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Crystal forms, phase transformation mechanisms and computational studies for PDA-OPA salts have been fully identified and analyzed.

The preparation of biodegradable polymer foams with a stable high volume-expansion ratio (VER) is challenging. For example, poly (butylene adipate-co-terephthalate) (PBAT) foams have a low melt strength and high shrinkage. In this study, polylactic acid (PLA), which has a high VER and crystallinity, was added to PBAT to reduce shrinkage during the supercritical molded-bead foaming process. The epoxy chain extender ADR4368 was used both as a chain extender and a compatibilizer to mitigate the linear chain structure and incompatibility and improve the foamability of PBAT. The branched-chain structure increased the energy-storage modulus (G’) and complex viscosity (η*), which are the key factors for the growth of cells, by 1–2 orders of magnitude. Subsequently, we innovatively used the CO2 and N2 composite gas method. The foam-shrinkage performance was further inhibited; the final foam had a VER of 23.39 and a stable cell was obtained. Finally, after steam forming, the results showed that the mechanical strength of the PBAT/PLA blended composite foam was considerably improved by the addition of PLA. The compressive strength (50%), bending strength, and fracture load by bending reached 270.23 kPa, 0.36 MPa, and 23.32 N, respectively. This study provides a potential strategy for the development of PBAT-based foam packaging materials with stable cell structure, high VER, and excellent mechanical strength.

Chemoenzymatic catalysis can give full play to the advantages of versatile reactivity of chemocatalysis and excellent chemo-, regio-, and stereoselectivities of biocatalysis. These chemoenzymatic methods can not only save resource, cost, and operating time but also reduce the number of reaction steps, and avoid separating unstable intermediates, leading to the generation of more products under greener circumstances and thereby playing an indispensable role in the fields of medicine, materials and fine chemicals. Although incompatible challenges between chemocatalyst and biocatalyst remain, strategies such as biphasic system, artificial metalloenzymes, immobilization or supramolecular host, and protein engineering have been designed to overcome these issues. In this review, chemoenzymatic catalysis according to different chemocatalysis types was classifiably described, and in particular, the classic dynamic kinetic resolutions (DKR) and cofactor regeneration were summarized. Finally, the bottlenecks and development of chemoenzymatic catalysis were summarized, and future development was prospected.

Al3+ doping combined with lignin coating improves the structural stability and electrochemical performance of the modified α-MnO2, L + Al@α-MnO2.

Almost all salt forms of nucleotides exist as crystalline hydrates. In this study, the hydrates of adenosine-3′,5′-cyclic phosphate sodium (cAMPNa·nH2O, n = 2, 4, 5, including its methanol solvate of n = 3) were systematically investigated for the crystal structures, their humidity sensibility, the transformation behaviors mediated by humidity, and the relationship between crystal water behaviors and specific structures. It was found that there are some major differences in crystal morphologies, molecular conformation, bonding profiles, and crystal water distribution in the lattices of different hydrates. The difference in the desorption dynamics of crystal water for the different hydrates was mainly attributed to their steric effects in the crystal lattice despite the relation to the interaction of water molecules with sodium ions and cAMP anions. The reversible conversions between the hydrates and their corresponding low hydrates or even anhydrates occur along with desorption/uptake of crystal water mediated by humidity, yet the reversible transformation capability would be disabled once the host structures were destroyed due to excessive loss of crystal water.

1,5-Pentanediamine carbonate (PDAC) can be used as the raw material to prepare pentamethylene diisocyanate (PDI), a new biobased aliphatic isocyanate. The preparation of high-quality PDAC by crysta...

Carbon monoxide (CO) is considered as the second gasotransmitter involved in a series of physiological and pathological processes. Although a number of organic fluorescent probes have been developed for imaging CO, these probes display excitation within the ultraviolet or visible range, which restrict their applications in the complex biosystems. In the present work, a strategy is developed to construct an upconversion nanoparticles-based nanosystem for upconversion luminescent (UCL) sensing CO. This nanosystem exhibits a fast response to CO with high sensitivity and selectivity in aqueous solution by a near-infrared-excited ratiometric UCL detection method. Meanwhile, laser scanning upconversion luminescence microscope experiments demonstrate that this nanosystem can visualize the endogenous CO bio-signaling in living cells, deep tissues, zebrafish, and living mice by ratiometric UCL imaging. In particular, this nanosystem has been successfully employed in visualization of the endogenous CO bio-signaling through up-regulation of heme oxygenase-1 (HO-1) in the progression of hypoxia, acute inflammation, or ischemic injury. This work demonstrates that the outstanding performance of the nanosystem not only can provide an effective tool for further understanding the role of CO in the physiological and pathological environment, but also may have great potential ability for tracking the expression of HO-1 in living systems.

Inspired by biocatalytic retrosynthesis, a multienzyme cascade system containing alcohol dehydrogenase, flavin-dependent halogenase and flavin reductase was developed for the synthesis of several halogenated indoles starting from amino alcohol. This redox-neutral system not only omitted co-substrate for nicotinamide cofactor (NADH) regeneration but also showed relatively higher conversion and chemoselectivity compared with individual biotransformation. Artificial nicotinamide cofactor (BNAH) was employed to replace NADH and flavin reductase for simplifying this system, providing a more convenient strategy for halogenated indoles.

In order to solve the toxic and hazardous issues of the agents in the chemical reduction process of graphene oxide (GO), disodium guanosine 5′-monophosphate (GMP-2Na) was used as an ideal reducing agent for the synthesis of functionalized GO (FGO) for lipase immobilization. At the condition of low amount adsorption of GMP-2Na indicated by the N1s spectra of X-ray photoelectron spectroscopy (XPS), the C/O atomic ratio of the FGO increased from 2.09 to 3.12, indicating the reduction of GO. As the amount of GMP-2Na increased, the intensity of the characteristic peak of GO in the XRD pattern decreased, and the I D /I G peak intensity of Raman spectra increased during the functionalization process. It was found that when the concentration of GMP-2Na is 0.20 mg/mL, the degree of hydrophobicity of FGO is conducive to the formation of optimal conformation of lipase. After immobilization, the activity of the immobilized enzyme reaches twice the value of free enzyme. At the same time, the protein loading reaches to 600 mg/g. The immobilized enzyme showed enhanced durability since no obvious decrease was observed after incubation for 8 h at pH 6.0 and pH 7.0. After storage for 35 days, the activity of GO-G@ enzyme was 54.47% higher than that of free enzyme. GO reduced by GMP-2Na provides a possibility to obtain a highly efficient lipase immobilization carrier.

A novel strategy to regulate cofactor balance in vivo for whole-cell biotransformation using a synthetic flavin analogue is reported. High efficiency, easy operation, and good applicability were observed for this system. Confocal laser scanning microscopy was employed to verify that the synthetic flavin analogue can directly permeate into Escherichia coli cells without modifying the cell membrane. This work provides a promising intracellular redox regulatory approach to construct more efficient cell factories.

The bio-based platform molecule furfural was converted to the high value chemical cyclopentanone over Ru/C (0.5 wt%) and Al11.6PO23.7 catalysts in good yield (84%) with water as the medium. After screening the reaction conditions, the selectivity for cyclopentanone and cyclopentanol could be controlled by adjusting the hydrogen pressure at the temperature of 433 K. Herein, we propose a new mechanism for the synergistic catalysis of a Bronsted acid and Lewis acid for the conversion of furfural to cyclopentanone through the cyclopentenone route, which is catalyzed by Ru/C and Al11.6PO23.7. In addition, based on cyclopentanone, higher octane number cyclic alkanes (>85% selectivity), which are used as hydrocarbon fuels, were synthesized via a C–C coupling reaction followed by hydrodeoxygenation.

The application of synthetic flavinium organocatalysts for the in situ regeneration of oxidized cofactors NAD(P)+ using O2 as the terminal oxidant without any special illumination or equipment is reported. With the aid of the highly active bridged flavinium catalyst, the rate of NAD(P)H oxidation is accelerated by 3 orders of magnitude. The results show that the catalytic activity of the bridged flavinium catalyst is not dependent on light but on only oxygen. Furthermore, this catalyst is compatible with various preparative enzymatic oxidation reactions. A hydride transfer mechanism is proposed for the presented system.

The effect of acetate (HAc) and propionate (HPr) on denitrifying phosphorus removal (DPR) was evaluated in a novel two-sludge A2/O - MBBR (anaerobic/anoxic/oxic - moving bed biofilm reactor) system. Results showed that it was the carbon source transformation and utilization especially the composition of poly-β-hydroxyalkanoates (PHA) (mainly poly-β-hydroxybutyrate (PHB) and poly-bhydroxyvalerate (PHV)) decided DPR performance, where the co-exist of HAc and HPr promoted the optimal nitrogen (85.77%) and phosphorus (91.37%) removals. It facilitated the balance of PHB and PHV and removing 1 mg NO3− (PO43−) consumed 3.04–4.25 (6.84–9.82) mgPHA, where approximately 40–45% carbon source was saved. Mass balance revealed the main metabolic pathways of carbon (MAn,C (consumed amount in anaerobic stage) and MA-O,C (consumed amount in anoxic and oxic stages): 66.38–76.19%), nitrogen (MDPR,N (consumed amount in DPR): 57.01–65.75%), and phosphorus (MWS,P (discharged amount in waste sludge): 81.05–85.82%). Furthermore, the relative abundance and microbial distribution were assessed to elucidate DPR mechanism (e.g. Accumulibacter, Acinetobacter, Dechloromonas, Competibacter, and Defluviicoccus) in the A2/O reactor and nitrification performance (e.g. Nitrosomonas, Nitrosomonadaceae and Nitrospira) in the MBBR. Carbon source was demonstrated as the key point to stimulate the biodiversity and bioactivity related to DPR potential, and the operational strategy of carbon source addition was proposed based on the utilizing rules of HAc and HPr.

Compared to the traditional chemical reduction method, a green and efficient strategy was successfully applied to regulate the surface heterogeneity of graphene oxide (GO). In this work, different kinds of amino acids were used to reduce and modify GO. The reduction and adsorption disparities of amino acids contributed to the difference of structural heterogeneity in terms of density, thermal tolerance and disorder of the oxygen-containing groups of GO. The modification also resulted in discrepancies in surface properties of the GO samples, such as hydrophobicity and surface charge. The functionalized GO was employed as a carrier for the immobilization of lipase from Thermomyces lanuginosus (lipase TL). The storage stability, the temperature and pH sensitivity of the immobilized biocatalysts and the free lipase TL were studied. Lipase immobilized on functionalized GO demonstrates superior enzymatic loading and relative activity compared to GO, with a maximum increase of 70% and 47%, respectively. The relative activity of lipase immobilized on functionalized GO was 19.21 times more than that of commercial immobilized lipase TLIM. Through molecular dynamics simulations we concluded that the increase in the relative activity of lipase TL is mainly related to its adsorption orientation and slight conformational change. Thus, our research offered a green and effective strategy to regulate the heterogeneity of nanomaterials for a suitable microenvironment to enhance the performance of immobilized lipase.

Diesel or jet fuel range C10–C17 branched and cyclic alkanes were produced by reaction of 3-pentanone derived from lactic acid with bio-based aldehydes through aldol condensation followed by hydrodeoxygenation. DBU (1,8-diazabicycloundec-7-ene) was identified as an efficient catalyst for the aldol reaction of 3-pentanone with furan based aldehydes, and the selectivity of single or double aldol condensation product could be easily controlled by adjusting the reaction temperature. For the reaction with aromatic aldehydes, aluminium phosphate demonstrated a higher catalytic activity than DBU and mechanisms were proposed for the difference in the catalytic activity. The final hydrodeoxygenation step could be achieved by using a simple Pd/C + H-beta zeolite system, excellent selectivity was observed under the present system, the clean formation of hydrocarbons with a narrow distribution of alkanes occurred in most cases.

Development and utilization of renewable biomass resources has great significance to ease the energy crisis and reduce enviromental pollution. Lignocellulosic biomass is much more concerned due to its abundant reserves, lower cost and fast-growing. The research progress of catalytic valorization of cellulose, hemicellulose and lignin were summarized. The catalytic conversion technology of lignocellulose such as thermo-chemical conversion, biocatalytic transformation and chemical transformation were introduced detailedly. The future development of utilization of lignocellulose was also previewed.

The recovery and purification of biobutanol based on the adsorption method were performed in dynamic conditions. Computational and theoretical modeling is an important tool in the characterization, development, and validation of fixed-bed columns. Relevant breakthrough curves provide valuable information for designing fixed-bed adsorption processes for field applications. In the present study, a general rate model (GRM), implementing convection/diffusion approach theory and a competitive isotherm model, was used to predict the competitive sorption dynamics of acetone–butanol–ethanol (ABE) on a KA-I resin in a fixed-bed column under different operating conditions, i.e., inlet feed flow rate, initial adsorbate concentration, and bed height. The model simulation was quantified by the absolute average deviation (AAD). The calculated AAD values, ranging from 0.05 to 0.1, indicated that the GRM gives a general prediction for experimental data. The axial dispersion, external mass transfer, and pore diffusion coefficients were calculated by a series of empirical correlations. Biot number was used to identify the rate controlling step for the adsorption process of ABE on the resin. And the pore diffusion coefficient was found to be major governing factor for adsorption of ABE. The data and modeling presented are valuable for designing the continuous chromatographic separation process and simulation of ABE.

A simple three-step preparation of magnetic nanoparticle-supported (diacetoxyiodo)benzene starting from 4-iodobenzoic acid is described. The nanoparticle reagent was obtained with good loading levels and has been successfully used for efficient oxidation of a wide range of alcohols. The supported reagent demonstrated comparable activity with that of its homogeneous counterpart (diacetoxyiodo)benzene and could be simply recycled with the assistance of an external magnet.

A simple, mild and highly efficient biomimetic oxidation of alcohols to the corresponding aldehydes or ketones with hypervalent iodine(III) reagent catalyzed by β-cyclodextrin was reported. β-cyclodextrin serves as a biological catalyst to enhance the reaction remarkably. The oxidation proceeded in water to afford aldehydes or ketones in excellent yields and high selectivity without remarkable over-oxidation to carboxylic acids. Selective oxidation of primary alcohols in the presence of secondary alcohols was also achieved. A possible mechanism for the oxidation was proposed.

An efficient oxidation of alcohols with tetra-n-butylammonium peroxymonosulfate catalyzed by ionic liquid immobilized TEMPO in ionic liquid [bmim][PF 6 ] was reported. TEMPO-IL serves as a homogeneous catalyst to enhance the reaction remarkably. The oxidation proceeded to afford aldehydes or ketones in excellent yields and high selectivity without remarkable over-oxidation to carboxylic acids. It is noteworthy to mention that the catalyst and solvent could easily be recycled and reused without loss of activity. A possible mechanism for the oxidation is proposed.

An efficient, facile, and mild oxidation of alcohols to the corresponding carbonyl compounds with m-chloroperbenzoic acid (mCPBA) and N-hydroxyphthalimide (NHPI) in the presence of a catalytic amount of iodobenzene was reported. The oxidation proceeded in mixed solvent at room temperature to afford carbonyl compounds in excellent yields. A possible mechanism for the oxidation was proposed.

An efficient, facile, and mild oxidation of alcohols to the corresponding aldehydes or ketones with potassium peroxodisulfate and 2,2,6,6-tetramethylpiperidinyl-1-oxy in the presence of a catalytic amount of iodobenzene is reported. The oxidation proceeded in a mixed solvent to afford carbonyl compounds in moderate to excellent yields. A possible mechanism for the oxidation is proposed.

Highly soluble dimedone-derived o-alkoxyphenyliodonium ylides have been prepared and characterized by single crystal X-ray diffraction. These new iodonium ylides are useful reagents for the preparation of oxazole derivatives by reaction with carbodiimides.

Isoxazolines can be efficiently synthesized in good yields via a hypoiodite mediated catalytic oxidative cyclization of aldoximes and alkenes. This reaction involves active iodine species generated in situ from catalytic amounts of KI and Oxone.