| 41. |
- Lundin, Lars-Christer, et al.
(författare)
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Continuous long-term measurements of soil-plant-atmosphere variables at a forest site
- 1999
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Ingår i: Agricultural and Forest Meteorology. - 0168-1923 .- 1873-2240. ; 98-99, s. 53-73
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Tidskriftsartikel (refereegranskat)abstract
- It is a major challenge in modem science to decrease the uncertainty in predictions of global climate change. One of the largest uncertainties in present-day global climate models resides with the understanding of processes in the soil-vegetation-atmosphere-transfer (SVAT) system. Continuous, long-term data are needed in order to correctly quantify balances of water, energy and CO2 in this system and to correctly model it. It is the objective of this paper to demonstrate how a combined system of existing sensor, computer, and network technologies could be set up to provide continuous and reliable long-term SVAT-process data from a forested site under almost all environmental conditions. The Central Tower Site (CTS) system was set up in 1993-1994 in a 25 m high boreal forest growing on a highly heterogeneous till soil with a high content of stones and blocks. It has successfully monitored relevant states and fluxes in the system, such as atmospheric fluxes of momentum, heat, water vapour and CO2, atmospheric profiles of temperature, water vapour, CO2, short-and long-wave radiation, heat storage in soil and trees, sap-dow and a variety of ecophysiological properties, soil-water contents and tensions, and groundwater levels, rainfall and throughfall. System uptime has been more than 90% for most of its components during the first 5 years of operation. Results from the first 5 years of operation include e.g., budgets for energy, water and CO2, information on important but rarely occurring events such as evaporation from snow-covered canopies, and reactions of the forest to extreme drought. The carbon budget shows that the forest may be a sink of carbon although it is still growing. The completeness of the data has made it possible to test the internal consistency of SVAT models. The pioneering set-up at the CTS has been adopted by a large number of SVAT-monitoring sites around the world. Questions concerning tower maintenance, long-term calibration plans, maintenance of sensors and data-collection system, and continuous development of the computer network to keep it up to date are, however, only partly of interest as a research project in itself. It is thus difficult to get it funded from usual research-funding agencies. The full value of data generated by the CTS system can best be appreciated after a decade or more of continuous operation. Main uses of the data would be to evaluate how SVAT models handle the natural variability of climate conditions, quantification of water. carbon and energy budgets during various weather conditions, rind development of new parameterisation schemes in global and regional climate models.
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| 42. |
- Lundin, Lars-Christer, et al.
(författare)
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System of information in NOPEX : retrieval, use, and query of climate data
- 1999
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Ingår i: Agricultural and Forest Meteorology. - 0168-1923 .- 1873-2240. ; 98-99, s. 31-51
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Tidskriftsartikel (refereegranskat)abstract
- The uncertainty in climate predictions caused by improper understanding of the role of the land-surface is underestimated and easy access to data from a series of landscape types around the globe would improve this. Such data exist from a series of large-scale land-surface experiments but access to them has been difficult. It is the objective of this paper to demonstrate how the System for Information in NOPEX (SINOP) could be set up to provide a combination of data archive and tool for executing various time-limited and long-term field activities. Setting up and running SINOP involved both technical and psychological issues. The major technical problems were associated with (i) the uninterrupted flow of large data volumes, (ii) data homogeneity, and (iii) the exploding technology development. The psychological and organisational problems were more difficult to tackle than the technical problems. Funding agencies assumed somebody else would take care of data archiving and documentation, academic organisations have difficulties to compete with the private market for database managers, many individual scientists were unwilling to deliver their datasets and, especially, unwilling to document them. It is suggested that changes in attitudes from scientists, academic organisations, and publishers are needed to give credit for the publication of good datasets and for the production of good documentation about them. CDs incorporating a subset of SINOP with well-documented datasets from NOPEX operations in 1994 and 1995 are published together with this NOPEX Special Issue. The CDs include climate variables, such as radiation, fluxes of heat, momentum, and water vapour, and various energy storage terms as well as hydrological variables from 13 sites within the central-Swedish NOPEX region, at the southern boundary of the boreal zone. The publication of these data is seen as a step towards giving data-set owners proper and citeable credit for their work.
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| 43. |
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Mallapura, Hemantha, et al.
(författare)
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Advancements in Microfluidic Cassette-Based iMiDEVTM Technology for Production of L-[11C]Methionine and [11C]Choline
- 2024
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Ingår i: Pharmaceuticals. - : MDPI. - 1424-8247. ; 17:2
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Tidskriftsartikel (refereegranskat)abstract
- Microfluidic technology is a highly efficient technique used in positron emission tomography (PET) radiochemical synthesis. This approach enables the precise control of reactant flows and reaction conditions, leading to improved yields and reduced synthesis time. The synthesis of two radiotracers, L-[11C]methionine and [11C]choline, was performed, using a microfluidic cassette and an iMiDEVTM module by employing a dose-on-demand approach for the synthesis process. We focused on optimizing the precursor amounts and radiosynthesis on the microfluidic cassette. L-[11C]methionine and [11C]choline were synthesized using a microreactor filled with a suitable resin for the radiochemical reaction. Trapping of the [11C]methyl iodide, its reaction, and solid-phase extraction purification were performed on a microreactor, achieving radiochemical yields of >80% for L-[11C]methionine and >60% for [11C]choline (n = 3). The total synthesis time for both the radiotracers was approximately 20 min. All quality control tests complied with the European Pharmacopeia standards. The dose-on-demand model allows for real-time adaptation to patient schedules, making it suitable for preclinical and clinical settings. Precursor optimization enhanced the cost efficiency without compromising the yield. The importance of dose-on-demand synthesis and optimized precursor utilization to produce L-[11C]methionine and [11C]choline was emphasized in this study. The results demonstrated the feasibility of dose-on-demand adaptations for clinical applications with reduced precursor quantities and high radiochemical yields.
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| 48. |
- Mallapura, Hemantha, et al.
(författare)
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Microfluidic-based production of [68Ga]Ga-FAPI-46 and [68Ga]Ga-DOTA-TOC using the cassette-based iMiDEVâ„¢ microfluidic radiosynthesizer
- 2023
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Ingår i: EJNMMI Radiopharmacy and Chemistry. - : Springer. - 2365-421X. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Background The demand for Ga-68-labeled radiotracers has significantly increased in the past decade, driven by the development of diversified imaging tracers, such as FAPI derivatives, PSMA-11, DOTA-TOC, and DOTA-TATE. These tracers have exhibited promising results in theranostic applications, fueling interest in exploring them for clinical use. Among these probes, Ga-68-labeled FAPI-46 and DOTA-TOC have emerged as key players due to their ability to diagnose a broad spectrum of cancers ([Ga-68]Ga-FAPI-46) in late-phase studies, whereas [Ga-68]Ga-DOTA-TOC is clinically approved for neuroendocrine tumors. To facilitate their production, we leveraged a microfluidic cassette-based iMiDEV radiosynthesizer, enabling the synthesis of [Ga-68]Ga-FAPI-46 and [Ga-68]Ga-DOTA-TOC based on a dose-on-demand (DOD) approach.Results Different mixing techniques were explored to influence radiochemical yield. We achieved decay-corrected yield of 44 +/- 5% for [Ga-68]Ga-FAPI-46 and 46 +/- 7% for [Ga-68]Ga-DOTA-TOC in approximately 30 min. The radiochemical purities (HPLC) of [Ga-68]Ga-FAPI-46 and [Ga-68]Ga-DOTA-TOC were 98.2 +/- 0.2% and 98.4 +/- 0.9%, respectively. All the quality control results complied with European Pharmacopoeia quality standards. We optimized various parameters, including Ga-68 trapping and elution, cassette batches, passive mixing in the reactor, and solid-phase extraction (SPE) purification and formulation. The developed synthesis method reduced the amount of precursor and other chemicals required for synthesis compared to conventional radiosynthesizers.Conclusions The microfluidic-based approach enabled the implementation of radiosynthesis of [Ga-68]Ga-FAPI-46 and [Ga-68]Ga-DOTA-TOC on the iMiDEV (TM) microfluidic module, paving the way for their use in preclinical and clinical applications. The microfluidic synthesis approach utilized 2-3 times less precursor than cassette-based conventional synthesis. The synthesis method was also successfully validated in a similar microfluidic iMiDEV module at a different research center for the synthesis of [Ga-68]Ga-FAPI-46 with limited runs. Our study demonstrated the potential of microfluidic methods for efficient and reliable radiometal-based radiopharmaceutical synthesis, contributing valuable insights for future advancements in this field and paving the way for routine clinical applications in the near future.
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| 49. |
- Mallapura, Hemantha, et al.
(författare)
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Production of [C-11]Carbon Labelled Flumazenil and L-Deprenyl Using the iMiDEV (TM) Automated Microfluidic Radiosynthesizer
- 2022
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Ingår i: Molecules. - : MDPI. - 1431-5157 .- 1420-3049. ; 27:24
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Tidskriftsartikel (refereegranskat)abstract
- In the last decade, microfluidic techniques have been explored in radiochemistry, and some of them have been implemented in preclinical production. However, these are not suitable and reliable for preparing different types of radiotracers or dose-on-demand production. A fully automated iMiDEV (TM) microfluidic radiosynthesizer has been introduced and this study is aimed at using of the iMiDEV (TM) radiosynthesizer with a microfluidic cassette to produce [C-11]flumazenil and [C-11]L-deprenyl. These two are known PET radioligands for benzodiazepine receptors and monoamine oxidase-B (MAO-B), respectively. Methods were successfully developed to produce [C-11]flumazenil and [C-11]L-deprenyl using [C-11]methyl iodide and [C-11]methyl triflate, respectively. The final products 1644 +/- 504 MBq (n = 7) and 533 +/- 20 MBq (n = 3) of [C-11]flumazenil and [C-11]L-deprenyl were produced with radiochemical purities were over 98% and the molar activity for [C-11]flumazenil and [C-11]L-deprenyl was 1912 +/- 552 GBq/mu mol, and 1463 +/- 439 GBq/mu mol, respectively, at the end of synthesis. All the QC tests complied with the European Pharmacopeia. Different parameters, such as solvents, bases, methylating agents, precursor concentration, and different batches of cassettes, were explored to increase the radiochemical yield. Synthesis methods were developed using 3-5 times less precursor than conventional methods. The fully automated iMiDEV (TM) microfluidic radiosynthesizer was successfully applied to prepare [C-11]flumazenil and [C-11]L-deprenyl.
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| 50. |
- Matheson, Granville J, et al.
(författare)
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Reliability of volumetric and surface-based normalisation and smoothing techniques for PET analysis of the cortex : A test-retest analysis using [11C]SCH-23390
- 2017
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Ingår i: NeuroImage. - : Elsevier BV. - 1053-8119 .- 1095-9572. ; 155, s. 344-353
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Tidskriftsartikel (refereegranskat)abstract
- Parametric voxelwise analysis is a commonly used tool in neuroimaging, as it allows for identification of regions of effects in the absence of a strong a-priori regional hypothesis by comparing each voxel of the brain independently. Due to the inherent imprecision of single voxel measurements, spatial smoothing is performed to increase the signal-to-noise ratio of single-voxel estimates. In addition, smoothing compensates for imprecisions in anatomical registration, and allows for the use of cluster-based statistical thresholding. Smoothing has traditionally been applied in three dimensions, without taking the tissue types of surrounding voxels into account. This procedure may be suitable for subcortical structures, but is problematic for cortical regions for which grey matter often constitutes only a small proportion of the smoothed signal. New methods have been developed for cortical analysis in which voxels are sampled to a surface, and smoothing is restricted to neighbouring regions along the cortical grey matter in two dimensions. This procedure has recently been shown to decrease intersubject variability and bias of PET data. The aim of this study was to compare the variability, bias and test-retest reliability of volumetric and surface-based methods as they are applied in practice. Fifteen healthy young males were each measured twice using the dopamine D1 receptor radioligand [11C]SCH-23390, and analyses were performed at the level of individual voxels and vertices within the cortex. We found that surface-based methods yielded higher BPND values, lower coefficient of variation, less bias, better reliability and more precise estimates of parametric binding. All in all, these results suggest that surface-based methods exhibit superior performance to volumetric approaches for voxelwise analysis of PET data, and we advocate for their use when a ROI-based analysis is not appropriate.
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