NIRS-aided monitoring and prediction of biogas yields from maize silage at a full-scale biogas plant applying lumped kinetics.

The aim of this study was to apply near-infrared spectroscopy (NIRS), available biogas plant data and lumped degradation kinetics to predict biogas production (BPr) of maize silage. A full-scale agricultural biogas plant was equipped with NIRS-metrology at the feeding station. Continuously NIR-spectra were collected for 520 d. Substrate samples were analyzed by means of feedstuff analysis. Biogas potential of the samples was calculated from the laboratory analysis results and for a sample-subset practically assessed by "Hohenheim biogas tests". NIRS-regression-models for all mentioned parameters were calibrated. Continuously gathered spectra, NIRS-models, actual plant-feeding data and degradation kinetics were used to calculate time-series of theoretically expectable BPr. Results were validated against measured gas quantity. Determination coefficients between calculated and measured BPr were up to 58.2%. This outcome was mainly due to the positive correlation between BPr and input amount since the substrate was very homogeneous. The use of NIRS seems more promising for plants with stronger substrate heterogeneity.

Prevalence of periimplant disease in partially edentulous patients: a practice-based cross-sectional study.

OBJECTIVES: Evaluation of the prevalence rates of periimplant mucositis and periimplantitis in partially edentulous patients in a private dental practice. MATERIAL AND METHODS: The data of 89 patients were collected (52 female, 37 male, age at time of implant placement: 51.8 ± 10.3 years). All patients had been treated with dental implants of the same type and fixed superstructures between January 1999 and June 2006 (observational period: 68.2 ± 24.8 months). RESULTS: The patient-related prevalence rate of periimplant mucositis (probing depth ≥ 4 mm and bleeding on probing [BOP]) was over all 44.9%. The respective rates in non-smokers without periodontal history were 30.4% and in smokers with periodontal history 80%. The multiple logistic regression analysis identified a significant association of mucositis with the independent variable "smoker" (odds ratio [OR] 3.77; P = 0.023). The patient-related prevalence rate of periimplantitis (probing depth ≥ 5 mm, BOP/pus, radiographic bone loss) was 11.2% (smokers with periodontal history: 53.3%, non-smokers: 2.8%). No periimplant disease was diagnosed in non-smoking patients without periodontal history and with a good compliance after treatment. Statistical analysis identified a significant association of periimplantitis with "smoker" (OR: 31.58; P<0.001) and "compliance" (OR: 0.09; P = 0.011). Periodontal history in general showed no significant association with periimplantitis. CONCLUSIONS: Smoking and compliance are important risk factors for periimplant inflammations in partially edentulous patients.