biomass and production of pretreated solids with high cellulose and low lignin contents. Moreover, the explosive discharge at the end of pretreatment had a positive effect on enzymatic saccharification, resulting in high hydrolyzability of the pretreated solids and elevated ethanol titers in the following high-gravity SSF. To the best of our knowledge, the ethanol concentration obtained with this method is the highest so far for birch biomass.
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| 17. |
- Matsakas, Leonidas, et al.
(författare)
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Lignin-first biomass fractionation using a hybrid organosolv – Steam explosion pretreatment technology improves the saccharification and fermentability of spruce biomass
- 2019
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Ingår i: Bioresource Technology. - : Elsevier. - 0960-8524 .- 1873-2976. ; 273, s. 521-528
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Tidskriftsartikel (refereegranskat)abstract
- For a transition to a sustainable society, fuels, chemicals, and materials should be produced from renewable resources. Lignocellulosic biomass constitutes an abundant and renewable feedstock; however, its successful application in a biorefinery requires efficient fractionation into its components; cellulose, hemicellulose and lignin. Here, we demonstrate that a newly established hybrid organosolv – steam explosion pretreatment can effectively fractionate spruce biomass to yield pretreated solids with high cellulose (72% w/w) and low lignin (delignification up to 79.4% w/w) content. The cellulose-rich pretreated solids present high saccharification yields (up to 61% w/w) making them ideal for subsequent bioconversion processes. Moreover, under high-gravity conditions (22% w/w) we obtained an ethanol titer of 61.7 g/L, the highest so far reported for spruce biomass. Finally, the obtained high-purity lignin is suitable for various advanced applications. In conclusion, hybrid organosolv pretreatment could offer a closed-loop biorefinery while simultaneously adding value to all biomass components.
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| 18. |
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| 19. |
- Papakokkinou, Eleni, et al.
(författare)
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Excess Morbidity Persists in Patients With Cushing’s Disease During Long-term Remission : A Swedish Nationwide Study
- 2020
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - Washington : Oxford University Press. - 0021-972X .- 1945-7197. ; 105:8, s. 2616-2624
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Tidskriftsartikel (refereegranskat)abstract
- Context: Whether multisystem morbidity in Cushing's disease (CD) remains elevated during long-term remission is still undetermined.Objective: To investigate comorbidities in patients with CD.Design, setting, and patients: A retrospective, nationwide study of patients with CD identified in the Swedish National Patient Register between 1987 and 2013. Individual medical records were reviewed to verify diagnosis and remission status.Main outcomes: Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were calculated by using the Swedish general population as reference. Comorbidities were investigated during three different time periods: (i) during the 3 years before diagnosis, (ii) from diagnosis to 1 year after remission, and (iii) during long-term remission.Results: We included 502 patients with confirmed CD, of whom 419 were in remission for a median of 10 (interquartile range 4 to 21) years. SIRs (95% CI) for myocardial infarction (4.4; 1.2 to 11.4), fractures (4.9; 2.7 to 8.3), and deep vein thrombosis (13.8; 3.8 to 35.3) were increased during the 3-year period before diagnosis. From diagnosis until 1 year after remission, SIRs (95% CI were increased for thromboembolism (18.3; 7.9 to 36.0), stroke (4.9; 1.3 to 12.5), and sepsis (13.6; 3.7 to 34.8). SIRs for thromboembolism (4.9; 2.6 to 8.4), stroke (3.1; 1.8 to 4.9), and sepsis (6.0; 3.1 to 10.6) remained increased during long-term remission.Conclusion: Patients with CD have an increased incidence of stroke, thromboembolism, and sepsis even after remission, emphasizing the importance of early identification and management of risk factors for these comorbidities during long-term follow-up.
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| 20. |
- Ragnarsson, Oskar, 1971, et al.
(författare)
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Overall and Disease-Specific Mortality in Patients With Cushing Disease: A Swedish Nationwide Study
- 2019
-
Ingår i: Journal of Clinical Endocrinology and Metabolism. - : ENDOCRINE SOC. - 0021-972X .- 1945-7197. ; 104:6, s. 2375-2384
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Tidskriftsartikel (refereegranskat)abstract
- Context: Whether patients with Cushing disease (CD) in remission have increased mortality is still debatable. Objective: To study overall and disease-specific mortality and predictive factors in an unselected nationwide cohort of patients with CD. Design, Patients, and Methods: A retrospective study of patients diagnosed with CD, identified in the Swedish National Patient Registry between 1987 and 2013. Medical records were systematically reviewed to verify the diagnosis. Standardized mortality ratios (SMRs) with 95% CIs were calculated and Cox regression models were used to identify predictors of mortality. Results: Of 502 identified patients with CD (n = 387 women; 77%), 419 (83%) were confirmed to be in remission. Mean age at diagnosis was 43 (SD, 16) years and median follow-up was 13 (interquartile range, 6 to 23) years. The observed number of deaths was 133 vs 54 expected, resulting in an overall SMR of 2.5 (95% CI, 2.1 to 2.9). The commonest cause of death was cardiovascular diseases (SMR, 3.3; 95% CI, 2.6 to 4.3). Excess mortality was also found associated with infections and suicide. For patients in remission, the SMR was 1.9 (95% CI, 1.5 to 2.3); bilateral adrenalectomy and glucocorticoid replacement therapy were independently associated with increased mortality, whereas GH replacement was associated with improved outcome. Conclusion: Findings from this large nationwide study indicate that patients with CD have excess mortality. The findings illustrate the importance of achieving remission and continued active surveillance, along with adequate hormone replacement and evaluation of cardiovascular risk and mental health.
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| 21. |
- Ragnarsson, Oskar, 1971, et al.
(författare)
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The incidence of Cushing’s disease : a nationwide Swedish study
- 2019
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Ingår i: Pituitary. - : Springer. - 1386-341X .- 1573-7403. ; 22:2, s. 179-186
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Tidskriftsartikel (refereegranskat)abstract
- Background: Studies on the incidence of Cushing’s disease (CD) are few and usually limited by a small number of patients. The aim of this study was to assess the annual incidence in a nationwide cohort of patients with presumed CD in Sweden.Methods: Patients registered with a diagnostic code for Cushing’s syndrome (CS) or CD, between 1987 and 2013 were identified in the Swedish National Patient Registry. The CD diagnosis was validated by reviewing clinical, biochemical, imaging, and histopathological data.Results: Of 1317 patients identified, 534 (41%) had confirmed CD. One-hundred-and-fifty-six (12%) patients had other forms of CS, 41 (3%) had probable but unconfirmed CD, and 334 (25%) had diagnoses unrelated to CS. The mean (95% confidence interval) annual incidence between 1987 and 2013 of confirmed CD was 1.6 (1.4–1.8) cases per million. 1987–1995, 1996–2004, and 2005–2013, the mean annual incidence was 1.5 (1.1–1.8), 1.4 (1.0–1.7) and 2.0 (1.7–2.3) cases per million, respectively. During the last time period the incidence was higher than during the first and second time periods (P < 0.05).Conclusion: The incidence of CD in Sweden (1.6 cases per million) is in agreement with most previous reports. A higher incidence between 2005 and 2013 compared to 1987–2004 was noticed. Whether this reflects a truly increased incidence of the disease, or simply an increased awareness, earlier recognition, and earlier diagnosis can, however, not be answered. This study also illustrates the importance of validation of the diagnosis of CD in epidemiological research.
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| 22. |
- Röding, Magnus, 1984, et al.
(författare)
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Three-dimensional reconstruction of porous polymer films from FIB-SEM nanotomography data using random forests
- 2021
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Ingår i: Journal of Microscopy. - : Wiley. - 1365-2818 .- 0022-2720. ; 281:1, s. 76-86
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Tidskriftsartikel (refereegranskat)abstract
- Combined focused ion beam and scanning electron microscope (FIB-SEM) tomography is a well-established technique for high resolution imaging and reconstruction of the microstructure of a wide range of materials. Segmentation of FIB-SEM data is complicated due to a number of factors; the most prominent is that for porous materials, the scanning electron microscope image slices contain information not only from the planar cross-section of the material but also from underlying, exposed subsurface pores. In this work, we develop a segmentation method for FIB-SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These materials are used for coating pharmaceutical oral dosage forms (tablets or pellets) to control drug release. We study three samples of ethyl cellulose and hydroxypropyl cellulose with different volume fractions where the hydroxypropyl cellulose phase has been leached out, resulting in a porous material. The data are segmented using scale-space features and a random forest classifier. We demonstrate good agreement with manual segmentations. The method enables quantitative characterization and subsequent optimization of material structure for controlled release applications. Although the methodology is demonstrated on porous polymer films, it is applicable to other soft porous materials imaged by FIB-SEM. We make the data and software used publicly available to facilitate further development of FIB-SEM segmentation methods. Lay Description For imaging of very fine structures in materials, the resolution limits of, e.g. X-ray computed tomography quickly become a bottleneck. Scanning electron microscopy (SEM) provides a way out, but it is essentially a two-dimensional imaging technique. One manner in which to extend it to three dimensions is to use a focused ion beam (FIB) combined with a scanning electron microscopy and acquire tomography data. In FIB-SEM tomography, ions are used to perform serial sectioning and the electron beam is used to image the cross section surface. This is a well-established method for a wide range of materials. However, image analysis of FIB-SEM data is complicated for a variety of reasons, in particular for porous media. In this work, we analyse FIB-SEM data from ethyl cellulose porous films made from ethyl cellulose and hydroxypropyl cellulose (EC/HPC) polymer blends. These films are used as coatings for controlled drug release. The aim is to perform image segmentation, i.e. to identify which parts of the image data constitute the pores and the solid, respectively. Manual segmentation, i.e. when a trained operator manually identifies areas constituting pores and solid, is too time-consuming to do in full for our very large data sets. However, by performing manual segmentation on a set of small, random regions of the data, we can train a machine learning algorithm to perform automatic segmentation on the entire data sets. The method yields good agreement with the manual segmentations and yields porosities of the entire data sets in very good agreement with expected values. The method facilitates understanding and quantitative characterization of the geometrical structure of the materials, and ultimately understanding of how to tailor the drug release.
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| 23. |
- Schleeh, Joel, 1986, et al.
(författare)
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Passivation of InGaAs/InAlAs/InP HEMTs using Al2O3 atomic layer deposition
- 2011
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Ingår i: Conference Proceedings - International Conference on Indium Phosphide and Related Materials. 2011 Compound Semiconductor Week and 23rd International Conference on Indium Phosphide and Related Materials, CSW/IPRM 2011, Berlin, 22-26 May 2011. - 1092-8669. - 9781457717536
-
Konferensbidrag (refereegranskat)abstract
- InGaAs/InAlAs/InP HEMTs (InP HEMTs) passivated by Al2O3 atomic layer deposition (ALD) demonstrated improved DC performance compared to Si3N4 plasma enhanced chemical vapour deposition (PECVD). DC measurements have been performed on 130 nm gate-length devices before and after passivation. An increase in maximum drain current density of 20% and extrinsic transconductance of 30% were observed after both ALD and PECVD device passivation. In comparison to PECVD passivated InP HEMTs, ALD passivated devices demonstrated a full suppression of a kink in the I-V characteristics associated with surface traps.
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| 24. |
- Sun, Jie, 1977, et al.
(författare)
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Direct Chemical Vapor Deposition of Large-Area Carbon Thin Films on Gallium Nitride for Transparent Electrodes: A First Attempt
- 2012
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Ingår i: IEEE Transactions on Semiconductor Manufacturing. - : Institute of Electrical and Electronics Engineers (IEEE). - 0894-6507 .- 1558-2345. ; 25:3, s. 494-501
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Tidskriftsartikel (refereegranskat)abstract
- Direct formation of large-area carbon thin films on gallium nitride by chemical vapor deposition without metallic catalysts is demonstrated. A high flow of ammonia is used to stabilize the surface of the GaN (0001)/sapphire substrate during the deposition at 950 degrees C. Various characterization methods verify that the synthesized thin films are largely sp(2) bonded, macroscopically uniform, and electrically conducting. The carbon thin films possess optical transparencies comparable to that of exfoliated graphene. This paper offers a viable route toward the use of carbon-based materials for future transparent electrodes in III-nitride optoelectronics, such as GaN-based light emitting diodes and laser diodes.
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| 25. |
- Sveningsson, Martin, 1977, et al.
(författare)
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Quantifying temperature-enhanced electron field emission from individual carbon nanotubes
- 2005
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Ingår i: Physical Review B. - : American Physical Society. ; 72:8
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Tidskriftsartikel (refereegranskat)abstract
- The electron field emission properties of individual multiwalled carbon nanotubes have been examined using a combined STM-TEM microscope. The measured electron emission, for low emission currents, can be fitted with a standard Fowler-Nordheim model. For higher electron emission, above 10 µA for an individual carbon nanotube, we observe a significantly increased emission current leading to a nonlinear Fowler-Nordheim plot. The nonlinearity is caused by thermally enhanced electron emission due to Ohmic heating of the carbon nanotube. This is verified by modeling the electron field emission current. In addition to the influence of radiative cooling and the temperature dependence of the nanotube resistivity, we clearly show that a consideration of the temperature change due to the electron emission process itself, known as the Nottingham effect, is crucial to obtain good agreement with the experimental data.
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| 26. |
- Abel, Edvard, 1970, et al.
(författare)
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Fatigue in Patients With Head and Neck Cancer Treated With Radiation Therapy: A Prospective Study of Patient-Reported Outcomes and Their Association With Radiation Dose to the Cerebellum
- 2022
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Ingår i: Advances in Radiation Oncology. - : Elsevier BV. - 2452-1094. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Although fatigue is a known side effect in patients with head and neck cancer (HNC) receiving radiation therapy, knowledge regarding long-term fatigue and dose-response relationships to organs at risk is scarce. The aim of this prospective study was to analyze patient-reported fatigue in patients with HNC receiving radiation therapy and to explore any possible association with organ-at-risk doses. Methods and Materials: Patients with HNC referred for curative radiation therapy were eligible for inclusion in the study. To assess patient-reported fatigue, quality of life questionnaires (European Organization for Research and Treatment of Cancer QLQ-C30 and QLQ-FA12) were distributed before treatment and 1, 3, 6, 12, 24, and 60 months after the start of treatment. Mean dose (Dmean) and near maximum dose (D2%) of the cerebellum and brain stem were evaluated in relation to baseline-adjusted fatigue scores at 3 months. Results: One hundred twenty-six patients treated with intensity modulated radiation therapy between 2008 and 2010 were available for final analysis. Female sex and age <60 years were associated with higher fatigue at baseline, whereas patients also treated with chemotherapy had reduced physical and emotional fatigue at 6 months. Physical fatigue (QLQ-FA12 scale) increased from baseline up to 3 months (29 vs 59; P < .0001) but showed no difference compared with baseline from 1 to 5 years. Emotional fatigue was significantly lower at 5 years compared with baseline (14 vs 28; P < .0001). Patients with cerebellum Dmean > 3.5 Gy had higher mean physical fatigue scores at 3 months (38 vs 27; P = .036). Conclusions: Although there is a significant increase in fatigue scores for patients with HNC up to 1 year after radiation therapy, this study showed a return to baseline levels at 5 years. A possible association was found between physical fatigue and a higher mean dose to the cerebellum.
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| 27. |
- Ahrentorp, Fredrik, et al.
(författare)
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Effective particle magnetic moment of multi-core particles
- 2015
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 380, s. 221-226
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Tidskriftsartikel (refereegranskat)abstract
- In this study we investigate the magnetic behavior of magnetic multi-core particles and the differences in the magnetic properties of multi-core and single-core nanoparticles and correlate the results with the nanostructure of the different particles as determined from transmission electron microscopy (TEM). We also investigate how the effective particle magnetic moment is coupled to the individual moments of the single-domain nanocrystals by using different measurement techniques: DC magnetometry, AC susceptometry, dynamic light scattering and TEM. We have studied two magnetic multi-core particle systems BNF Starch from Micromod with a median particle diameter of 100 am and FeraSpin R from nanoPET with a median particle diameter of 70 nm - and one single-core particle system - SHP25 from Ocean NanoTech with a median particle core diameter of 25 nm. (C) 2014 Elsevier B.V. All rights reserved.
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| 28. |
- Alaverdyan, Yury, 1976, et al.
(författare)
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Optical antennas based on coupled nanoholes in thin metal films
- 2007
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Ingår i: Nature Physics. - : Springer Science and Business Media LLC. - 1745-2481 .- 1745-2473. ; 3:12, s. 884-889
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Tidskriftsartikel (refereegranskat)abstract
- The ability to control optical effects at the nanoscale is a challenge that could be of great importance for a range of photonic applications. However, progress requires a deep understanding of the relationship between near-field and far-field properties of the individual elements of the nanostructure, as well as of the role of nano-optical interactions. Here, we show that the strong interaction between nanoholes in optically thin metal films can be used to readily tune their spectral response and visibility. Control of this interaction in short chains of nanoholes enables either amplification or almost total suppression of the scattered light. The phenomena are interpreted in terms of hole coupling mediated via antisymmetric surface plasmon polaritons, which makes the nanohole chains effectively behave as linear wire antennas.
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| 29. |
- Aljassim, Obaid, et al.
(författare)
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Inflammatory response and platelet activation after off-pump coronary artery bypass surgery.
- 2006
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Ingår i: Scandinavian cardiovascular journal : SCJ. - : Informa UK Limited. - 1401-7431 .- 1651-2006. ; 40:1, s. 43-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cardiac surgery induces a systemic inflammatory activation and alterations in the hemostatic cascade. The responses contribute to postoperative complications but may also have protective effects. We investigated the relationship between inflammation, hemostasis and bleeding after off-pump coronary artery bypass surgery (OPCAB). METHODS: Ten OPCAB patients were included in a prospective descriptive study. Selected markers of inflammation (IL-6, IL-8, PMN-elastase, C3a, and SC5b-9), and hemostasis (platelet count, ss-thromboglobulin, anti-thrombin, D-dimer and fibrinogen) were measured before and immediately after surgery. Postoperative bleeding was registered. RESULTS: Inflammatory variables did not alter significantly during surgery while ss-thromboglobulin concentrations increased and anti-thrombin and fibrinogen decreased. There were significant postoperative correlations between PMN-elastase and ss-thromboglobulin (r=0.82, p=0.004), between PMN-elastase and fibrinogen (r=0.69, p=0.03) and between C3a and ss-thromboglobulin (r=0.71, p=0.02). In addition, there were significant inverse correlations between postoperative bleeding and pre- and postoperative fibrinogen levels (r=-0.76, p=0.011 and r=-0.84, p=0.002 respectively), between bleeding and postoperative ss-thromboglobulin levels (r=-0.66, p=0.04) and between bleeding and postoperative PMN-elastase (r=-0.75, p=0.01). CONCLUSIONS: The results give further evidence for an association between the inflammatory response and hemostasis after cardiac surgery.
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| 30. |
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| 31. |
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| 32. |
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| 33. |
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| 34. |
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| 35. |
- Annadi, A., et al.
(författare)
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Anisotropic two-dimensional electron gas at the LaAlO3/SrTiO3 (110) interface
- 2013
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 4
-
Tidskriftsartikel (refereegranskat)abstract
- The observation of a high-mobility two-dimensional electron gas between two insulating complex oxides, especially LaAlO3/SrTiO3, has enhanced the potential of oxides for electronics. The occurrence of this conductivity is believed to be driven by polarization discontinuity, leading to an electronic reconstruction. In this scenario, the crystal orientation has an important role and no conductivity would be expected, for example, for the interface between LaAlO3 and (110)-oriented SrTiO3, which should not have a polarization discontinuity. Here we report the observation of unexpected conductivity at the LaAlO3/SrTiO3 interface prepared on (110)-oriented SrTiO3, with a LaAlO3-layer thickness-dependent metal-insulator transition. Density functional theory calculation reveals that electronic reconstruction, and thus conductivity, is still possible at this (110) interface by considering the energetically favourable (110) interface structure, that is, buckled TiO2/LaO, in which the polarization discontinuity is still present. The conductivity was further found to be strongly anisotropic along the different crystallographic directions with potential for anisotropic superconductivity and magnetism, leading to possible new physics and applications.
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| 36. |
- Antonsson, Jakob, et al.
(författare)
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Modeling Colloidal Particle Aggregation Using Cluster Aggregation with Multiple Particle Interactions
- 2024
-
Ingår i: Journal of Physical Chemistry B. - 1520-6106 .- 1520-5207. ; 128:18, s. 4513-4524
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Tidskriftsartikel (refereegranskat)abstract
- In this study, we investigate the aggregation dynamics of colloidal silica by generating simulated structures and comparing them to experimental data gathered through scanning transmission electron microscopy (STEM). More specifically, diffusion-limited cluster aggregation and reaction-limited cluster aggregation models with different functions for the probability of particles sticking upon contact were used. Aside from using a constant sticking probability, the sticking probability was allowed to depend on the masses of the colliding clusters and on the number of particles close to the collision between clusters. The different models of the sticking probability were evaluated based on the goodness-of-fit of spatial summary statistics. Furthermore, the models were compared to the experimental data by calculating the structures’ fractal dimension and mass transport properties from simulations of flow and diffusion. The sticking probability, depending on the interaction with multiple particles close to the collision site, led to structures most similar to the STEM data.
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| 37. |
- Asgari, H., et al.
(författare)
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Effect of grain size on high strain rate deformation of rolled Mg-4Y-3RE alloy in compression
- 2015
-
Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 633, s. 92-102
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium alloys are widely used in automotive and aerospace industries, where they can be exposed to high strain rate conditions such as car crash and ballistic impact. Grain size is an important factor that can affect the mechanical behavior of magnesium alloys at high strain rates. Therefore, it is very important to evaluate the effects of grain size on the dynamic mechanical response of magnesium alloys under shock-loading conditions. In this research, texture evolution, microstructural changes and dynamic mechanical behavior of rolled Mg-4Y-3RE alloy samples, with grain sizes of 8, 25 and 46 mu m, deformed under compressive shock-loading are investigated. Dynamic shock loading tests were conducted using Split Hopkinson Pressure Bar at room temperature at a strain rate of 1200 s(-1). Texture measurements indicate development of a double-peak (00.2) basal texture in all the samples during shock loading. However, slightly higher intensities were observed for coarse-grained samples. Both strength and ductility were found to decrease with increasing grain size, while twining fraction and strain hardening rate increase with increasing grain size. The activity of double and contraction twins increased with increase in grain size. Furthermore, activation of pyramidal (c + a) slip system during the shock loading of the Mg-4Y-3RE alloy was confirmed using the 'g.b' analysis method.
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| 38. |
- Asgari, H., et al.
(författare)
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Effect of yttrium on the twinning and plastic deformation of AE magnesium alloy under ballistic impact
- 2015
-
Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 623, s. 10-21
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Tidskriftsartikel (refereegranskat)abstract
- In this research, effect of yttrium on the texture formation, microstructural evolution and mechanical response of AE42 and AE44 cast magnesium alloys were investigated under ballistic impact. The selected strain rates were 800 and 1100 s(-1) and the tests were conducted using Split Hopkinson Pressure Bar. It was inferred that after high velocity impact, a weaker basal texture developed in the samples with lower content of yttrium. Experimental results also showed that by increasing the concentration of yttrium in the cast AE alloys, strength, ductility and dislocation density of the impacted alloys increased but, the fraction of twinning decreased, which indicate the effective influence of yttrium on the nucleation and growth of twins. Moreover, it was inferred that accumulation of dislocations at intersections of the twins led to the cracking and fracture of the samples under shock loading conditions.
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| 39. |
- Asgari, H., et al.
(författare)
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Experimental and simulation analysis of texture formation and deformation mechanism of rolled AZ31B magnesium alloy under dynamic loading
- 2014
-
Ingår i: Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing. - : Elsevier BV. - 0921-5093. ; 618, s. 310-322
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Tidskriftsartikel (refereegranskat)abstract
- Magnesium alloys components are potentially used under shock loading conditions. Considering the fact that deformation behavior is completely different under high strain rate conditions compared to quasi-static conditions, it is very important to evaluate the dynamic mechanical response and deformation mechanisms of magnesium alloys under impact loading. In this research, texture formation, microstructural changes and dynamic deformation behavior of rolled AZ31B in the tempered H24 stress-relieved conditions, shock-loaded under compressive dynamic loading, were investigated. Texture measurements showed that the as-received AZ31B alloy had a strong (00.2) basal texture. Four groups of cylindrical samples were cut in the rolling direction (RD), in 45 degrees to the RD, in the transverse direction (TD) and in the direction perpendicular to the RD-TD plane. Dynamic shock loading of the test samples were conducted using Split Hopkinson Pressure Bar at room temperature at strain rates ranging from 600 to 1100 s(-1), while loading direction was parallel to the longitudinal axis of the cylindrical samples. After high strain rate deformation, although the loading direction was different, a strong (00.2) basal texture was observed in all samples. It was inferred that increasing the strain rate led to an increase in strength and ductility, but to a decrease in twinning fraction, indicating the possible activation of non-basal slip systems. Besides, a high degree of mechanical anisotropy was found for all strain rates used such that the lowest strength was registered for the samples cut along the direction parallel to the rolling direction. A viscoplastic self-consistent model with a tangent approach was used to corroborate the experimental textures and possible deformation mechanisms by simulation.
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| 40. |
- Asgari, H., et al.
(författare)
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Grain size dependence of dynamic mechanical behavior of AZ31B magnesium alloy sheet under compressive shock loading
- 2015
-
Ingår i: Materials Characterization. - : Elsevier BV. - 1044-5803. ; 106, s. 359-367
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Tidskriftsartikel (refereegranskat)abstract
- The effects of grain size on the dynamic deformation behavior of rolled AZ31B alloy at high strain rates were investigated. Rolled AZ31B alloy samples with grain sizes of 6,18 and 37 pm, were subjected to shock loading tests using Split Hopkinson Pressure Bar at room temperature and at a strain rate of 1100 s(-1) It was found that a double-peak basal texture formed in the shock loaded samples. The strength and ductility of the alloy under the high strain-rate compressive loading increased with decreasing grain size. However, twinning fraction and strain hardening rate were found to decrease with decreasing grain size. In addition, orientation imaging microscopy showed a higher contribution of double and contraction twins in the deformation process of the coarse-grained samples. Using transmission electron microscopy, pyramidal dislocations were detected in the shock loaded sample, proving the activation of pyramidal slip system under dynamic impact loading.
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| 41. |
- Aurino, Pier Paolo, 1985, et al.
(författare)
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Nano-patterning of the electron gas at the LaAlO3/SrTiO3 interface using low-energy ion beam irradiation
- 2013
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:20, s. 201610-
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Tidskriftsartikel (refereegranskat)abstract
- The quasi-two dimensional electron gas formed at the interface between LaAlO3 (LAO) and SrTiO3 (STO) shows fascinating properties, such as two-dimensional superconductivity, giant electric field effect, and the possible co-existence of ferromagnetic and superconducting phases. In this work, we demonstrate that the conducting LAO/STO interface can be made insulating after short irradiation by a beam of low energy Ar+ ions. The irradiation process does neither result in physical removal of the LAO film nor produces oxygen vacancies in the STO layer. Using electron beam lithography and low ion beam energy irradiation, we fabricated conducting nano-structures in the LAO/STO interface with dimensions down to 50 nm. Such a reliable and robust method of nano-patterning may be a prerequisite for future electronic applications of the LAO/STO interface.
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| 42. |
- Aurino, Pier Paolo, 1985, et al.
(författare)
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Reversible metal-insulator transition of Ar-irradiated LaAlO3/SrTiO3 interfaces
- 2015
-
Ingår i: Physical Review B - Condensed Matter and Materials Physics. - 2469-9950 .- 2469-9969. ; 92:15
-
Tidskriftsartikel (refereegranskat)abstract
- The conducting state of a quasi-two-dimensional electron gas (q2DEG), formed at the heterointerface between the two wide-bandgap insulators LaAlO3 (LAO) and SrTiO3, can be made completely insulating by low-energy, 150-eV, Ar+ irradiation. The metallic behavior of the interface can be recovered by high-temperature oxygen annealing. The electrical transport properties of the recovered q2DEG are exactly the same as before the irradiation. Microstructural investigations confirm that the transition is not due to physical etching or crystal lattice distortion of the LAO film below its critical thickness. They also reveal a correlation between electrical state, LAO film surface amorphization, and argon ion implantation. The experimental results are in agreement with density functional theory calculations of Ar implantation and migration in the LAO film. This suggests that the metal-insulator transition may be caused by charge trapping in the defect amorphous layer created during the ion irradiation.
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| 43. |
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| 44. |
- Bauch, Thilo, 1972, et al.
(författare)
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High critical temperature superconductor Josephson junctions for quantum circuit applications
- 2009
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Ingår i: Physica Scripta. ; T137, s. 014006-
-
Konferensbidrag (refereegranskat)abstract
- Recent findings of macroscopic quantum properties in high critical temperature superconductor (HTS) Josephson junctions (JJs) point toward the need to revise the role of zero energy quasi-particles in this novel superconductor. We will discuss the possibility of designing superconducting artificial atoms in a transmon configuration to study the low energy excitation spectra of HTS. We have engineered high quality grain boundary JJs on low dielectric constant substrates. By fabricating submicron junctions, we extract values of capacitance and Josephson critical current densities that satisfy the main transmon design requirements. Moreover, the measured critical current noise power extrapolated at 1 Hz gives a dephasing time of 25 ns, which indicates that the observation of macroscopic quantum coherent effects in HTS JJ is a feasible task.
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| 45. |
- Benedet, Mattia, et al.
(författare)
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Efficient photoactivated hydrogen evolution promoted by Cu x O-gCN-TiO 2 -Au (x = 1,2) nanoarchitectures
- 2024
-
Ingår i: RSC Advances. - 2046-2069. ; 14:10, s. 7221-7228
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we propose an original and potentially scalable synthetic route for the fabrication of CuxO-gCN-TiO2-Au (x = 1,2) nanoarchitectures, based on Cu foam anodization, graphitic carbon nitride liquid-phase deposition, and TiO2/Au sputtering. A thorough chemico-physical characterization by complementary analytical tools revealed the formation of nanoarchitectures featuring an intimate contact between the system components and a high dispersion of gold nanoparticles. Modulation of single component interplay yielded excellent functional performances in photoactivated hydrogen evolution, corresponding to a photocurrent of ≈−5.7 mA cm−2 at 0.0 V vs. the reversible hydrogen electrode (RHE). These features, along with the very good service life, represent a cornerstone for the conversion of natural resources, as water and largely available sunlight, into added-value solar fuels.
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| 46. |
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| 47. |
- Bergqvist, J., et al.
(författare)
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Sub-glass transition annealing enhances polymer solar cell performance
- 2014
-
Ingår i: Journal of Materials Chemistry A. - 2050-7488 .- 2050-7496. ; 2:17, s. 6146-6152
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Tidskriftsartikel (refereegranskat)abstract
- Thermal annealing of non-crystalline polymer:fullerene blends typically results in a drastic decrease in solar cell performance. In particular aggressive annealing above the glass transition temperature results in a detrimental coarsening of the blend nanostructure. We demonstrate that mild annealing below the glass transition temperature is a viable avenue to control the nanostructure of a non-crystalline thiophene–quinoxaline copolymer:fullerene blend. Direct imaging methods indicate that coarsening of the blend nanostructure can be avoided. However, a combination of absorption and luminescence spectroscopy reveals that local changes in the polymer conformation as well as limited fullerene aggregation are permitted to occur. As a result, we are able to optimise the solar cell performance evenly across different positions of the coated area, which is a necessary criterion for large-scale, high throughput production.
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| 48. |
- Boikov, Iouri, 1949, et al.
(författare)
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Variations in the electrical resistivity of La0.67Ca0.33MnO3 films and induced interconversions of ferromagnetic and nonferromagnetic inclusions in their bulk
- 2011
-
Ingår i: Physics of the Solid State. - 1063-7834 .- 1090-6460. ; 53:10, s. 2168-2173
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Tidskriftsartikel (refereegranskat)abstract
- A significant (similar to 1.8%) positive unit between the parameters of the crystal lattice is the reason of tetragonal distortion (a (aSyen)/a (aEuro-) a parts per thousand 1.04) and reduction in the volume of the unit cell of La(0.67)Ca(0.33)MnO(3) films (15 nm) quasicoherently grown on the (001) surface of a LaAlO(3) substrate. The films consist of single-crystal blocks with the lateral size of 30-50 nm. The atomically smooth LaAlO(3)-La(0.67)Ca(0.33)MnO(3) interphase boundary has no misfit dislocations. At T = 4.2 K, the transformation of nonferromagnetic phase inclusions into ferromagnetic ones in a constant magnetic field H is accompanied by a stable reduction in the electrical resistivity rho of manganite films with time, so that the curve rho(t) is well approximated by the relationship rho(t) similar to rho(1)(t - t (0))(1/2), (where t (0) is the time for establishment of the specified value (mu(0) H = 5 T) of the magnetic field and rho(1) is a coefficient independent of H). The magnetocrystalline anisotropy due to the elastic deformation of films by the substrate and stratification of electronic phases are the reasons of the distinct hysteresis in the dependences rho(mu(0) H, T 0 -> -5 T -> 0 -> 5 T. At T = 50 K and mu(0) H = 0.4 T, the magnetoresistance MR = 100% [rho(mu(0) H) - rho(mu(0) H = 0)]/rho(mu(0) H = 0) of LCMO films attains 150%.
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| 49. |
- Bounechada, Djamela, 1984, et al.
(författare)
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Mechanisms behind sulfur promoted oxidation of methane
- 2013
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Ingår i: Physical Chemistry Chemical Physics. - : Royal Society of Chemistry (RSC). - 1463-9084 .- 1463-9076. ; 15:22, s. 8648-8661
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Tidskriftsartikel (refereegranskat)abstract
- The promoting effect of SO2 on the activity for methane oxidation over platinum supported on silica, alumina and ceria has been studied by flow-reactor, in situ infrared spectroscopy and in situ high-energy x-ray diffraction experiments under transient reaction conditions. The catalytic activity is clearly dependent on the support material and its interaction with the noble metal both in absence and presence of sulfur. On platinum, the competitive reactant adsorption favors oxygen dissociation such that oxygen self-poisoning is observed for Pt/silica and Pt/alumina. Contrarily for Pt/ceria, no oxygen self-poisoning is observed, which seems to be due to additional reaction channels via sites on the platinum-ceria boundary and/or ceria surface considerably far from the Pt crystallites. Addition of sulfur dioxide generally leads to the formation of ad-SOx species on the supports with a concomitant removal and/or blockage/rearrangement of surface hydroxyl groups. Thereby, the methane oxidation is inhibited for Pt/silica, enhanced for Pt/alumina and temporary enhanced followed by inhibition after long-term exposure to sulfur for Pt/ceria. The observations can be explained by competitive oxidation of SO2 and CH4 on Pt/silica, formation of new active sites at the noble metal-support interface promoting dissociative adsorption of methane on Pt/alumina, and in the case of Pt/ceria, formation of promoting interfacial surface sulfates followed by formation of deactivating bulk-like sulfate species. Furthermore, it can be excluded that reduction of detrimental high oxygen coverage and/or oxide formation on the platinum particles through SO2 oxidation is the main cause for the promotional effects observed.
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| 50. |
- Bäcke, Olof, 1984, et al.
(författare)
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Enhanced thermal stability of a polymer solar cell blend induced by electron beam irradiation in the transmission electron microscope
- 2017
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Ingår i: Ultramicroscopy. - : Elsevier BV. - 1879-2723 .- 0304-3991. ; 173, s. 16-23
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Tidskriftsartikel (refereegranskat)abstract
- We show by in situ microscopy that the effects of electron beam irradiation during transmission electron microscopy can be used to lock microstructural features and enhance the structural thermal stability of a nanostructured polymer:fullerene blend. Polymer:fullerene bulk-heterojunction thin films show great promise for use as active layers in organic solar cells but their low thermal stability is a hindrance. Lack of thermal stability complicates manufacturing and influences the lifetime of devices. To investigate how electron irradiation affects the thermal stability of polymer:fullerene films, a model bulk-heterojunction film based on a thiophene-quinoxaline copolymer and a fullerene derivative was heat-treated in-situ in a transmission electron microscope. In areas of the film that exposed to the electron beam the nanostructure of the film remained stable, while the nanostructure in areas not exposed to the electron beam underwent large phase separation and nucleation of fullerene crystals. UV–vis spectroscopy shows that the polymer:fullerene films are stable for electron doses up to 2000 kGy.
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