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Exploring a novel natural cryoprotectant and understanding its antifreeze mechanism allows the rational design of future sustainable antifreeze analogues. In this study, various antifreeze polysaccharides were isolated from wheat bran, and the antifreeze activity was comparatively studied in relation to the molecular structure. The antifreeze mechanism was further revealed based on the interactions of polysaccharides and water molecules through dynamic simulation analysis. The antifreeze polysaccharides showed distinct ice recrystallization inhibition activity, and structural analysis suggested that the polysaccharides were arabinoxylan, featuring a xylan backbone with a majority of Ara f and minor fractions of Man p , Gal p , and Glc p involved in the side chain. The antifreeze arabinoxylan, characterized by lower molecular weight, less branching, and more flexible conformation, could weaken the hydrogen bonding of the surrounding water molecules more evidently, thus retarding the transformation of water molecules into the ordered ice structure.

Late-stage functionalization (LSF) introduces functional group or structural modification at the final stage of the synthesis of natural products, drugs, and complex compounds. It is anticipated that late-stage functionalization would improve drug discovery's effectiveness and efficiency and hasten the creation of various chemical libraries. Consequently, late-stage functionalization of natural products is a productive technique to produce natural product derivatives, which significantly impacts chemical biology and drug development. Carbon-carbon bonds make up the fundamental framework of organic molecules. Compared with the carbon-carbon bond construction, the carbon-carbon bond activation can directly enable molecular editing (deletion, insertion, or modification of atoms or groups of atoms) and provide a more efficient and accurate synthetic strategy. However, the efficient and selective activation of unstrained carbon-carbon bonds is still one of the most challenging projects in organic synthesis. This review encompasses the strategies employed in recent years for carbon-carbon bond cleavage by explicitly focusing on their applicability in late-stage functionalization. This review expands the current discourse on carbon-carbon bond cleavage in late-stage functionalization reactions by providing a comprehensive overview of the selective cleavage of various types of carbon-carbon bonds. This includes C-C(sp), C-C(sp 2 ), and C-C(sp 3 ) single bonds; carbon-carbon double bonds; and carbon-carbon triple bonds, with a focus on catalysis by transition metals or organocatalysts. Additionally, specific topics, such as ring-opening processes involving carbon-carbon bond cleavage in three-, four-, five-, and six-membered rings, are discussed, and exemplar applications of these techniques are showcased in the context of complex bioactive molecules or drug discovery. This review aims to shed light on recent advancements in the field and propose potential avenues for future research in the realm of late-stage carbon-carbon bond functionalization.

Hydrogels with porous networks have received considerable attention in smart pesticide delivery due to their inherent versatility. In this study, acaricide cyetpyrafen (CPF)-loaded borax (BO) cross-linked hydroxypropyl guar gum (HPG) (CPF@BO- co -HPG, CBG) hydrogels were prepared by cross-linking and pesticide loading simultaneously. The flowable CBG hydrogels with 3D porous network structures had better wetting and spreading ability on Citrus reticulata Blanco leaves and a hydrophobic interface. The nonflowable CBG hydrogels had pH- and temperature-responsive release properties. Meanwhile, the acaricidal efficacy of CBG against Panonychus citri (McGregor) at both 24 and 48 h was significantly higher than those of CPF-loaded BO-free HPG hydrogels. Furthermore, CBG had a nutritional function for cotton growth and environmental safety for zebrafish. This research developed a BO cross-linked HPG hydrogel as a smart pesticide delivery vehicle and crop nutrient replenishment, which can be widely applied in sustainable agriculture.

In this study, we reported the synthesis of 1-(4-bromobenzoyl)-1,3-dicyclohexylurea by the reaction of DCC ( N , N '-dicyclohexylcarbodiimide) with 4-bromobenzoic acid. Subsequently, we further synthesized a new series of 1-(4-arylbenzoyl)-1,3-dicyclohexylurea ( 5a - g ) derivatives using a Suzuki cross-coupling reaction between 1-(4-bromobenzoyl)-1,3-dicyclohexylurea ( 3 ) and various aryl/heteroaryl boronic acids ( 4 ). Thus, density functional theory (DFT) calculations have been performed to examine the electronic structure of the synthesized compounds ( 3 , 5a - g ) and to calculate their spectroscopic data. Moreover, optimized geometries and thermodynamic properties, such as frontier molecular orbitals (HOMO, LUMO), molecular electrostatic potential surfaces, and reactivity descriptors, were also calculated at the PBE0-D3BJ/def2-TZVP/SMD 1,4-dioxane level of theory to validate the structures of the synthesized compounds., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

Phenazine-1-carboxylic acid (PCA) secreted by Pseudomonas chlororaphis has been commercialized and widely employed as an antifungal pesticide. However, it displays potential hazards to nontarget microorganisms and the environment. Although the PCA degradation characteristics have received extensive attention, the biodegradation efficiency is still insufficient to address the environmental risks. In this study, an engineered Pseudomonas capable of degrading PCA was constructed by introducing heterologous PCA 1,2-dioxygenase (PcaA1A2A3A4). By integrating the PCA degradation module in the chemical mutagenesis mutant P3, 7.94 g/L PCA can be degraded in 60 h, which exhibited the highest PCA degradation efficiency to date and was 35.4-fold higher than that of the PCA natural degraders. Additionally, PCA was converted to 1-methoxyphenazine through structure modification by introducing the functional enzymes PhzS Pa and PhzM La , which has good antifungal activity and environmental compatibility. This work demonstrates new possibilities for developing PCA-derived biopesticides and enables targeted control of the impact of PCA in diverse environments.

Visible light-induced photocatalytic treatment of organic waste is considered a green and efficient route. This study explored the structural and photocatalytic performance of graphene quantum dot (GQD)-incorporated TiO 2 nanocomposites to treat reactive yellow 145 (RY145) dye. For the effective removal of the RY145, efforts were made to better understand the kinetics of the process and optimization of the treatment parameters. Different GQD-doped TiO 2 nanocomposites were synthesized employing the sol-gel method. Physicochemical characteristics of the synthesized nanocomposites were studied through FTIR, XRD, UV-visible spectroscopy, SEM, and EDX. Screening studies were conducted for synthesis and reaction optimization. The results indicated that GQD-TiO 2 significantly enhanced the photocatalytic discoloration for RY145 dye. Among the synthesized nanocomposites, 15GQD-TiO 2 calcined at 300 exhibited 99.3% RY145 discoloration in 30 min under visible light irradiation. Following the pseudo-first-order reaction, the photocatalytic reaction constant K app progressively declined with an increase in the concentration of RY145. The heterogeneous reaction system conformed to the Langmuir-Hinshelwood isotherm, as indicated by the K C (1.08 mg L -1 min -1 ) and the K LH (0.18 L mg -1 ) values. O 2 •- was found to be the major contributor in GQD-TiO 2 -300 to decolorize RY154, while TiO 2 and GQDs played a vital role in generation of electrons and holes. Additionally, after recycling to the seventh cycle, only 9% decline in photocatalytic performance was observed for the synthesized nanocomposite., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)

This study examined the catalytic and bactericidal properties of polymer-doped copper oxide (CuO). For this purpose, a facile co-precipitation method was used to synthesize CuO nanostructures doped with CS-g-PAA. Various concentrations (2, 4, and 6%) of dopants were systematically incorporated into a fixed amount of CuO. The prepared samples were analyzed by different optical, structural, and morphological characterizations. Field emission scanning electron microscopy and transmission electron microscopy micrographs indicated that doping transformed CuO's agglomerated rod-like surface morphology to form nanoflakes. UV-vis spectroscopy revealed that the optical spectra of the samples exhibit a redshift after doping, leading to a decrease in band gap energy from 3.3 to 2.5 eV. The purpose of the study was to test the catalytic activity of pristine and CS-g-PAA doped CuO for the degradation of methylene blue in acidic, basic, and neutral conditions using NaBH 4 as a reducing agent in an aqueous medium. Furthermore, antibacterial activity was evaluated against Gram-positive and Gram-negative bacteria, namely, Staphylococcus aureus ( S. aureus ) and Escherichia coli ( E. coli ). Overall, enhanced bactericidal performance was observed upon doping CS-g-PAA into CuO, i.e., 4.25-6.15 and 4.40-8.15 mm against S. aureus and 1.35-4.20 and 2.25-5.25 mm against E. coli at the lowest and highest doses, respectively. The relevant catalytic and bactericidal action mechanisms of samples are also proposed in the study. Moreover, in silico molecular docking studies illustrated the role of these prepared nanomaterials as possible inhibitors of FabH and FabI enzymes of the fatty acid biosynthetic pathway., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Two-dimensional mixed convection radiative nanofluid flow along with the non-Darcy permeable medium across a wavy inclined surface are observed in the present analysis. The transformation of the plane surface from the wavy irregular surface is executed via coordinate alteration. The fluid flow has been evaluated under the outcomes of heat source, thermal radiation, and chemical reaction rate. The nonlinear system of partial differential equations is simplified into a class of dimensionless set of ordinary differential equations (ODEs) through a similarity framework, where the obtained set of ODEs are further determined by employing the computational technique parametric continuation method (PCM) via MATLAB software. The comparative assessment of the current outcomes with the earlier existing literature studies confirmed that the present findings are quite reliable, and the PCM technique is satisfactory. The effect of appropriate dimensionless flow constraints is studied versus energy, mass, and velocity profiles and listed in the form of tables and figures. It is perceived that the inclination angle and wavy surface assist to improve the flow velocity by lowering the concentration and temperature. The velocity profile enhances with the variation of the inclination angle of the wavy surface, non-Darcian term, and wavy surface term. Furthermore, the rising value of Brownian motion and thermophoresis effect diminishes the heat-transfer rate., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

In the current study, the pseudoplastic model is used to analyze the mass and energy transmission through trihybrid nanofluid flow across a stretched permeable surface. The Darcy-Forchheimer relation is employed in the momentum equation to examine the influence of porosity. Energy and mass diffusion expressions are obtained by employing the double diffusion theories, which were proposed by Cattaneo and Christov and is broadly used by several researchers. The thermal efficiency of the trihybrid nanocrystals is evaluated by integrating them with a pseudoplastic substrate. The study of titanium dioxide (TiO 2 ), cobalt ferrite (CoFe 2 O 4 ), and magnesium oxide (MgO) nanocomposite base hybrid nanofluids across a stretchable sheet is receiving considerable interest in innovation and research due to their extensive spectrum of applicability. For this reason, the phenomena are modeled in the form of a system of PDEs with the effects of a heat source, magnetic field, natural convection, and chemical reaction. Through resemblance substitutions, these are reduced to an ODE system. The resultant first-order differential equations are further processed using the computational approach PCM. For authenticity and reliability, the values are reviewed against the existing literature. The findings are displayed through figures. When compared to the simple nanofluid, the hybrid and trihybrid nanofluid have a greater tendency for fluid energy and velocity propagation rate. The velocity and heat transition rate enhance 11.73% by varying nanoparticles' values from 0.01 to 0.04, while the thermal conductivity of base fluid boosts with the addition of hybrid and trihybrid nanocomposites, up to 32% and 61%, respectively., Competing Interests: The authors declare no competing financial interest., (© 2022 The Authors. Published by American Chemical Society.)

Pseudomonas chlororaphis has been demonstrated as a valuable source of antimicrobial metabolites for plant disease biocontrol and biopesticide development. Although phenazine-1-carboxylic acid (PCA) secreted by P. chlororaphis has been commercialized as an antifungal biopesticide, it shows poor antibacterial activity. Questiomycin A, with versatile antibacterial activities, is mainly discovered in some well-known phenazine-producing strains but not in Pseudomonas . Its low titer hinders practical applications. In this work, a metabolite was first identified as Questiomycin A in P. chlororaphis -derived strain HT66Δ phzB Δ Nat . Subsequently, Questiomycin A has been elucidated to share the same biosynthesis process with PCA by gene deletion and in vitro assays. Through rational metabolic engineering, heterologous phenoxazinone synthase introduction, and medium optimization, the titer reached 589.78 mg/L in P. chlororaphis , the highest production reported to date. This work contributes to a better understanding of Questiomycin A biosynthesis and demonstrates a promising approach to developing a new antibacterial biopesticide in Pseudomonas .

An increase in temperature of up to 2 °C occurs when the amount of CO 2 reaches a range of 450 ppm. The permanent use of mineral oil is closely related to CO 2 emissions. Maintaining the sustainability of fossil fuels and eliminating and reducing CO 2 emissions is possible through carbon capture and storage (CCS) processes. One of the best ways to maintain CCS is hydrate-based gas separation. Selected type T1-5 (0.01 mol % sodium dodecyl sulphate (SDS) + 5.60 mol % tetrahydrofuran (THF), with the help of this silica gel promotion was strongly stimulated. A pressure of 36.5 bar of CO 2 is needed in H 2 O to investigate the CO 2 hydrate formation. Therefore, ethylene glycol monoethyl ether (EGME at 0.10 mol %) along with SDS (0.01 mol %) labeled as T1A-2 was used as an alternative to THF at the comparable working parameters in which CO 2 uptake of 5.45 mmol of CO 2 /g of H 2 O was obtained. Additionally, it was found that with an increase in tetra- n -butyl ammonium bromide (TBAB) supplementation of CO 2 , the hydrate and operating capacity of the process increased. When the bed height was reduced from 3 cm to 2 cm with 0.1 mol % TBAB and 0.01% SDS (labelled as T3-2) in fixed bed reactor (FBR), the outcomes demonstrated a slight expansion in gas supply to 1.54 mmol of CO 2 /g of H 2 O at working states of 283 K and 70 bar. The gas selectivity experiment by using the high-pressure volume analysis through hydrate formation was performed in which the highest CO 2 uptake for the employment of silica contacts with water in fuel gas mixture was observed in the non-IGCC conditions. Thus, two types of reactor configurations are being proposed for changing the process from batch to continuous with the employment of macroporous silica contacts with new consolidated promoters to improve the formation of CO 2 hydrate in the IGCC conditions. Later, much work should be possible on this with an assortment of promoters and specific performance parameters. It was reported in previous work that the repeatability of equilibrium moisture content and gas uptake attained for the sample prepared by the highest rates of stirring was the greatest with the CIs of ±0.34 wt % and ±0.19 mmol of CO 2 /g of H 2 O respectively. This was due to the amount of water occluded inside silica gel pores was not an issue or in other words, vigorous stirring increased the spreadability. The variation of pore size to improve the process can be considered for future work., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)

Very high spatially resolved satellite-derived ground-level concentrations of particulate matter with an aerodynamic diameter of less than 2.5 μm (PM 2.5 ) have multiple potential applications, especially in air quality modeling and epidemiological and climatological research. Satellite-derived aerosol optical depth (AOD) and columnar water vapor (CWV), meteorological parameters, and land use data were used as variables within the framework of a linear mixed effect model (LME) and a random forest (RF) model to predict daily ground-level concentrations of PM 2.5 at 1 km × 1 km grid resolution across the Indo-Gangetic Plain (IGP) in South Asia. The RF model exhibited superior performance and higher accuracy compared with the LME model, with better cross-validated explained variance ( R 2 = 0.87) and lower relative prediction error (RPE = 24.5%). The RF model revealed improved performance metrics for increasing averaging periods, from daily to weekly, monthly, seasonal, and annual means, which supported its use in estimating PM 2.5 exposure metrics across the IGP at varying temporal scales (i.e., both short and long terms). The RF-based PM 2.5 levels over the middle and lower IGP, with the annual mean exceeding 110 μg/m 2.5 levels over the middle and lower IGP, with the annual mean exceeding 110 μg/m 3 concentrations of >170 μg/m 2.5 concentrations of >170 μg/m 3 .

Pseudomonas chlororaphis have been demonstrated to be environmentally friendly biocontrol strains, and most of them can produce phenazine compounds. Phenazine-1,6-dicarboxylic acid (PDC), with a potential antibacterial activity, is generally found in Streptomyces but not in Pseudomonas . The present study aimed to explore the feasibility of PDC synthesis and the function of PhzG in Pseudomonas . A PDC producer was constructed by replacing phzG in P. chlororaphis with lphzG from Streptomyces lomondensis . Through gene deletion, common start codon changing, gene silence, and in vitro assay, our result revealed that the yield of PDC in P. chlororaphis is associated with the relative expression of phzG to phzA and phzB . In addition, it is found that PDC can be spontaneously synthesized without PhzG. This study provides an efficient way for PDC production and promotes a better understanding of PhzG function in PDC biosynthesis. Moreover, this study gives an alternative opportunity for developing new antibacterial biopesticides.

Lipoproteins are essential for bacterial survival. Bacterial lipoprotein biosynthesis is accomplished by sequential modification by three enzymes in the inner membrane, all of which are emerging antimicrobial targets. The X-ray crystal structure of prolipoprotein diacylglyceryl transferase (Lgt) and apolipoprotein N -acyl transferase (Lnt) has been reported. However, the mechanisms of the post-translational modification catalyzed by these enzymes have not been understood. Here, we studied the mechanism of the transacylation reaction catalyzed by Lgt, the first enzyme for lipoprotein modification using molecular docking, molecular dynamics, and quantum mechanics/molecular mechanics (QM/MM) calculations. Our results suggest that Arg143, Arg239, and Glu202 play a critical role in stabilizing the glycerol-1-phosphate head group and activating the glycerol C3-O ester bond of the phosphatidylglycerol (PG) substrate. With PG binding, the opening of the L6-7 loop mediated by the highly conserved Arg236 residue as a gatekeeper is observed, which facilitates the release of the modified lipoprotein product, as well as the entry of another PG substrate. Further QM/MM studies revealed that His103 acts as a catalytic base to abstract a proton from the cysteine residue of the preproliprotein, initiating the diacylglyceryl transfer from PG to preprolipoprotein. This is the first study on the mechanism of lipoprotein modification catalyzed by a post-translocational processing enzyme. The transacylation mechanism of Lgt would shed light on the development of novel antimicrobial therapies targeting the challenging enzymes involved in the post-translocational modification pathway of lipoproteins.

Novel LaFeO 3 /Ag 2 CO 3 nanocomposites are synthesized by co-precipitation method for photocatalytic degradation of Rhodamine B (RhB) and p -chlorophenol under visible light irradiation. Heterostructures between LaFeO 3 and Ag 2 CO 3 semiconductors are formed during the synthesis of these nanocomposites. Among the nanocomposites prepared with different ratios of LaFeO 3 and Ag 2 CO 3 , 1% LaFeO 3 /Ag 2 CO 3 shows the highest photocatalytic activity for the degradation of RhB. Maximum electron-hole pair decoupling efficiency is observed in 1% LaFeO 3 /Ag 2 CO 3 , which causes the greater activity of the heterostructure. Degradation efficiency of 99.5% for RhB and 59% for p -chlorophenol has been obtained under natural sunlight within 45 min. Interestingly, the stability of Ag 2 CO 3 is improved dramatically after making nanocomposite, and no decomposition of the catalyst was observed even after several photocatalytic cycles. Reactive oxygen species scavenging experiments with p -benzoquinone, isopropyl alcohol, and ammonium oxalate suggest that a major degradation process is caused by holes. Degradation of RhB into small organic moieties is detected using LC-MS technique. Further, the efficient mineralization of the degradation products occurs during the catalytic process., Competing Interests: The authors declare no competing financial interest.

Muconic acid is a platform chemical and an important intermediate in the degradation process of a series of aromatic compounds. Herein, a plasmid-free synthetic pathway in Pseudomonas chlororaphis HT66 is constructed for the enhanced biosynthesis of muconic acid by connecting endogenous ubiquinone biosynthesis pathway with protocatechuate degradation pathway using chromosomal integration. Instead of being plasmid and inducer dependent, the engineered strains could steadily produce the high muconic acid using glycerol as a carbon source. The engineered strain HT66-MA6 achieved a 3376 mg/L muconic acid production with a yield of 187.56 mg/g glycerol via the following strategies: (1) block muconic acid conversion and enhance muconic acid efflux pumping with phenazine biosynthesis cluster; (2) increase the muconic acid precursors supply through overexpressing the rate-limiting step, and (3) coexpress the "3-dehydroshikimate-derived" route in parallel with the "4-hydroxybenzoic acid-derived" route to create a synthetic "metabolic funnel". Finally, on the basis of the glycerol feeding strategies, the muconic acid yield reached 0.122 mol/mol glycerol. The results suggest that the construction of synthetic pathway with a plasmid-free strategy in P. chlororaphis displays a high biotechnological perspective.

The persistence of potential tracers of dissolved organic matter (DOM) generated from farm waste-amended soil was investigated by fluorescence spectroscopy coupled with classification and regression tree (CART) and principal component analysis (PCA) during a short-term (8 days) to midterm (60 days) biodegradation study. Pig manure (PM), cow manure (CM), wheat straw (WS), and soil alone (SA) treatment inputs were used. Waste amendments were potential sources of higher DOM concentrations. PCA revealed the DOM quality differences between farm wastes and soil alone as well as a significant shift observed from the biochemical to the geochemical fluorescent fraction in SA and PM treatments. The tryptophan:Humic-Like ratio and tryptophan zone were the potential discriminators of recent and midterm pollution by farm wastes. Integral intensities of the Fulvic-Like zone and region III discriminated the PM from CM and WS during the 60 days. CART analysis showed 90 and 100% potential for farm wastes discrimination from soil during P1 and P2, respectively. The prediction successes were 72 and 57% for PM from other wastes and 60 and 100% for WS during both periods. Fluorescence spectroscopy in combination with CART analysis can be a nondestructive innovative method for monitoring susceptible farm waste contamination.