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- Fricke, W, et al.
(författare)
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The short-term growth response to salt of the developing barley leaf
- 2006
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Ingår i: Journal of Experimental Botany. - : Oxford University Press (OUP). - 0022-0957 .- 1460-2431. ; 57:5, s. 1079-1095
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Tidskriftsartikel (refereegranskat)abstract
- Recent results concerning the short-term growth response to salinity of the developing barley leaf are reviewed. Plants were grown hydroponically and the growth response of leaf 3 was studied between 10 min and 5 d following addition of 100 mM NaCl to the root medium. The aim of the experiments was to relate changes in variables that are likely to affect cell elongation to changes in leaf growth. Changes in hormone content (ABA, cytokinins), water and solute relationships (osmolality, turgor, water potential, solute concentrations), gene expression (water channel), cuticle deposition, membrane potential, and transpiration were followed, while leaf elongation velocity was monitored. Leaf elongation decreased close to zero within seconds following addition of NaCl. Between 20 and 30 min after exposure to salt, elongation velocity recovered rather abruptly, to about 46% of the pre-stress level, and remained at the reduced rate for the following 5 d, when it reached about 70% of the level in non-stressed plants. Biophysical and physiological analyses led to three major conclusions. (i) The immediate reduction and sudden recovery in elongation velocity is due to changes in the water potential gradient between leaf xylem and peripheral elongating cells. Changes in transpiration, ABA and cytokinin content, water channel expression, and plasma membrane potential are involved in this response. (ii) Significant solute accumulation, which aids growth recovery, is detectable from 1 h onwards; growing and non-growing leaf regions and mesophyll and epidermis differ in their solute response. (iii) Cuticular wax density is not affected by short-term exposure to salt; transpirational changes are due to stomatal control.
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- Alexandersson, Tomas, et al.
(författare)
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Treatment of packaging board whitewater in anaerobic/aerobic biokidney
- 2005
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Ingår i: Water Science and Technology. - 0273-1223. ; 52:10-11, s. 289-298
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Tidskriftsartikel (refereegranskat)abstract
- Whitewater from production of packaging board was treated in a combined anaerobic/aerobic biokidney, both in laboratory scale and pilot plant experiments. Both the laboratory experiments and the pilot plant trial demonstrate that a combined anaerobic/aerobic process is suitable for treating whitewater from a packaging mill. It is also possible to operate the process at the prevailing whitewater temperature. In the laboratory under mesophilic conditions the maximal organic load was 12 kg COD/m(3)*d on the anaerobic reactor and 6.7 kg COD/m(3)*d on the aerobic reactor. This gave a hydraulic retention time, HRT, in the anaerobic reactor of 10 hours and 2 hours in the aerobic reactor. The reduction of COD was between 85 and 90% after the first stage and the total reduction was between 88 to 93%. Under thermophilic conditions in the laboratory the organic load was slightly lower than 9.6 COD/m(3)*d and between 10 and 16 COD/m(3)*d, respectively. The HRT was 16.5 and 3.4 hours and the removal was around 75% after the co anaerobic reactor and 87% after the total process. For the pilot plant experiment at a mill the HRT in the anaerobic step varied between 3 and 17 hours and the corresponding organic load between 4 and 44 kg COD/m(3)*d. The HRT in the aerobic step varied between 1 and 6 hours and the organic load between 1.5 and 26 kg COD/m(3)*d. The removal of soluble organic matter was 78% in the anaerobic step and 86% after the combined treatment at the lowest loading level. The removal efficiency at the highest loading level was about 65% in the anaerobic step and 77% after the aerobic step. In the pilot plant trial the removal efficiency was not markedly affected by the variations in whitewater composition that were caused b y change of production. The variations, however, made the manual control of the nutrient dosage inadequate co and resulted in large variations in effluent nutrient concentration. This demonstrates the need for an automatic nutrient dosage system. The first step towards such a system was to evaluate two different on-line instruments. Both had severe stability problems, which made them unsuitable as parts in a system for control of the nutrient dosage.
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- Wass, Caroline, 1976, et al.
(författare)
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Phencyclidine affects memory in a nitric oxide-dependent manner: working and reference memory
- 2006
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Ingår i: Behav Brain Res. ; 174:1, s. 49-55
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Tidskriftsartikel (refereegranskat)abstract
- Phencyclidine (PCP), a non-competitive NMDA receptor antagonist, was used to model schizophrenia-like cognitive dysfunctions of learning and memory in rats using the Morris water maze model for spatial memory. A protocol introduced by Baldi and co-workers was used to distinguish working memory from reference memory. Male Sprague-Dawley rats were administered PCP (2.0 mg/kg) before the first swimming trial on each of five spatial memory acquisition days, either alone or after pre-treatment with the nitric oxide synthase inhibitor, L-NAME (10 mg/kg). Probe tests for memory were conducted before and after each acquisition session. The results showed that PCP disrupted the acquisition of both working and reference memory. Pre-treatment with L-NAME reversed both these effects of PCP. L-NAME treatment by itself did not significantly alter either acquisition or retention of spatial memory.
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