| 1. |
- Frisk, Andreas, 1983-, et al.
(författare)
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Composition, structure and magnetic properties of ultra-thin Fe/Ni multilayers sputter deposited on epitaxial Cu/Si(001)
- 2018
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Ingår i: Thin Solid Films. - : Elsevier BV. - 0040-6090 .- 1879-2731. ; 646, s. 117-125
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Tidskriftsartikel (refereegranskat)abstract
- Sputter deposited symmetric multilayers of (n Fe)/(n Ni), with individual thicknesses from n = 4 to n = 48 monolayers (ML), were deposited on epitaxial Cu/Si(001), and their microstructural evolution and magnetic properties versus n have been studied. Elemental layering can be seen with transmission electron microscopy down to n = 4 ML layer thickness, although an intermixed region characterized by a finite interface width is found to be present. This width is composed of the interface roughness as well as the interdiffusion between layers, but the relative contributions from these two sources could not be concluded by the techniques used. The measured elemental layering and X-ray reflectivity (XRR) give an upper limit to the interface width which must be smaller than the thinnest layers, 4 ML. Electron energy loss spectroscopy (EELS), depth profiling X-ray photoelectron spectroscopy (XPS) and also XRR reveal that Fe has a higher tendency to mix with Ni than vice versa. XPS does not have the resolution to measure this thin elemental layering: composition variations for n = 8 ML which are clearly seen by EELS are barely resolved by XPS. The structure was determined by X-ray diffraction, and an epitaxial fcc (001) structure is found to be maintained throughout the multilayers up to n less than or similar to 8 ML. For larger n values, relaxation starts by Fe-fcc(001) layers changing into Fe-bcc(110), which is then followed by Ni-fcc(001) changing from (001) to (111) orientation along the growth direction. A decreased total measured magnetic moment for the fully epitaxial multilayers can be explained by the fcc Fe layers being partly anti-ferromagnetic, whereas the relaxed multilayers exhibit the expected magnetic properties of (bcc Fe) +(fcc Ni).
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| 2. |
- Frisk, Andreas, et al.
(författare)
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Magnetic and structural characterization of CoFeZr thin films grown by combinatorial sputtering
- 2019
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Ingår i: Physical Review Materials. - 2475-9953. ; 3:7
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Tidskriftsartikel (refereegranskat)abstract
- We report on a detailed investigation of structural and magnetic properties of thin CoFeZr films, produced by combinatorial cosputtering, with compositions in the ranges 30-85 at.% Co, 12-63 at.% Fe, and 4-8 at.% Zr. Extended x-ray absorption fine structure and x-ray diffraction measurements reveal that alloys with a Zr content below 5 at.% are polycrystalline with a bcc structure, while an amorphous morphology is stabilized at Zr contents above 6 at.%. All samples display a growth-induced in-plane uniaxial anisotropy, which is closely related to the Zr concentration gradients across the wafers. A model for the angular dependence of the reduced remanence, including a Gaussian distribution of easy/hard anisotropy axes, is presented and successfully used to fit the data for all samples. The magnetic moments of the polycrystalline films approximately follow the Slater-Pauling curve, and the magnetic moments of the amorphous films follow a similar trend, but with about 20 % lower values. X-ray magnetic circular dichroism measurements show, for the amorphous films, that the Co moments are virtually constant at 1.7(2)μB/atom.
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| 3. |
- Frisk, Andreas, 1983-, et al.
(författare)
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Resonant x-ray diffraction revealing chemical disorder in sputtered L10 FeNi on Si(0 0 1)
- 2016
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 28:40
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Tidskriftsartikel (refereegranskat)abstract
- In the search for new rare earth free permanent magnetic materials, FeNi with a L1(0) structure is a possible candidate. We have synthesized the phase in the thin film form by sputtering onto HF-etched Si(001) substrates. Monatomic layers of Fe and Ni were alternately deposited on a Cu buffer layer, all of which grew epitaxially on the Si substrates. A good crystal structure and epitaxial relationship was confirmed by in-house x-ray diffraction (XRD). The chemical order, which to some part is the origin of an uniaxial magnetic anisotropy, was measured by resonant XRD. The 001 superlattice reflection was split in two symmetrically spaced peaks due to a composition modulation of the Fe and Ni layers. Furthermore the influence of roughness induced chemical anti-phase domains on the RXRD pattern is exemplified. A smaller than expected magnetic uniaxial anisotropy energy was obtained, which is partly due to the composition modulations, but the major reason is concluded to be the Cu buffer surface roughness.
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| 4. |
- Frisk, Andreas, et al.
(författare)
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Strain Engineering for Controlled Growth of Thin-Film FeNi L10
- 2017
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 50:8
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Tidskriftsartikel (refereegranskat)abstract
- FeNi thin films in the L1(0) phase were successfully grown by magnetron sputtering on HF-etched Si(001) substrates on Cu/Cu100-xNix buffers. The strain of the FeNi layer, (c/a)(FeNi), was varied in a controlled manner by changing the Ni content of the Cu100-xNix buffer layer from x = 0 at.% to x = 90 at.%, which influenced the common in- plane lattice parameter of the CuNi and FeNi layers. The presence of the L1(0) phase was confirmed by resonant x-ray diffraction measurements at various positions in reciprocal space. The uniaxial magnetocrystalline anisotropy energy K-U is observed to be smaller (around 0.35 MJ m(-3)) than predicted for a perfect FeNi L1(0) sample, but it is larger than for previously studied films. No notable variation in K-U with strain state (c/a)(FeNi) is observed in the range achieved (0.99 less than or similar to (c/a)(FeNi) less than or similar to 1.02), which is in agreement with theoretical predictions.
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| 5. |
- Frisk, Andreas, 1983-, et al.
(författare)
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Tailoring anisotropy and domain structure in amorphous TbCo thin films through combinatorial methods
- 2016
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Ingår i: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 49:3
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Tidskriftsartikel (refereegranskat)abstract
- We apply an in-plane external magnetic field during growth of amorphous TbCo thin films and examine the effects on the magnetic anisotropy and domain structure. A combinatorial approach is employed throughout the deposition and analysis to study a continuous range of compositions between 7–95 at.% Tb. Magnetometry measurements show that all samples have a strong out-of-plane anisotropy, much larger than any in-plane components, regardless of the presence of a growth field. However, magnetic force microscopy demonstrates that the growth field does indeed have a large effect on the magnetic domain structure, resulting in elongated domains aligned along the imprinting field direction. The results show that the anisotropy can be tuned in intricate ways in amorphous TbCo films giving rise to unusual domain structures. Furthermore the results reveal that a combinatorial approach is highly effective for mapping out these material properties.
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| 6. |
- Frisk, Andreas, 1983-
(författare)
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The Importance of Controlling Composition to Tailor the Properties of Magnetic Thin Films
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many physical properties, for example structural or magnetic, of a material are directly dependent on elemental composition. Tailoring of properties through highly accurate composition control is possible in thin films. This work exemplifies such tailoring.A short review is given of the current status for research in the area of permanent magnets, focusing on rare earth element free alternatives, where FeNi in the L10 phase is a possible candidate. Epitaxial FeNi L10 thin films were successfully synthesized by magnetron sputtering deposition of monoatomic layers of Fe and Ni on HF-etched Si(001) substrates with Cu or Cu100-xNix/Cu buffers. The in-plane lattice parameter aCuNi of the Cu100-xNix buffer layer was tuned by the Ni content. Through matching of aFeNi to aCuNi, the strain state (c/a)FeNi was controlled, where c is the out-of-plane lattice parameter. The 001 reflection indicative of chemical order, as measured by resonant x-ray diffraction, was in most cases split in two peaks due to a composition modulation of Fe and Ni. This chemical disorder contributed to that the uniaxial magnetocrystalline anisotropy energy, KU≈0.35 MJ/m3, was smaller than predicted. In later experiments the composition modulation could partly be compensated for. Remaining discrepancies with respect to predicted KU values were attributed to additional disorder induced by surface roughness of the buffer layer.The interface sharpness between Fe and Ni was explored by producing epitaxial symmetric multilayers with individual layer thicknesses n = 4-48 monolayers (ML). For n ≤ 8 ML the films had pure fcc structure, with antiferromagnetic Fe layers. For n ≥ 8 ML the Fe layers relaxed to bcc structure.A combinatorial sputter chamber, which has the capability to deposit samples with composition and thickness gradients, was assembled. A model for simulation of composition and thickness across large substrates, for the conditions in this chamber, is presented. The model is verified by comparison to experimental data. Some challenges inherent in combinatorial sputtering are discussed, and two experimental studies employing the technique are presented as examples. These investigated magnetic and structural properties of Tb-Co films, with 7-95 at.% Tb, and of amorphous and crystalline ternary gradient Co-Fe-Zr films, respectively.
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| 7. |
- Frisk, Gabriella
(författare)
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Breast cancer : brain metastases and treatment aspects
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: In Sweden breast cancer is the most common malignant cancer disease among women, with 8000 new individual cases each year. The prognosis is generally very good, but nevertheless many patients still die of breast cancer every year. The general aim of this thesis is to gain increased knowledge of brain metastases due to breast cancer, including incidence, predictors and treatment aspects and better knowledge of the potential benefit of low-dose aspirin among women with breast cancer in different stages. Patients, methods and results: In study I and II we aimed to assess if the incidence of brain metastases have increased in Sweden over time. In study I, all Swedish patients with breast cancer during 1998-2006 were identified from the Swedish National Cancer Register. These individuals were matched to the National Patient Register to get information on admissions to hospital due to distant metastases. In the cohort of 50 528 identified breast cancer patients, 696 (1.4%) had admissions to hospital due to brain metastases. Patients were at 44% increased risk of being admitted to hospital with brain metastases if diagnosed with a primary breast cancer in 2004-2006 compared with 1998-2000. In study II we used the BcBaSe cohort (based on three quality-of-care registers in the Stockholm-Gotland, Uppsala-Örebro and the North region). Here, we identified all women with a first breast cancer 2002-2012 (N=30 996) and used ICD-codes for distant metastases from both non-primary outpatient care and hospital admissions. Overall, 789 (2.5 %) patients were registered with brain metastases at diagnosis or during follow-up. According to preliminary results, patients diagnosed with breast cancer in 2009-2012 were at a 37% increased risk of developing brain metastases compared with the period 2002-2004. In study III we aimed to evaluate survival and level of care following whole brain radiotherapy due to brain metastases among breast cancer patients in Stockholm. We identified 241 patients treated at the Karolinska University hospital radiotherapy units 1999 to 2012. We gathered data on outcome and prognostic factors including level of care before and after the radiotherapy treatment through reviews of the patients’ medical files. Median survival following whole brain radiotherapy was 2.9 months and 57 (24%) of the patients could never be discharged from hospital-care. Patients with poor performance status (WHO 3-4) had a median survival of 0.9 months and women with triple-negative primary tumors a median survival of 2.0 months. Poor performance status and being admitted to hospital before radiotherapy were associated with increased risk of not coming home. In study IV we aimed to evaluate if low-dose aspirin use may have a role in the treatment of breast cancer, accounting for clinical characteristics. In this study we used the BcBaSe linkage to identify a cohort of 21 414 women diagnosed with a primary stage I-III breast cancer and 621 women diagnosed in stage IV 2006 to 2012. We analysed information from Swedish health-care registers on dispensings of low-dose aspirin, comorbidity and dates and causes of death. We found no clear association between low-dose aspirin use and breast-cancer specific death overall, nor with risk of recurrence in a subgroup analysis. A possible benefit was however noted in women with smaller breast cancer tumors, stage I, which warrants further study. Discussion: The incidence of brain metastases in breast cancer appears to have increased in Sweden in recent years perhaps due to improved disease control outside of the brain. When a decision is made of treating brain metastases in breast cancer with whole brain radiotherapy, we should take into account the patient’s need of hospital care before treatment, performance status and choice of level of care in the late palliative stage of disease and the end-of-life period, since the median survival is short and many patients can never be discharged from the hospital after whole brain radiotherapy. Low-dose aspirin use in breast cancer does not seem to have any clear role in improving outcomes for breast cancer patients.
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| 8. |
- Frisk, Gabriella, et al.
(författare)
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No association between low-dose aspirin use and breast cancer outcomes overall : a Swedish population-based study
- 2018
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Ingår i: Breast Cancer Research. - : BioMed Central. - 1465-5411 .- 1465-542X. ; 20
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Tidskriftsartikel (refereegranskat)abstract
- Background: Results from previous studies indicate that use of low-dose aspirin may improve breast cancer prognosis. We evaluated aspirin use and breast cancer outcomes in relation to clinical characteristics as well as dose and duration of aspirin use.Methods: We used information from the Regional Breast Cancer Quality-of-Care Registries in three Swedish regions to identify 21,414 women diagnosed with a first stage I-III breast cancer between 1 April 2006 and 31 December 2012. The cohort was further linked to nationwide registers to retrieve information about dispensing low-dose aspirin before and after breast cancer diagnosis, comorbidity and causes of death. In a separate analysis, we investigated time to breast cancer death among 621 women with stage IV disease at diagnosis. Associations were evaluated using a multivariable Cox proportional hazards model.Results: Among women with stage I-III breast cancer, 2660 (12.4%) used low-dose aspirin shortly before breast cancer diagnosis and 4091 (19.1%) were users during follow-up. Women were followed for a median of 3.8years after diagnosis. There was no association between aspirin use and breast cancer-specific death in multivariable analyses (use before diagnosis: hazard ratio (HR) 0.93, 95% confidence interval (CI) 0.77-1.12; use after diagnosis: HR 1.00, 95% CI 0.74-1.37). Similarly, aspirin use was not associated with risk of first recurrence/metastases in a subgroup of stage I-III breast cancer patients (HR 0.97, 95% CI 0.86-1.10). However, in analyses stratified by stage, an inverse association between low-dose aspirin use after diagnosis and breast cancer death was found for women with stage I tumors (HR 0.53, 95% CI 0.29-0.96). Among women with stage IV disease at diagnosis, aspirin use was not associated with time to breast cancer death (HR 0.91, 95% CI 0.67-1.23).Conclusion: In this large population-based cohort study there was no evidence that low-dose aspirin use before or after breast cancer diagnosis is associated with a reduced risk of adverse outcomes overall in breast cancer. However, a potential benefit was noted among women with stage I tumors, warranting further investigation.
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| 9. |
- Hedman, Christel, et al.
(författare)
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Deprescribing in Palliative Cancer Care
- 2022
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Ingår i: Life. - : MDPI AG. - 0024-3019 .- 2075-1729. ; 12:5
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Forskningsöversikt (refereegranskat)abstract
- The aim of palliative care is to maintain as high a quality of life (QoL) as possible despite a life-threatening illness. Thus, the prescribed medications need to be evaluated and the benefit of each treatment must be weighed against potential side effects. Medications that contribute to symptom relief and maintained QoL should be prioritized. However, studies have shown that treatment with preventive drugs that may not benefit the patient in end-of-life is generally deprescribed very late in the disease trajectory of cancer patients. Yet, knowing how and when to deprescribe drugs can be difficult. In addition, some drugs, such as beta-blockers, proton pump inhibitors, anti-depressants and cortisone need to be scaled down slowly to avoid troublesome withdrawal symptoms. In contrast, other medicines, such as statins, antihypertensives and vitamins, can be discontinued directly. The aim of this review is to give some advice according to when and how to deprescribe medications in palliative cancer care according to current evidence and clinical praxis. The review includes antihypertensive drugs, statins, anti-coagulants, aspirin, anti-diabetics, proton pump inhibitors, histamin-2-blockers, bisphosphonates denosumab, urologicals, anti-depressants, cortisone, thyroxin and vitamins.
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| 10. |
- Karlsson, S. C. Hannah, et al.
(författare)
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Combining CAR T cells and the Bcl-2 family apoptosis inhibitor ABT-737 for treating B-cell malignancy
- 2013
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Ingår i: Cancer Gene Therapy. - : Springer Science and Business Media LLC. - 0929-1903 .- 1476-5500. ; 20:7, s. 386-393
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Tidskriftsartikel (refereegranskat)abstract
- B-cell malignancies upregulate the B-cell lymphoma 2 (Bcl-2) family inhibitors of the intrinsic apoptosis pathway, making them therapy resistant. However, small-molecule inhibitors of Bcl-2 family members such as ABT-737 restore a functional apoptosis pathway in cancer cells, and its oral analog ABT-263 (Navitoclax) has entered clinical trials. Gene engineered chimeric antigen receptor (CAR) T cells also show promise in B-cell malignancy, and as they induce apoptosis via the extrinsic pathway, we hypothesized that small-molecule inhibitors of the Bcl-2 family may potentiate the efficacy of CAR T cells by engaging both apoptosis pathways. CAR T cells targeting CD19 were generated from healthy donors as well as from pre-B-ALL (precursor-B acute lymphoblastic leukemia) patients and tested together with ABT-737 to evaluate apoptosis induction in five B-cell tumor cell lines. The CAR T cells were effective even if the cell lines exhibited different apoptosis resistance profiles, as shown by analyzing the expression of apoptosis inhibitors by PCR and western blot. When combining T-cell and ABT-737 therapy simultaneously, or with ABT-737 as a presensitizer, tumor cell apoptosis was significantly increased. In conclusion, the apoptosis inducer ABT-737 enhanced the efficacy of CAR T cells and could be an interesting drug candidate to potentiate T-cell therapy.
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