Chemical Pathways Research Articles

Decarbonization of the chemical industry through electrification: Barriers and opportunities

The chemical industry is a major source of economic productivity and employment globally and among the top 3 industrial sources of greenhouse gas (GHG) emissions, along with steel and cement. As global demand for chemical products continues to grow, there is an urgency to develop and deploy sustainable chemical production pathways and to reconsider continued investment in current emission-intensive production technologies. This perspective describes the challenges and opportunities to decarbonize the chemical industry via electrification powered by low-carbon electricity supply, both in the near term and long term, and it discusses four technological pathways ranging from the more mature direct substitution of heat with electricity and use of hydrogen to technologically less mature, yet potentially more selective, approaches based on electrochemistry and plasma. Finally, we highlight the key elements of integrating an electrified industrial process with the power sector to leverage process flexibility to reduce energy costs of chemical production and provide valuable power grid support services. Unlocking such plant-to-grid coordination and the four electrification pathways has significant potential to facilitate rapid and deep decarbonization of the chemical industry sector. The chemical industry is a major source of economic productivity and employment globally and among the top 3 industrial sources of greenhouse gas (GHG) emissions, along with steel and cement. As global demand for chemical products continues to grow, there is an urgency to develop and deploy sustainable chemical production pathways and to reconsider continued investment in current emission-intensive production technologies. This perspective describes the challenges and opportunities to decarbonize the chemical industry via electrification powered by low-carbon electricity supply, both in the near term and long term, and it discusses four technological pathways ranging from the more mature direct substitution of heat with electricity and use of hydrogen to technologically less mature, yet potentially more selective, approaches based on electrochemistry and plasma. Finally, we highlight the key elements of integrating an electrified industrial process with the power sector to leverage process flexibility to reduce energy costs of chemical production and provide valuable power grid support services. Unlocking such plant-to-grid coordination and the four electrification pathways has significant potential to facilitate rapid and deep decarbonization of the chemical industry sector.

Development of bio-inspired multi-functional polymeric-based fibers (BioFiber) for advanced delivery of bacterial-based self-healing agent in concrete

The goal of this research is to develop innovative damage-responsive bacterial-based self-healing fibers (hereafter called BioFiber) that can be incorporated into concrete to enable two functionalities simultaneously: (1) crack bridging functionality to control crack growth and (2) crack healing functionality when a crack occurs. The BioFiber is comprised of a load-bearing core fiber, a sheath of bacteria-laden hydrogel, and an outer impermeable strain-responsive shell coating. An instant soaking manufacturing process was used with multiple reservoirs containing bacteria-laden, hydrophilic prepolymer and crosslinking reagents to develop BioFiber. Sodium-alginate was used as a prepolymer to produce calcium-alginate hydrogel via ionic crosslinking on the core fiber. The dormant bacteria (spore) of Lysinibacillus sphaericus was incorporated in hydrogel as a self-healing agent. Then, an impermeable polymeric coating was applied to the hydrogel-coated core fibers. The impermeable strain-responsive shell coating material was manufactured using the polymer blend of polystyrene and polylactic acid. The high swelling capacity of calcium-alginate provides the water required for the microbially induced calcium carbonate precipitation (MICP) chemical pathway, i.e., ureolysis in this study. The strain-responsive impermeable coating provides adequate flexibility during concrete casting to protect the spores and alginate before cracking and sufficient stress-strain behavior to grant damage-responsiveness upon crack occurrence to activate MICP. To evaluate the behavior of developed BioFiber, the swelling capacity of the hydrogel, the impermeability of shell coating, the spore casting survivability, and MICP activities were investigated.

Harnessing abiotic organic chemistry in living systems for biomedical applications.

Living systems are composed of a complex network of bioactive small molecules, proteins, ions and electrons, which present a wealth of opportunities for researchers to explore. Recently, organic chemists have developed a keen interest to move chemical reactions from laboratory flasks into living systems. This offers a new avenue for addressing challenges in current organic chemistry, expands the range of chemical transformations accessible to living systems, and provides a versatile tool for understanding and manipulating living systems. In this tutorial review, we include both the fundamental mechanisms and specific examples of how chemical reactions that typically occur outside of the biological context can be adapted for use within living systems. We also highlight the use of the resulting functional organic materials for biomedical applications including but not limited to imaging, therapy, theranostics and organic electronics. Finally, we discuss current challenges and future perspectives in this exciting field. We envision this tutorial review will serve as a guide for designing new chemical reactions and pathways in living systems that can expand the range of biological processes and functions and will accelerate the development of new biomaterials, biocatalysts, and therapeutics for precision medicine and other social needs.

(R)-8-Methylsulfinyloctyl isothiocyanate from Nasturtium officinale inhibits LPS-induced immunoinflammatory responses in mouse peritoneal macrophages: chemical synthesis and molecular signaling pathways involved.

The aim of this study was to develop an optimal synthetic route to obtain natural (R)-8-methylsulfinyloctyl isothiocyanate ((R)-8-OITC), present in watercress, based on the "DAG methodology" as well as to evaluate its potential antioxidant and immunomodulatory effects, exploring possible signaling pathways that could be involved in an ex vivo model of murine peritoneal macrophages stimulated with LPS. Treatment with (R)-8-OITC inhibited the levels of pro-inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-17 and IL-18), intracellular ROS production and expression of pro-inflammatory enzymes (COX-2, iNOS and mPGES-1) through modulation of the expression of Nrf2, MAPKs (p38, JNK and ERK) and JAK/STAT, and the canonical and non-canonical pathways of the inflammasome. Taking all these together, our results provide a rapid and cost-effective synthetic route to obtain natural (R)-8-OITC and demonstrate that it could be a potential nutraceutical candidate for managing immuno-inflammatory pathologies. Therefore, further in vivo trials are warranted.

Metabolic Roles of Colony-Forming Tissue Stem Cells in the Maculae Flavae of Newborn Vocal Fold In Vivo

Tissue stem cells in the maculae flavae (a stem cell niche) of the human vocal fold form colonies in vivo like stem cells in vitro. However, the roles of colony-forming aggregated cells in the maculae flavae in vivo have not yet been determined. This study investigated the glycolysis, of the colony-forming aggregated cells in the maculae flavae of the human newborn vocal fold in vivo. Three normal newborn vocal folds were investigated under light microscopy with immunohistochemistry and transmission electron microscopy. Colony-forming aggregated cells in the newborn maculae flavae strongly expressed glucose transporter-1 and glycolytic enzymes (hexokinase II, glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase A). The colony-forming aggregated cells did not express phosphofructokinase-1 (rate-limiting enzyme of regular glucose metabolism pathway) but expressed glucose-6-phosphate dehydrogenase (rate-limiting enzyme) indicating the cells relied more on the pentose phosphate pathway. The colony-forming aggregated cells' strong expression of lactate dehydrogenase A indicated that they rely more on anaerobic glycolysis in an anaerobic microenvironment. Mitochondrial cristae of the colony-forming aggregated cells in the newborn maculae flavae were sparse. Consequently, the microstructural features of the mitochondria suggested that their metabolic activity and oxidative phosphorylation were low. The colony-forming aggregated cells in the maculae flavae of the newborn vocal fold seemed to rely more on anaerobic glycolysis using the pentose phosphate pathway for energy supply in vivo. Microstructural features of the mitochondria and the glycolytic enzyme expression of the colony-forming aggregated cells suggested that the oxidative phosphorylation activity was low. Already at birth, in the anaerobic microenvironment of the macular flavae in vivo, there is likely a complex cross-talk regarding metabolism between the colony-forming aggregated cells along the adhesion machinery and chemical signaling pathways which reduces toxic oxygen species and is favorable to maintaining the stemness and undifferentiated states of the tissue stem cells.

Quantitative definition of chemical synthetic pathway complexity of organic compounds

Irrespective of the final application of a molecule, synthetic accessibility is the rate-determining step in discovering and developing novel entities. However, synthetic complexity is challenging to quantify as a single metric, since it is a composite of several measurable metrics, some of which include cost, safety, and availability. Moreover, defining a single synthetic accessibility metric for both natural products and non-natural products poses yet another challenge given the structural distinctions between these two classes of compounds. Here, we propose a model for synthetic accessibility of all chemical compounds, inspired by the Central Limit Theorem, and devise a novel synthetic accessibility metric assessing the overall feasibility of making chemical compounds that has been fitted to a Gaussian distribution. Our approach utilizes a Gaussian mixture model (GMM) and Autoencoder, which rank synthetic complexity for natural products. This model can inform total synthesis of natural products, process chemistry in pharmaceutical contexts, materials science, and chemical engineering. Based on our findings, we conclude that the Autoencoder model is better suited to model the true probability distribution of synthetic complexity for natural products.

The origin of anode–electrolyte interfacial passivation in rechargeable Mg-metal batteries

The formation of H2O molecules competitively solvating Mg-ion solvation structures and their decomposition in electrochemical and/or chemical reaction pathways with inherent H2O ligands result in dendritic and passivated electrodeposition.

Multicompartment calcium alginate microreactors to reduce substrate inhibition in enzyme cascade reactions.

The formation of macromolecularly enriched condensates through associative or segregative liquid-liquid phase separation phenomena is known to play a central role in controlling various cellular functions in nature. The potential to spatially and temporally modulate multistep chemical reactions and pathways has inspired the use of phase-separated systems for the development of various synthetic colloidal micro- and nanoreactor systems. Here, we report a rational and synthetically minimal design strategy to emulate intended spatiotemporal functions in morphologically intricate and structurally defined calcium alginate hydrogel microreactors possessing multicompartmentalized internal architectures. Specifically, we implement a thermal phase separation protocol to achieve fine-control over liquid-liquid phase separation inside complex aqueous emulsion droplet templates that are loaded with hydrophilic polymer mixtures. Subsequent gelation of alginate-containing droplet templates using a novel freeze-thaw approach that can be applied to both scalable batch production or more precise microfluidic methods yields particle replicas, in which subcompartmentalized architectures can be retained. Larger active components can be enriched in the internal compartments due to their preferential solubility, and we show that selective sequestration of enzymes serves to create desired microenvironments to control and tune the reaction kinetics of a multistep enzyme cascade by reducing their mutual interference. This demonstration of mitigating substrate inhibition that is based primarily on optimizing the multicompartmentalized hydrogel particle morphology offers new opportunities for the simple and synthetically-minimal batch generation of hydrogel-based synthesis microreactors.

From rosin to novel bio-based silicone rubber: a review.

Rosin is a characteristic natural renewable resource. In view of the unique hydrogenated phenanthrene ring skeleton structure of rosin, it can be designed and synthesized to modify silicone rubber for improving its mechanical properties, thermal stability, and other properties. In this paper, the research progress of silicone rubber modified by rosin and its derivatives is reviewed, including internal or surface modification of room temperature or high temperature vulcanized silicone rubber. The different chemical modifications and polymerization pathways to obtain bio-based silicone rubber (e.g. rosin-based silicone cross-linking agent, filler compound rosin-based silicone cross-linking agent, rosin-based polymer, and rosin quaternary ammonium salt bifunctional antibacterial coating) are discussed and its research prospect is reviewed. Overall, the present review article will provide a quantitative experimental basis for rosin to produce bio-renewable multifunctional silicone rubber to increase our level of understanding of the behavior of this important class of silicone rubber and other similar bio-based polymers.

Quantum chemical calculation and growth process of Ga2O3 grown via TEGa under different oxygen sources in MOCVD

The chemical reaction pathway and growth process of Ga2O3 grown via TEGa and H2O/O2/N2O in MOCVD were investigated.

On the disparity in reporting Li-rich layered oxide cathode materials.

Lithium-rich layered oxides are considered one of the most promising cathode materials for next generation lithium-ion batteries due to their extraordinary specific capacity of over 280 mA h g-1 and superior energy density of over 1000 W h kg-1. Despite the excellent performance, LRLOs still suffer from low Coulombic efficiency, serious capacity/voltage decay upon cycling, voltage hysteresis, short lifespan, and poor rate capability. Driven by the thirst for high-energy-density battery technologies, various strategies have been developed to address these issues with great progress being achieved in the past several years. However, the emerging disparity among the published results severely precludes meaningful comparisons between different LRLOs and material modification strategies, which has become an impediment to the development and commercialization of LRLOs. Although the significance of standardization has been recognized in the battery community, the standardization of LRLOs is worth particular attention due to their complicated compositions and unique electrochemical properties. This perspective analyzes the underlying parameters that can cause varied and even controversial results observed in LRLOs, from the synthesis procedure to the electrochemical evaluation procedure, followed by preliminary suggestions for the standard protocols of chemical compositions, synthesis pathways, calcination conditions, electrode preparation, battery fabrication, and battery testing. Hopefully, this perspective can help build a reliable baseline for LRLO research, thus aligning the huge research effort toward the practical applications of LRLOs.

Linking nanomaterial-induced mitochondrial dysfunction to existing adverse outcome pathways for chemicals_suppl2

Linking nanomaterial-induced mitochondrial dysfunction to existing adverse outcome pathways for chemicals_suppl2

Linking nanomaterial-induced mitochondrial dysfunction to existing adverse outcome pathways for chemicals_suppl1

Linking nanomaterial-induced mitochondrial dysfunction to existing adverse outcome pathways for chemicals_suppl1

Process optimization by NMR-assisted investigation of chemical pathways during depolymerization of PET in subcritical water

A novel NMR-based method allows for unsurpassed description of PET hydrolysis providing grounds for energy-efficient process design.

Chemical insights into the base-tuned hydrothermal treatment of side stream biomasses

Underlining chemical pathways of artificial humic substance formation in pH-programmed hydrothermal treatment of waste biomass aiming CO2 sequestration and soil improvement for sustainable and efficient agricultural processes.

QM/MM Modeling of Vibrational Polariton Induced Energy Transfer and Chemical Dynamics.

Vibrational strong coupling (VSC) provides a novel means to modify chemical reactions and energy transfer pathways. To efficiently model chemical dynamics under VSC in the collective regime, herein a hybrid quantum mechanical/molecular mechanical (QM/MM) cavity molecular dynamics (CavMD) scheme is developed and applied to an experimentally studied chemical system. This approach can achieve linear scaling with respect to the number of molecules for a dilute solution under VSC by assuming that each QM solute molecule is surrounded by an independent MM solvent bath. Application of this approach to a dilute solution of Fe(CO)5 in n-dodecane under VSC demonstrates polariton dephasing to the dark modes and polariton-enhanced molecular nonlinear absorption. These simulations predict that strongly exciting the lower polariton may provide an energy transfer pathway that selectively excites the equatorial CO vibrations rather than the axial CO vibrations. Moreover, these simulations also directly probe the cavity effect on the dynamics of the Fe(CO)5 Berry pseudorotation reaction for comparison to recent two-dimensional infrared spectroscopy experiments. This theoretical approach is applicable to a wide range of other polaritonic systems and provides a tool for exploring the use of VSC for selective infrared photochemistry.

Machine Learning Assisted Chemical Process Parameter Mapping on Lignin Hydrogenolysis

Lignin depolymerization has been studied for decades to produce carbon-neutral chemicals/biofuels and biopolymers. Among different chemical reaction pathways, catalytic hydrogenolysis favors reactions under relatively mild conditions, while its yield of bio-oil and high-value aromatic products is relatively high. In this study, the influence of reaction parameters on lignin hydrogenolysis are discussed by chemical process parameter mapping and modeled using three different machine learning algorithms based upon literature experimental data. The best R2 scores for solid residue and aromatic yield were 0.92 and 0.88 for xgboost, respectively. The parameter importance was examined, and it was observed that lignin-to-solvent ratio and average pore size have a larger impact on lignin hydrogenolysis results. Finally, the optimal conditions of lignin hydrogenolysis were predicted by chemical process parameter mapping using the best-fit machine learning model, which indicates that further process improvements can potentially generate higher yields in industrial applications.

Fabrication of r-GO/GO/α-Fe2O3/Fe2TiO5 Nanocomposite Using Natural Ilmenite and Graphite for Efficient Photocatalysis in Visible Light

Hematite (α-Fe2O3) and pseudobrookite (Fe2TiO5) suffer from poor charge transport and a high recombination effect under visible light irradiation. This study investigates the design and production of a 2D graphene-like r-GO/GO coupled α-Fe2O3/Fe2TiO5 heterojunction composite with better charge separation. It uses a simple sonochemical and hydrothermal approach followed by L-ascorbic acid chemical reduction pathway. The advantageous band offset of the α-Fe2O3/Fe2TiO5 (TF) nanocomposite between α-Fe2O3 and Fe2TiO5 forms a Type-II heterojunction at the Fe2O3/Fe2TiO5 interface, which efficiently promotes electron-hole separation. Importantly, very corrosive acid leachate resulting from the hydrochloric acid leaching of ilmenite sand, was successfully exploited to fabricate α-Fe2O3/Fe2TiO5 heterojunction. In this paper, a straightforward synthesis strategy was employed to create 2D graphene-like reduced graphene oxide (r-GO) from Ceylon graphite. The two-step process comprises oxidation of graphite to graphene oxide (GO) using the improved Hummer's method, followed by controlled reduction of GO to r-GO using L-ascorbic acid. Before the reduction of GO to the r-GO, the surface of TF heterojunction was coupled with GO and was allowed for the controlled L-ascorbic acid reduction to yield r-GO/GO/α-Fe2O3/Fe2TiO5 nanocomposite. Under visible light illumination, the photocatalytic performance of the 30% GO/TF loaded composite material greatly improved (1240 Wcm-2). Field emission scanning electron microscopy (FE-SEM) and high-resolution transmission electron microscopy (HR-TEM) examined the morphological characteristics of fabricated composites. X-ray photoelectron spectroscopy (XPS), Raman, X-ray diffraction (XRD), X-ray fluorescence (XRF), and diffuse reflectance spectroscopy (DRS) served to analyze the structural features of the produced composites.

UV-C photon integrated surface dielectric barrier discharge hybrid reactor: A novel and energy-efficient route for rapid mineralisation of aqueous azo dyes

The study describes developing an energy-efficient and scalable alternative to conventional non-thermal plasma systems by integrating surface dielectric barrier discharge (SDBD) and UV-C radiation sources. The unprecedented enhancement in the mineralisation rate of an azo dye (brilliant red 5B) by the hybrid reactor (photo-SDBD) is demonstrated thoroughly as a function of dye concentrations, pH, and background salts. The photo-SDBD is 1.25 – 4.9 times more energy efficient than SDBD under similar experimental conditions. The photo-SDBD could overcome the problems such as the recombination of hydroxyl radicals and scavenging of radicals by salts (NaCl, Na2SO4, Na2CO3) observed in conventional non-thermal plasma systems. The TOC and HR-MS analysis establish the complete mineralisation potential and chemical mineralisation pathway. Besides, the phytotoxicity of the treated water is tested and demonstrated its utility as a liquid fertiliser for enhanced germination of mung bean seeds. The optical emission spectroscopy measurements were performed to estimate the plasma's electron temperature (1.6 ± 0.2 eV) and density (1021/m3). The emission line ratio (I763.5/I738.3) approach is used to compare the influence of UV-C on plasma parameters in the SDBD reactor. The study opens a new pathway for developing energy-efficient and scalable plasma-assisted mineralisation of complex and emerging organic pollutants.

The PhotoDissociation Region Toolbox: Software and Models for Astrophysical Analysis

The PhotoDissociation Region Toolbox provides comprehensive, easy-to-use, public software tools and models that enable an understanding of the interaction of the light of young, luminous, massive stars with the gas and dust in the Milky Way and in other galaxies. It consists of an open-source Python toolkit and photodissociation region (PDR) models for analysis of infrared and millimeter/submillimeter line and continuum observations obtained by ground-based and suborbital telescopes, and astrophysics space missions. PDRs include all of the neutral gas in the interstellar medium where far-ultraviolet photons dominate the chemistry and/or heating. In regions of massive star formation, PDRs are created at the boundaries between the H ii regions and neutral molecular cloud, as photons with energies 6 eV < h ν < 13.6 eV photodissociate molecules and photoionize metals. The gas is heated by photoelectrons from small grains and large molecules and cools mostly through far-infrared (FIR) fine-structure lines like [O i] and [C ii]. The models are created from state-of-the art PDR codes that include molecular freeze-out; recent collision, chemical, and photorates; new chemical pathways, such as oxygen chemistry; and allow for both clumpy and uniform media. The models predict the emergent intensities of many spectral lines and FIR continuum. The tools find the best-fit models to the observations and provide insight into the physical conditions and chemical makeup of the gas and dust. The PDR Toolbox enables novel analysis of data from telescopes such as the Infrared Space Observatory, Spitzer, Herschel, the Stratospheric Terahertz Observatory, the Stratospheric Observatory for Infrared Astronomy, the Submillimeter Wave Astronomy Satellite, the Atacama Pathfinder Experiment, the Atacama Large Millimeter/submillimeter Array, and the JWST.