Fluorine-rich poly(arylene amine) membranes for the separation of liquid aliphatic compounds.

We explored the potential for membrane materials to reduce energy and carbon requirements for the separation of aliphatic hydrocarbon feedstocks and products. We developed a series of fluorine-rich poly(arylene amine) polymer membranes that feature rigid polymer backbones with segregated perfluoroalkyl side chains. This combination imbues the polymers with resistance to dilation induced by hydrocarbon immersion without the loss of solution-based membrane fabrication techniques.

Separation of 2,3-Butanediol from Fermentation Broth via Cyclic and Simulated Moving Bed Adsorption Over Nano-MFI Zeolites.

The biomass-based platform molecule 2,3-butanediol (2,3-BDO) has a wide range of applications in production of sustainable fuels, chemicals, synthetic rubber, and others. However, the selective separation of 2,3-BDO from multicomponent fermentation broths presents challenges due to its low concentration, high solubility in water, high boiling point, and presence of many other species. Here, we demonstrate remarkably selective enrichment and recovery of 2,3-BDO from a corn stover hydrolysate fermentation broth by a pure-silica nano-MFI-type zeolite adsorbent.

Engineering allosteric transcription factors guided by the LacI topology.

Allosteric transcription factors (aTFs) are used in a myriad of processes throughout biology and biotechnology. aTFs have served as the workhorses for developments in synthetic biology, fundamental research, and protein manufacturing. One of the most utilized TFs is the lactose repressor (LacI).

Support Pore Structure and Composition Strongly Influence the Direct Air Capture of CO on Supported Amines.

A variety of amine-impregnated porous solid sorbents for direct air capture (DAC) of CO have been developed, yet the effect of amine-solid support interactions on the CO adsorption behavior is still poorly understood. When tetraethylenepentamine (TEPA) is impregnated on two different supports, commercial γ-AlO and MIL-101(Cr), they show different trends in CO sorption when the temperature (-20 to 25 °C) and humidity (0-70% RH) of the simulated air stream are varied. IR spectroscopy is used to probe the mechanism of CO sorption on the two supported amine materials, with weak chemisorption (formation of carbamic acid) being the dominant pathway over MIL-101(Cr)-supported TEPA and strong chemisorption (formation of carbamate) occurring over γ-AlO-supported TEPA.

Performance Prediction of Fundamental Transcriptional Programs.

Transcriptional programming leverages systems of engineered transcription factors to impart decision-making (, Boolean logic) in chassis cells. The number of components used to construct said decision-making systems is rapidly increasing, making an exhaustive experimental evaluation of iterations of biological circuits impractical. Accordingly, we posited that a predictive tool is needed to guide and accelerate the design of transcriptional programs.

Direct Air Capture of CO Using Poly(ethyleneimine)-Functionalized Expanded Poly(tetrafluoroethylene)/Silica Composite Structured Sorbents.

The rapidly increasing atmospheric CO concentration has driven research into the development of cost- and energy-efficient materials and processes for the direct air capture of CO (DAC). Solid-supported amine materials can give high CO uptakes and acceptable sorption kinetics, but they are generally prepared in powder forms that are likely not practically deployable in large-scale operations due to significant pressure drops associated with packed-bed gas-solid contactors. To this end, the development of effective gas-solid contactors for CO capture technologies is important to allow processing high flow rates of gas with low-pressure drops and high mass transfer rates.

Perspective - the need and prospects for negative emission technologies - direct air capture through the lens of current sorption process development.

We provide a perspective on the development of direct air capture (DAC) as a leading candidate for implementing negative emissions technology (NET). We introduce DAC based on sorption, both liquid and solid, and draw attention to challenges that these technologies will face. We provide an analysis of the limiting mass transfer in the liquid and solid systems and highlight the differences.

Biological signal processing filters via engineering allosteric transcription factors.

Signal processing is critical to a myriad of biological phenomena (natural and engineered) that involve gene regulation. Biological signal processing can be achieved by way of allosteric transcription factors. In canonical regulatory systems (e.

Designing the bioproduction of Martian rocket propellant via a biotechnology-enabled in situ resource utilization strategy.

Mars colonization demands technological advances to enable the return of humans to Earth. Shipping the propellant and oxygen for a return journey is not viable. Considering the gravitational and atmospheric differences between Mars and Earth, we propose bioproduction of a Mars-specific rocket propellant, 2,3-butanediol (2,3-BDO), from CO, sunlight and water on Mars via a biotechnology-enabled in situ resource utilization (bio-ISRU) strategy.

Defining Targets for Adsorbent Material Performance to Enable Viable BECCS Processes.

Target properties of CO capture adsorbents that would ensure economic viability of bioenergy with carbon capture and storage (BECCS) are defined. The key role of sorbent lifetime in the process cost is demonstrated, and an optimal heat of adsorption for BECCS is postulated through a balance of adsorbent-adsorbate affinity and regeneration energy demand. Using an exponential decay model of sorbent capacity increases the process cost and results in an optimum sorbent lifetime.

Biomolecular Systems Engineering: Unlocking the Potential of Engineered Allostery via the Lactose Repressor Topology.

Allosteric function is a critical component of many of the parts used to construct gene networks throughout synthetic biology. In this review, we discuss an emerging field of research and education, biomolecular systems engineering, that expands on the synthetic biology edifice-integrating workflows and strategies from protein engineering, chemical engineering, electrical engineering, and computer science principles. We focus on the role of engineered allosteric communication as it relates to transcriptional gene regulators-i.

Engineering allosteric communication.

Protein allostery is a vitally important protein function that has proven to be a vexing problem to understand at the molecular level. Allosteric communication is a hallmark of many protein functions. However, despite more than four decades of study the details regarding allosteric communication in protein systems are still being developed.

Similarities in Recalcitrant Structures of Industrial Non-Kraft and Kraft Lignin.

This work compares the structure of industrially isolated lignin samples from kraft pulping and three alternative processes: butanol organosolv, supercritical water hydrolysis, and sulfur dioxide/ethanol/water fractionation. Kraft processes are known to produce highly condensed lignin, with reduced potential for catalytic depolymerization, whereas the alternative processes have been hypothesized to impact the lignin less. The structural properties most relevant to catalytic depolymerization are characterized by elemental analysis, quantitative C and 2 D HQSC NMR spectroscopy, gel permeation chromatography, and thermogravimetric analysis.

Solvent Selection for Lignin Value Prior to Pulping.

Solvent selection guides are crucial in chemical process design and development. Lignin from lignocellulosic biomass is a potentially attractive feedstock for sustainable chemical feedstocks. One approach would use a solvent to recover lignin prior to the traditional pulping process to make cellulose fibers: lignin value prior to pulping (LVPP).

Critical Comparison of Structured Contactors for Adsorption-Based Gas Separations.

Recent advances in adsorptive gas separations have focused on the development of porous materials with high operating capacity and selectivity, useful parameters that provide early guidance during the development of new materials. Although this material-focused work is necessary to advance the state of the art in adsorption science and engineering, a substantial problem remains: how to integrate these materials into a fixed bed to efficiently utilize the separation. Structured sorbent contactors can help manage kinetic and engineering factors associated with the separation, including pressure drop, sorption enthalpy effects, and external heat integration (for temperature swing adsorption, or TSA).

New approach for optimal electricity planning and dispatching with hourly time-scale air quality and health considerations.

Integrating accurate air quality modeling with decision making is hampered by complex atmospheric physics and chemistry and its coupling with atmospheric transport. Existing approaches to model the physics and chemistry accurately lead to significant computational burdens in computing the response of atmospheric concentrations to changes in emissions profiles. By integrating a reduced form of a fully coupled atmospheric model within a unit commitment optimization model, we allow, for the first time to our knowledge, a fully dynamical approach toward electricity planning that accurately and rapidly minimizes both cost and health impacts.

An effective chemical pretreatment method for lignocellulosic biomass with substituted imidazoles.

Lignocellulosic biomass is the most abundant naturally renewable organic resource for biofuel production. Because of its recalcitrance to enzymatic degradation, pretreatment is a crucial step before hydrolysis of the feedstock. A variety of pretreatment methods have been developed and intensively studied to achieve optimal yield without imposing significant adverse impact on the environment.

Protein engineering of cellulases.

This review covers the topic of protein engineering of cellulases, mostly after 2009. Two major trends that are identified in this work are: first, the increased importance of results from computational protein engineering to drive ideas in the field, as experimental ideas and results often are still scarce, and, second, the further development of helper proteins for cellulose hydrolysis, such as lytic polysaccharide monooxygenase (LPO). The discussion in this work focuses both on improved attributes of cellulases and on the domains of cellulase that have been improved.

SO2 -catalyzed steam explosion: the effects of different severity on digestibility, accessibility, and crystallinity of lignocellulosic biomass.

Lignocellulosic biomass is the most promising feedstock for biofuels production. To enhance the efficiency of enzymatic hydrolysis, lignocellulosics needs to be pretreated to lower their recalcitrance. SO(2) -catalyzed steam explosion is an efficient and relatively cost-efficient pretreatment method for softwood.

Elucidation of cellulose accessibility, hydrolysability and reactivity as the major limitations in the enzymatic hydrolysis of cellulose.

The precipitous decline in the rates of enzymatic hydrolysis of cellulose with conversion is one of the major limitations to the commercialization of second-generation biofuel. In this work, various rate-limiting factors (fractal kinetics, changes in crystallinity, accessibility, reactivity and hydrolysable fraction, enzyme clogging, and degree of polymerization) were investigated employing experimental as well as computational studies. Model-guided experiments showed cellulose accessibility and the hydrolysable fraction of accessible substrate (a previously undefined and unreported quantity) to decrease steadily until a conversion level of nearly 70%, while cellulose reactivity, defined in terms of hydrolytic activity per amount of actively adsorbed cellulase, remained constant.

Biological pretreatment of cellulose: enhancing enzymatic hydrolysis rate using cellulose-binding domains from cellulases.

In this study, cellulose-binding domains (CBDs) of cellulases from Trichoderma reesei were used in a pretreatment step and were found to effectively reduce the crystallinity of cellulose (both Avicel and fibrous cellulose). This, in turn, led to higher glucose concentrations (up to 25% increase) in subsequent hydrolysis of cellulose using a mixture of cellulases and without the need for any intermediate purification step. CBDs were shown to be active in a range of temperatures (up to 50°C), while cellulase hydrolytic activity was greatly reduced after incubation at 50°C.

Life cycle energy and greenhouse gas emissions for an ethanol production process based on blue-green algae.

Ethanol can be produced via an intracellular photosynthetic process in cyanobacteria (blue-green algae), excreted through the cell walls, collected from closed photobioreactors as a dilute ethanol-in-water solution, and purified to fuel grade ethanol. This sequence forms the basis for a biofuel production process that is currently being examined for its commercial potential. In this paper, we calculate the life cycle energy and greenhouse gas emissions for three different system scenarios for this proposed ethanol production process, using process simulations and thermodynamic calculations.

Multivariate statistical analysis of X-ray data from cellulose: a new method to determine degree of crystallinity and predict hydrolysis rates.

The enzymatic hydrolysis of cellulose by cellulases is one of the major steps in the production of ethanol from lignocellulosics. However, cellulosic biomass is not particularly susceptible to enzymatic attack and crystallinity of the substrates is one of the key properties that determine the hydrolysis rates. In this work, by quantifying the respective contributions of amorphous and crystalline cellulose to the X-ray diffraction spectra of cellulose with intermediate degrees of crystallinity, a new method to obtain consistent crystallinity index values was developed.

Cellulose crystallinity--a key predictor of the enzymatic hydrolysis rate.

The enzymatic hydrolysis of cellulose encounters various limitations that are both substrate- and enzyme-related. Although the crystallinity of pure cellulosic Avicel plays a major role in determining the rate of hydrolysis by cellulases from Trichoderma reesei, we show that it stays constant during enzymatic conversion. The mode of action of cellulases was investigated by studying their kinetics on cellulose samples.