1,720,989 research outputs found
Optimizing storage emissions of wood flakes by gas sensor controlled thermal oxidation of lipids
No full textPost-mortem volatiles of vertebrate tissue
No full textVolatile emission during vertebrate decay is a complex process that is understood incompletely. It depends on many factors. The main factor is the metabolism of the microbial species present inside and on the vertebrate. In this review, we combine the results from studies on volatile organic compounds (VOCs) detected during this decay process and those on the biochemical formation of VOCs in order to improve our understanding of the decay process. Micro-organisms are the main producers of VOCs, which are by- or end-products of microbial metabolism. Many microbes are already present inside and on a vertebrate, and these can initiate microbial decay. In addition, micro-organisms from the environment colonize the cadaver. The composition of microbial communities is complex, and communities of different species interact with each other in succession. In comparison to the complexity of the decay process, the resulting volatile pattern does show some consistency. Therefore, the possibility of an existence of a time-dependent core volatile pattern, which could be used for applications in areas such as forensics or food science, is discussed. Possible microbial interactions that might alter the process of decay are highlighted
Storage-induced emissions from different wood species
No full textIn this study, the extractive contents and the storage-induced emissions from chips of Salix alba, Betula pendula, Populus tremula, and Alnus glutinosa are compared with emissions from Pinus sylvestris chips. Soxhlet extraction was performed, and carbon monoxide (CO) and O-2 concentration in the gas phase as well as gas chromatography-mass spectrometry analysis of volatile organic compounds were analyzed. Pinus sylvestris showed the highest extractive content in the petrol ether fraction and emitted CO in the highest concentration. Salix alba, B. pendula, P. tremula, and A. glutinosa have lower extractive contents in the petrol ether fraction and the CO concentrations decreased in the headspace accordingly. The emission of aldehydes was lower in the case of woods with lower petrol ether contents (P. sylvestris, S. alba, and B. pendula), but the situation was not as clear for P. tremula and A. glutinosa. The origin of CO and aldehyde emissions is discussed in view of the possible oxidative degradation processes of lipids and terpenes.BMELV; FN
Monitoring of Eucalyptus globulus tissue thermal degradation by semi-conductor metal-oxide sensors for early fire detection in eucalypt forests
No full textCost Comparison of Drone and Foot Based Early Bark Beetle Detection
No full textEarly bark beetle detection is still a challenge, as the symptoms of early infestation stages are hard to identify. Conventional foot-based detection is time consuming, and the associated costs mostly depend on stand characteristics. Detection by gas sensor equipped drones has the potential to be more economical, as it does not rely on the limitations of walking speed on the ground. A novel drone-based system for early bark beetle detection by means of resin odor cues was compared to conventional foot-based detection. The results showed that the cost efficiency of the drone system was highly dependent on flight speed and hourly costs of the pilot, while the cost efficiency of the foot-based assessment highly depended on terrain slope and forest floor characteristics. In general, the drone-based detection of early infestation stages becomes more economical in comparison to the conventional foot-based detection method as forest areas, terrain slopes and understory density increase
Volatile Combustion Products of Wood Attract Acanthocnemus nigricans (Coleoptera: Acanthocnemidae)
No full textAcanthocnemus nigricans is an Australian pyrophilic beetle approaching smoldering logs for mating and oviposition. We investigated the behavior of the beetles towards combustion products of cellulose (5-methylfurfural, hydroxacetone, karrikinolide), lignin (4-methylguaiacol, 4-ethylguaiacol, eugenol), and (Z)-3-hexen-1-ol in a custom built dynamic two arm olfactometer. The beetles were attracted by 5-methylfurfural, 4-methylguaiacol, 4-ethylguaiacol, eugenol, and hydroxyacetone at different concentrations. Abundances of beetles caught in traps baited with a mixture of the most attractive volatiles showed only a trend to higher numbers. These results are discussed with respect to weather conditions and complementing infrared perception of the pyrophilic beetles
Utilization of black locust (Robinia pseudoacacia) sawdust as an alternative pelletization raw material
No full textAbstract
European pellet production will be a future challenge due to two effects: (1) the share of hardwood species in Europe will increase and (2) the pellet market will face raw material shortages. Therefore, we investigated the blending of conifer sawdust with black locust sawdust. Twenty-one physical and chemical pellet quality parameters were recorded, including combustion emissions. Our statistical evaluation showed a strong linear correlation (
p
>0.8 or
p
<−0.8) of the share of black locust with nine quality parameters. Fifty-three percent of the overall variation in the data was explained by the major principal component, which included the share of black locust. The cause of the decreasing pellet quality with increasing share of black locust sawdust was attributed to the heat conductance in the dye, which was affected by the hydrophobicity and rigidity of the black locust saw dust. A share of 25% black locust in blends with conifer sawdust is proposed as the limit to meet the A2 standard criteria in the European DIN EN ISO 17255-2. This would allow a black locust sawdust consumption of app. 6 mio t per year in Europe, which is far above the estimated abundance and indicates a high potential for hardwood sawdust as an alternative feedstock for pellet production in general.Bundesministerium für Bildung und Forschung http://dx.doi.org/10.13039/501100002347Georg-August-Universität Göttingen 50110000338
Volatile Emission of Decomposing Pig Carcasses (Sus scrofa domesticus L.) as an Indicator for the Postmortem Interval
No full textThis study aimed at correlating selected carcass borne volatile organic compounds (VOCs) with the postmortem interval (PMI). Selected volatiles should 1st be reliably emitted during vertebrate decay, 2nd be emitted at high concentrations, and 3rd show a reproducible quantitative dynamic during the decaying process. Four pigs (Sus scrofa domesticus L.) were placed in a deciduous forest in different seasons and volatiles emitted during the decaying process were sampled. Seventeen compounds were identified and quantified by GC-MS. Electrophysiological experiments on the antenna of female Calliphora vicina and additional data of Dermestes maculans were used as an evolutionary tuned information filter to evaluate the 1st criterion. The relative quantitative emission of hexanal, nonanal, dimethyl disulfide, dimethyl trisulfide, 1-butanol, and phenol were correlated with the PMI, and the observed stages of decay and the limitations of this model were discussed.Cusanuswerk, Bischofliche Studienstiftung, German
Semi-conductor metal oxide gas sensors for online monitoring of oak wood VOC emissions during drying
No full textTreeSeg—A Toolbox for Fully Automated Tree Crown Segmentation Based on High-Resolution Multispectral UAV Data
Full text linkSingle-tree segmentation on multispectral UAV images shows significant potential for effective forest management such as automating forest inventories or detecting damage and diseases when using an additional classifier. We propose an automated workflow for segmentation on high-resolution data and provide our trained models in a Toolbox for ArcGIS Pro on our GitHub repository for other researchers. The database used for this study consists of multispectral UAV data (RGB, NIR and red edge bands) of a forest area in Germany consisting of a mix of tree species consisting of five deciduous trees and three conifer tree species in the matured closed canopy stage at approximately 90 years. Information of NIR and Red Edge bands are evaluated for tree segmentation using different vegetation indices (VIs) in comparison to only using RGB information. We trained Faster R-CNN, Mask R-CNN, TensorMask and SAM in several experiments and evaluated model performance on different data combinations. All models with the exception of SAM show good performance on our test data with the Faster R-CNN model trained on the red and green bands and the Normalized Difference Red Edge Index (NDRE) achieving best results with an F1-Score of 83.5% and an Intersection over Union of 65.3% on highly detailed labels. All models are provided in our TreeSeg toolbox and allow the user to apply the pre-trained models on new data
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