David L. Damm

Spectral Radiative Heat Transfer Analysis of the Planar SOF

Droplet Impingement Chemical Reactors and Methods of Processing Fuel

Fuel processors, methods of using fuel processors, and the like, are disclosed

IMECE2004-60142 SPECTRAL RADIATIVE HEAT TRANSFER ANALYSIS OF THE PLANAR SOFC

ABSTRACT Thermo-mechanical failure of components in planar-type solid oxide fuel cells (SOFCs) depends strongly on the local temperature gradients at the interfaces of different materials. Therefore, it is of paramount importance to accurately predict the temperature fields within the stack, especially near the interfaces. Because of elevated operating temperatures (of the order of 1000 K or even higher), radiation heat transfer could become a dominant mode of heat transfer in the SOFCs. In this study, we extend our recent work on radiative effects in solid oxide fuel cells (Journal of Power Sources, Vol. 124

Stable autosolitons in dispersive media with saturable gain and absorption

We introduce the simplest one-dimensional model of a dispersive optical medium with saturable dissipative nonlinearity and filtering (dispersive loss) which gives rise to stable solitary pulses (autosolitons). In the particular case when the dispersive loss is absent, the same model may also be interpreted as describing a stationary field in a planar optical waveguide with uniformly distributed saturable gain and absorption. In a certain region of the model's parameter space, two coexisting solitary-pulse solutions are found numerically, one of which may be stable. Solving the corresponding linearized eigenvalue problem, we identify stability borders for the solitary pulses in their parametric plane. Beyond one of the borders, the symmetric pulse is destroyed by asymmetric perturbations, and at the other border it undergoes a Hopf bifurcation, which may turn it into a breather.Comment: A latex text file and four ps files with figures. Physics Letters A, in pres

Lattice Boltzmann Simulations of Multiple Droplet Interactions During Impingement on the Substrate

Studying material interface evolution in the course of multiple droplet interactions is critical for understanding the material additive process in inkjet deposition. In this paper, we have developed a novel numerical model based on the Lattice Boltzmann Method (LBM) to simulate the interface dynamics during impingement and interaction of multiple droplets. A lattice Boltzmann formulation is proposed to solve the governing equations of the continuous phasefield model that are used in commercial software COMSOL. The LBM inter-particle force is derived by comparing the recovered macroscopic equations from LBM equations with the governing equations of the phase-field model. In addition, a new set of boundary conditions for the LBM formulation is proposed based on conservation of mass and momentum to ensure correct evolution of contact line dynamics. The results of LBM simulations are compared with those of COMSOL and experimental data from literature. The comparison shows the proposed LBM model not only yields a significant improvement in computational speed, but also results in better accuracy than COMSOL as validated against the experiments. We have also demonstrated the capability of the developed LBM numerical solver for simulating interactions between multiple droplets impinging on the substrate, which is critical for development and optimization of inkjet manufacturing.Mechanical Engineerin

The dynamic mass spectrometry probe (DMSP) - Advanced process analytics for therapeutic cell manufacturing, health monitoring and biomarker discovery

Spatially and temporally resolved in situ monitoring of biochemical cell culture environments, e.g., in application to therapeutic cell bioreactors, is of critical importance for facilitating the development of new and reliable quality control methodologies for cell therapies. Identifying and monitoring secreted biomolecular critical quality attributes (CQAs) to enable online feedback control will enable large scale, cost-effective manufacturing of therapeutic cells. These CQA biomarkers have varying concentrations within a bioreactor, both in time and space. Current methods for monitoring these diverse biomolecules are generally ex-situ, time consuming, destructive, provide bulk measurements, or lack the ability to reveal the complete secretome/metabolome composition. The Dynamic Mass Spectrometry Probe (DMSP) synergistically incorporates a sampling interface for localized intake of a small fluid volume of the cellular content, a micro-fabricated mass exchanger for sample conditioning and inline separation, and an integrated electrospray ionization (ESI) emitter for softly ionizing (i.e. preserved biochemical structure) extracted biomolecules for mass spectrometry (MS). ESI-MS via DMSP treatment enables both biomarker discovery and transient (~1 min) analysis of biochemical information indicative of cell health and potency. DMSP is manufactured using advanced batch microfabrication techniques, which minimize dead volume (~20 nL) and ensure repeatable operation and precise geometry of each device. DMSP treatment removes 99% of compounds that interfere with mass spectrometry analysis, such as inorganic salts, while retaining biomolecules of interest within the sample for ESI-MS analysis. DMSP has demonstrated the ability to substantially increase signal to noise ratio in MS detection of biomolecules, and to further enhance sensitivity for probing lower biomarker concentrations via introduction of ESI-MS enhancing molecules (i.e. proton donating chemicals, protein denaturing solvents, and supercharging agents) into the sample within the integrated mass exchanger. To exemplify the DMSP’s unique capabilities, Fig. 1 demonstrates detection of multiple low-concentration protein biomarkers sampled from a biochemically-complex cell media solution serving as a proxy to samples taken directly from cell growth bioreactors [1]. Please click Additional Files below to see the full abstract

Geopolitical Security of Russia: Remarks on the Problem Statement

This paper summarizes the results of the seminar "Geopolitical Security of Russia: Remarks on the Problem Statement", held on August 26, 2022, at the Immanuel Kant Baltic Federal University, Kaliningrad. During the seminar, the Institute of Geopolitical and Regional Studies of the university announced an initiative to devise a system of monitoring the geopolitical (regional) security of Russia. The debate centred around the development of a conceptual framework and a geopolitical security model as a prerequisite for the system. The discussion also covered other relevant issues, including the definition of geopolitical security and geopolitical space as well as the types of geopolitical threats and vulnerabilities. Another topic on the agenda was the analysis of theoretical approaches applicable to monitoring the geopolitical security in Russia. A constructivist approach based on discursive practices was viewed as the most promising for tracking changes in geopolitical threats. In this work, the emphasis should be placed on regional issues, i. e. the situation in particular regions. Other promising avenues for further research are the operationalization of relevant concepts and the development of a set of indicators of geopolitical threats and vulnerabilities, which Russia has already faced and may face in the future

Molecular biomarkers in Batagay megaslump permafrost deposits reveal clear differences in organic matter preservation between glacial and interglacial periods

The Batagay megaslump, a permafrost thaw feature in north-eastern Siberia, provides access to ancient permafrost up to ∼650 kyr old. We aimed to assess the permafrost-locked organic matter (OM) quality and to deduce palaeo-environmental information on glacial–interglacial timescales. We sampled five stratigraphic units exposed on the 55 m high slump headwall and analysed lipid biomarkers (alkanes, fatty acids and alcohols). Our findings revealed similar biogeochemical signatures for the glacial periods: the lower ice complex (Marine Isotope Stage (MIS) 16 or earlier), the lower sand unit (sometime between MIS 16–6) and the upper ice complex (MIS 4–2). The OM in these units has a terrestrial character, and microbial activity was likely limited. Contrarily, the n-alkane and fatty acid distributions differed for the units from interglacial periods: the woody layer (MIS 5), separating the lower sand unit and the upper ice complex, and the Holocene cover (MIS 1), on top of the upper ice complex. The woody layer, marking a permafrost degradation disconformity, contained markers of terrestrial origin (sterols) and high microbial decomposition (iso- and anteiso-fatty acids). In the Holocene cover, biomarkers pointed to wet depositional conditions and we identified branched and cyclic alkanes, which are likely of microbial origin. Higher OM decomposition characterised the interglacial periods. As climate warming will continue permafrost degradation in the Batagay megaslump and in other areas, large amounts of deeply buried ancient OM with variable composition and degradability are mobilised, likely significantly enhancing greenhouse gas emissions from permafrost regions

Northern Eurasian large lakes history: sediment records obtained in the frame of Russian-German research project PLOT

Russian-German project PLOT (Paleolimnological Transect) aims at investigating the regional responses of the quaternary climate and environment on external forcing and feedback mechanisms along a more than 6000 km long longitudinal transect crossing Northern Eurasia. The well-dated record from Lake El´gygytgyn used as reference site for comparison the local climatic and environmental histories. Seismic surveys and sediment coring up to 54 m below lake floor performed in the frame of the project on Ladoga Lake (North-West of Russia; 2013), Lake Bolshoye Shchuchye (Polar Ural; 2016), Lake Levinson-Lessing and Lake Taymyr (Taymyr Peninsula; 2016-2017), Lake Emanda (Verkhoyansk Range; 2017). Fieldwork at Polar Ural and Taymyr Peninsula was conducted in collaboration with the Russian-Norwegian CHASE (Climate History along the Arctic Seaboard of Eurasia) project. Here, we present the major results of the project obtained so far