Side Products Research Articles

Same Day Access to Folded Synthetic Proteins.

Understanding protein function is a cornerstone of modern biology. Research centers worldwide dedicate significant efforts to prepare individual proteins for study, the isolation and purification of which can take days to months. We developed a workflow that enables same-day access to functional synthetic proteins. Chemical synthesis provides access to crude protein chains in hours, but the removal of the synthetic side products is typically a days-long process. We find that chemical modifications on side products lead to significant and unpredictable changes in the folding behavior. Consistent with these findings, we discovered that approaches based on biophysical properties characteristic of the folded protein target can discriminate against chemically similar species. Confirming our protocol with nine protein targets, we show that appropriate desalting followed by different folding strategies enables isolation of functional single-domain proteins in hours instead of days. Each target was isolated in under 10 h, including some proteins with post-translational modifications, non-natural amino acids, and disulfide bonds. Rapid biological discovery requires on-demand access to proteins, and the folding pipeline described here is uniquely suited to enabling these efforts. The folding process presented here was not assessed on complex proteins, and therefore, it may require further optimization in those cases.

Oxidative Release of Natural Glycans: Unraveling the Mechanism for Rapid N-Glycan Glycomics Analysis.

N-glycosylation is a critical post-translational modification involved in various biosynthetic pathways and disease mechanisms. In this study, we present an optimized oxidative release of natural glycans (ORNG) method using household bleach that enables the rapid and efficient release of N-glycans from biological samples. We thoroughly investigated the ORNG mechanism, identifying key intermediates and side products and providing valuable insights into the oxidative release process. The method is highly efficient, releasing a wide range of N-glycans, including high-mannose, hybrid, and complex structures, with minimal sample processing. Our ORNG-based specific N-glycan profiling approach has demonstrated high sensitivity and efficiency, particularly in releasing N-glycans resistant to enzymatic digestion, such as core α3-fucosylated N-glycans from soy protein. Validation through mass spectrometry confirmed the method's ability to accurately profile N-glycans from complex biological samples, including human serum, with results comparable to traditional PNGase F digestion. The ORNG-based method's scalability, versatility, and use of low-cost reagents make it especially suited for large-scale glycomics studies. Furthermore, the mass spectrometry data revealed that the ORNG-based method achieves high sensitivity and specificity, positioning it as a robust alternative for comprehensive glycan profiling and functional studies. Our findings highlight ORNG's potential to advance N-glycomics, offering promising improvements in speed, efficiency, and breadth of glycan analysis.

Visible Light-Induced Radical Cascade Functionalization of Quinoxalin-2(1H)-ones: Three-Component 1,2-Di(hetero)arylation Approach with Styrenes and Thianthrenium Salts.

The additive-free visible light-induced three-component 1,2-di(hetero)arylation of styrenes was developed using quinoxalin-2(1H)-ones and thianthrenium salts. The purple visible light excitable quinoxalin-2(1H)-ones were utilized for the single-electron transfer to aryl thianthrenium salts, where the generated aryl radical species underwent the addition cascade to styrenes and quinoxalin-2(1H)-ones. The direct aryl radical addition to quinoxalin-2(1H)-ones also led to the formation of a side product, C3-aryl quinoxalin-2(1H)-ones, capable of a photoredox process to help the formation of 1,2-di(hetero)arylation products.

Synthetic Routes to 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amines: Cross-Coupling and Challenges in SEM-Deprotection

7-Azaindoles are compounds of considerable medicinal interest. During development of the structure–activity relationship for inhibitors of the colony stimulated factor 1 receptor tyrosine kinase (CSF1R), a specific 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amine was needed. Two different synthetic strategies were evaluated, in which the order of the key C-C and C-N cross-coupling steps differed. The best route relied on a chemoselective Suzuki–Miyaura cross-coupling at C-2 on a 2-iodo-4-chloropyrrolopyridine intermediate, and subsequently a Buchwald–Hartwig amination with a secondary amine at C-4. Masking of hydroxyl and pyrroles proved essential to succeed with the latter transformation. The final trimethylsilylethoxymethyl (SEM) deprotection step was challenging, as release of formaldehyde gave rise to different side products, most interestingly a tricyclic eight-membered 7-azaindole. The target 2-aryl-1H-pyrrolo[2,3-b]pyridin-4-amine (compound 3c) proved to be 20-fold less potent than the reference inhibitor, confirming the importance of the N-3 in the pyrrolopyrimidine parent compound for efficient CSF1R inhibition.

Consumption targeted innovation for women: From principle to practice?

This study explores the gendered dimension of innovation policy, taking the perspective of women as users and consumers of innovation, rather than as participants in the innovative workforce; a perspective which has not yet been fully analysed. Based on an analysis of policy documents by supra-national, national, and sub-national agencies and elite interviews, the research examines the beginnings of a new policy we term “Consumption Targeted Innovation for Women” (CTIW) in a limited number of advanced economies: The EU, and the specific cases of Austria and Israel. Elaborating on the necessity of this policy, the dynamics of its spread and its challenges moving forward, the research contributes conceptually to the budding literature on inclusive innovation policy, and practically to the analysis of emerging policies that are likely to further gender equality in innovation. We argue that CTIW is a response to market failure in the form of innovation designs that systematically cater to male needs and preferences while mostly ignoring those of women. The spread of CTIW policies is driven by policy entrepreneurs from the academic world. Policy adoption depends on the degree to which government in general is committed to gender equality and more specifically gender mainstreaming policy. However, even where the environment is ideologically favorable, CTIW must contend with the fact that most policy attention is focused on measures dedicated to furthering gender-equality on the production side.

Degradation Mechanism and Enhanced Stability of Organolithium for Chemical Lithiation

AbstractOrganolithium solutions, especially Li‐arene solutions (LASs) with high reactivity and controllable redox potentials, have gained significant attention because of their wide applications in chemical lithiation, liquid anodes, and battery recycling. However, the sudden loss of reactivity when stored or applied at room temperature is still puzzling and inhibits the application of LASs. In this work, the degradation mechanism of LASs is fully investigated and revealed by combining various experimental characterization and computational simulations. A hierarchical reaction mechanism for lithium biphenyl/2‐methyl tetrahydrofuran (Li‐Bp‐2MT), a lithiation solution used for most anodes, explains degradation and side product formation. Specifically, the dimerization of the active component Li1Bp[2MT]1 forms an inactive dimer that is irreversibly reduced in the presence of locally accumulated highly reductive Li0. This reaction mechanism reveals the atomic origins of lithiation solution deactivation and accounts for all solid and gaseous byproducts. LiH is identified as the dominating solid byproduct, indicating irreversible destruction of the active components and facilitating side reactions producing H2 and CH4. Based on reaction mechanism insights, modifying molecular interactions and reaction kinetics are experimentally shown to inhibit Li0 aggregation kinetics, enhancing long‐term prelithiation performance. This research provides comprehensive guidelines for practical applications of LASs.

A comprehensive characterisation of food waste for its sustainable and holistic management using thermochemical processes

ABSTRACT This work presents a comprehensive physico-chemical analysis of mixed food waste (MFW) as a good feed for the thermochemical conversion process followed by its utilisation in the pyrolysis and gasification processes. The chemical analysis showed that MFW contained not only typical biomass contents, such as lignin (15.04%), cellulose (26.20%) and hemicellulose (5.05%) but also nutrients, such as protein (12.15%), starch (14.13%) and lipids (25.02%). Additionally, physical analyses, such as TGA, XRD, FTIR and FESEM, shed light on thermal behaviour, morphological structural and functional substituents in food waste. Post-analysis, 100-gm food waste was processed first via pyrolysis to produce bio-oil (40%) and bio-char (27%), then the biochar generated from pyrolysis was used as a feed in the steam gasification process which produced syngas (2.75 m3/Kg) as a main product and food waste ash as a side product. This food waste ash, in turn, was used as a support and promoter for Ni catalyst whose use in steam gasification showed a substantial increase in syngas production (1.26 m3/Kg from RFW and 3.6 m3/kg from bio-char).

Mandatory Notice of Layoff, Job Search, and Efficiency

Abstract In all OECD countries, mandatory notice (MN) policies require firms to inform workers in advance of a layoff. In our theoretical framework, MN helps workers avoid unemployment and find better jobs by encouraging them to search for a new job while still employed, thereby increasing future production. The magnitude of this production gain depends on the relative effectiveness of search while employed versus unemployed. But on-the-job search and diminished work incentives reduce current production. If future gains outweigh current production losses, longer advance notice improves production efficiency. If not, Coasian bargaining predicts that firms offer a larger severance instead of longer notice. With bargaining, the sole efficiency loss of MN is due to delayed separations of unproductive job matches. We test these predictions using novel Swedish administrative data on layoff notifications. Workers eligible for extended MN receive longer notice and larger severance, resulting in less exposure to nonemployment spells and higher-paying jobs. These favorable labor market outcomes are solely due to longer notice; in contrast, larger severance delays job finding and has no impact on wages. We also show that advance notice replaces job search while unemployed with more effective search while employed. On the production side, we document a productivity drop among notified workers and estimate a production loss due to delayed separations. Using our estimates of production gains and losses to evaluate the overall production efficiency, we conclude that the gains of MN seem to outweigh the losses.

In Vitro Characterization of Kitasetaline Biosynthesis Reveals a Bifunctional P450 Decarboxylase and a Vinyl β-Carboline Intermediate Susceptible to Nonenzymatic Thiol Addition.

Kitasetaline is one of the very few β-carbolines isolated from bacteria. It features a unique N-acetylcysteine moiety linked to the β-carboline core through a thioether bond. While earlier in vivo experiments identified the gene cluster and reported several putative biosynthetic intermediates, how the C-S bond linkage is constructed has remained elusive. Herein, in vitro reconstitution of kitasetaline biosynthesis reveals the involvement of a Pictet-Spenglerase (KslB) and a promiscuous dehydrogenase (KslA) that generate the characteristic β-carboline ring system. In addition, the P450 enzyme KslC was found to catalyze oxidative decarboxylation of 1-(2-carboxyethyl)-9H-pyrido[3,4-b]indole-3-carboxylic acid to yield the biosynthetic intermediate 1-vinyl-9H-pyrido[3,4-b]indole-3-carboxylic acid. KslC is also capable of catalyzing further oxidation of its product to yield an N-hydroxylated side product. Importantly, the vinyl intermediate was found to undergo nonenzymatic nucleophilic addition by N-acetyl-l-cysteine to generate the C-S bond leading directly to kitasetaline without the involvement of a mycothiolated intermediate proposed in a previous biosynthetic model. Thus, this work not only demonstrates that biosynthesis of β-carboline compounds is rich in unexpected chemistry but also adds to the growing realization that biological thiolation reactions are often nonenzymatic in nature, relying instead on enzymatic formation of reactive electrophiles.

„Býti národním v umění je směšný pleonasmus. Národní je i spánek.“ K německočeské debatě nad moderním meziválečným uměním

As an art historian who has long focused on the manifestations of the visual culture of the German-speaking scene in the Czech lands, I have repeatedly encountered the topic of perceiving the “Czechness” and “worldliness” of domestic production. From my research perspective, I see two levels in this beautiful and provocative challenge. The first is the evergreen of German-Bohemian art, i.e. if we apply a national or geographical scale to the artistic expressions that emerged from the Czech lands. Today, of course, we take a geographical view, but if we look at the production of individual regions side by side, it is impossible not to see clear differences on the part of the ethnically Czech and German scenes. Capturing and defining more universally some of the subliminal specifics that are apparent at first glance is a challenge that still occupies me mentally, despite the awareness of the absurdity of searching for a national definition of art. Fixing the key features is complicated by the existence of multicultural exceptions, which often introduce an element of Judaism into the traditional dualism of the period under review. These exceptions successfully disrupt the flattened idea of parallel Czech- and German-speaking cultural and social worlds of the Czech lands. Moreover, it is precisely these exceptions that are often the bearers of tendencies towards imaginary worldliness, which brings us to the second level of this consideration – to what extent and through what phenomena the territorially and numerically relatively small art scene of the Czech lands can be perceived as world-class. The answer may be the market, or a confident search for regional authenticity. In the words of Josef Kroutvor, “minor branches of modernity.” It seems to me that in today’s global world, their offsprings are more important than many textbook examples of the avant-garde.

Linking Ab initio density functional theory with modelling reaction microkinetics to understand catalytic fatty acids hydro-deoxygenation intermediate species selectivity

Catalyst surfaces enable the catalytic reactions via binding of substrates and lowering the reaction barriers to obtain the desired products. Separating the binding process from the reaction barriers enables us the understanding of surface properties and enables the reaction engineering strategies such as choice of solvents or functional groups protections. Through the modelling of the hydrodeoxygenation (HDO) of fatty acids, namely Stearic, Oleic, Linoleic, Myristic and Decanoic acid we show why the alkanes are the ideal solvent choice for NiMoS catalyst, why the alcohols side products form, regardless of the kinetic constant indicating fast dehydration, why the aldehydes intermediates are rarely detected and why hydrogenation of double bonds supersedes other kinetics events. We confirm the DFT calculations by integrating them into the kinetic model which confirms that the obtained results are sensible and usable in reaction engineering. The results are supported by the detailed characterization of the NiMoS catalyst.

Mechanistic Analysis of Lithium-Air Battery with Organic Redox Mediator-Coated Air-Electrode

Redox mediators (RMs) suppress the charging overpotential to enhance the cycle performance of lithium-air batteries (LABs), but inappropriate RM incorporation can adversely shorten cycle life. In this study, three typical organic RMs; tetrathiafulvalene (TTF), 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO), and 10-methylphenothiazine (MPT), were incorporated into the air-electrode (AE) of the LAB (RM-on-AE), rather than dissolving them in the electrolyte (RM-in-EL), to maximize the RM effect throughout the cycle life. The discharge/charge cycle test confirmed that the cells with RM-on-AE prevented the reductive decomposition of RM with the lithium anode, deriving the RM effect for a longer cycle life than the cells with RM-in-EL. The measurement of AE deposits revealed that the TTF- and TEMPO-on-AE cells failed to generate a quantitative amount of Li2O2 discharge product. In contrast, the MPT-on-AE provided a 96% yield of Li2O2 after the first discharge because of the reductive tolerance of the MPT as organic RM. The quantitative analysis also revealed an accumulation of Li2CO3 on the AEs, along with the generation of carboxylate, as the side products of irrelevant battery reactions. This study provides a practical methodology for selecting RMs and their incorporation for developing long-life LABs.

Furanic jet fuels – Water-free aldol condensation of furfural and cyclopentanone

A method for the water-free, large-scale synthesis of bio-jet fuel precursors, distinct from traditional fossil-based sources, is introduced. This approach involves the aldol condensation of furfural with cyclopentanone, producing C10-C15 fuel precursors eligible for further hydrodeoxygenation to high-performance diesel and jet fuel hydrocarbons. In the context of process integration, aldol condensation reactions were conducted under water-free conditions, utilizing excess furfural as the solvent. Evaluation of various commercial catalysts confirmed the feasibility of running in excess furfural. Both basic and acidic catalysts demonstrated significant activity, with CaO and amorphous silica-alumina achieving ≥80 mol% conversion of cyclopentanone and yielding ≥80 mol% selectivity towards the desired fuel components within 5 h of reaction. However, an overlooked aspect is the notable formation of undesired heavy side products. Observations indicated that the high furfural concentration, combined with the use of strong acidic catalysts, were the primary cause of heavy side product formation. The strong base catalyst, CaO, significantly reduced the formation of these oligomers, but did not appear to stop it completely. Interestingly, water content did not appear to play a major role in byproduct selectivity. To further suppress the formation of oligomers, the use of process-owned intermediates as solvents is proposed.

Metabolic Engineering and Process Intensification for Muconic Acid Production Using Saccharomyces cerevisiae

The efficient production of biobased organic acids is crucial to move to a more sustainable and eco-friendly economy, where muconic acid is gaining interest as a versatile platform chemical to produce industrial building blocks, including adipic acid and terephthalic acid. In this study, a Saccharomyces cerevisiae platform strain able to convert glucose and xylose into cis,cis-muconic acid was further engineered to eliminate C2 dependency, improve muconic acid tolerance, enhance production and growth performance, and substantially reduce the side production of the intermediate protocatechuic acid. This was achieved by reintroducing the PDC5 gene and overexpression of QDR3 genes. The improved strain was integrated in low-pH fed-batch fermentations at bioreactor scale with integrated in situ product recovery. By adding a biocompatible organic phase consisting of CYTOP 503 and canola oil to the process, a continuous extraction of muconic acid was achieved, resulting in significant alleviation of product inhibition. Through this, the muconic acid titer and peak productivity were improved by 300% and 185%, respectively, reaching 9.3 g/L and 0.100 g/L/h in the in situ product recovery process as compared to 3.1 g/L and 0.054 g/L/h in the control process without ISPR.

Oxidative Rearomatization of Tetrahydroisoquinolines Promoted by Pyridine-N-oxide.

Isoquinolines are ubiquitous arenes found in many biologically useful molecules. While direct substitution at the heterocyclic ring is uncommon, reductive functionalization to form tetrahydroisoquinolines (THIQs) is straightforward. Herein, we describe a facile method for producing C4-functionalized isoquinolines from a readily available parent THIQ. This high-temperature transformation utilizes pyridine-N-oxide as an oxidant generating only volatile side products and is functional-group-tolerant.

Multiphase nitrosation based on N2O3 intermediate and process intensification in a microflow reactor

Nitrosation of alcohols with nitrous acid is widely used to prepare alkyl nitrites, but the reaction mechanism and formation pathways of gaseous side products remain unclear. Here, we propose a nitrosation mechanism based on a highly reactive intermediate, dinitrogen trioxide (N2O3). The N2O3-based mechanism shows a lower energy barrier than the previously reported acid-catalyzed and nitrosyl cation mechanism. Furthermore, a microfluidic platform was established to investigate the gas–liquid-liquid reaction system and characterize the gas holdup of the multiphase reaction system. The results suggest that the reaction rate and selectivity primarily depend on the interfacial mass transfer of N2O3 between the aqueous-organic and gaseous-organic phases. A tubular microreactor was employed to intensify the nitrosation process of isopropanol. In contrast to the batch process operated by adding reactants dropwise in several hours, the product yield of 95 % can be achieved in a residence time of only 10 s in the microflow reactor.

Isomeric Speciation of Bisbenzoxazine Intermediates by Ion Spectroscopy and Ion Mobility Mass Spectrometry.

Bisbenzoxazines (BisBz) are a relevant model for the diverse bifunctional benzoxazines that are used to increase the polybenzoxazines cross-linking extensions and modulate the final resin properties for various usages. The presence of side products and intermediates during monomer formation can influence the resin characteristics by inducing chain termination and ramifications, affecting the polymerization and cure processes. This work investigated the diverse isomeric intermediates and side products that are present during the BisBz formation from bisphenol A, aniline, and formaldehyde by ion mobility coupled to tandem mass spectrometry (MS/MS) and ion spectroscopy techniques. The species detected in this work suggest that these multifunctional phenols open diverse concurrent reaction pathways based on two main reactive steps: (i) the imine/iminium phenol attack to form a phenylamino intermediate and (ii) the formaldehyde attack followed by dehydration to form the oxazine ring. The species observed also support previous studies of the benzoxazine formation mechanism and showcase the application of advanced analytical techniques in studying complex chemical systems.

Farmers as prosumers: Evidence from cadmium‐contaminated rice in China

AbstractWe study farmer responses in rice production and consumption to China's cadmium‐contaminated rice (CCR) event in 2013. We show that the CCR event reduced both rice production and consumption but did not significantly affect the quantity and price of rice sold by farmers in areas affected by cadmium pollution. Households with young children reduced their rice production and consumption by a larger amount than others, whereas the responses are reversed for households with elderly people. The decrease in rice production was mainly driven by the decrease in farmers' consumption of self‐produced rice instead of through price or income channels, indicating that farmers are prosumers who make production decisions not purely to maximize profit but also to satisfy their own consumption needs. Farmers being prosumers helped promote production side responses to new information about food safety.

N[sbnd]O bond cleavage and N2 activation reactions of the Nitrosyl-Bridged complex [Mo2Cp2(µ-PtBu2)(µ-NO)(NO)2]

The title compound was prepared through a three-step procedure starting with the hydride complex [Mo2Cp2(µ-H)(µ-PtBu2)(CO)4], which was first dehydrogenated through reaction with HBF4·OEt2 to give the unsaturated complex [Mo2Cp2(µ-PtBu2)(CO)4](BF4) (Mo=Mo), which displays a transoid structure according to experimental (Mo-Mo = 2.8283(7) Å) and Density Functional Theory studies. The latter was then reacted with NO to give the dinitrosyl derivative [Mo2Cp2(µ-PtBu2)(CO)2(NO)2](BF4), which in turn was further decarbonylated and nitrosylated upon reaction with [N(PPh3)2]NO2 to give the title nitrosyl-bridged complex (Mo-Mo = 2.905(1) Å). This complex displayed a structure comparable to that of its PCy2-bridged analogue, with similar pyramidalization of the bridging nitrosyl, but a more pronounced folding of the central MoPMoN skeleton and bending of terminal nitrosyls. It also displayed a similar NO bond activation chemistry, as shown by its reactions with HBF4·OEt2 to give the nitroxyl-bridged complex [Mo2Cp2(µ-PtBu2)(µ-k1:η2-HNO)(NO)2](BF4) (HNO = 1.330(8) Å), with P(OEt)3 to give the phosphoraniminate-bridged complex [Mo2Cp2(µ-PtBu2){µ-NP(OEt)3}(NO)2], and with Na(Hg) to give the amide-bridged derivative [Mo2Cp2(µ-PtBu2)(µ-NH2)(NO)2]. Under a nitrogen atmosphere, however, the latter reaction also gave a minor side product identified as the dinitrogen-bridged derivative [Mo4Cp4(µ-PtBu2)2(µ4-N2)(NO)4]. This tetranuclear complex displays a dinitrogen molecule bridging four metal atoms in the novel µ4-k1:k1:k1:k1 coordination mode, with strong metal-nitrogen interactions taking the N2 ligand to the diazendiide (N22-) limit (NN = 1.241(3) Å).

Chemical reaction enhanced graph learning for molecule representation.

Molecular representation learning (MRL) models molecules with low-dimensional vectors to support biological and chemical applications. Current methods primarily rely on intrinsic molecular information to learn molecular representations, but they often overlook effectively integrating domain knowledge into MRL. In this article, we develop a reaction-enhanced graph learning (RXGL) framework for MRL, utilizing chemical reactions as domain knowledge. RXGL introduces dual graph learning modules to model molecule representation. One module employs graph convolutions on molecular graphs to capture molecule structures. The other module constructs a reaction-aware graph from chemical reactions and designs a novel graph attention network on this graph to integrate reaction-level relations into molecular modeling. To refine molecule representations, we design a reaction-based relation learning task, which considers the relations between the reactant and product sides in reactions. In addition, we introduce a cross-view contrastive task to strengthen the cooperative associations between molecular and reaction-aware graph learning. Experiment results show that our RXGL achieves strong performance in various downstream tasks, including product prediction, reaction classification, and molecular property prediction. The code is publicly available at https://github.com/coder-ACAC/RLM.