| 1. |
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| 2. |
- Tatte, T, et al.
(författare)
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Transparent and conductive Sb-doped tin oxide SPM tips prepared by sol-gel method
- 2002
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Ingår i: Materials Science and Engineering C: Materials for Biological Applications. - 0928-4931. ; 19:1-2, s. 101-104
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Tidskriftsartikel (refereegranskat)abstract
- The rapid progress in scanning probe microscopy (SPM) techniques in the last decade has induced an increasing need for manufacturing advanced SPM tips. One important case is conductive and transparent tips. For such tips, only a few techniques have been proposed. which are either expensive or have poor reproducibility. We here propose a simple and cheap sol-gel technique to prepare fibers with a suitably sharp apex so that they can be used as SPM tips. The fibers were spinned off from a high-viscosity solution of tin alkoxide and SbCl3 hydrolysed in hurnid air and baked at 520 degreesC for several hours. The radii of the resulting tips were estimated by transmission electron microscopy to be less than 50 am. The resistivity of the transparent fibers was measured using different Sb-doping (0.5-1 wt.%) of the tin oxide, The temperature dependence of the conductivity and light absorption were investigated down to liquid He temperatures.
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| 3. |
- Erts, D, et al.
(författare)
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Instrumentation of STM and AFM combined with transmission electron microscope
- 2001
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 72:7, s. 71-74
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Tidskriftsartikel (refereegranskat)abstract
- A scanning tunneling microscope (STM) combined with a transmission electron microscope (TEM) is a powerful tool for direct investigation of structures, electronic properties, and interactions at the atomic scale. Here, we report on two different designs of such TEM-STM as well as an extension with an atomic force microscope (TEM-AFM). In the first TEM-STM design, a stepper motor, combined with a one-dimensional inertial slider, was used to perform the coarse approach. The advantage of this design was the strong pulling force that enabled notched metallic wires to be broken inside the TEM, which lead to clean sample surfaces. A second design, with a three-dimensional inertial slider, allowed lateral motion inside the TEM, which simplified the adjustment of tip location on the sample. By replacing the STM tip with a standard AFM-cantilever chip, a new combination was demonstrated: TEM-AFM. Here the force was simply measured by direct TEM imaging of the motion of the AFM tip. Some experimental results are included to illustrate the capabilities of TEM-STM and TEM-AFM.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Pokropivny, A.V., et al.
(författare)
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Study of Nanoscale Contacts with the Help of Combined TEM-AFM Technique and Theoretical MD-TM Calculations: In situ Transformations of Gold Nanowires
- 2004
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Ingår i: Physics of low-Dimensional structures. - 0204-3467. ; 1-2, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- Nanoscale gold contacts were investigated both experimentally and theoretically. Simulations of in situ processes in a new combined TEM-AFM microscope were performed by molecular dynamics and theoretical mechanics methods. Atomistic transformations of gold nanometer-sized wires (nanowires) between Au-probe and Au-surface were studied in processes both of loading-unloading and in the normal, lateral, diagonal and zigzag directions of the probe motion. Molecular dynamics was used for studies of "adhesion avalanche", shear and strain deformations. Theoretical mechanics was used for studies of jump-to-contact and jump-off-contact phenomena. Reorientations from (100) to (111) planes with formation of extended zigzag, vacancy cavities, a double-neck creation and a slip along the (110) plane with formation of twins and steps were observed. Deformation mechanisms were shown to depend on schemes of motions and on the ratio between the relative velocity of the probe and surface motion and the velocity of the defect relaxation.
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| 8. |
- Tatte, T, et al.
(författare)
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Metal oxide based SPM tips prepared by sol-gel method
- 2002
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Ingår i: Physics of Low-Dimensional Structures. - 0204-3467. ; 5-6, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- Up to date SNOM tips have. been prepared from SiO2 based materials using etching or locally melt fibre's stretching for tip sharpening [1,2] Usage of other metal oxides has been restricted because of the lack Of methods for obtaining the tips with suitable geometrical configuration. In our previous work we have proposed the technique for preparing transparent and electroconductive SnO2 fibres and tips by sol-gel method [3]. In the present investigation we have demonstrated that the sol-gel method provides the wide range of metal oxides to obtain SPM fibre tips. The new method of preparation enables to study tips based on oxide or oxide mixtures to create sensors with new properties for different applications. We propose some methods for preparing suitable precursors for spinning of pure and mixed TiO2, SnO2, SiO2 fibres. In those new methods the sharpening of tips is achieved in fibre drawing procedure. That is carried out at room temperature in humid atmosphere and then fibres are baked at 300-700degreesC for crystallisation of the material.
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| 9. |
- Andzane, J., et al.
(författare)
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Application of Tuning Fork Sensors for In-situ Studies of Dynamic Force Interactions Inside Scanning and Transmission Electron Microscopes
- 2012
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Ingår i: Medziagotyra. - : Kaunas University of Technology (KTU). - 1392-1320. ; 18:2, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- Mechanical properties of nanoscale contacts have been probed in-situ by specially developed force sensor based on a quartz tuning fork resonator (TF). Additional control is provided by observation of process in scanning electron microscope (SEM) and transmission electron microscope (TEM). A piezoelectric manipulator allows precise positioning of atomic force microscope (AFM) probe in contact with another electrode and recording of the IF oscillation amplitude and phase while simultaneously visualizing the contact area in electron microscope. Electrostatic control of interaction between the electrodes is demonstrated during observation of the experiment in SEM. In the TEM system the TF sensor operated in shear force mode: Use of TEM allowed for direct control of separation between electrodes. New opportunities for in situ studies of nanomechanical systems using these instruments are discussed.
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| 10. |
- Finér, L., et al.
(författare)
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Variation in fine root biomass of three European tree species : Beech (Fagus sylvatica L.), Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.)
- 2007
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Ingår i: Plant Biosystems. - : Informa UK Limited. - 1126-3504 .- 1724-5575. ; 141:3, s. 394-405
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Tidskriftsartikel (refereegranskat)abstract
- Fine roots (< 2 mm) are very dynamic and play a key role in forest ecosystem carbon and nutrient cycling and accumulation. We reviewed root biomass data of three main European tree species European beech, (Fagus sylvatica L.), Norway spruce (Picea abies L. Karst.) and Scots pine (Pinus sylvestris L.), in order to identify the differences between species, and within and between vegetation zones, and to show the relationships between root biomass and the climatic, site and stand factors. The collected literature consisted of data from 36 beech, 71 spruce and 43 pine stands. The mean fine root biomass of beech was 389 g m(-2), and that of spruce and pine 297 g m(-2) and 277 g m(-2), respectively. Data from pine stands supported the hypothesis that: root biomass is higher in the temperate than in the boreal zone. The results indicated that the root biomass of deciduous trees is higher than that of conifers. The correlations between root biomass and site fertility characteristics seemed to be species specific. There was no correlation between soil acidity and root biomass. Beech fine root. biomass decreased with stand age whereas pine root biomass increased with stand age. Fine root biomass at tree level. correlated better than stand level root biomass with stand characteristics. The results showed that there exists a strong relationship between the fine root biomass and the above-ground biomass.
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| 11. |
- Lohmus, M., et al.
(författare)
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Effects of temperature and growth hormone on individual growth trajectories of wild-type and transgenic coho salmon Oncorhynchus kisutch
- 2010
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 76:3, s. 641-654
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Tidskriftsartikel (refereegranskat)abstract
- In this study, individual growth patterns of wild-type and growth-enhanced coho salmon Oncorhynchus kisutch at 8, 12 and 16 degrees C water temperature were followed. Despite large differences among individuals in growth rates, there was generally little variation in the shape of the growth curves among O. kisutch individuals of both genotypes and at all temperatures. Typically, individuals that were relatively large initially were also relatively large at the end of the growth period. The limitation in variation was more pronounced in the growth-enhanced O. kisutch than in the wild type, where the relative size of some individuals reared at 12 and 8 degrees C changed by the end of the trial. As a warmer temperature seems to decrease the plasticity of growth trajectories in wild-type fish, it is possible that global warming will influence the ability of wild fish to adapt their growth to changing conditions.
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| 12. |
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| 13. |
- Ostonen, I., et al.
(författare)
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Specific root length as an indicator of environmental change
- 2007
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Ingår i: Plant Biosystems. - : Informa UK Limited. - 1126-3504 .- 1724-5575. ; 141:3, s. 426-442
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Tidskriftsartikel (refereegranskat)abstract
- Specific root length (SRL, m g(-1)) is probably the most frequently measured morphological parameter of fine roots. It is believed to characterize economic aspects of the root system and to be indicative of environmental changes. The main objectives of this paper were to review and summarize the published SRL data for different tree species throughout Europe and to assess SRL under varying environmental conditions. Meta-analysis was used to summarize the response of SRL to the following manipulated environmental conditions: fertilization, irrigation, elevated temperature, elevated CO(2), Al-stress, reduced light, heavy metal stress and physical disturbance of soil. SRL was found to be strongly dependent on the fine root classes, i.e. on the ectomycorrhizal short roots (ECM), and on the roots < 0.5 mm, < 1 mm, < 2 mm and 1-2 mm in diameter SRL was largest for ECM and decreased with increasing diameter. Changes in soil factors influenced most strongly the SRL of ECM and roots < 0.5 mm. The variation in the SRL components, root diameter and root tissue density, and their impact on the SRL value were computed. Meta-analyses showed that SRL decreased significantly under fertilization and Al-stress; it responded negatively to reduced light, elevated temperature and CO(2). We suggest that SRL can be used successfully as an indicator of nutrient availability to trees in experimental conditions.
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| 14. |
- Pernin, Vincent, et al.
(författare)
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Long-Term Prolonged-Release Tacrolimus-Based Immunosuppression in De Novo KidneyTransplant Recipients : 5-Y Prospective Follow-Up of Patients in the ADVANCE study
- 2023
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Ingår i: Transplantation direct. - : Wolters Kluwer. - 2373-8731. ; 9:3
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Tidskriftsartikel (refereegranskat)abstract
- Background. Although prolonged-release tacrolimus (PR-T) is widely approved for posttransplantation immunosuppres-sion in kidney recipients, large-scale studies are required to assess long-term outcomes. We present follow-up data from the ADVANCE trial, in which kidney transplant patients (KTPs) received corticosteroid minimization with PR-T.Methods. ADVANCE was a 24-wk, randomized, open-label, phase-4 study. De novo KTPs received PR-T with basiliximab and mycophe-nolate mofetil and were randomized to receive an intraoperative corticosteroid bolus plus tapered corticosteroids until day 10 (arm 1) or an intraoperative corticosteroid bolus (arm 2). In this 5-y, noninterventional follow-up, patients received maintenance immunosuppression according to standard practice. Primary endpoint included graft survival (Kaplan-Meier). Secondary end-points included patient survival, biopsy-confirmed acute rejection–free survival, and estimated glomerular filtration rate (4-vari-able modification of diet in renal disease).Results. Follow-up study included 1125 patients. Overall graft survival at 1 and 5 y posttransplant was 93.8% and 88.1%, respectively, and was similar between treatment arms. At 1 and 5 y, patient survival was 97.8% and 94.4%, respectively. Five-year graft and patient survival rates in KTPs who remained on PR-T were 91.5% and 98.2%, respectively. Cox proportional hazards analysis demonstrated similar risk of graft loss and death between treatment arms. Five-year biopsy-confirmed acute rejection–free survival was 84.1%. Mean ± standard deviation values of estimated glo-merular filtration rate were 52.7 ± 19.5 and 51.1 ± 22.4 mL/min/1.73 m2 at 1 and 5 y, respectively. Fifty adverse drug reactions were recorded, probably tacrolimus-related, in 12 patients (1.5%).Conclusions. Graft survival and patient survival—over-all and for KTPs who remained on PR-T—were numerically high and similar between treatment arms at 5 y posttransplant.
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| 15. |
- Sandberg, Roland, et al.
(författare)
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Magnetic information calibrates celestial cues during migration
- 2000
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Ingår i: Animal Behaviour. - : Elsevier BV. - 1095-8282 .- 0003-3472. ; 60:4, s. 453-462
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Tidskriftsartikel (refereegranskat)abstract
- Migratory birds use celestial and geomagnetic directional information to orient on their way between breeding and wintering areas. Cue-conflict experiments involving these two orientation cue systems have shown that directional information can be transferred from one system to the other by calibration. We designed experiments with four species of North American songbirds to: (1) examine whether these species calibrate orientation information from one system to the other; and (2) determine whether there are species-specific differences in calibration. Migratory orientation was recorded with two different techniques, cage tests and free-flight release rests, during autumn migration. Cage tests at dusk in the local geomagnetic field revealed species-specific differences: red-eyed vireo, Vireo olivaceus, and northern waterthrush, Seiurus noveboracensis, selected seasonally appropriate southerly directions whereas indigo bunting, Passerina cyanea, and grey catbird, Dumetella carolinensis, oriented towards the sunset direction. When tested in deflected magnetic fields, vireos and waterthrushes responded by shifting their orientation according to the deflection of the magnetic field, but buntings and catbirds failed to show any response to the treatment. In release tests, all four species showed that they had recalibrated their star compass on the basis of the magnetic field they had just experienced in the cage tests. Since release tests were done in the local geomagnetic field it seems clear that once the migratory direction is determined, most likely during the twilight period, the birds use their recalibrated star compass for orientation at departure. (C) 2000 The Association for the Study of Animal Behaviour.
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| 16. |
- Sundström, L. Fredrik, 1972, et al.
(författare)
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Dispersal potential is affected by growth-hormone transgenesis in coho salmon (Oncorhynchus kisutch).
- 2007
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 113:4, s. 403-410
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Tidskriftsartikel (refereegranskat)abstract
- Potential ecological consequences on the natural environment of fast-growing transgenic fish with elevated intrinsic growth rates is an important question should such fish be allowed in commercial production systems. One trait that will strongly affect the spatial extent of consequences is the propensity of transgenic fish to disperse. We addressed this question in three experiments using different measures of spatial dispersal where we compared very young genotypically wild coho salmon with transgenic conspecifics in terms of: (i) group cohesion, (ii) exploratory behavior, and (iii) up- and downstream movements. Transgenic fish were more loosely aggregated, more likely to explore, and less likely to swim upstream, but equally likely to disperse downstream compared with genetically wild fish. These results show that dispersal behavior has been affected by transgenesis and that transgenic fish therefore may venture into habitats previously not used by wild fish. Given the importance of dispersal in ecological risk-assessment of transgenic fish, continued work within this area is warranted and experimental habitats should mimic the potential receiving natural habitats to which transgenic fish are likely to escape or be released to.
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| 17. |
- Sundström, L. Fredrik, 1972, et al.
(författare)
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Feeding on profitable and unprofitable prey: Comparing behaviour of growth-enhanced transgenic and normal coho salmon (Oncorhynchus kisutch)
- 2004
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Ingår i: Ethology. - : Wiley. - 0179-1613 .- 1439-0310. ; 110:5, s. 381-396
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Tidskriftsartikel (refereegranskat)abstract
- We compared the performance of normal and growth hormone-transgenic coho salmon feeding on surface drifting edible and inedible novel prey items in various social environments. With an inherently higher appetite, we predicted that transgenic fish would be more willing to feed on novel prey, and that visual company with another fish would enhance this difference further. Transgenic and normal fish, of similar size and age, were equally willing to attack both the edible (live insects) and inedible (artificial angling lure flies) prey, but transgenic fish did so faster and were more likely to make repeated attacks. Transgenic fish managed to seize and consume the edible prey after fewer attacks than did normal fish. However, swallowing of prey took longer than for normal fish. More transgenic individuals interacted with the inedible prey compared with normal salmon, and initially, transgenic fish in visual company with another fish also interacted more with the prey than single transgenic or any constellation of normal focal fish. With repeated exposures, the number of individuals attacking and the number of interactions with the prey decreased. These responses were stronger in transgenic fish, partly explained by the initially low response in normal fish. The observed differences are most likely the consequences of elevated levels of growth hormone in transgenic fish generating enhanced feeding motivation and reinforcement capacity. In a natural environment, the performance of a growth hormone-transgenic fish may therefore depend on the relative abundance of profitable vs. unprofitable prey, as well as the presence of other transgenic individuals.
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| 18. |
- Sundström, L. Fredrik, et al.
(författare)
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Gene-environment interactions influence feeding and anti-predator behavior in wild and transgenic coho salmon
- 2016
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 26:1, s. 67-76
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Tidskriftsartikel (refereegranskat)abstract
- Environmental conditions are known to affect phenotypic development in many organisms, making the characteristics of an animal reared under one set of conditions not always representative of animals reared under a different set of conditions. Previous results show that such plasticity can also affect the phenotypes and ecological interactions of different genotypes, including animals anthropogenically generated by genetic modification. To understand how plastic development can affect behavior in animals of different genotypes, we examined the feeding and risk-taking behavior in growth-enhanced transgenic coho salmon (with two-to threefold enhanced daily growth rates compared to wild type) under a range of conditions. When compared to wild-type siblings, we found clear effects of the rearing environment on feeding and risk-taking in transgenic animals and noted that in some cases, this environmental effect was stronger than the effects of the genetic modification. Generally, transgenic fish, regardless of rearing conditions, behaved similar to wild-type fish reared under natural-like conditions. Instead, the more unusual phenotype was associated with wild-type fish reared under hatchery conditions, which possessed an extreme risk averse phenotype compared to the same strain reared in naturalized conditions. Thus, the relative performance of genotypes from one environment (e.g., laboratory) may not always accurately reflect ecological interactions as would occur in a different environment (e.g., nature). Further, when assessing risks of genetically modified organisms, it is important to understand how the environment affects phenotypic development, which in turn may variably influence consequences to ecosystem components across different conditions found in the complexity of nature.
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| 19. |
- Sundström, L. Fredrik, 1972, et al.
(författare)
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Growth hormone transgenic salmon pay for growth potential with increased predation mortality
- 2004
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Ingår i: Proceedings of the Royal Society of London Series B-Biological Sciences. - 0962-8452. ; 271
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Tidskriftsartikel (refereegranskat)abstract
- Recent advances in gene technology have been applied to create fast-growing transgenic fish, which are of great commercial interest owing to their potential to shorten production cycles and increase food production. However, there is growing concern and speculation over the impact that escaped growth hormone (GH)-transgenic fish may have on the natural environment. To predict these risks it is crucial to obtain empirical data on the relative fitness of transgenic and non-transgenic fish under nature-like conditions. Using landscaped stream aquaria with live food and predators, we show that the predation mortality of newly hatched GH-transgenic coho salmon fry (Oncorhynchus kisutch) is much higher than in non-transgenic conspecifics, and that this difference is amplified when food abundance decreases. The growth rate of transgenic and non-transgenic fish is similar at high food levels, whereas transgenic fish grow more slowly than non-transgenic fish when food abundance is reduced. Our results suggest that the fitness of young GH-transgenic coho salmon in the wild will be determined by both predation pressure and food availability.
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| 20. |
- Sundström, L. Fredrik, 1972, et al.
(författare)
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Selection on increased intrinsic growth rates in coho salmon, Oncorhynchus kisutch
- 2005
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Ingår i: Evolution. - 0014-3820. ; 59:7, s. 1560-1569
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Tidskriftsartikel (refereegranskat)abstract
- Substantial evidence from the animal kingdom shows that there is a trade-off between benefits and costs associated with rapid somatic growth. One would therefore expect growth rates under natural conditions to be close to an evolutionary optimum. Nevertheless, natural selection in many salmonid species appears to be toward larger size and earlier emergence from spawning redds, indicating a potential for increased growth rate to evolve. We tested how selection for genetic variants (growth hormone transgenic coho salmon, Oncorhynchus kisutch, with more than doubled daily growth rate potential relative to wild genotypes) depended on predator timing and food abundance during the early period of life (fry stage). In artificial redds, fry of the fast-growing genotypes showed a highly significant developmental shift, emerging from gravel nests approximately two weeks sooner, but with an 18.6% reduced survival, relative to wild-genotype fry. In seminatural streams, fry of the fast-growing genotypes suffered higher predation than those of wild genotypes when predators were present at the time of fry emergence, but this difference was less pronounced when food was scarce. In streams where predators were introduced after emergence, fry survived equally well regardless of food availability. Surviving fry grew faster in habitats provided with more food, and fast-growing genotypes also grew faster than Wild genotypes when predators arrived late and food was abundant. Fewer fish migrated downstream past a waterfall when food availability was high and in the presence of predators, and wild-genotype fry were more likely to migrate than fry of the fast-growing genotypes. After being returned to the experimental streams after migration, fast-growing genotypes survived equally well as those of the same genotypes that did not migrate, whereas migrating wild genotypes experienced higher mortality relative to those of the same genotypes that did not migrate. Comparisons of growth rates between siblings retained under hatchery conditions and those from habitats with the fastest growth in the experimental stream revealed that growth rates were similar for wild genotypes in both environments, whereas the fast-growing genotypes in the streams only realized 90% of their growth potential. The present study has shown that a major shift in developmental timing can alter critical early stages affecting survival and can have a significant effect on fitness. Furthermore, ecological conditions such as food abundance and predation pressure can strongly influence the potential for fast-growing variants to survive under natural conditions. The large-scale removal of many predatory species around the world may augment the evolution of increased intrinsic growth rates in some taxa.
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