•Assessment of calcite formation on steam flown concrete crack surfaces.•Combined evaluation of crack healing by mineralogical analysis and flow measurement.•Calcite layers increases along the steam ...exposure time up to a stable level.•Evidence of mass flow reduction in steam flown cement cracks by autogenous healing.
Under accidental conditions, concrete containments of nuclear power plants often remain as final barrier to the environment. To evaluate the contribution of self-healing processes of cracked concrete containments, small scale experiments were conducted for given accident scenarios to examine the mineralogical processes on cement crack surfaces in contact with hot steam-air mixes. The surface analyses with ESEM, µ-RFA and microscope showed a calcite formation, where layer thicknesses increased along the exposure times until reaching a stable level. The potential for crack healing was principally demonstrated through flow measurements, where the outflowing mass decreased during the experiments along with increasing calcite formation.
Intense reuse of treated wastewater in agriculture is practiced all over the world, especially in arid and water-scarce regions. In doing so, pharmaceutical residues in the water are irrigated to the ...soil and subsequently can percolate into the local aquifers. Since evaporation rates in these areas are typically high, persistent substances might enrich in the groundwater recharge of closed catchments like the Jordan Valley. Against this background, unsaturated column tests were conducted to investigate the potential for evaporative accumulation of the two pharmaceuticals bezafibrate and carbamazepine under simulated arid climate conditions. Parallel tests were conducted with inhibited microbiological activity where both substances showed an increase in the effluent concentrations proportional to the evaporation loss of the inflow solution. The mean accumulation factors of the pharmaceuticals correspond to the evaporated water loss. The experiments indicate the accumulation potential for pharmaceuticals with high persistence against biodegradation. For the first time, the overall potential for evaporative enrichment could be demonstrated for pharmaceuticals. Under the given experimental conditions, the two investigated pharmaceuticals did not enrich faster than chloride, which might result in soil salting prior to reaching harmful pharmaceutical concentrations in soil water. The findings are relevant to future assessments of environmental impacts of persistent trace substances, which need to take into account that concentrations in the aquatic cycle might increase further due to evaporative enrichment.
•Evaporative enrichment of pharmaceuticals was demonstrated in unsaturated columns.•Outflowing concentrations were higher than the inflowing for inhibited microbiology.•Pharmaceutical enrichment occurred at the same rate like chloride.•Microbiological degradation of carbamazepine was higher at 35 °C compared to 20 °C.•Uninhibited columns showed the potential to remove the easy degradable bezafibrate.
Two different in situ spectrophotometers are compared that were used in the field to determine nitrate-nitrogen (NO3-N) concentrations at two distinct spring discharge sites. One sensor was a double ...wavelength spectrophotometer (DWS) and the other a multiple wavelength spectrophotometer (MWS). The objective of the study was to review the hardware options, determine ease of calibration, accuracy, influence of additional substances and to assess positive and negative aspects of the two sensors as well as troubleshooting and trade-offs. Both sensors are sufficient to monitor highly time-resolved NO3-N concentrations in emergent groundwater. However, the chosen path length of the sensors had a significant influence on the sensitivity and the range of detectable NO3-N. The accuracy of the calculated NO3-N concentrations of the sensors can be affected if the content of additional substances such as turbidity, organic matter, nitrite or hydrogen carbonate significantly varies after the sensors have been calibrated to a particular water matrix. The MWS offers more possibilities for calibration and error detection but requires more expertise compared with the DWS.
Elimination of pathogens and emerging pollutants represents a key factor in integrated water resources management in arid regions. Within the SMART Jordan Valley project it is the objective of this ...study to assess the occurrence and examine the elimination of selected emerging pollutants and pathogens in waste water treatment and aquifer recharge. In batch and soil column studies non-chlorinated organophosphorous compounds (tri-n-butylphosphate, triphenylphosphate) and endocrine disruptors (e.g. 17-ß-estradiol, bisphenol A) proved to be biodegradable, while the X-ray contrast agents iomeprol and iopromide were eliminated in the soil columns only, and the chlorinated trialkylphosphates showed persistency. Treating waste water in a membrane bioreactor (MBR) in combination with powdered activated carbon (PAC) resulted in considerable removal rates also for the more persistent compounds such as the antiepileptic carbamazepine. Viruses were shown to be present in most of the Jordan Valley surface water samples. MBR treatment resulted in a decrease of MS2 bacteriophages used as model viruses.
At the Material Testing and Research Institute (MPA Karlsruhe) leakage experiments with concrete specimens containing a single penetrating crack were performed on behalf of GRS. The specimens had a ...prismatic shape and the dimensions 4.0 cm × 4.0 cm × 11.0 cm. The crack width was adjustable and ranged from 0.05 mm to 0.25 mm in the experiments. On top of the leakage measurement two sets of additional measurements were performed. In leakage experiments with air at room temperature the exit velocity of the leakage flow was measured with a hot-wire anemometer. The measured velocities were compared to the velocities calculated by leakage rate formulas. The formulas compare well to measurement results. Differences depend greatly on the crack width and the respective assumptions on the friction coefficient proposed by the authors. In a second set of experiments, hot air and hot steam/air mixtures were used. At the beginning of the experiment the specimen had room temperature; due to heat transfer from the leaking fluid to the specimen and the thermal expansion of the specimen, the crack width was reduced, and the leakage rate significantly decreased. The leakage process including fluid-structure interaction was simulated using the coupling of the thermal-hydraulic system code ATHLET, which has been developed and validated by GRS, and the structure mechanical finite element code ANSYS Mechanical.
Summary Local recurrent of disease in advanced carcinomas of the head and neck is strongly correlated with the presence of positive or close resection margins after operative treatment. The purpose ...of this study is to present a new method of assessing resection margins intraoperatively using image-guided surgery based on positron emission tomography/computed tomography (PET/CT) image fusion. In 6 patients who underwent surgical treatment of head and neck stage for T4a–T4b carcinomas PET/CT image fusion was done on the workstation of a 3D-navigation system. Intraoperative image-guided navigation of the defect following surgical ablation of the tumour was performed in every patient. Intraoperative navigation of the ablative defect showed an unsafe resection margin in 4 patients. In three of these patients additional image-guided resection allowed local control of the tumour to be achieved. In one patient additional resection was not possible due to skull base invasion. The histopathological exam of the four tumour specimens confirmed positive or close resection margins. The current results suggest that intraoperative control of the surgical margins using a 3D-navigation system based on PET/CT image fusion can be a useful tool to assess and improve local control in advanced cancer of the head and neck.
Objective Bisphosphonate-related osteonecrosis of the jaw (BONJ) is a common complication of bisphosphonate treatment that has been well documented over the past decade. Nevertheless, its ...pathogenesis is poorly understood, and treatment guidelines are based mostly on expert recommendations. Clinicians must be aware of malignancy mimicking BONJ, of which a few cases have been documented in the literature. Study Design Three patients undergoing long-term treatment with intravenous bisphosphonates for malignant disease demonstrated the distinct diagnostic signs of BONJ. Surgical treatment was performed by resecting the affected bone. In all cases, histologic specimens were taken for analysis. Results Histologic analysis of the bone specimen with surrounding soft tissue revealed necrotic bone with signs of inflammation, but also with cells of the underlying malignant disease. Conclusions Clinical and radiographic diagnosis of BONJ should be confirmed by histologic analysis in patients with underlying malignant disease.
Purpose Anterior alveolar osteodistraction is a common method for enlargement of the dentoalveolar process, and bone-borne distraction devices are hypothesized to avoid the risk of dental tipping and ...periodontal impairment during distraction. The aim of this study was to objectify this thesis and to determine the reliability of bone-borne osteodistraction of the anterior alveolar process. Patients and Methods The study group consisted of 18 consecutive patients who underwent anterior alveolar segmental distraction with a bone-borne distraction device for the treatment of dental crowding or alveolar retrusion from 2008 through 2011. Clinical and radiologic changes within the apical base and dentoalveolar process were analyzed after bone-borne distraction osteogenesis. All measurements were carried out using cone-beam computed tomography. Results Surgery and the postoperative period were uneventful in all patients. Mean alveolar movement was 8.2° ± 2.4°. Skeletal movement was 97.6% and absolute dental tipping was 2.4%. A mean change in the occlusal plane of 1.9° ± 1.1° was verified. The apical base enlargement showed a mean of 7.9 ± 1.4 mm, and the dentoalveolar arch a mean increase of 12.7 ± 2.1 mm. Within the distraction zone, a mean vertical bone loss of 3.5 ± 0.7 mm and a mean horizontal bone loss of 3.9 ± 0.8 mm were seen. After orthodontic gap closure, both were clinically irrelevant, with no need for additional bone grafts. Periodontal impairment (gingival recessions of 1 mm) was observed in 7 patients but affected only the teeth bordering the vertical osteotomy line. Conclusions Bone-borne anterior alveolar osteodistraction is sufficient for enlargement of the apical base and the dentoalveolar arch of the mandible. Skeletal movement of the alveolar segment was predictable and dental tipping was clinically irrelevant. This technique presents further indications and approaches in orthognathic surgery.
Purpose Segmental distraction osteogenesis of the anterior alveolar process has been introduced as a technique designed to avoid extractions in patients with severe dental crowding. The aim of this ...study was to quantify the degree of dental tipping within the alveolar segment after distraction osteogenesis. Patients and Methods Patients treated for dental crowding, retruded anterior alveolar process, or flat curves of Spee using segmental distraction osteogenesis of the anterior alveolar process were included in the study. Dental-borne distraction devices were used while measuring points, and angles were defined to analyze the amount of dental tipping of the lower incisors after distraction. The measurements were performed using cone-beam computed tomographic scans. Periodontal health (eg, gingival recession, tooth mobility, and dental socket depths) was evaluated after distraction. A descriptive statistical analysis was performed. Results Fifteen patients were included in the study. The amount of dental tipping within the total movement of the alveolar process showed a mean of 24% after distraction osteogenesis, whereas the skeletal movement was 76%. Dental socket depths and tooth mobility remained at the same levels as those before distraction osteogenesis. In one third of patients, gingival recession was observed around the canines. Conclusions Segmental distraction osteogenesis of the anterior process is a powerful technique that can prevent extractions in patients with dental crowding. The technique can also compensate for retruded anterior alveolar process and accelerate or decelerate the curve of Spee. Patients with constricted periodontal health and those with a thin mandibular symphysis, however, cannot be treated with this technique because of the increased risk of dental tipping. Severe gingival recession must also be considered a possible side effect associated with this technique.
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