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The Hofmeister series characterizes the ability of salt anions to precipitate polyampholytes/proteins. However, the variation of protein size in the bulk solution of acids and the effect of salts on the same have not been studied well. In this article, the four acids (CH3COOH, HNO3, H2SO4, and HCl) and their effects on the hydrodynamic radius (RH) of gelatin in the bulk solution are investigated. The effects of Na salt with the same anions are also considered to draw a comparison between the interactions of acids and salts with polyampholytes. It is suggested that the interactions of polyampholytes with acids are different from those of salts. The interaction series of polyampholytes with acids with respect to the RH of the polyampholyte is C H 3 CO O − > N O 3 − > C l − > S O 4 2 − whereas the interaction series with salts is S O 4 2 − > C H 3 CO O − > C l − > N O 3 − . These different interactions are due to equilibration between acid dissociation and protonation of polyampholytes. Another important factor contributing to the interactions in weak acids is the fact that undissociated acid hinders the movement of dissociated acid. Experiments and simulations were performed to understand these interactions, and the results were identical in terms of the trend in RH (from the experiments) and the radius of gyration (Rg) (from the simulations). It is concluded that the valence of ions and dissociation affect the interaction in the case of acids. However, the interactions are influenced by the kosmotropic and chaotropic effect, hydration, and mobility in the case of salts. [ABSTRACT FROM AUTHOR]

Designing and predicting self-organized pattern formation in out-of-equilibrium chemical and biochemical reactions holds fundamental significance. External perturbations like light and electric fields exert a crucial influence on reaction-diffusion systems involving ionic species. While the separate impacts of light and electric fields have been extensively studied, comprehending their combined effects on spatiotemporal dynamics is paramount for designing versatile spatial orders. Here, we theoretically investigate the spatiotemporal dynamics of chlorine dioxide-iodine-malonic acid reaction-diffusion system under photo-illumination and circularly polarized electric field (CPEF). By applying CPEF at varying intensities and frequencies, we observe the predominant emergence of oscillating hexagonal spot-like patterns from homogeneous stable steady states. Furthermore, our study unveils a spectrum of intriguing spatiotemporal instabilities, encompassing stripe-like patterns, oscillating dumbbell-shaped patterns, spot-like instabilities with square-based symmetry, and irregular chaotic patterns. However, when we introduce periodic photo-illumination to the hexagonal spot-like instabilities induced by CPEF in homogeneous steady states, we observe periodic size fluctuations. Additionally, the stripe-like instabilities undergo alternating transitions between hexagonal spots and stripes. Notably, within the Turing region, the interplay between these two external influences leads to the emergence of distinct superlattice patterns characterized by hexagonal-and square-based symmetry. These patterns include parallel lines of spots, target-like formations, black-eye patterns, and other captivating structures. Remarkably, the simple perturbation of the system through the application of these two external fields offers a versatile tool for generating a wide range of pattern-forming instabilities, thereby opening up exciting possibilities for future experimental validation. [ABSTRACT FROM AUTHOR]

Fragmentation methods such as MIM (Molecules-in-Molecules) provide a route to accurately model large systems and have been successful in predicting their structures, energies, and spectroscopic properties. However, their use is often limited to systems at equilibrium due to the inherent complications in the choice of fragments in systems away from equilibrium. Furthermore, the presence of charges resulting from any heterolytic bond breaking may increase the fragmentation error. We have previously suggested EE-MIM (Electrostatically Embedded Molecules-In-Molecules) as a method to mitigate the errors resulting from the missing long-range interactions in molecular clusters in equilibrium. Here, we show that the same method can be applied to improve the performance of MIM to solve the longstanding problem of dependency of the fragmentation energy error on the choice of the fragmentation scheme. We chose four widely used acid dissociation reactions (HCl, HClO4, HNO3, and H2SO4) as test cases due to their importance in chemical processes and complex reaction potential energy surfaces. Electrostatic embedding improves the performance at both one and two-layer MIM as shown by lower EE-MIM1 and EE-MIM2 errors. The EE-MIM errors are also demonstrated to be less dependent on the choice of the fragmentation scheme by analyzing the variation in fragmentation energy at the points with more than one possible fragmentation scheme (points where the fragmentation scheme changes). EE-MIM2 with M06-2X as the low-level resulted in a variation of less than 1 kcal/mol for all the cases and 1 kJ/mol for all but three cases, rendering our method fragmentation scheme-independent for acid dissociation processes. [ABSTRACT FROM AUTHOR]

The fragmentation of fulminic acid, HCNO, after excitation and ionization of core electrons was investigated using Auger-electron–photoion coincidence spectroscopy. A considerable degree of site-selectivity is observed. Ionization of the carbon and oxygen 1s electron leads to around 70% CH+ + NO+, while ionization at the central N-atom produces only 37% CH+ + NO+, but preferentially forms O+ + HCN+ and O+ + CN+. The mass-selected Auger-electron spectra show that these fragments are associated with higher binding energy final states. Furthermore, ionization of the C 1s electron leads to a higher propensity for C–H bond fission compared to O 1s ionization. Following resonant Auger–Meitner decay after 1s → 3π excitation, 12 different ionic products are formed. At the C 1s edge, the parent ion HCNO+ is significantly more stable compared to the other two edges, which we also attribute to the higher contribution of final states with low binding energies in the C 1s resonant Auger electron spectra. [ABSTRACT FROM AUTHOR]

Luminescent cyclometallated iridium(III) complexes bearing a 2-formylphenylboronic acid moiety were designed; one of the complexes was utilised to modify peptides containing an N-terminal cysteine to afford luminescent conjugates with selective organelle-targeting or furin-responsive properties. [ABSTRACT FROM AUTHOR]

An effective protocol for synthesis of some new pyrazolylbarbiturate derivatives is reported through a one-pot, three-component reaction between barbituric/thiobarbituric acid, aroylphenylhydrazones and arylglyoxal derivatives. All reactions were conducted in ethanol as solvent without using any catalyst and products were obtained by simple filtering of the precipitated solids in high yields. All products were characterized by 1H and 13C NMR and IR spectral and elemental analysis data. [ABSTRACT FROM AUTHOR]

This study reports the copper‐catalyzed α‐indolmethylation of 2‐pyridylacetates with 3‐indoleacetic acids. This reaction offers an approach to generating alkylideneindolenine electrophiles via the oxidative decarboxylation of 3‐indoleacetic acids. The developed reaction system demonstrates good versatility, extending beyond the indolmethylation of 2‐pyridylacetates to include activated esters and nitroalkanes. Moreover, a biological evaluation revealed that several products exhibited antiproliferative activity against different cancer cell lines. [ABSTRACT FROM AUTHOR]

The selective reduction of an aromatic trifluoromethyl substituent to a difluoromethyl substituent may be achieved by base‐promoted elimination to form a difluoro‐p‐quinomethide which is trapped by an intramolecular nucleophile. High yields are obtained when the nucleophilic trap entails the conformationally favoured cyclisation of an aminoisobutyric acid (Aib) derivative. The resulting cyclised difluoromethyl‐substituted arylimidazolidinone products are readily converted to versatile difluoromethyl‐substituted aldehydes by reduction and hydrolysis. Defluorination is successful on a range of benzenoid (both para and ortho CF3‐substituted) and heterocyclic substrates. Double defluorination may likewise be achieved sequentially, or in a single step, from an Aib dipeptide derivative. [ABSTRACT FROM AUTHOR]

The selective reduction of an aromatic trifluoromethyl substituent to a difluoromethyl substituent may be achieved by base‐promoted elimination to form a difluoro‐p‐quinomethide which is trapped by an intramolecular nucleophile. High yields are obtained when the nucleophilic trap entails the conformationally favoured cyclisation of an aminoisobutyric acid (Aib) derivative. The resulting cyclised difluoromethyl‐substituted arylimidazolidinone products are readily converted to versatile difluoromethyl‐substituted aldehydes by reduction and hydrolysis. Defluorination is successful on a range of benzenoid (both para and ortho CF3‐substituted) and heterocyclic substrates. Double defluorination may likewise be achieved sequentially, or in a single step, from an Aib dipeptide derivative. [ABSTRACT FROM AUTHOR]

Here, we report a proof-of-concept resistive pulse method for analyzing chiral amino acids utilizing metal-amino acid crystallization differences. This method involves introducing an amino acid sample solution into a micropipette through a pressure-driven flow. The sample then mixes with a metal ion solution inside the pipette, forming metal-amino acid crystals. The crystal size depends on the enantiomeric excess (x) of chiral amino acid samples. Large x values lead to large crystals. The crystal size difference is then reflected in the resistive pulse size as they block the ionic transport in a micropipette to different extents. We used Cd-cystine crystallization as a model system and found approximately five times the mean current pulse size difference for racemic (x = 0) and L-only (x = +1) cystine samples. A similar result was observed for aspartate. Our discovery opens up new opportunities for micro/nanoscopic chiral amino acid analysis, which can potentially be used in single-cell analysis. [ABSTRACT FROM AUTHOR]

D-amino acids (D-AAs) are the enantiomeric counterparts of L-amino acids (L-AAs) and important functional factors with a wide variety of physiological activities and applications in the food manufacture industry. Some D-AAs, such as D-Ala, D-Leu, and D-Phe, have been favored by consumers as sweeteners and fragrances because of their unique flavor. The biosynthesis of D-AAs has attracted much attention in recent years due to their unique advantages. In this review, we comprehensively analyze the structure-function relationships, biosynthesis pathways, multi-enzyme cascade and whole-cell catalysis for the production of D-AAs. The state-of-the-art strategies, including immobilization, protein engineering, and high-throughput screening, are summarized. Future challenges and perspectives of strategies-driven by bioinformatics technologies and smart computing technologies, as well as enzyme immobilization, are also discussed. These new approaches will promote the commercial production and application of D-AAs in the food industry by optimizing the key enzymes for industrial biocatalysts. [ABSTRACT FROM AUTHOR]

A novel strategy for the chemoselective conversion of sulfoxides to sulfide utilizing D-camphorsulfonic acid (D-CSA) as a reducing reagent has been developed under metal and additive-free conditions. A variety of sulfoxides such as alkyl–aryl, allyl–aryl, benzyl–aryl, aryl–ethyl sulfoxides have been effectively utilized to achieve the corresponding reduced products in good to excellent yields under mild conditions without any additive. The proposed method offers a practical solution for the deoxygenation of sulfoxides, which has potential applications in various fields such as pharmaceuticals, materials science, and organic synthesis. A novel strategy for the chemoselective deoxygenation of diverse sulfoxides without metal and additive has been disclosed using D-camphorsulfonic acid (D-CSA) as the reducing agent. The reaction proceeds under mild conditions to afford the sulphides in moderate to good yields with great tolerance of diverse functional groups. [ABSTRACT FROM AUTHOR]

The work presented here establishes the experimental findings of the reaction between secondary/tertiary propargylic alcohol (PA) and 1,3,5‐trimethoxybenzene (TMB) in the presence of acetonitrile solvent (MeCN) based on theoretical calculations. When secondary PA reacts, the reaction goes via SN2 pathway, where the reaction barrier is about 14.32 kcal/mol. On the other hand, tertiary PA reacts with TMB via SN2′ and SN1′ pathway, and the corresponding reaction barriers are 17.59 and 17.86 kcal/mol. Other possible pathways, namely, SN1, SN1′, etc. for secondary PA, and SN2, SN1 pathways for tertiary PA are also investigated and the associated barrier heights are found higher. Rates of those reactions are also calculated considering the rate‐determining steps only. Reaction of secondary PA with TMB is found to be much faster than the reaction of tertiary PA and the results are in accordance with the experimental findings. [ABSTRACT FROM AUTHOR]

Wolfiporia cocos is a medicinal mushroom used in China. It biosynthesizes pachymic acid (PA), a main therapeutic triterpene associated with therapies. Nowadays, the unknown PA biosynthesis leads to difficulties in increasing its content in W. cocos. Herein, we report sequencing, assembling, and characterization of the genome and several transcriptomes of W. cocos. Sequence mining determined candidate genes that encode lanosterol synthase, sterol O-acyltransferase, and sterol C-24 methyltransferase likely involved in the steps from lanosterol to PA. Gene cluster analysis identified four CYP450 cDNAs likely involved in the biosynthesis of PA, namely WcCYP64-1, WcCYP64-2, WcCYP52, and WcCYP_FUM15, which were subjected to both overexpression and silencing in mycelia. The overexpression of each of WcCYP64-1, WcCYP52 and WcCYP_FUM15 increased the content of PA, 16α-hydroxytrametenolic acid, eburicoic acid, and tumulosic acid, while the silencing of each gene either significantly or slightly decreased the contents of these four compounds, indicating their involvement in the PA biosynthesis. In addition, different temperatures affected the expression of these genes and the formation of PA. By contrast, the overexpression and silencing of WcCYP64-2 did not alter the formation of these compounds. Taken together, these findings determine more potential steps in the biosynthetic pathway of PA for metabolic engineering. This study reports sequencing, assembly, and characterization of the genome and transcriptome of Wolfiporia cocos. In addition, Three CYP450s were identified to be involved in the biosynthesis of its active component, pachymic acid. [ABSTRACT FROM AUTHOR]

Photoactivated dynamic ultralong room‐temperature phosphorescent (PAD‐URTP) materials with changing emission colors are attractive and meaningful but are rarely reported. Herein, a one‐pot heat treatment strategy for embedding 1‐hydroxy‐2‐naphthoic acid (1H2NA) and 2‐hydroxy‐1‐naphthoic acid (2H1NA) into boric acid (BA) matrix (named 1H2NA@BA and 2H1NA@BA) to construct PAD‐URTP materials is developed, which exhibits rapid and reversible photoactivated phosphorescence, as well as photo‐stimulated dynamic change of luminescence color. The luminescent color of 1H2NA@BA could continuously change from blue‐purple to bright cyan‐white upon prolonged 365 nm UV light irradiation, which is attributed to the combined effect of static blue fluorescence and dynamic photoactivated green phosphorescence. Significantly, it could emit over 10 s green afterglow after switching off the UV irradiation. The combination of experiment and theoretical calculation results reveal that their PAD‐URTP behavior is attributed to the energy accumulation of triplet states under UV light irradiation. Finally, a series of information encryption and a complete story of "a mouse and cake" are successfully fabricated by using 1H2NA@BA with other luminescence materials. Thus, this study demonstrates fast PAD‐URTP materials with dynamic color‐changing luminescence and opens up new possibilities as the photo‐responsive luminescent material for further mechanistic understanding and future application. [ABSTRACT FROM AUTHOR]

The cascade functionalizations of alkynes have provided many elegant methods for the synthesis of useful scaffolds. Amongst these functionalizations, the ones comprising C−C and C−O bond formation have been utilized extensively due to the abundant presence of oxygenated motifs in various bio‐active natural as well as unnatural products. Transition‐metal catalysis is a mainstay for these tandem functionalizations as they are very efficient. However, their utilization does typically involve stoichiometric additives like other metal salts and/or Lewis acids/Brønsted acids (LA/BA). Thus, approaches that rely solely on using LA/BA, make these vital transformations not only eco‐friendly and atom economical but also cost beneficial are fast emerging as complementary alternatives. The present review addresses the gap in the literature by summarizing recent developments in LA/BA mediated 1,1/1,2‐carboxygenation and carboalkoxylation of alkynes for the synthesis of oxa‐cycles. The reaction mechanisms are particularly emphasized to bring out understanding needed from the point of future developments in this domain. [ABSTRACT FROM AUTHOR]

5-hydroxyvaleric acid (5-HV) is a versatile C5 intermediate of bio-based high-value chemical synthesis pathways. However, 5-HV production faces a few shortcomings involving the supply of cofactors, especially α-ketoglutaric acid (α-KG). Herein, we established a two-cell biotransformation system by introducing L- glutamate oxidase (GOX) to regenerate α-KG. Additionally, the catalase KatE was adapted to inhibit α-KG degradation by the H 2 O 2 produced during GOX reaction. We searched for the best combination of genes and vectors and optimized the biotransformation conditions to maximize GOX effectiveness. Under the optimized conditions, 5-HV pathway with GOX showed 1.60-fold higher productivity than that of without GOX, showing 11.3 g/L titer. Further, the two-cell system with GOX and KatE was expanded to produce poly(5-hydroxyvaleric acid) (P(5HV)), and it reached at 412 mg/L of P(5HV) production and 20.5% PHA contents when using the biotransformation supernatant. Thus, the two-cell biotransformation system with GOX can potentially give the practical and economic alternative of 5-HV production using bio-based methods. We also propose direct utilization of 5-HV from bioconversion for P(5HV) production. • 5-hydroxyvaleric acid (5-HV) is a versatile C5 intermediate of high-value chemical synthesis pathways. • Two-cell biotransformation system was established for high 5-HV production by introducing L-glutamate oxidase (GOX). • Catalase (KatE) was simultaneously applied to inhibit the degradation of α-ketoglutaric acid. • By introducing GOX, 11.3 g/L titer of 5-HV was produced and 1.60-fold faster turnover was observed. • Our research was expanded to the synthesis of poly(5-hydroxyvaleric acid) (P(5HV)), and 412 mg/L of P(5HV) was obtained. [ABSTRACT FROM AUTHOR]

A visible light-induced oxidative esterification reaction of mandelic acid with alcohols has been developed for the synthesis of α-ketoesters. The reaction is characterised by transition metal-free nature, good yields, broad functional group tolerance, and ease of operation. A practical, neutral and mild synthetic approach is provided for α-ketoesters, which are important units of many bioactive compounds and useful precursors in a wide range of drugs. Preliminary mechanistic studies suggest that this reaction takes place via the free radical pathway. [ABSTRACT FROM AUTHOR]

Passerini polymerization using naturally occurring α-lipoic acid as a raw material yields polyamides with 1,2-dithiolane functional groups in a one-step reaction. The polyamide exhibits characteristics of an adaptable dynamically crosslinked network through reversible ring-opening reaction of 1,2-dithiolane, enabling self-healing, reusable strong adhesion, and regeneration through decrosslinking and re-crosslinking. [ABSTRACT FROM AUTHOR]

We present the gas-phase synthesis of 2-methyl-prop-1-ene-1,1-diol, an unreported higher energy tautomer of isobutyric acid. The enol was captured in an argon matrix at 3.5 K, characterized spectroscopically and by DFT computations. The enol rearranges likely photochemically to isobutyric acid and dimethylketene. We also identified propene, likely photochemically formed from dimethylketene. [ABSTRACT FROM AUTHOR]

A succinct synthetic approach to mugineic acids and 2'‐hydroxynicotianamine was established. Unlike all other synthetic methods, this approach utilized epoxide ring‐opening reactions to form two C−N bonds and is characterized by the absence of redox reactions. Mugineic acid was synthesized from three readily available fragments on a gram scale in 6 steps. The protected 2'‐hydroxynicotianamine was also synthesized in 4 steps, and the dansyl group, serving as a fluorophore, was introduced through a click reaction after propargylation of the 2'‐hydroxy group. The dansyl‐labeled nicotianamine (NA) iron complexes were internalized by oocytes overexpressing ZmYS1 (from maize) or PAT1 (from human) transporters, indicating successful transport of the synthesized NA‐probe through these transporters. [ABSTRACT FROM AUTHOR]

A succinct synthetic approach to mugineic acids and 2'‐hydroxynicotianamine was established. Unlike all other synthetic methods, this approach utilized epoxide ring‐opening reactions to form two C−N bonds and is characterized by the absence of redox reactions. Mugineic acid was synthesized from three readily available fragments on a gram scale in 6 steps. The protected 2'‐hydroxynicotianamine was also synthesized in 4 steps, and the dansyl group, serving as a fluorophore, was introduced through a click reaction after propargylation of the 2'‐hydroxy group. The dansyl‐labeled nicotianamine (NA) iron complexes were internalized by oocytes overexpressing ZmYS1 (from maize) or PAT1 (from human) transporters, indicating successful transport of the synthesized NA‐probe through these transporters. [ABSTRACT FROM AUTHOR]

A simple hydrothermal method was employed for synthesizing MgZnAl layered triple hydroxide nanoplates (MgZnAl LTH) as an efficient adsorbent for removing the Acid Yellow 76 (AY76) azo dye. A batch process was used to perform adsorptions were and investigate the effects of experimental parameters including temperature, adsorbent dosage, solution pH. The best adsorption conditions obtained were pH of 4, MgZnAl LTH dosage of 20 mg and temperature of 55 °C. The kinetics of adsorption was studied using pseudo‐first‐order, pseudo‐second‐order, Elovich, and intraparticle diffusion models. To obtain equilibrium absorption data, Freundlich, Langmuir, and Temkin isotherms were utilized. The findings showed that the adsorption data based on the experiment had a good agreement with the Freundlich model. The highest capacity of adsorption equal to 277.8 mg/g was obtained for the MgZnAl LTH nanoplates toward AY76. Thermodynamic results showed that the process of adsorption of AY76 onto MgZnAl LTH nanoplates had a spontaneous and endothermic nature. [ABSTRACT FROM AUTHOR]

γ‐Valerolactone (GVL) can be obtained by efficient hydrogenation of levulinic acid using ruthenium‐based catalysts in an aqueous medium. This paper reports an in‐depth study on the activity and selectivity of Ru catalysts supported on zirconia‐alumina, focusing on the effect of Ru concentration (0.5, 1.5 and 3 wt. % of Ru) and the selection of operational reaction variables. The results showed that the activity strongly depends on the number and oxidation state of the supported ruthenium particles. The most active catalyst, Ru3/ZA, presented the highest number of nanometric particles of zerovalent Ru and the highest number of acid sites. This catalyst gave ca. 100 % selectivity towards GVL, at high conversion of levulinic acid (over 99 %) under the best operating conditions evaluated (120 °C, 3 MPa H2 pressure, 1 h of reaction, and 0.1 g of catalyst). In addition, this catalyst kept high levels of conversion and selectivity after successive reuse cycles. [ABSTRACT FROM AUTHOR]

Non‐noble Ni−Cu alloys serve as an alternative catalytic material for noble metal‐based catalysts that could be applied in the efficient conversion of levulinic acid (LA) into the high value γ‐valerolactone (GVL). However, maintaining the catalytic stability for Ni−Cu nanoparticles in the LA hydrogenation process remains a substantial challenge, Herein, this problem is solved by constructing carbon‐protected catalytic sites within carbon layer‐coated Ni−Cu nanoalloy composite via pyrolysis of NiCux(OH)/glucose precursor. The optimized NiCu0.68@C catalyst exhibits excellent stability and selectivity to GVL (>99 %) in the hydrogenation of LA reaction. Various characterization indicates that the enhancement in stability originates from the protective effect of the carbon layer, which prevents the metal leaching, oxidation and aggregation of Ni−Cu nanoparticles during the reaction process. This work greatly advances non‐noble metal‐catalyzed conversion of LA to GVL and helps the rational design of bimetallic catalysts. [ABSTRACT FROM AUTHOR]

A growing interest in more sustainable and alternative food sources has brought seaweed and macroalgae to the spotlight for the general worldwide cuisine. Algae are often praised for their high nutritional value and are rich in potassium, calcium, and magnesium. Abundant in base precursors, algae are particularly interesting from an acid-base perspective. Their unique biochemical composition suggests a low potential renal acid load (PRAL), which is a commonly used estimate for the amount of acid or base a certain food produces in humans. Here, we analyzed the PRAL value of n = 106 macroalgae. Results suggested a strong alkalizing potential, with a mean PRAL value of −86.76 mEq/100 g. The lowest PRAL values were found for Laminaria ochroleuca (−286.78 mEq/100 g), Gelidium micropterum (−268.46 mEq/100 g), and Palmaria palmata (−259.16 mEq/100 g). We observed a strong inverse relationship of PRAL with algae's potassium content (Spearman's rho = −0.79, p < 0.001) and a moderate relationship with algae's calcium content (Spearmen's rho: −0.34, p < 0.001). Our data point at a potential role for several macroalgae as potent alkalizing marine drugs and suggest that a 10 g edible portion of some algae alone could contribute to a substantial PRAL reduction of up to −28.68 mEq. This might be of particular importance for individuals who benefit from a more alkaline diet and warrants further investigation in future studies. [ABSTRACT FROM AUTHOR]

Background: The structural diversity of extracellular polymeric substances produced by microorganisms is attracting particular attention. Poly-gamma-glutamic acid (γ-PGA) is a widely studied extracellular polymeric substance from Bacillus species. The function of γ-PGA varies with its molecular weight (Mw). Results: Herein, different endogenous promoters in Bacillus licheniformis were selected to regulate the expression levels of pgdS, resulting in the formation of γ-PGA with Mw values ranging from 1.61 × 103 to 2.03 × 104 kDa. The yields of γ-PGA and exopolysaccharides (EPS) both increased in the pgdS engineered strain with the lowest Mw and viscosity, in which the EPS content was almost tenfold higher than that of the wild-type strain. Subsequently, the compositions of EPS from the pgdS engineered strain also changed. Metabolomics and RT-qPCR further revealed that improving the transportation efficiency of EPS and the regulation of carbon flow of monosaccharide synthesis could affect the EPS yield. Conclusions: Here, we present a novel insight that increased pgdS expression led to the degradation of γ-PGA Mw and changes in EPS composition, thereby stimulating EPS and γ-PGA production. The results indicated a close relationship between γ-PGA and EPS in B. licheniformis and provided an effective strategy for the controlled synthesis of extracellular polymeric substances. [ABSTRACT FROM AUTHOR]

In recent years, bacteria of the genus Massilia have been identified as promising sources of bioactive natural products. In this study, we used mass spectrometry (MS)‐based molecular networking for the first comprehensive analysis of the secondary metabolome of these microorganisms. Annotation of the detected metabolite clusters with a mass fragmentation database revealed several compounds not previously known to be produced by Massilia species. To secure sufficient material for further structural analyses as well as biological testing, we selected the most promising producer strains from our molecular networking analysis and subjected them to larger‐scale cultivation. Following extraction and UV‐directed isolation, we obtained five metabolites in milligram quantities. In addition to a cyclic dipeptide, we elucidated the structures of four acyl amino acids that are related to thalassotalic acid C from the marine bacterium Thalassotalea sp. The Massilia‐derived kyonggic acids were found to inhibit the enzyme tyrosinase, which is involved in melanin biosynthesis influencing skin and hair pigmentation. This study illustrates the value of combining spectroscopic and computational tools in natural product discovery in order to detect and guide the isolation of previously overlooked bioactive compounds. [ABSTRACT FROM AUTHOR]

The multicomponent assembly of a nitrile‐based directing group in a set of arylacetic acids under solvent‐free mechanochemical conditions using the Passerini 3‐CR and the subsequent Pd(II)‐mediated meta‐C(sp2)−H bond olefination process has been achieved. The protocol demonstrated that removing the DG under mild conditions from the activated Passerini adducts affords a novel N‐(tert‐butyl)‐2‐(2‐cyanophenyl)‐2‐hydroxyacetamide, which can be re‐utilized in the future as DG in other distal activation processes. [ABSTRACT FROM AUTHOR]

Cronobacter spp. are high acid resistance pathogens classified as Class A pathogens in powdered infant formula. Herein, we investigated the function of Cronobacter luxS in acid response. Results showed that luxS significantly increased the resistance to acid, demonstrating bacterial survival, bacterial morphology and biofilm formation. Furthermore, LuxS might enhance acid response by mediating the up‐regulation of 5‐methyltetrahydropteroyltriglutamate–homocysteine S‐methyltransferase and homocysteine S‐methyltransferase and the down‐regulation of methionine adenosyltransferase in the quorum sensing pathway. Therefore, the quorum sensing pathway mediated by luxS is the key control target for Cronobacter survival in acidic environments. [ABSTRACT FROM AUTHOR]

The nosocomial bacterium Acinetobacter baumannii is protected from antibiotic treatment by acquiring antibiotic resistances and by forming biofilms. Cell attachment, one of the first steps in biofilm formation, is normally induced by environmental metabolites. We hypothesized that vanillic acid (VA), the oxidized form of vanillin and a widely available metabolite, may play a role in A. baumannii cell attachment. We first discovered that A. baumannii actively breaks down VA through the evolutionarily conserved vanABKP genes. These genes are under the control of the repressor VanR, which we show binds directly to VanR binding sites within the vanABKP genes bidirectional promoter. VA in turn counteracts VanR inhibition. We identified a VanR binding site and searched for it throughout the genome, especially in pili encoding promoter genes. We found a VanR binding site in the pilus encoding csu operon promoter and showed that VanR binds specifically to it. As expected, a strain lacking VanR overproduces Csu pili and makes robust biofilms. Our study uncovers the role that VA plays in facilitating the attachment of A. baumannii cells to surfaces, a crucial step in biofilm formation. These findings provide valuable insights into a previously obscure catabolic pathway with significant clinical implications. [ABSTRACT FROM AUTHOR]

Understanding the complex flow behavior along a rough-walled fracture under complex chemical conditions is of great significance to deep rock engineering in carbonate rocks. This study investigates the influence of acid dissolution on the nonlinear flow behavior of rough-walled limestone fractures. Fracture flow tests are performed under different flow rates to obtain the correlation between pressure gradients and flow rates before and after acidizing. The fitting results indicate that both the Forchheimer equation and the Izbash equation are suitable for characterizing the flow nonlinearity caused by inertial effects after acidizing. The generation of dominant etching channels is a key factor that influences the change in the nonlinear flow properties along the rough-walled fracture surface. The change rate of nonlinear coefficient B after the formation of the dominant etching channel is affected by the combined effect of the acid injection rate and the fracture roughness. For the acidized fracture without generating the dominant etching channel, the variation of microscale roughness after acidizing changes the local vortex area and the inertial resistance of the flow field, and thus influences the nonlinear flow behavior along the limestone fracture. Highlights: The correlation between pressure gradients and flow rates before and after acidizing along rough-walled limestone fractures is captured. The generation of etching channels exerts a significant influence on the flow nonlinearity along rough-walled fracture surfaces. The change rate of the nonlinear coefficient increases with the increase of the acid injection rates. The fracture flow nonlinearity is affected by the combined effect of the acid injection rate and the fracture roughness. The variation of the microscale roughness after acid treatment impacts the nonlinear flow behavior along a limestone fracture. [ABSTRACT FROM AUTHOR]

For complete utilization of high glucose at ∼100 g/L, a high cell density (HCD) continuous fermentation system was established using Lb. delbrueckii NCIM 2025 for the bioproduction of lactic acid (LA). An integrated membrane cell recycling system coupled with the continuous bioreactor, aided to achieve the highest 34.77 g/L h LA productivity and 0.94−0.98 g/g yield. ∼34 times higher productivity was observed (in comparison to batch fermentation conducted in this study), when the continuous operations were carried out at the maximum dilution rate and wet cell weight i.e. 0.36 h−1 and 230 g/L, respectively. These results show the potential of this method for large-scale lactic acid production because it not only produces high titers but also ensures that glucose is used effectively. The method's superior performance in comparison to earlier studies suggests it as an affordable and sustainable alternative for the production of LA. [ABSTRACT FROM AUTHOR]

The effects of different types of acid coagulants and nano fish bone (NFB) additives on the characteristics of tofu were investigated using texture analyzers, SEM, FT‐IR, and other techniques. The breaking force and penetration distance, in descending order, were found in the tofu induced by glucono‐d‐lactone (GDL) (180.27 g and 0.75 cm), citric acid (152.90 g and 0.74 cm), lactic acid (123.33 g and 0.73 cm), and acetic acid (69.84 g and 0.58 cm), respectively. The syneresis of these tofu samples was in the reverse order (35.00, 35.66, 39.66, and 44.50%). Lightness and whiteness were not significantly different among the different samples. Regardless of the acid type, the soluble calcium content in the soybean milk was significantly increased after adding NFB. As a result, the breaking force and penetration distance of all tofu samples increased significantly, but the syneresis decreased. Compared with tofu coagulated by other acids, GDL tofu formed a more uniform and dense gel network maintained by the highest intermolecular forces (especially hydrophobic interactions). Regarding the secondary structure, the lowest percentage of α‐helix (22.72%) and, correspondingly, the highest β‐sheet (48.32%) and random coil (18.81%) were noticed in the GDL tofu. The effects of NFB on the tofu characteristics can be explained by the changes in the gel network, intermolecular forces, and secondary structure, which were in line with the acid type. The characteristics of acid‐induced tofu can be most synergistically improved by coagulation with GDL and NFB. [ABSTRACT FROM AUTHOR]

The present work represents a novel methodology for the selective arylation of coumarin‐3‐carboxylates with arylboronic acids via a photochemical route, marking the first‐ever attempt for the direct alkenyl C−H arylation using rose bengal as a photocatalyst, which is a readily available and cost‐effective alternative to transition metal catalysis. The reaction proceeds smoothly in MeOH/H2O solvent media in the presence of radical initiator affording the arylated products in good yields (60–80 %). The reaction parameters such as visible light, radical initiator, oxidant, anhydrous solvent, and inert atmosphere play a crucial role for the success of this methodology. The substituents present on the substrate show a significant effect on the conversion. This study provides a valuable contribution to the field of organic synthesis offering a new and efficient approach to the arylation of coumarin‐3‐carboxylic acid esters with a broad substrate scope and high functional group tolerance. It is a versatile method and provides a direct access to biologically relevant 4‐arylcoumarin‐3‐carboxylates. [ABSTRACT FROM AUTHOR]

Oryzamutaic acids, possessing a nitrogen-containing heterocyclic skeleton, have been isolated and identified from a rice mutant. Although oryzamutaic acids are expected to be functional ingredients, their functionality is difficult to evaluate, because of their wide variety and presence in trace amounts. Furthermore, how oryzamutaic acid is synthesized in vivo is unclear. Therefore, we developed a simple enzymatic synthesis method for these compounds in vitro. We focused on L-lysine ε-dehydrogenase (LysDH) from Agrobacterium tumefaciens , which synthesizes α-aminoadipate-δ-semialdehyde—a precursor of oryzamutaic acids. LysDH was cloned and expressed in Escherichia coli. Analysis of activity revealed that LysDH catalyzed the synthesis of oryzamutaic acid H at neutral pH in vitro. We synthesized 1.6 mg oryzamutaic acid H from 100 mg L-lysine. The synthesized oryzamutaic acid H exhibited UVA absorption, stability of temperature, and stability at a wide pH range. To our knowledge, this study is the first to report the enzymatic synthesis of oryzamutaic acid H in vitro and provides a basis for understanding the mechanisms of oryzamutaic acid synthesis in vivo. • L-lysine ε-dehydrogenase from A. tumefaciens was expressed and characterized. • Oryzamutaic acid H was synthesized in vitro by LysDH. • The synthesized oryzamutaic acid H exhibited UVA absorption. [ABSTRACT FROM AUTHOR]

Despite the significant role of pyruvic acid in biotransformations, the utilization of pyruvates in the field of catalytic asymmetric synthesis has been unexpectedly limited. This statement also applies to enamine catalysis, in which pyruvates seem to be challenging substrates. Recently, the first illustration of the asymmetric addition of pyruvic acid to β‐nitrostyrenes, catalyzed by a NahE enzyme using the enamine mechanism, has appeared in the literature. Now, we demonstrate pyrrolidine‐based catalyst can mimick enamine mechanism used by this enzyme to activate pyruvates in the asymmetric addition to structurally diverse nitroalkenes to produce highly enantioenriched Michael adducts without the limitations in substrate structures associated with biocatalysts. In addition to confirming that optically pure pyrrolidines can serve as ultimately small organic catalysts in pyruvate activation, we present an exceedingly simple and versatile method for the synthesis of optically pure γ‐nitro acids, which are precursors for well‐known active pharmaceutical ingredients namely GABA derivatives [ABSTRACT FROM AUTHOR]

BACKGROUND: Acanthosis nigricans is a common hyperpigmentation disorder with a profound aesthetic impact. The primary concern of most patients is the cosmetic improvement, that is way there is a continuous search for the most effective cosmetic therapeutic option. METHODS: 40 acanthosis nigricans patients were included, lesions are split into equal halves; right side treated with TCA 15% peel and left side was treated with microneedling followed by TCA 15% peel, both sides were treated monthly for three months. Response to treatment was assessed by acanthosis nigricans grade improvement along with the percentage of improvement in texture and pigmentation individually. RESULTS: There was statistically signiffcant improvement in acanthosis nigricans grade after treatment in both sides. The combination side showed more improvement in terms of texture and pigmentation. CONCLUSION: Both TCA 15% alone or combined with microneedling were effective in improving acanthosis nigricans with superior results in combination modality. [ABSTRACT FROM AUTHOR]

Multi-stage acid fracturing can boost productivity in low-permeability limestone reservoirs, with success hinging on differential etching and the strength of undissolved regions to keep fractures open. Traditional rock strength test methods have strong randomness and error. This study explores the influence of four acid systems (hydrochloric acid, single-phase retarded acid, gelled acid, and emulsified acid) on fracture surface strength based on a new continuous strength test method. The rock strength weakening variation under different acid types and injection conditions was quantified, and the mechanism of single-phase retarded acid slowing down rock strength reduction was revealed. The results indicated that the fracture surfaces were reduced to a lesser extent than in traditional rock mechanical failure studies. Hydrochloric acid caused up to 28% of rock strength depletion, followed by 23% for gelled acid, 18% for emulsified acid, and 11.8% for single-phase retarded acid. Adjusting the acid injection parameters revealed that longitudinal leak-off at the fracture surface changes the rock's strength failure tendency. The microscopic results confirmed that the appropriate acid-rock reaction rate and viscosity are beneficial in reducing strength by forming the dominant wormhole that "siphons" the subsequent acid more profoundly into the formation, thereby reducing the reaction of the acid with the fracture surface. This study can help to understand better the mechanism by which acid reduces the strength of fracture surfaces and can provide guidance for selecting appropriate acid fluids for acid fracturing in low-permeability limestone reservoirs. [ABSTRACT FROM AUTHOR]

Antimicrobial photodynamic inactivation (aPDI) is a method that specifically kills target cells by combining a photosensitizer and irradiation with light at the appropriate wavelength. The natural amino acid, 5-aminolevulinic acid (5-ALA), is the precursor of endogenous porphyrins in the heme biosynthesis pathway. This review summarizes the recent progress in understanding the biosynthetic pathways and regulatory mechanisms of 5-ALA synthesis in biological hosts. The effectiveness of 5-ALA-aPDI in destroying various groups of pathogens (viruses, fungi, yeasts, parasites) was presented, but greater attention was focused on the antibacterial activity of this technique. Finally, the clinical applications of 5-ALA in therapies using 5-ALA and visible light (treatment of ulcers and disinfection of dental canals) were described. [ABSTRACT FROM AUTHOR]

The human Mediator complex subunit MED25 binds transactivation domains (TADs) present in various cellular and viral proteins using two binding interfaces, named H1 and H2, which are found on opposite sides of its ACID domain. Here, we use and compare deep learning methods to characterize human MED25–TAD interfaces and assess the predicted models to published experimental data. For the H1 interface, AlphaFold produces predictions with high‐reliability scores that agree well with experimental data, while the H2 interface predictions appear inconsistent, preventing reliable binding modes. Despite these limitations, we experimentally assess the validity of MED25 interface predictions with the viral transcriptional activators Lana‐1 and IE62. AlphaFold predictions also suggest the existence of a unique hydrophobic pocket for the Arabidopsis MED25 ACID domain. [ABSTRACT FROM AUTHOR]

The failure of the circulation pump in a sulfur recovery unit occurred after 11 years of operation, during which it was exposed to the weak acid process stream. The A494-CW6M impeller of the pump was found to be completely shattered, leading to the failure. Despite the long operating period, the failure appearance was unusual, and further investigation was needed to understand the cause of the failure. To this end, the detailed metallurgical characterization was performed using the electron microscope and commercially available thermodynamic software. The experimental results showed that the leached regions exhibited more than 50% of the impeller thickness, and those were matched with topological closed phases (M6C, Sigma, P phase), which commonly had low Cr (10 ~ 11 wt.%) and high Mo (56 ~ 58 wt.%) composition. The failure was attributed to the weak corrosion resistance of the low Cr phases when exposed to oxidizing weak acid streams. In addition, thermodynamic phase calculation showed that a large amount of TCPs precipitation was likely due to the malpractice of the heat treatment process. The detailed failure analysis result will be discussed in the present paper. [ABSTRACT FROM AUTHOR]

The evolution of the synthesis of a benzothiophene‐2‐yl‐boronic acid ‐ a key building block for the anti‐cancer agent Rogaratinib ‐ is reported from multi‐gram scale to industrialization. The pitfalls and learnings during process development are outlined, describing the optimization of the initial research synthesis route, investigation of an alternative approach based on a palladium‐catalyzed Newman‐Kwart rearrangement and finally changing the synthetic strategy from thiophene‐construction to benzene‐ring formation. Although the initial route was utilized to deliver material on kg‐scale, the requirements for market‐supply triggered the decision to pursue a new synthetic route. Catalyst costs, high purity‐requirements, and not the least technical practicality caused the change to a synthesis with indeed higher step‐count. However, this could be mitigated by repeated application of a telescoping approach. The free boronic acid was finally selected and manufactured as a stable isolated intermediate after challenges like proto‐deboronation and trimerization to boroxine upon drying could be solved by an optimized crystallization procedure. [ABSTRACT FROM AUTHOR]

This study investigated the incorporation of nervonic acid into the chemical structure of phosphatidylcholine via a lipase-catalyzed acidolysis reaction to obtain a functional phospholipid. Lipase immobilization was conducted, and Amberlite XAD7-HP was selected as a carrier to immobilize phospholipase A1 (PLA1) for subsequent experiments. The main acidolysis reaction parameters, including enzyme load, substrate ratio, temperature, and water content, were studied against the reaction time. The optimum reaction conditions obtained were enzyme load, 20%; reaction temperature, 55 °C; water content, 1%; and reaction time, 9 h. The maximum incorporation of nervonic acid into phosphatidylcholine was 48 mol%, with PC recovery at 61.6 mol%. The positional distribution of structured phosphatidylcholine shows that nervonic acid was found in the sn-1 position due to enzyme specificity and in the sn-2 position, possibly due to acyl migration. [ABSTRACT FROM AUTHOR]

Herein, a novel grafted chitosan nanogel with 3,4-methylenedioxycinnamic acid was carried out aiming at the encapsulation of the monoterpenes carvacrol and thymol, with the purpose of developing a material that can be used in the control of the fungus Microsporum canis. The nanogel encapsulation efficiency showed an encapsulation capacity of 12.9% carvacrol and 13.3% thymol. When in an aqueous medium the nanogel with the respective encapsulated monoterpene oils was able to form stable nanoparticles. The nanogels chitosan-g-3,4-methylenedioxycinnamic acid-carvacrol and chitosan-g-3,4-methylenedioxycinnamic acid-thymol showed antifungal potential against the fungus Microsporum canis, being able to inhibit mycelial growth by 100.00 and 93.13%, respectively. [ABSTRACT FROM AUTHOR]

Inverted fatty acid β-oxidation represents a versatile biochemical platform for biosynthesis by the engineered microbial strains of numerous value-added chemicals from convenient and abundant renewable carbon sources, including biomass-derived sugars. Although, in recent years, significant progress has been made in the production through this pathway of n-alcohols, 1,3-diols, and carboxylic acids and its 2,3-unsaturated derivatives, the potential of the pathway for the biosynthesis of 3-hydroxycarboxylic acids remained almost undisclosed. In this study, we demonstrate the microaerobic production of even-chain-length C4–C8 3-hydroxycarboxylic acids from glucose through the inverted fatty acid β-oxidation by engineered E. coli strains. The notable accumulation of target compounds was achieved upon the strong constitutive expression of the genes atoB, fadA, fadB, fadE/fabI, and tesB, which code for the key enzymes catalysing reactions of aerobic fatty acid β-oxidation and thioesterase II, in strains devoid of mixed-acid fermentation pathways and lacking nonspecific thioesterase YciA. The best performing recombinants were able to synthesise up to 14.5 mM of 3-hydroxycarboxylic acids from glucose with a total yield of 0.34 mol/mol and a C4/C6/C8 ratio averaging approximately 63/28/9. The results provide a framework for the development of highly efficient strains and processes for the bio-based production of valuable 3-hydroxycarboxylates from renewable raw materials. [ABSTRACT FROM AUTHOR]

This article discusses the synthesis of aryl-C-glycosides, specifically focusing on 2-deoxy-aryl-C-glycosides, which have potential biological activities. The authors present a new method using palladium catalysts for the synthesis of these compounds through 1,4-conjugate addition reactions. They conducted an optimization study to determine the best reaction conditions and found that palladium acetate and acetic acid were effective additives. The article also provides detailed information on the preparation and characterization of several compounds, including their chemical structures and physical properties. This information can be valuable for researchers studying these compounds or related chemical reactions. [Extracted from the article]

A spectroscopic method of chemical analysis is used to determine the mole fraction solubilities of 3,5-dimethoxybenzoic acid dissolved in propanenitrile, in eleven additional alkanol solvents (1-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-methyl-1-propanol, 2-pentanol, 2-methyl-1-butanol, 3-methyl-1-butanol, 4-methyl-2-pentanol, 2-ethyl-1-hexanol, cyclopentanol) and in three additional alkyl alkanoate solvents (isopropyl acetate, tert-butyl acetate, methyl butyrate) at 298.15 K. Results from our experimental measurements, combined with published partition coefficient and solubility data, are used to calculate the Abraham model solute descriptors of the monomeric form of 3,5-dimethoxybenzoic acid. In total 62 experimental data points were used in the computation. The calculated solute descriptors describe the experimental solubility and partition coefficient data to within an overall standard deviation of 0.064 log units. [ABSTRACT FROM AUTHOR]

Carbon ion radiotherapy (CIRT) has received attention for the treatment of locally recurrent rectal cancer. When the surrounding primary organs are close to the irradiation site, a spacer is required to ensure safe irradiation. This work describes a novel technique using a bioabsorbable polyglycolic acid spacer placed laparoscopically and presents a technical report with five case studies. The short‐term surgical outcomes were as follows: mean operating time 235 min with blood loss of 38 mL. CIRT was planned, and the patients underwent irradiation within 2 months of surgery. No pelvic infections occurred, and all procedures were performed safely. Herein, were present a technical report with reference to a video of the surgical procedure. [ABSTRACT FROM AUTHOR]