Concrete carbonation is a process that can limit the lifetime of reinforced concrete structures. ... more Concrete carbonation is a process that can limit the lifetime of reinforced concrete structures. The resistance of concrete samples to carbonation is usually determined by accelerated tests under relatively high CO2-concentrations and a fixed relative humidity. No general agreement exists on whether and how the results of these experiments can be extrapolated to a natural setting. This note presents a partial review of existing extrapolation strategies, particularly of explicit prediction formulas. A summary of the problems and limitations which are known from experiments and theoretical modelling is given. Special focus is directed to the different moisture transport characteristics in both natural and accelerated settings. Some strategies are proposed on how to deal with the problems.
... 3.8). 2.3 Further material and process functions and constants The numerical values of the fo... more ... 3.8). 2.3 Further material and process functions and constants The numerical values of the following constants will be introduced in sections 4 and 6. Dwk - effective diffusion coefficient for moisture in nk(t), k = 1, 2, Dck - effective diffusion coefficient for CO2(aq) .(cf. footnote 2), ...
This prospective study assessed the impact of (18)F-fluorodeoxyglucose (FDG) positron emission to... more This prospective study assessed the impact of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) on the staging and possible consequential changes of treatment regimen in patients with Hodgkin's lymphoma (HL). A total of 88 consecutive patients with histologically verified Hodgkin's lymphoma underwent a PET scan in addition to conventional staging procedures. Treatment was based on the conventional staging only, and the results of the FDG-PET did not affect the treatment strategy. The evaluation focused on the suggested change in clinical stage according to the Ann Arbor classification and on the suggested change in treatment strategy rather than on a lesion-by-lesion analysis. Using all the methods performed as the standard of reference, (18)F-FDG-PET staging was concordant with conventional staging in 70 out of 88 patients (80%). (18)F-fluorodeoxyglucose positron emission tomography suggested a change to a different clinical stage in 18 patients (20%). Manag...
For optimized logistics for the sentinel lymphadenectomy (SL) it might be helpful for the clinics... more For optimized logistics for the sentinel lymphadenectomy (SL) it might be helpful for the clinics involved if a longer time period between the lymphoscintigraphy (LS) and surgery is possible. Therefore, we investigated if a precise localization of the sentinel lymph node is possible 24 hours after LS. 78 patients with primary malignant melanoma (MM; n = 44) or with MM pre-operated by excisional biopsy (n = 34) were investigated. In 40 cases the tumor was localized on the trunk and in 38 cases on the extremities. Mean MM thickness was 2.68 mm (range: 0.29 to 12 mm). In all patients a lymphoscintigraphy (LS) with an average of 85 MBq of Tc-99m nanocolloid was performed one day prior to surgery. Immediately after tracer application dynamic data acquisition was started at a LFOV gamma camera followed by a whole body scan. With a hand-held gamma detector (C-Trak) 2, 4, 6, 8, and 24 hours after tracer administration the SLN was identified and the counts registered. 94 SLNs were identified in 87 lymphatic basins from which 86 could be resected. Nine MM showed two draining channels. After 24 hours 15.5% (as an average) of the initial counts could be measured in the SLN. The uptake in the SLN in pre-operated versus patients with primary tumor was statistically not significant (p = 0.4). In 16 cases (20.5%) the SLN was tumor positive. Four of those patients developed distant metastases and two died within the first year. None of the patients with negative SLN developed distant metastases or died. The remaining activity in the SLN up to 24 hours after administration is sufficient for their intra operative localization. The method of lymphoscintigraphy and localization of the SLN by a hand-held gamma detector optimizes the intra operative identification of the SLN in patients with malignant melanoma.
ABSTRACT This work is part of an International Cooperation Agreement for the conservation of hist... more ABSTRACT This work is part of an International Cooperation Agreement for the conservation of historical monuments made of reinforced concrete in Brasilia. This research is based on a routine inspection of the National Theatre of Brasilia, a city recognized by UNESCO in 1987 as world cultural heritage. The structure, entirely made of reinforced concrete, was conceived by architect Oscar Niemeyer, and has a total of 48 m of height and 42,000 m2 of constructed area. After examining the available documentation, the existing damage was then identified and mapped. The concrete shows a good state of conservation, with the exception of some regions of the structure: the damages found were exposed armature, oxidation of armature, infiltration, mold and efflorescence.Este trabajo es parte de un Acuerdo de Cooperación Internacional para la conservación de monumentos históricos de hormigón armado en Brasilia. Esta investigación es el resultado de una inspección rutinaria en el Teatro Nacional de Brasilia, ciudad reconocida por la UNESCO, en 1987, como patrimonio cultural de la humanidad. La estructura, toda en hormigón armado, fue concebida por el arquitecto Osear Niemeyer, con un total de 48 m de altura y 42.000 m2 de área construida. Tras investigar la documentación disponible, se procedió a la identificación y al estudio de los daños existentes. El hormigón presenta un buen estado de conservación, salvo en algunas regiones de la estructura: estructura armada expuesta, oxidación de la estructura armada, infiltración, moho y eflorescencia son algunos de los daños que se encontraron.
Concrete carbonation is a process that can limit the lifetime of reinforced concrete structures. ... more Concrete carbonation is a process that can limit the lifetime of reinforced concrete structures. The resistance of concrete samples to carbonation is usually determined by accelerated tests under relatively high CO2-concentrations and a fixed relative humidity. No general agreement exists on whether and how the results of these experiments can be extrapolated to a natural setting. This note presents a partial review of existing extrapolation strategies, particularly of explicit prediction formulas. A summary of the problems and limitations which are known from experiments and theoretical modelling is given. Special focus is directed to the different moisture transport characteristics in both natural and accelerated settings. Some strategies are proposed on how to deal with the problems.
... 3.8). 2.3 Further material and process functions and constants The numerical values of the fo... more ... 3.8). 2.3 Further material and process functions and constants The numerical values of the following constants will be introduced in sections 4 and 6. Dwk - effective diffusion coefficient for moisture in nk(t), k = 1, 2, Dck - effective diffusion coefficient for CO2(aq) .(cf. footnote 2), ...
This prospective study assessed the impact of (18)F-fluorodeoxyglucose (FDG) positron emission to... more This prospective study assessed the impact of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) on the staging and possible consequential changes of treatment regimen in patients with Hodgkin's lymphoma (HL). A total of 88 consecutive patients with histologically verified Hodgkin's lymphoma underwent a PET scan in addition to conventional staging procedures. Treatment was based on the conventional staging only, and the results of the FDG-PET did not affect the treatment strategy. The evaluation focused on the suggested change in clinical stage according to the Ann Arbor classification and on the suggested change in treatment strategy rather than on a lesion-by-lesion analysis. Using all the methods performed as the standard of reference, (18)F-FDG-PET staging was concordant with conventional staging in 70 out of 88 patients (80%). (18)F-fluorodeoxyglucose positron emission tomography suggested a change to a different clinical stage in 18 patients (20%). Manag...
For optimized logistics for the sentinel lymphadenectomy (SL) it might be helpful for the clinics... more For optimized logistics for the sentinel lymphadenectomy (SL) it might be helpful for the clinics involved if a longer time period between the lymphoscintigraphy (LS) and surgery is possible. Therefore, we investigated if a precise localization of the sentinel lymph node is possible 24 hours after LS. 78 patients with primary malignant melanoma (MM; n = 44) or with MM pre-operated by excisional biopsy (n = 34) were investigated. In 40 cases the tumor was localized on the trunk and in 38 cases on the extremities. Mean MM thickness was 2.68 mm (range: 0.29 to 12 mm). In all patients a lymphoscintigraphy (LS) with an average of 85 MBq of Tc-99m nanocolloid was performed one day prior to surgery. Immediately after tracer application dynamic data acquisition was started at a LFOV gamma camera followed by a whole body scan. With a hand-held gamma detector (C-Trak) 2, 4, 6, 8, and 24 hours after tracer administration the SLN was identified and the counts registered. 94 SLNs were identified in 87 lymphatic basins from which 86 could be resected. Nine MM showed two draining channels. After 24 hours 15.5% (as an average) of the initial counts could be measured in the SLN. The uptake in the SLN in pre-operated versus patients with primary tumor was statistically not significant (p = 0.4). In 16 cases (20.5%) the SLN was tumor positive. Four of those patients developed distant metastases and two died within the first year. None of the patients with negative SLN developed distant metastases or died. The remaining activity in the SLN up to 24 hours after administration is sufficient for their intra operative localization. The method of lymphoscintigraphy and localization of the SLN by a hand-held gamma detector optimizes the intra operative identification of the SLN in patients with malignant melanoma.
ABSTRACT This work is part of an International Cooperation Agreement for the conservation of hist... more ABSTRACT This work is part of an International Cooperation Agreement for the conservation of historical monuments made of reinforced concrete in Brasilia. This research is based on a routine inspection of the National Theatre of Brasilia, a city recognized by UNESCO in 1987 as world cultural heritage. The structure, entirely made of reinforced concrete, was conceived by architect Oscar Niemeyer, and has a total of 48 m of height and 42,000 m2 of constructed area. After examining the available documentation, the existing damage was then identified and mapped. The concrete shows a good state of conservation, with the exception of some regions of the structure: the damages found were exposed armature, oxidation of armature, infiltration, mold and efflorescence.Este trabajo es parte de un Acuerdo de Cooperación Internacional para la conservación de monumentos históricos de hormigón armado en Brasilia. Esta investigación es el resultado de una inspección rutinaria en el Teatro Nacional de Brasilia, ciudad reconocida por la UNESCO, en 1987, como patrimonio cultural de la humanidad. La estructura, toda en hormigón armado, fue concebida por el arquitecto Osear Niemeyer, con un total de 48 m de altura y 42.000 m2 de área construida. Tras investigar la documentación disponible, se procedió a la identificación y al estudio de los daños existentes. El hormigón presenta un buen estado de conservación, salvo en algunas regiones de la estructura: estructura armada expuesta, oxidación de la estructura armada, infiltración, moho y eflorescencia son algunos de los daños que se encontraron.
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