| 41. |
- Blomqvist, Peter, et al.
(författare)
-
Effects of additions of DOC on pelagic biota in a clearwater system : results from a whole lake experiment in northern Sweden
- 2001
-
Ingår i: Microbial Ecology. - : Springer Science and Business Media LLC. - 0095-3628 .- 1432-184X. ; 42:3, s. 383-394
-
Tidskriftsartikel (refereegranskat)abstract
- An oligotrophic clearwater lake, initially characterized by a pronounced dominance of autotrophic phytoplankton and mostly by one species, the green alga Botryococcus, was subject to additions of dissolved organic carbon in the form of white sugar (sucrose) during two consecutive years. The hypothesis tested was that it is organic carbon per se, and not other possible effects of humic substances, that determines the differences in structure of the planktonic ecosystem between humic and clearwater lakes. The additions of DOC resulted in a significant increase in bacterial biomass and a decrease in the biomass of autotrophic phytoplankton. The biomass of mixotrophic and heterotrophic flagellates instead increased significantly, whereas no effects were found to propagate to higher trophic levels. As a result of the changes among biota, total planktonic biomass also decreased to a level typical of nearby humic lakes. We suggest that it is the carbon component of humic material and its utilization by bacterioplankton that determines the structure and function of the pelagic food web in humic lakes.
|
|
| 42. |
- Blomqvist, Peter, et al.
(författare)
-
Lakes. Origin, ontogeny and natural functions
- 1999
-
Ingår i: Sustainable Water Management in the Baltic Sea Basin Vol. 1: Water in Nature. ; , s. 93-108
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 43. |
|
|
| 44. |
|
|
| 45. |
- BLOMQVIST, Peter, et al.
(författare)
-
PLANKTON AND WATER CHEMISTRY IN LAKE NJUPFATET BEFORE AND AFTER LIMING
- 1995
-
Ingår i: CANADIAN JOURNAL OF FISHERIES AND AQUATIC SCIENCES. - 0706-652X. ; 52:3, s. 551-565
-
Tidskriftsartikel (refereegranskat)abstract
- Moderately acidified Lake Njupfatet was studied during 2 consecutive years, before and after liming (calcite), and compared with corresponding data from six reference lakes. After liming, the concentration of total phosphorus in the lake water decreased b
|
|
| 46. |
|
|
| 47. |
- Blomqvist, Peter
(författare)
-
Structural and Magnetic Properties of Fe/Co (001) and Fe/V (001) Superlattices
- 2001
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The structural and magnetic properties of Fe/Co (001) and Fe/V (001) superlattices have been investigated. The thin film structures were deposited on MgO (001) substrates using a four source ultra-high-vacuum based sputtering equipment.Reflection high energy electron diffraction showed that the body-centered cubic phase of Co could be stabilized up to a thickness of about eight atomic monolayers. X-ray diffraction measurements confirmed that the Fe/Co superlattices were single-crystalline with a pure body-centered cubic structure. The crystalline quality and the interface profile were found to be strongly dependent on the growth temperature. Furthermore, the Fe/Co superlattices were also found to exhibit novel magnetic properties. The first order magnetic anisotropy constant for the body-centered cubic Co phase was determined to be negative with a magnitude of 110 kJ/m3. Magnetization and Mössbauer measurements showed that the Fe and Co magnetic moments in the superlattices were enhanced. Spin polarized neutron reflectometry proved that all the magnetic moments were collinear.The interlayer exchange coupling and the giant magnetoresistance effect in Fe/V superlattices were also studied. The strength of the coupling was found to be dependent on the thickness of the Fe and the V layers. This was also true for the giant magnetoresistance effect. Mössbauer measurements showed that the V-on-Fe interfaces (V deposited on Fe) were more abrupt and less diffuse than the Fe-on-V interfaces. Finally, the lattice parameters of a series of different Fe/V superlattices were determined by x-ray diffraction. The experimental lattice expansion was found to be in good agreement with a simple theoretical model.
|
|
| 48. |
- Borgh, Ida, et al.
(författare)
-
Investigation of phase separation in the (TI, ZR)C system
- 2012
-
Ingår i: Advances in Powder Metallurgy and Particulate Materials - 2012, Proceedings of the 2012 International Conference on Powder Metallurgy and Particulate Materials, PowderMet 2012. - 9780985339722 ; , s. 81-810
-
Konferensbidrag (refereegranskat)abstract
- The hardness of cemented carbide (WC-Co) cutting tools can be improved by the addition of TiC or ZrC to the matrix. It is possible that an even better hardness can be obtained by utilizing phase separation of a mixed (Ti, Zr)C where the mixed (Ti, Zr)C phase is stable at high temperature, but decomposes to TiC and ZrC at lower temperatures. In the present work, the decomposition is experimentally and theoretically investigated. The mixed carbide is first formed by synthesis from oxide powders at 2200°C and aging treatments are conducted at 1380 and 1450°C. X-ray diffraction analysis show that the synthesized mixed (Ti, Zr)C will decompose to TiC and ZrC. The experimental work is supplemented by thermodynamic and first-principles calculations.
|
|
| 49. |
- Borgh, Ida, et al.
(författare)
-
Synthesis and phase separation of (Ti,Zr)C
- 2014
-
Ingår i: Acta Materialia. - : Elsevier BV. - 1359-6454 .- 1873-2453. ; 66, s. 209-218
-
Tidskriftsartikel (refereegranskat)abstract
- Synthesis and phase separation of (Ti,Zr)C were investigated in the present work. The (Ti,Zr)C phase was synthesized at 2200 C and subsequently aged at 1300 C for different times. The microstructure was investigated using X-ray diffraction and electron microscopy, and supplemented by first-principles calculations. The (Ti,Zr)C phase separates into a lamellar nanostructure with alternating Ti- and Zr-rich face-centered cubic domains as well as non-stoichiometric TiC and ZrC. The lamellar structure is a consequence of phase separation within the miscibility gap that is directionally constrained by high coherency stresses, as indicated by the first-principles calculations. Moreover, the increased hardness due to the phase separation suggests that the mixed carbide could be used as a strengthening constituent in, for example, cemented carbides.
|
|
| 50. |
- Brechensbauer Brandin, Madeleine, et al.
(författare)
-
Centralen : Studier i området kring Stockholms Centralstation
- 1989
-
Rapport (populärvet., debatt m.m.)abstract
- Denna skrift handlar om Centralen i Stockholm och dess närmaste omgivningar, Centralplan, T-centralen, Vasagatan och Klarabergsgatan. Den är resultatet av Arkitekturskolans arbete läsåret 1983- 84 och innehåller förutom en rad projekt också historiska utblickar och samtidskritiska resonemang. En stor del av innehållet redovisades redan våren 1984 - det skedde genom en utställning på Arkitekturmuseet och en preliminär publikation. Materialet har sedan svällt ut med innehållsrika uppsatser om Centralen, om äldre och nyare insatser för att förena konst och arkitektur och om den föga kända, ännu obebyggda Blekholmen.
|
|
