Distribution of (210)Pb and (210)Po in boreal forest soil

Vertical distribution and activity contents of ²¹⁰Pb and ²¹⁰Po were investigated in forest soils of Scots pine-dominated (Pinus sylvestris L.) stands from seven different locations in Finland. The mean total inventory in the soil profile, up to 20 cm, of ²¹⁰Pb was 4.0 kBq m^− 2 (range 3.1-5.0 kBq m^− 2) and ²¹⁰Po 5.5 kBq m^− 2 (range 4.0-7.4 kBq m^− 2), the organic soil layer containing 45% of the total inventory of both nuclides. In both the organic and the mineral layers the ²¹⁰Po/²¹⁰Pb ratio was close to unity indicating a radioactive equilibrium between them. In the litter layer there was, however, a clear excess of ²¹⁰Po suggesting that polonium is recycled via root uptake from the root zone to the ground surface. The activity concentration (Bq kg^− 1) of ²¹⁰Pb clearly correlated with organic matter and the Fe, Al and Mn concentrations in soil indicating that radioactive lead is associated both with humic substances and the oxides of iron, aluminium and manganese. Radioactive lead was also seen to follow the behavior of stable lead. No systematic correlation between polonium and soil properties was seen.     

Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis

We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisocyanate as the chain extender. The resulting polymer is a thermoplastic poly(ester-urethane). The polymer samples were carefully characterized with ¹³C-NMR, GPC, DSC, and IR. The results indicate that high conversions of lactic acid can be achieved, as well as independent control of the stereostructure, long chain branches, molecular weight average, and molecular weight distribution. Lactic acid is converted into a poly(ester-urethane) with a weight average molecular weight as high as 390,000 g/mol and a glass transition temperature of 53.7°C. The analyzed content of the monomer in the prepolymer is less than 1 mol % and the lactide content 2.4 mol %, while the final poly(ester-urethane) is essentially monomer and lactide free. The mechanical properties of the poly(ester-urethane) are comparable to those of polylactides. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 63: 1091–1100, 1997     

Redds of brown trout in the deep channels of a hydroelectric power station

Natural spawning redds of brown trout were surveyed for the first time in 1?6‐m deep urban channels of a hydroelectric power station (HEP) between two lakes in Finland, by scuba diving and wading. Before damming a century ago, thousands of lake migrating trout spawners ascended through the rapids to upstream spawning areas. Between 2015 and 2018, 11 trout redds were observed at depths of 250?340 cm; these may be the deepest reported in running waters. Nine redds were found at depths of 75?230 cm. The nearest redds were situated only 55 m upstream and 110 m downstream from the HEP inflow and outflow, respectively. Channel substrate and trout redds were dominated by particle size classes 32?64, 64?128, and 16?32 mm. The risk of diving in the area increased due to the high amount of litter on the riverbed. Observations of wild trout parr by local anglers provide evidence that natural spawning produces some fish in the HEP channels.     

Impact of antenna radiation pattern variation on the performance of SPMA at 28 GHz

The target of this paper is to analyze the impact of variation in antenna radiation pattern on the performance of Single Path Multiple Access (SPMA) in urban/dense-urban environment. For this study, an extended 3GPP antenna model, and 3D building data from an urban area of Helsinki city is used. The simulations are performed at 28 GHz frequency using “sAGA” a MATLAB based 3D ray tracing tool. The variables considered for the series of simulations are Front to Back Ratio (FBR), Side Lobe Level (SLL), and Half Power Beamwidth (HPBW) of an antenna in horizontal and vertical plane. Network performance is compared in terms of metrics like signal strength, SINR, and capacity. This paper also presents the spectral efficiency and power efficiency analysis. The performance of SPMA was found susceptible to the change in antenna radiation pattern, and the simulation results show a significant impact of radiation pattern on the capacity gain offered by SPMA. Interestingly, SPMA was found a fairly power efficient solution with respect to the traditional macro cellular network approach. However, the level of power efficiency heavily depends upon the antenna beamwidth and on other beam parameters.     

High-Pressure Gelatinization of Barley Starch at Low Moisture Levels and Elevated Temperature

High-pressure gelatinization of barley starch at low water contents and at elevated temperature was performed in a differential scanning calorimeter equipped with a pressure chamber. Microscopic examination of the samples showed complete loss of birefringence and rupture of granular structure in most samples. The results indicated that enthalpy levels much higher than those in high-moisture gelatinization are needed to attain proper gelatinization and plastification of starch at low water contents.     

Evaluating the basic performance of the Intel iPSC/860 parallel computer

We evaluate the basic performance of the Intel iPSC/860 computer, which can have up to 128 Intel i860-based nodes connected together with a hypercube network topology. After giving a brief overview of the system, the properties and bottlenecks of the hardware architecture and software environment are discussed. Basic memory, scalar and vector performance of a single node is evaluated, and the communication performance and the overlap of computation and communication are analysed.