| 1. |
- Sandström, K. J. Mattias, et al.
(författare)
-
Biosensors in air monitoring
- 1999
-
Ingår i: Journal of Environmental Monitoring. - : Royal Society of Chemistry. - 1464-0325 .- 1464-0333. ; 1:4, s. 293-298
-
Forskningsöversikt (refereegranskat)
|
|
| 2. |
- Blank, Vladimir D., et al.
(författare)
-
High-pressure polymerized phases of C60
- 1998
-
Ingår i: Carbon. - 0008-6223 .- 1873-3891. ; 36:4, s. 319-343
-
Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract
- Data from recent experimental studies of C60 under high pressures are collected and analyzed, concentrating on the polymerized states where covalent intermolecular bonds have been formed through treatment of molecular C60 at high pressures and temperatures at or above room temperature. We give an overview of the observed phase transformations and the structures of metastable polymeric phases, both crystalline and disordered, as analyzed under ambient conditions, and we present and discuss a pressure-temperature diagram showing which synthesis conditions result in which final phases in the pressure range up to 20 GPa (200 kbar) and at temperatures up to 2300 K. The physical properties of the various phases are discussed whenever enough data are available. The pressure-temperature stability limits for C60 and the conditions for the transformation of C60 into graphite, diamond and chaoite-type carbon are derived.
|
|
| 3. |
- Campbell, D, et al.
(författare)
-
Chlorophyll fluorescence analysis of cyanobacterial photosynthesis and acclimation
- 1998
-
Ingår i: Microbiology and molecular biology reviews. - 1092-2172 .- 1098-5557. ; 62:3, s. 667-
-
Forskningsöversikt (refereegranskat)abstract
- Cyanobacteria are ecologically important photosynthetic prokaryotes that also serve as popular model organisms for studies of photosynthesis and gene regulation. Both molecular and ecological studies of cyanobacteria benefit from real-time information on photosynthesis and acclimation. Monitoring in vivo chlorophyll fluorescence can provide noninvasive measures of photosynthetic physiology in a wide range of cyanobacteria and cyanolichens and requires only small samples. Cyanobacterial fluorescence patterns are distinct from those of plants, because of key structural and functional properties of cyanobacteria. These include significant fluorescence emission from the light-harvesting phycobiliproteins; large and rapid changes in fluorescence yield (state transitions) which depend on metabolic and environmental conditions; and flexible, overlapping respiratory and photosynthetic electron transport chains. The fluorescence parameters F-V/F-M. F-V'/F-M', q(p),q(N), NPQ, and phi PS II were originally developed to extract information from the fluorescence signals of higher plants. In this review, we consider how the special properties of cyanobacteria can be accommodated and used to extract biologically useful information from cyanobacterial in vivo chlorophyll fluorescence signals. We describe how the pattern of fluorescence yield versus light intensity can be used to predict the acclimated light level for a cyanobacterial population, giving information valuable for both laboratory and field studies of acclimation processes. The size of the change in fluorescence yield during dark-to-light transitions can provide information on respiration and the iron status of the cyanobacteria. Finally, fluorescence parameters cart be used to estimate the electron transport rate at the acclimated growth light intensity.
|
|
| 4. |
|
|
| 5. |
- Huner, Norman P. A., et al.
(författare)
-
Energy balance and acclimation to light and cold
- 1998
-
Ingår i: Trends in Plant Science. - 1360-1385 .- 1878-4372. ; 3:6, s. 224-230
-
Forskningsöversikt (refereegranskat)abstract
- Changes in environmental conditions such as light intensity or temperature result in an imbalance between the light energy absorbed through photochemistry versus the energy utilized through metabolism. Such an energy imbalance is sensed through alterations in photosystem II excitation pressure, which reflects the relative reduction state of the photosystem. Modulation of this novel, chloroplastic redox signal either by excess light or by low temperature initiates a signal transduction pathway. This appears to coordinate photosynthesis-related gene expression and to influence the nuclear expression of a specific cold-acclimation gene, plant morphology and differentiation in cyanobacteria. Thus, in addition to its traditional role in energy transduction, the photosynthetic apparatus might also be an environmental sensor.
|
|
| 6. |
- Igamberdiev, A U, et al.
(författare)
-
Origins and metabolism of formate in higher plants
- 1999
-
Ingår i: Plant physiology and biochemistry (Paris). - 0981-9428 .- 1873-2690. ; 37:7-8, s. 503-513
-
Forskningsöversikt (refereegranskat)abstract
- Formate, a simple one-carbon compound, is readily metabolized in plant tissues. In greening potato tubers, similar to some procaryotes, formate is directly synthesized via a ferredoxin-dependent fixation of CO2, serving as the main precursor for carbon skeletons in biosynthetic pathways. In other plant species and tissues, formate appears as a side-product of photorespiration and of fermentation pathways, but possibly also as a product of direct CO2 reduction in chloroplasts. Formate metabolism is closely related to serine synthesis and to all subsequent reactions originating from serine. Formate may have a role in biosynthesis of numerous compounds, in energetic metabolism and in si,signal transduction pathways related to stress response. This review summarizes the current state of formate research, physiological/biochemical and molecular aspects. (C) Elsevier, Paris.
|
|
| 7. |
- Jansson, Stefan, 1959-
(författare)
-
A guide to the Lhc genes and their relatives in Arabidopsis
- 1999
-
Ingår i: Trends in Plant Science. - 1360-1385 .- 1878-4372. ; 4:6, s. 236-240
-
Forskningsöversikt (refereegranskat)abstract
- The Lhc super-gene family encodes the light-harvesting chlorophyll al b-binding (LHC) proteins that constitute the antenna system of the photosynthetic, apparatus, and also includes some relatives whose functions are more or less unknown. The Lhc super-gene family of Arabidopsis contains >30 members and the databases contain >1000 EST clones originating from these genes. This article presents an overview of these genes and provides some tools for researchers who want to use them in their studies.
|
|
| 8. |
- Kiviranta, Ilkka, et al.
(författare)
-
Effects of mechanical loading and immobilization on the articular cartilage
- 1997
-
Ingår i: Bailliere's Clinical Orthopaedics. - 1074-8814. ; 2:1, s. 109-122
-
Forskningsöversikt (refereegranskat)abstract
- Articular cartilage provides nearly frictionless surfaces for joint movemants and reduces contact pressures, protecting the underlying suchondral bone from excess stress. The unique properties of articular cartilage are based on the interaction of the main components of the extracellular matrix: proteoglycans (PGs), collagen and interstitial fluid. Animal experiments and in vitro studies demonstrate that one of the most important regulators of the extracellular matrix metabolism is mechanical loading acting on the joints. Unloading and immobilization leads to PG depletion and softening of articular cartilage, increasing the risk of permanent cartilage degeneration. Moderate running exercise and increased weight bearing increases cartilage thickness, PG concentration and improves biomechanical properties of articular cartilage. With further increase in training intensity this positive influence of exercise disappears and cartilage shows changes analogous to immobilization of the joint, i.e. PG depletion and softening of the tissue. In humans most epidemiological studies have failed to prove the connection between running training and cartilage degeneration, but there is evidence that sports activities exposing joints to impact loading might increase the risk of osteoarthrosis.
|
|
| 9. |
- Sundqvist, Bertil
(författare)
-
Fullerenes under high pressures
- 1999
-
Ingår i: Advances in Physics. - : Informa UK Limited. - 0001-8732 .- 1460-6976. ; 48:1, s. 1-134
-
Forskningsöversikt (övrigt vetenskapligt/konstnärligt)abstract
- This paper reviews the properties and phases of fullerenes and their derivatives and compounds under high pressures. For obvious reasons most of the paper deals with C60 but the materials reviewed also include C70, simple derivatives of C60, carbon nanotubes, and intercalation compounds of C60 with both acceptors and donors, mainly alkali metals. After a brief overview of high-pressure techniques and the structures and properties of C60 at atmospheric pressure, the structural phase diagram of C60 from atmospheric pressure to above 40GPa (400kbar) is reviewed. The evolution with pressure of the orientational and translational structure of 'normal' molecular C60 in the range up to 1-5GPa (depending on temperature) is discussed in some detail, as is the appearance of a large number of polymeric phases at higher pressures and temperatures, some of them known to have extreme mechanical properties. At very high static (or shock) pressures or temperatures, C60 transforms into ordered or disordered forms of diamond or graphite. The phase diagram is reasonably well investigated up to near 10GPa, but at higher pressures there are still large gaps in our knowledge. Available experimental data for the physical properties of both monomeric and polymeric C60 under high pressures are reviewed as far as possible. The compression behaviour of C60 has been well investigated and is discussed in detail because of its basic importance, but optical, electrical and lattice properties have also been studied for several of the many structural phases of C60. Whenever possible, experimental data are compared with the results of theoretical calculations. The phase diagram and properties of C70 are much less known because of the larger complexity caused by the anisotropy of the molecule, and very little is known about most compounds of C60. However, noble-gas intercalation in C60 has been reasonably well investigated. Finally, the high-pressure properties of superconducting alkali-metalintercalated C60 are briefly reviewed.
|
|
