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3. Pure-Water-Fed Forward-Bias Bipolar Membrane CO2 Electrolyzer

Author

Heßelmann, Matthias, Lee, Jason Keonhag, Chae, Sudong, Tricker, Andrew, Keller, Robert Gregor, Wessling, Matthias, Su, Ji, Kushner, Douglas, Weber, Adam Z, and Peng, Xiong

Subjects
Macromolecular and Materials Chemistry, Engineering, Chemical Sciences, Climate Action, Affordable and Clean Energy, electrochemical CO2 reduction, water-fed, forward-bias, asymmetric, bipolar membrane, cell design, Nanoscience & Nanotechnology, Chemical sciences, Physical sciences
Abstract

Coupling renewable electricity to reduce carbon dioxide (CO2) electrochemically into carbon feedstocks offers a promising pathway to produce chemical fuels sustainably. While there has been success in developing materials and theory for CO2 reduction, the widespread deployment of CO2 electrolyzers has been hindered by challenges in the reactor design and operational stability due to CO2 crossover and (bi)carbonate salt precipitation. Herein, we design asymmetrical bipolar membranes assembled into a zero-gap CO2 electrolyzer fed with pure water, solving both challenges. By investigating and optimizing the anion-exchange-layer thickness, cathode differential pressure, and cell temperature, the forward-bias bipolar membrane CO2 electrolyzer achieves a CO faradic efficiency over 80% with a partial current density over 200 mA cm-2 at less than 3.0 V with negligible CO2 crossover. In addition, this electrolyzer achieves 0.61 and 2.1 mV h-1 decay rates at 150 and 300 mA cm-2 for 200 and 100 h, respectively. Postmortem analysis indicates that the deterioration of catalyst/polymer-electrolyte interfaces resulted from catalyst structural change, and ionomer degradation at reductive potential shows the decay mechanism. All these results point to the future research direction and show a promising pathway to deploy CO2 electrolyzers at scale for industrial applications.

Published
2024

20. Recent Developments in Blockchain Technology and their Impact on Energy Consumption

Author

Sedlmeir, Johannes, Buhl, Hans Ulrich, Fridgen, Gilbert, and Keller, Robert

Subjects
Computer Science - Cryptography and Security, Computer Science - Distributed, Parallel, and Cluster Computing
Abstract

The enormous power consumption of Bitcoin has led to undifferentiated discussions in science and practice about the sustainability of blockchain and distributed ledger technology in general. However, blockchain technology is far from homogeneous - not only with regard to its applications, which now go far beyond cryptocurrencies and have reached businesses and the public sector, but also with regard to its technical characteristics and, in particular, its power consumption. This paper summarizes the status quo of the power consumption of various implementations of blockchain technology, with special emphasis on the recent 'Bitcoin Halving' and so-called 'zk-rollups'. We argue that although Bitcoin and other proof-of-work blockchains do indeed consume a lot of power, alternative blockchain solutions with significantly lower power consumption are already available today, and new promising concepts are being tested that could further reduce in particular the power consumption of large blockchain networks in the near future. From this we conclude that although the criticism of Bitcoin's power consumption is legitimate, it should not be used to derive an energy problem of blockchain technology in general. In many cases in which processes can be digitised or improved with the help of more energy-efficient blockchain variants, one can even expect net energy savings., Comment: This is a translated version of a German article published in Informatik Spektrum

Published
2021
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25. Current developments in S corporations.

Author

Jamison, Robert W., Jr., Keller, Robert S., Mitchell, Kirk T., Nitti, Tony, Orbach, Kenneth N., and Walsh, Kevin J.

Subjects
S corporations -- Surveys, Tax law -- Surveys, United States. Internal Revenue Service -- Surveys, Tax law
Abstract

Fourteen sections of the Internal Revenue Code are central to the taxation of Subchapter S corporations and their shareholders. (1) Over the 12-month period ending March 2024 covered by this [...]

Published
2024

27. Korea--3 August 1950--the Corps goes to war

Author

Keller, Robert P., LtGen, Ret

Subjects
MARINE CORPS AVIATION - History, KOREAN WAR, 1950-1953 - Aerial Operations, American, CLOSE AIR SUPPORT - History
Abstract

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Published
2004

28. Current developments in S corporations.

Author

Brajcich, Andrew M., Hill, Kristin, Jamison, Robert W., Jr., Keller, Robert S., Mitchell, Kirk T., Orbach, Kenneth N., Nitti, Tony, Walsh, Kevin J., and Williamson, Jonathan

Subjects
American Institute of Certified Public Accountants -- Powers and duties -- Management, Tax planning -- Laws, regulations and rules -- Methods, Tax consultants -- Laws, regulations and rules -- Management, S corporations -- Laws, regulations and rules -- Taxation, Taxpayer compliance -- Laws, regulations and rules -- Management, Stockholders -- Laws, regulations and rules -- Taxation, United States. Internal Revenue Service -- Aims and objectives -- Powers and duties, Government regulation, Company business management
Abstract

Fourteen sections of the Internal Revenue Code are central to the taxation of Subchapter S corporations and their shareholders. (1) Over the 12-month period ending March 2023 covered by this [...]

Published
2023

35. Program Language Translation Using a Grammar-Driven Tree-to-Tree Model

Author

Drissi, Mehdi, Watkins, Olivia, Khant, Aditya, Ojha, Vivaswat, Sandoval, Pedro, Segev, Rakia, Weiner, Eric, and Keller, Robert

Subjects
Computer Science - Machine Learning, Computer Science - Programming Languages, Statistics - Machine Learning
Abstract

The task of translating between programming languages differs from the challenge of translating natural languages in that programming languages are designed with a far more rigid set of structural and grammatical rules. Previous work has used a tree-to-tree encoder/decoder model to take advantage of the inherent tree structure of programs during translation. Neural decoders, however, by default do not exploit known grammar rules of the target language. In this paper, we describe a tree decoder that leverages knowledge of a language's grammar rules to exclusively generate syntactically correct programs. We find that this grammar-based tree-to-tree model outperforms the state of the art tree-to-tree model in translating between two programming languages on a previously used synthetic task., Comment: Accepted at the ICML workshop Neural Abstract Machines & Program Induction v2. 4 pages excluding acknowledgements/references (6 pages total)

Published
2018

43. Current developments in S corporations.

Author

Brajcich, Andrew M., Hill, Kristin, Jamison, Robert W., Keller, Robert S., Mitchell, Kirk T., Orbach, Kenneth N., Scott, Alexander, and Walsh, Kevin J.

Subjects
S corporations -- Laws, regulations and rules -- Taxation, Corporate income taxes -- Laws, regulations and rules -- Research, Government regulation
Abstract

Fourteen sections of the Internal Revenue Code are central to the taxation of Subchapter S corporations and their shareholders. Over the 12-month period ending February 2022, some of these sections [...]

Published
2022

49. Electro‐Conductive Ti3C2 MXene Multilayered Membranes: Dye Removal and Antifouling Performance.

Author

Zandi, Zahra, Rastgar, Masoud, Mohseni, Mojtaba, Firouzjaei, Mostafa Dadashi, Dilokekunakul, Waralee, Anasori, Babak, Vecitis, Chad D., Keller, Robert, Wessling, Matthias, Elliott, Mark, Rahimpour, Ahmad, and Sadrzadeh, Mohtada

Subjects
SURFACE energy, CARBOXYMETHYLCELLULOSE, SURFACE analysis, WASTEWATER treatment, ELECTRIC conductivity
Abstract

This work describes the fabrication of a novel electroconductive membrane made of Ti3C2Tx (MXene) nanosheet coating through a one‐step pressure‐assisted technique. Ti3C2‐MXene is firmly attached over a polyamide–imide (PAI) microfilter by employing a binder composed of carboxymethyl cellulose (CMC)/glutaraldehyde (GA). Through coating a proper amount of multilayer Ti3C2‐MXene, the electrical conductivity of 174 ± 0.16 S m−1 is achieved. The rejection rates of reactive red 120 (RR120), reactive black (RB), and methyl orange (MO) by the pristine PAI membrane are 45.2%, 40.81%, and 33.65%, respectively. However, rejection rates significantly improve with the Ti3C2 MXene coating to over 99.71%, 97.95%, and 68.91% for RR120, RB, and MO. Applying a 4 V cathodic potential resulted in a flux recovery ratio (FRR) of 99.83% and a flux decline rate (FDR) of less than 1% during humic acid (HA) filtration. Without applying voltage, the MXene‐coated membrane shows an FRR and FDR of 92.51% and 45.56%, respectively. Surface energy analysis reveals strong repulsive interactions between foulants and the membrane surface. Moreover, the surface free energy indicates that foulants such as sodium alginate (SA) and bovine serum albumin (BSA) exhibit stronger adhesion to the membrane than HA, consistent with the fouling experiment results. [ABSTRACT FROM AUTHOR]

Published
2024
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