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1. A parametric study of the techno‐economics of direct CO 2 air capture systems using solid adsorbents

   https://doi.org/10.1002/aic.16607  

   Sinha, Anshuman ; Realff, Matthew J. ( April 2019 , AIChE Journal)

   Direct air capture (DAC) can help in reduction of atmospheric CO₂levels by capturing CO₂from disperse emission sources. We analyze DAC process through solid adsorbent and perform comprehensive energy and techno‐economic analysis for different parametric scenarios. The parameters are varied such that it reflects list of possible cases of DAC solid adsorbent systems ranging from worst case to best case situations. A mid‐range estimate has also been analyzed which considers the parameter values feasible with the current state of the art. The modeling results for the mid‐range estimate indicate that the cost of DAC lies between $86 and 221 per tCO₂, the thermal energy range varies from 3.4 to 4.8 GJ per tCO₂captured and the electrical energy range varies from 0.55 to 1.12 GJ per tCO₂captured. For the best and worst case scenarios, the cost of DAC ranges from $14 to 1,065 per tCO2, thermal energy ranges from 1.85 to 19.30 per tCO₂captured and the electrical energy ranges from 0.08 to 3.79 GJ per tCO₂captured. Flux and intensity estimates have been performed which shows higher flux and lower intensity of DAC process as compared to a tropical tree.

    

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2. Environmental trade-offs of direct air capture technologies in climate change mitigation toward 2100

   https://doi.org/10.1038/s41467-022-31146-1  

   Qiu, Yang ; Lamers, Patrick ; Daioglou, Vassilis ; McQueen, Noah ; de Boer, Harmen-Sytze ; Harmsen, Mathijs ; Wilcox, Jennifer ; Bardow, André ; Suh, Sangwon ( June 2022 , Nature Communications)

   Direct air capture (DAC) is critical for achieving stringent climate targets, yet the environmental implications of its large-scale deployment have not been evaluated in this context. Performing a prospective life cycle assessment for two promising technologies in a series of climate change mitigation scenarios, we find that electricity sector decarbonization and DAC technology improvements are both indispensable to avoid environmental problem-shifting. Decarbonizing the electricity sector improves the sequestration efficiency, but also increases the terrestrial ecotoxicity and metal depletion levels per tonne of CO₂sequestered via DAC. These increases can be reduced by improvements in DAC material and energy use efficiencies. DAC exhibits regional environmental impact variations, highlighting the importance of smart siting related to energy system planning and integration. DAC deployment aids the achievement of long-term climate targets, its environmental and climate performance however depend on sectoral mitigation actions, and thus should not suggest a relaxation of sectoral decarbonization targets.

    

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3. Loop Current SSH Forecasting: A New Domain Partitioning Approach for a Machine Learning Model

   https://doi.org/10.3390/forecast3030036  

   Wang, Justin L. ; Zhuang, Hanqi ; Chérubin, Laurent ; Muhamed Ali, Ali ; Ibrahim, Ali ( September 2021 , Forecasting)

   A divide-and-conquer (DAC) machine learning approach was first proposed by Wang et al. to forecast the sea surface height (SSH) of the Loop Current System (LCS) in the Gulf of Mexico. In this DAC approach, the forecast domain was divided into non-overlapping partitions, each of which had their own prediction model. The full domain SSH prediction was recovered by interpolating the SSH across each partition boundaries. Although the original DAC model was able to predict the LCS evolution and eddy shedding more than two months and three months in advance, respectively, growing errors at the partition boundaries negatively affected the model forecasting skills. In the study herein, a new partitioning method, which consists of overlapping partitions is presented. The region of interest is divided into 50%-overlapping partitions. At each prediction step, the SSH value at each point is computed from overlapping partitions, which significantly reduces the occurrence of unrealistic SSH features at partition boundaries. This new approach led to a significant improvement of the overall model performance both in terms of features prediction such as the location of the LC eddy SSH contours but also in terms of event prediction, such as the LC ring separation. We observed an approximate 12% decrease in error over a 10-week prediction, and also show that this method can approximate the location and shedding of eddy Cameron better than the original DAC method. 

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4. Evolution of photoresist layer structure and surface morphology under fluorocarbon‐based plasma exposure

   https://doi.org/10.1002/ppap.201900026  

   Pranda, Adam ; Gutierrez Razo, Sandra A. ; Fourkas, John T. ; Oehrlein, Gottlieb S. ( March 2019 , Plasma Processes and Polymers)

   Ion bombardment of photoresist materials during plasma etching results in the formation of a surface dense amorphous carbon (DAC) layer that contributes to both etch resistance and the development of surface roughness. Real‐time ellipsometric measurements/analysis reveals that a C₄F₈‐containing plasma interacts with an Ar‐plasma‐formed DAC layer to produce a modified DAC/fluorocarbon (FC) layer by FC deposition/diffusion of fluorine into the surface. The depletion of the DAC layer via modification and ion bombardment causes the etch rate of the bulk layer to increase. As the modified surface layer is formed, a noticeable decrease in surface roughness decrease is observed. These findings provide an understanding of the mechanisms of atomic layer etching processes in photoresist materials.

    

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5. Theoretical and experimental studies of compression and shear deformation behavior of Osmium to 280 GPa

   https://doi.org/10.1088/2631-8695/ac34c4  

   Lin, Chia Min ; Burrage, Kaleb C ; Perreault, Chris ; Chen, Wei-Chih ; Chen, Cheng-Chien ; Vohra, Yogesh K ( October 2021 , Engineering Research Express)

   null (Ed.)

   Abstract The compression behavior of osmium metal was investigated up to 280 GPa (volume compression V/Vo =0.725) under nonhydrostatic conditions at ambient temperature using angle dispersive axial x-ray diffraction (A-XRD) with a diamond anvil cell (DAC). In addition, shear strength of osmium was measured to 170 GPa using radial x-ray diffraction (R-XRD) technique in DAC. Both diffraction techniques in DAC employed platinum as an internal pressure standard. Density functional theory (DFT) calculations were also performed, and the computed lattice parameters and volumes under compression are in good agreement with the experiments. DFT predicts a monotonous increase in axial ratio (c/a) with pressure and the structural anomalies of less than 1 % in (c/a) ratio below 150 GPa were not reproduced in theoretical calculations and hydrostatic measurements. The measured value of shear strength of osmium (τ) approaches a limiting value of 6 GPa above a pressure of 50 GPa in contrast to theoretical predictions of 24 GPa and is likely due to imperfections in polycrystalline samples. DFT calculations also enable the studies of shear and tensile deformations. The theoretical ideal shear stress is found along the (001)[1-10] shear direction with the maximal shear stress ~24 GPa at critical strain ~0.13. 

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