https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1131&context=usdoepub

A review of polymer electrolyte membrane fuel cells: Technology, applications,and needs on fundamental research

Patterns, mechanisms, projections, and consequences of tree mortality and associated broad-scale forest die-off due to drought accompanied by warmer temperatures—“hotter drought”, an emerging characteristic of the Anthropocene—are the focus of rapidly expanding literature. Despite recent observational, experimental, and modeling studies suggesting increased vulnerability of trees to hotter drought and associated pests and pathogens, substantial debate remains among research, management and policy-making communities regarding future tree mortality risks. We summarize key mortality-relevant findings, differentiating between those implying lesser versus greater levels of vulnerability. Evidence suggesting lesser vulnerability includes forest benefits of elevated [CO2] and increased water-use efficiency; observed and modeled increases in forest growth and canopy greening; widespread increases in woody-plant biomass, density, and extent; compensatory physiological, morphological, and genetic mechanisms; dampening ecological feedbacks; and potential mitigation by forest management. In contrast, recent studies document more rapid mortality under hotter drought due to negative tree physiological responses and accelerated biotic attacks. Additional evidence suggesting greater vulnerability includes rising background mortality rates; projected increases in drought frequency, intensity, and duration; limitations of vegetation models such as inadequately represented mortality processes; warming feedbacks from die-off; and wildfire synergies. Grouping these findings we identify ten contrasting perspectives that shape the vulnerability debate but have not been discussed collectively. We also present a set of global vulnerability drivers that are known with high confidence: (1) droughts eventually occur everywhere; (2) warming produces hotter droughts; (3) atmospheric moisture demand increases nonlinearly with temperature during drought; (4) mortality can occur faster in hotter drought, consistent with fundamental physiology; (5) shorter droughts occur more frequently than longer droughts and can become lethal under warming, increasing the frequency of lethal drought nonlinearly; and (6) mortality happens rapidly relative to growth intervals needed for forest recovery. These high-confidence drivers, in concert with research supporting greater vulnerability perspectives, support an overall viewpoint of greater forest vulnerability globally. We surmise that mortality vulnerability is being discounted in part due to difficulties in predicting threshold responses to extreme climate events. Given the profound ecological and societal implications of underestimating global vulnerability to hotter drought, we highlight urgent challenges for research, management, and policy-making communities.

/pdf/on-underestimation-of-global-vulnerability-to-tree-mortality-1w5zrntf70.pdf

On underestimation of global vulnerability to tree mortality and forest die‐off from hotter drought in the Anthropocene

https://iopscience.iop.org/article/10.1149/2.1441707jes/pdf

Review—SEI: Past, Present and Future

/pdf/high-resolution-x-ray-computed-tomography-in-geosciences-a-3sj7249knj.pdf

High-resolution X-ray computed tomography in geosciences: A review of the current technology and applications

3.8.2. Temperature Distribution Measurements 4749 3.8.3. Two-Phase Visualization 4750 3.8.4. Experimental Validation 4751 3.9. Modeling the Catalyst Layer at Pore Level 4751 3.10. Summary and Outlook 4752 4. Direct Methanol Fuel Cells 4753 4.1. Technical Challenges 4754 4.1.1. Methanol Oxidation Kinetics 4754 4.1.2. Methanol Crossover 4755 4.1.3. Water Management 4755 4.1.4. Heat Management 4756 4.2. DMFC Modeling 4756 4.2.1. Needs for Modeling 4756 4.2.2. DMFC Models 4756 4.3. Experimental Diagnostics 4757 4.4. Model Validation 4758 4.5. Summary and Outlook 4760 5. Solid Oxide Fuel Cells 4760 5.1. SOFC Models 4761 5.2. Summary and Outlook 4762 6. Closing Remarks 4763 7. Acknowledgments 4763 8. References 4763

Fundamental models for fuel cell engineering.

Characterization of Two Japanese Ancient Swords through Neutron Imaging

Just after the start into the new millennium the concept for combined neutron and X-ray imaging was introduced by extending the standard configuration of the thermal neutron imaging NEUTRA instrument with a complementary 320 kV X-ray tube setup. Using essentially the same detector configuration for both neutron and X-ray imaging enables a pixel-wise (in radiography) and a voxel-wise (in tomography) correlation and combination of attenuation data. The optimal use and analyses of such complementary data sets depend on the specific investigation and research question and range from a combinatory interpretation of separately analyzed images to full data fusion approaches. Here, several examples from more than a decade of bimodal neutron and X-ray imaging at NEUTRA at PSI shall be reviewed.

/pdf/the-xtra-option-at-the-neutra-facility-more-than-10-years-of-4nmhdc9x7a.pdf

The XTRA Option at the NEUTRA Facility—More Than 10 Years of Bi-Modal Neutron and X-ray Imaging at PSI

Existing non-destructive techniques for analysis of the water absorbing behavior of stone material have a different nature. This leads to discrepancies in practical application and measuring area, resulting in difficulties when comparing results of different methods. The present study focuses on the comparison of different non-destructive methods in terms of practical application, influence of variable factors and accuracy in relation to the open porosity and the capillary rise measurements. The comparison was based on repetitive measurements and X-ray and neutron radiography of the water absorption by lithotypes with a varying open porosity. The methods under study are the Karsten tube (KT), the contact sponge method (CSM) and the Mirowski pipe (MIR). It can be concluded that KT and CSM have complementary fields of investigation, whereas MIR produces unreliable results due to practical discommodities. The most significant variable factor influencing the measurements is the surface of the contact area. A study of analytical models describing the capillary water absorption as reference for interpretation of results of the different methods is currently ongoing.

http://iscs.icomos.org/pdf-files/NewYorkConf/vandetal.pdf

Comparison of non-destructive techniques for analysis of the water absorbing behavior of stone

https://www.dora.lib4ri.ch/psi/islandora/object/psi%3A22397/datastream/PDF/Mannes-2017-Gemmological_investigations_on_pearls_and-%28published_version%29.pdf

Gemmological Investigations on Pearls and Emeralds using Neutron Imaging

https://www.dora.lib4ri.ch/psi/islandora/object/psi%3A22367/datastream/PDF/Lehmann-2017-Methodical_progress_in_neutron_imaging-%28published_version%29.pdf

Eberhard Lehmann

Papers

Characterization of Two Japanese Ancient Swords through Neutron Imaging

The XTRA Option at the NEUTRA Facility—More Than 10 Years of Bi-Modal Neutron and X-ray Imaging at PSI

Comparison of non-destructive techniques for analysis of the water absorbing behavior of stone

Gemmological Investigations on Pearls and Emeralds using Neutron Imaging

Methodical Progress in Neutron Imaging at PSI