Publications by authors named "Lena Falk"

5 Publications

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Doctoral students' perceived working environment, obstacles and opportunities at a Swedish medical faculty: a qualitative study.

BMC Med Educ 2019 Jul 8;19(1):250. Epub 2019 Jul 8.

Angered Hospital, Gothenburg, Sweden.

Background: Investment in research is high on the agenda of many countries in recognition of the fact that research is important for the development of society. Doctoral students have a vital role and represent a substantial part of this investment. It is therefore imperative to reduce the risk of students dropping out from doctoral studies. The aim of this qualitative study was to gain deeper insight into the working conditions of, and obstacles and opportunities for, doctoral students at an institute of medicine in Sweden.

Methods: Semi-structured interviews were conducted in 2013 with 17 doctoral students-of varying genders, professions and fields of research-from the Institute of Medicine, Sahlgrenska Academy, at the University of Gothenburg, Sweden. The recorded interviews were transcribed and analysed using systematic text condensation.

Results: Four categories emerged from the data. They were: Safety, Frustrating Structures, Others - not me, and the future. They included positive as well as negative perceptions. Among the positive perceptions were recognition of the importance of the supervisor, as well as secure conditions, and personal development. Frustrating structures in the academic culture, stress and differences in career building constituted the negative points.

Conclusions: Our findings suggest that there is a need for structures within the university that support doctoral students who feel they are not receiving the assistance they need, who believe they have unreasonable working conditions, or who may need to change supervisors in order to complete their graduate research studies. Our study also highlights the fact that supervisors have a major influence on the work environment of doctoral students, and that the general and academic perception of the research area likewise has an effect on the successful completion of the research project and dissertation. Providing leadership training for supervisors could be an important measure that may help improve conditions for the doctoral students they supervise.
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http://dx.doi.org/10.1186/s12909-019-1684-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6615109PMC
July 2019

Graphitic encapsulation of catalyst particles in carbon nanotube production.

J Phys Chem B 2006 Apr;110(15):7666-70

Department of Physics, Göteborg University, SE-412 96 Göteborg, Sweden.

A new model is proposed for the encapsulation of catalyst metal particles by graphite layers that are obtained, for example, in low-temperature chemical vapor deposition production of carbon nanotubes (CNTs). In this model graphite layers are primarily formed from the dissolved carbon atoms in the metal-carbide particle when the particle cools. This mechanism is in good agreement with molecular dynamics simulations (which show that precipitated carbon atoms preferentially form graphite sheets instead of CNTs at low temperatures) and experimental results (e.g., encapsulated metal particles are found in low-temperature zones and CNTs in high-temperature regions of production apparatus, very small catalyst particles are generally not encapsulated, and the ratio of the number of graphitic layers to the diameter of the catalyst particle is typically 0.25 nm(-1)).
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http://dx.doi.org/10.1021/jp055485yDOI Listing
April 2006

Structure and catalytic properties of nanosized alumina supported platinum and palladium particles synthesized by reaction in microemulsion.

J Colloid Interface Sci 2003 Dec;268(2):348-56

Department of Applied Surface Chemistry, Chalmers University of Technology, SE-412 96, Göteborg, Sweden.

Mixtures of nanosized platinum and palladium particles have been prepared by reduction of salt-containing microemulsion droplets using hydrazine as the reducing agent. To avoid possible negative effects of the presence of sulfur compounds during the preparation the microemulsion was made using the sulfur-free nonionic polyoxyethylene 4 lauryl ether surfactant. Transmission electron microscopy showed that the as-prepared mixtures contained crystalline platinum particles of fairly homogeneous size (20 to 40 nm) with adsorbed amorphous palladium particles 2 to 5 nm in size. Catalyst samples were prepared by depositing the nanoparticles on a gamma-Al(2)O(3) support followed by heating in air at 600 degrees C. Alloyed particles of platinum and palladium with sizes ranging from 5 to 80 nm were obtained during the heating. The majority of the particles had the fcc structure and their compositional range was dependent upon the Pt:Pd molar ratio of the microemulsion. A catalyst prepared from a microemulsion with a 20:80 Pt:Pd molar ratio showed the highest catalytic activity for CO oxidation, while pure platinum and palladium catalysts showed higher sulfur resistance. These results differ from the performance of conventional wet-impregnated catalysts, where a 50:50 Pt:Pd molar ratio resulted in the highest catalytic activity as well as the highest sulfur resistance.
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http://dx.doi.org/10.1016/j.jcis.2003.07.041DOI Listing
December 2003

Higher expression of alpha7 nicotinic acetylcholine receptors in human fetal compared to adult brain.

Brain Res Dev Brain Res 2003 May;142(2):151-60

Neurotec Department, Division of Molecular Neuropharmacology, Huddinge University Hospital, S-141 86, Stockholm, Sweden.

Neuronal nicotinic acetylcholine receptors are thought to be involved in regulation of several processes during neurogenesis of the brain. In this study the expression of the alpha7 nicotinic acetylcholine receptor subtype was investigated in human fetal (9-11 weeks of gestation), middle-aged (28-51 years) and aged (68-94 years) medulla oblongata, pons, frontal cortex, and cerebellum. The specific binding of the alpha7 receptor antagonist [(125)I]alpha-bungarotoxin was significantly higher in fetal than in both middle-aged and aged medulla oblongata and aged pons. No significant decrease in [(125)I]alpha-bungarotoxin binding sites was observed from fetal to adult cortex and cerebellum. The alpha7 mRNA expression was significantly higher in all fetal brain regions investigated, except for aged cortex, than in corresponding middle-aged and aged tissue. The high expression of alpha7 nicotinic acetylcholine receptors in fetal compared to adult brain supports the view that these receptors play an important role during brain development.
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http://dx.doi.org/10.1016/s0165-3806(03)00063-4DOI Listing
May 2003

The alpha7 nicotinic receptors in human fetal brain and spinal cord.

J Neurochem 2002 Feb;80(3):457-65

Department of Clinical Neuroscience, Occupational Therapy and Elderly Care Research, Karolinska Institutet, Huddinge University Hospital, Stockholm, Sweden.

The alpha7 nicotinic acetylcholine receptor subtype is believed to be involved in the regulation of neuronal growth, differentiation and synapse formation during the development of the human brain. In this study the expression of the alpha7 nicotinic acetylcholine receptor was investigated in human fetal brain and spinal cord of 5-11 weeks gestational age. Both the specific binding of [125I]alpha-bungarotoxin to prenatal brain membranes and the expression of alpha7 mRNA were significantly higher in the pons, medulla oblongata, mesencephalon and spinal cord of 9-11 weeks gestational age compared with cerebellum, cortex and subcortical forebrain. A significant positive correlation between gestational age and the expression of alpha7 mRNA was observed in all brain regions except cortex. A positive correlation was also observed between the gestational age and the [125I]alpha-bungarotoxin binding in the pons, medulla oblongata, mesencephalon, and cerebellum. Consequently, a significant relationship between the alpha7 mRNA levels and the binding sites for [125I]alpha-bungarotoxin was found in the fetal brain. The increasing levels of the alpha7 nicotinic acetylcholine receptor during the first trimester support the important role of nAChRs for the development of the central nervous system.
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http://dx.doi.org/10.1046/j.0022-3042.2001.00714.xDOI Listing
February 2002