On the Outskirts of Physics: Eva von Bahr as an Outsider Within in Early 20th Century Swedish Experimental Physics

Abstract.   Eva von Bahr (1874–1962) got her doctorate in experimental physics at the Physics Institute at Uppsala University in 1908. Subsequently she became the first woman assistant professor in physics in Sweden. In the face of many obstacles, she worked as a physicist for six years in Uppsala and Berlin. In 1914 she took a position as a school teacher. This article explores von Bahr's trajectory through academic experimental physics. It is argued that network connections with male scientists enabled her work. Her associations were a mix between institutional relationships and informal connections, resulting in what is labeled a 'hybrid of connections'. Furthermore it is argued that von Bahr became an 'outsider within' in academic experimental physics. Her connections created openings, but these coexisted with hindrances. It is argued that von Bahr oscillated between being an insider and an outsider which created a fractured identity. Her position and identity was a mix between membership and non-membership. Through examining von Bahr's career this article aims to bring together historical research on women in science and theoretical work in science studies. Furthermore, the article argues the analytical value of feminist perspectives on scientific collaborations as a way to a deeper understanding of the network structures of science.     

Influence of Plate Size on the Evaporation Rate of a Heated Droplet

The purpose of this study is to numerically investigate how the width of a plate influences natural convection around a droplet. Droplets evaporating on hot surfaces have many applications including drying of dishes and paint. Evaporation rate and deposition of particles withheld in the fluid are of great importance in both cases. As a first step to investigate how the drying rate and deposition mechanisms can be controlled, this work aims to investigate how the external flow around a water droplet influences the evaporation rate. Natural convection caused by the hot plate on which the droplet rests is considered and the effect of different widths is examined. Results show that an extension of the plate past the droplet will increase the maximum velocity in the domain due to natural convection while the flow close to the surface is decreased due to the no-slip condition and temperature gradient. A decrease of the evaporation rate is therefore observed when the plate is extended past the droplet as compared to the case when the plate and droplet have the same diameter. Simulations furthermore show that the results from the heat and mass transfer analogy only compare well to the results of Fick's law when the droplet and plate have the same width.     

Ammonia emissions after application of human urine to a clay soil for barley growth

Important amounts of plant nutrients excreted by humans are found in human urine. This provides the motivation for separating urine and recycling it, as fertiliser, back to agricultural land for food or fodder production. There are some housing estates in Sweden, both blocks of flats and separate houses, in which urine-separating toilets have been installed. The urine is stored in covered basins and spread on agricultural land. The objective of the present study was to evaluate the influence of application rate, application techniques and time on NH₃ emissions after application of source-separated human urine. Human urine was spread at different application rates (10, 20 and 60 Mg ha^–1) before sowing (year 1 to 3) and when the barley crop was 20-30 cm high (year 2). Urine was spread with a plot spreader using two band-application techniques (with bands 0.25 m apart): trailing hoses and trailing shoes. In spring, band-spread urine with trailing hoses was incorporated with a harrow four hours after application. The four (year 1 and 3) or six (year 2) treatments were organised into a randomised block design with three replicates. An equilibrium concentration method was used for measuring ammonia emissions directly after application. After spring application with trailing hoses and harrowing after four hours, the nitrogen [N] loss as ammonia [NH₃], average over 3 years, was 5% of the applied N, irrespective of the application rate. The largest loss (10% of the applied N) was measured after application of 60 t of urine per hectare in spring. Hardly any NH₃ loss occurred after incorporation with a harrow, with the exception of the highest application rate. Loss of NH₃ was very low, close to 1% of the applied N, when the urine was incorporated directly into the soil in spring by band application with trailing shoes. Virtually no emissions were detected when the urine was applied to the growing crop, neither by trailing hoses nor by trailing shoes. This study shows that it is possible to apply human urine on bare soil or in growing barley crop with very low losses of N as NH₃. Together with careful handling and the use of covered storage, nutrients in human urine could be recycled from households to agricultural land with low NH₃ emissions.     

Lipoprotein composition and serum cholesterol ester fatty acids in nonwesternized melanesians

In this study, the relationships between dietary fat [as measured by serum cholesterol ester fatty acids (CE-FA)], age, smoking, body mass index, and serum lipids were analyzed in 151 subsistence horticulturalists, aged 20–86 yr, from Kitava, Trobriand Islands, Papua New Guinea. Their diet consists of tubers, fruit, coconut, fish, and vegetables with a negligible influence of western food and alcohol. Total fat intake is low [21% of energy (en%)], while saturated fat intake from coconuts is high (17 en%, mainly lauric and myristic acid). In multivariate analysis, 11–43% of the variation of the serum lipoprotein composition was explained by CE-FA, age, and smoking habits. The proportion of CE20∶5n-3 explained much of the variation of triglycerides (TG, negative relation) and high density lipoprotein-cholesterol (HDL-C, positive) in both sexes and serum apolipoprotein A1 (ApoA1, positive) in the males. CE16∶0 was positively related to TG and negatively related to HDL-C and ApoA1 in both sexes, and in males it related negatively to total cholesterol (TC) and low density lipoprotein-cholesterol (LDI-C). In males, negative relationships were present between CE18∶2n-6 and TC and between CE14∶0 and serum lipoprotein(a). Smoking was independently associated with lower ApoA1 in both sexes and with lower HDL-C and higher TG, TC, LDL-C, and apolipoprotein B in males. In conclusion, marine n-3 fatty acids and linoleic acid showed the same potentially beneficial relationships with lipoproteins and apolipoproteins as in western populations. The relations of palmitic acid to serum lipids may be explained in terms of endogenous fat synthesis at a low-fat intake, rather than reflecting its relative intake.     

Airborne chemistry coupled to Raman spectroscopy

In this paper, the use of airborne chemistry (acoustically levitated drops) in combination with Raman spectroscopy is explored. We report herein the first Raman studies of crystallization processes in levitated drops and the first demonstration of surface-enhanced Raman scattering (SERS) detection in this medium. Crystallization studies on the model compounds benzamide and indomethacin resulted in the formation of two crystal modifications for each compound, suggesting that this methodology may be useful for investigation of polymorphs. SERS detection resulted in a signal enhancement of 27 000 for benzoic acid and 11 000 for rhodamine 6-G. The preliminary results presented here clearly indicate that several important applications of the combination between Raman spectroscopy and acoustic drop levitation can be expected in the future.     

Affinity two-phase partitioning in acoustically levitated drops

Miniaturized (<1 microL) biospecific affinity two-phase partitioning in an acoustically levitated drop is described. Miniaturization commonly gives unfavorable surface/volume ratios, but in the levitation approach adsorption problems are minimized since the only surrounding wall is the liquid/air interface of the drop. Biotinylated liposomes were partitioned in aqueous poly(ethylene glycol)/dextran two-phase drops with NeutrAvidin-dextran as the affinity ligand. A two-phase drop was trapped and manipulated in a node of a standing ultrasonic wave. Alternatively, a two-phase system was formed by levitation and evaporation of a polymer one-phase drop. Phase mixing was achieved by adjusting the ultrasonic field and phase separation by readjusting the field. NeutrAvidin-dextran brought about the redistribution of biotinylated liposomes from the poly(ethylene glycol)-rich phase into the dextran-rich phase. Thus, an entire affinity two-phase separation procedure, including mixing of the phases and incubation to allow affinity interactions to develop under constant volume, followed by phase separation under controlled evaporation, can be performed in a single levitated drop. This miniaturized technique would allow the separation of biologically active membranes or organelles from individual cells for analysis.     

Evolving technological systems for diesel engine emission control: balancing GHG and local emissions

The Triad—North America, Japan and Europe—now addresses diesel vehicle emissions by requiring 40–80% reductions from new heavy-duty trucks and passenger car diesels. The requirements imply introduction of new technology and fuels stepwise during 2005–2012 that will leave emissions from new diesel vehicles on par with the levels of gasoline passenger cars. This paper studies the recent development of diesel engine emission control in response to new regulation. The role for Swedish actors, including two of the world’s major truck manufacturers, is especially studied. The increasingly global Technological System for diesel engine emission control is compelled to manage further reductions of nitrogen oxides emissions and fuel consumption and CO₂, the balance of which has been the subject of several large legal disputes. Swedish OEMs are at present split into two technological sub-trajectories, while the future may be multi-pronged and include new engine types and fuels. Interestingly, similar commercial advantages that were sought by the pioneers introducing advanced feedback loop catalysis in gasoline cars in the 1970s are now sought by some heavy-duty diesel engine manufacturers by conversely avoiding the mainstream—Selective catalytic reduction—solution. Incremental innovation is the new radical.     

Dissolution and precipitation behavior of ternary solid dispersions of ezetimibe in biorelevant media

Abstract

The effects of different formulations and processes on inducing and maintaining the supersaturation of ternary solid dispersions of ezetimibe (EZ) in two biorelevant media fasted-state simulated intestinal fluid (FaSSIF) and fasted-state simulated gastric fluid (FaSSGF) at different temperatures (25?°C and 37?°C) were investigated in this work.

Ternary solid dispersions of EZ were prepared by adding polymer PVP-K30 and surfactant poloxamer 188 using melt-quenching and spray-drying methods. The resulting solid dispersions were characterized using scanning electron microscopy, differential scanning calorimetry (DSC), modulated DSC, powder X-ray diffraction and Fourier transformation infrared spectroscopy. The dissolution of all the ternary solid dispersions was tested in vitro under non-sink conditions.

All the prepared solid dispersions were amorphous in nature. In FaSSIF at 25?°C, the melt-quenched (MQ) solid dispersions of EZ were more soluble than the spray-dried (SD) solid dispersions and supersaturation was maintained. However, at 37?°C, rapid and variable precipitation behavior was observed for all the MQ and SD formulations. In FaSSGF, the melting method resulted in better solubility than the spray-drying method at both temperatures.

Ternary solid dispersions show potential for improving solubility and supersaturation. However, powder dissolution experiments of these solid dispersions of EZ at 25?°C may not predict the supersaturation behavior at physiologically relevant temperatures.     

Bubble formation and motion in non-crimp fabrics with perturbed bundle geometry

The motion of the liquid front during impregnation of non-crimp fabrics has been considered by using Sethian’s level set method. Particular attention is put on the creation of bubbles at the liquid front and a virtual 3D model mimicking biaxial fabrics has been built for this purpose. The saturated fluid flow is governed by the Navier–Stokes Equations and Darcy law, while capillary pressure has been accounted for at the liquid flow front and continuity maintained. The influence of perturbation in the bundle geometry has been investigated. Local correlations of the dimensions of neighbouring gaps formed between the bundles are of paramount importance. Focus is on inter-bundle bubbles. An existing model for bubble dynamics is used based on a probabilistic approach for bubbles moving, splitting, merging, and dissolving. The same approach was used for intra-bundle bubbles, the difference being that their motion appears to be much slower. The obtained void fractions of inter-bundle bubbles at different vacuum levels applied at the liquid flow front are compared to those from real mouldings with a high degree of conformity.     

A review of the tidal current energy resource in Norway

As interest in renewable energy sources is steadily on the rise, tidal current energy is receiving more and more attention from politicans, industrialists, and academics. In this article, the conditions for and potential of tidal currents as an energy resource in Norway are reviewed. There having been a relatively small amount of academic work published in this particular field, closely related topics such as the energy situation in Norway in general, the oceanography of the Norwegian coastline, and numerical models of tidal currents in Norwegian waters are also examined. Two published tidal energy resource assessments are reviewed and compared to a desktop study made specifically for this review based on available data in pilot books. The argument is made that tidal current energy ought to be an important option for Norway in terms of renewable energy.