Synthesis of terephthalic acid via Diels-Alder reactions with ethylene and oxidized variants of 5-hydroxymethylfurfural

Terephthalic acid (PTA), a monomer in the synthesis of polyethylene terephthalate (PET), is obtained by the oxidation of petroleum-derived p-xylene. There is significant interest in the synthesis of renewable, biomass-derived PTA. Here, routes to PTA starting from oxidized products of 5-hydroxymethylfurfural (HMF) that can be produced from biomass are reported. These routes involve Diels-Alder reactions with ethylene and avoid the hydrogenation of HMF to 2,5-dimethylfuran. Oxidized derivatives of HMF are reacted with ethylene over solid Lewis acid catalysts that do not contain strong Brønsted acids to synthesize intermediates of PTA and its equally important diester, dimethyl terephthalate (DMT). The partially oxidized HMF, 5-(hydroxymethyl)furoic acid (HMFA), is reacted with high pressure ethylene over a pure-silica molecular sieve containing framework tin (Sn-Beta) to produce the Diels-Alder dehydration product, 4-(hydroxymethyl)benzoic acid (HMBA), with 31% selectivity at 61% HMFA conversion after 6 h at 190 °C. If HMFA is protected with methanol to form methyl 5-(methoxymethyl)furan-2-carboxylate (MMFC), MMFC can react with ethylene in the presence of Sn-Beta for 2 h to produce methyl 4-(methoxymethyl)benzenecarboxylate (MMBC) with 46% selectivity at 28% MMFC conversion or in the presence of a pure-silica molecular sieve containing framework zirconium (Zr-Beta) for 6 h to produce MMBC with 81% selectivity at 26% MMFC conversion. HMBA and MMBC can then be oxidized to produce PTA and DMT, respectively. When Lewis acid containing mesoporous silica (MCM-41) and amorphous silica, or Brønsted acid containing zeolites (Al-Beta), are used as catalysts, a significant decrease in selectivity/yield of the Diels-Alder dehydration product is observed

Using Problem-Based Learning in Natural Resources Curriculum to Promote Critical Thinking

Our workshop will model the use of problem-based learning (PBL) to enhance higher- order thinking skills and promote content retention. After a brief introduction to the process and benefits of PBL, we will guide attendees through a problem case. Our Urban Deer Management case will allow participants to experience firsthand how PBL promotes critical thinking

BLAST Autonomous Daytime Star Cameras

We have developed two redundant daytime star cameras to provide the fine pointing solution for the balloon-borne submillimeter telescope, BLAST. The cameras are capable of providing a reconstructed pointing solution with an absolute accuracy < 5 arcseconds. They are sensitive to stars down to magnitudes ~ 9 in daytime float conditions. Each camera combines a 1 megapixel CCD with a 200 mm f/2 lens to image a 2 degree x 2.5 degree field of the sky. The instruments are autonomous. An internal computer controls the temperature, adjusts the focus, and determines a real-time pointing solution at 1 Hz. The mechanical details and flight performance of these instruments are presented.Comment: 8 pages, 6 figures, 1 table. To be published in conference proceedings for the "Ground-based and Airborne Instrumentation for Astronomy" part of the SPIE Astronomical Telescopes and Instrumentation Symposium that will be held 24-31 May 2006 in Orlando, F

Strategic Surrogates or Sad Sinners: U.S. Taxation of Bartering in Digital Services

The COVID-19 pandemic caused both a surge in technology use and a deterioration in government finances. At the same time, big tech companies are under scrutiny by lawmakers for tax avoidance, antitrust issues, and other concerns. These realities call for governments to reassess tax policy toward tech companies and for tech companies to reassess legal strategy toward taxes. State and federal governments\u27 tax bases are eroding because of the noncash, barter nature of modern transactions. When a taxpayer uses “free” digital services such as e-mail, social media, or search engines, she pays via access to her personal data or attention. From a legal and policy standpoint, these barter transactions should be taxed just as if cash had changed hands, but because it is not practicable to identify, value, and tax the data and time of each user, they have escaped taxation, giving many tech companies an unintended tax advantage. To address this unfairness, this article proposes a surrogate tax, through which the tech company acts as a proxy to pay the tax that is technically the liability of its users. In contrast to Digital Services Taxes (DSTs), which have been the main focus of policy makers and the extant literature, surrogate taxes adhere closely to standards of good tax policy, providing an administrable means of capturing untaxed digital barter while advancing fairness across the industry\u27s business models. From a legal strategy standpoint, this article argues that tech companies themselves should support surrogate taxes, to avoid facing more onerous, “sin”-like taxes, such as DSTs

Joshua Miller MEMS Independent Study Report – Fall 2019

µ-BEC: The stud µ-BEC: The study of microbes performing extracellular electron uptake (EEU) has multiple uses for biotechnological applications. To that end, a high-throughput platform comprising an array of bioelectrochemical cells (essentially small chambers for electrochemical analysis of biological cells) is necessary to provide the opportunity for proper study of microbes performing EEU. Utilizing traditional cleanroom microfabrication techniques (photolithography, metallization, and lift-off), a 16-chamber micro bio-electrochemical cell (µ-BEC) array was fabricated. Each cell utilized a 3-electrode system, achieving successful electrochemical measurements for 8 of 16 chambers. The 8 chambers that failed exhibited peeling of electrodes due to processing errors. More robust fabrication processes are being explored to improve yield. IDTs: µ-BEC: The study of microbes performing extracellular electron uptake (EEU) has multiple uses for biotechnological applications. To that end, a high-throughput platform comprising an array of bioelectrochemical cells (essentially small chambers for electrochemical analysis of biological cells) is necessary to provide the opportunity for proper study of microbes performing EEU. Utilizing traditional cleanroom microfabrication techniques (photolithography, metallization, and lift-off), a 16-chamber micro bio-electrochemical cell (µ-BEC) array was fabricated. Each cell utilized a 3-electrode system, achieving successful electrochemical measurements for 8 of 16 chambers. The 8 chambers that failed exhibited peeling of electrodes due to processing errors. More robust fabrication processes are being explored to improve yield. IDTs: The field of microscale acoustofluidics is extremely useful for numerous bioanalytical applications involved with studying swimming cells including bacteria. To that end, an experiment was performed using acoustic focusing devices that produce standing surface acoustic waves (SSAWs) excited in a piezoelectric substrate by micropatterned interdigital transducers (IDTs). These waves were used to trap bacterial cells at nodes and antinodes of the SSAWs, creating visible patterns. Experiments proved that 2 µm average diameter swimming cells can be successfully patterned with a 24.1-MHz actuation frequency. y of microbes performing extracellular electron uptake (EEU) has multiple uses for biotechnological applications. To that end, a high-throughput platform comprising an array of bioelectrochemical cells (essentially small chambers for electrochemical analysis of biological cells) is necessary to provide the opportunity for proper study of microbes performing EEU. Utilizing traditional cleanroom microfabrication techniques (photolithography, metallization, and lift-off), a 16-chamber micro bio-electrochemical cell (µ-BEC) array was fabricated. Each cell utilized a 3-electrode system, achieving successful electrochemical measurements for 8 of 16 chambers. The 8 chambers that failed exhibited peeling of electrodes due to processing errors. More robust fabrication processes are being explored to improve yield. IDTs: The field of microscale acoustofluidics is extremely useful for numerous bioanalytical applications involved with studying swimming cells including bacteria. To that end, an experiment was performed using acoustic focusing devices that produce standing surface acoustic waves (SSAWs) excited in a piezoelectric substrate by micropatterned interdigital transducers (IDTs). These waves were used to trap bacterial cells at nodes and antinodes of the SSAWs, creating visible patterns. Experiments proved that 2 µm average diameter swimming cells can be successfully patterned with a 24.1-MHz actuation frequency

Impacts of Harmful Algal Blooms on Dissolved Organic Carbon in the Lower York River Estuary

Estuaries are important sites of carbon cycling; however, the impact of increasingly prevalent harmful algal blooms (HABs) on cycling in these systems remains unclear. To examine the impact of two bloom species, Alexandrium monilatum and Margalefidinium polykrikoides on the quantity and composition of the dissolved organic carbon (DOC) and chromophoric dissolved organic matter (CDOM) pools and rates of benthic and pelagic microbial respiration in the lower York River Estuary, VA, a series field samplings and laboratory incubations were performed. The two HAB species greatly increased the size of the DOC and CDOM pools and altered the character of the CDOM pool, causing it to shift towards higher molecular weights and lower levels of aromaticity. DOC released by A. monilatum and M. polykrikoides both stimulated increased respiration by pelagic microbes, but displayed different levels of microbial lability in the DOC produced suggesting species level differences in how HABs affect DOC cycling. HAB produced organic matter did not stimulate increased levels of benthic microbial respiration as measured in sediment core incubations, suggesting that benthic microbial communities are not carbon limited. These findings show that HABs alter the quality and quantity of the DOC pool which in turn affects pelagic microbial respiration. This study also highlighted the need for species level analysis of HABs to be factored in to future estuarine carbon budgets in HAB affected systems

Why Use Multiple Choice Questions with Excess Information?

The examinations administered by accounting instructors, professional certification examiners, textbook writers, and preparatory accounting software all routinely include multiple-choice (MC) questions with excess (yet related) information. Despite their widespread use, little is known about how MC questions with excess information (hereafter MCE questions) affect student test performance. Based on an empirical analysis of the tests of 374 students in two introductory accounting classes at a single university, we found that average performance was lower on MCE questions than non-MCE questions, but was sensitive to the overall difficulty of the tested concept. We also found no significant difference in the power of the two question types to discriminate—both types appeared equally competent in differentiating between low- and high-performing students. Although accounting professors may wish to use MC questions with excess information for a number of other reasons, we found that MCE questions, as used in the present setting, do not appear to better discriminate student understanding relative to non-MCE questions