Publications by authors named "Yunjian Ma"

Enzymatic oxygenation of various cyclic ketones into lactones via Baeyer-Villiger monooxygenases (BVMOs) could provide a promising route for synthesizing fragrances and pharmaceutical ingredients. However, unsatisfactory catalytic activity and thermostability restricted their applications in the pharmaceutical and food industries. In this study, we successfully improved the catalytic activity and thermostability of a Baeyer-Villiger monooxygenase (BVMO) from by reshaping the binding pocket.

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The realm of photobiocatalytic alkane biofuel synthesis has burgeoned recently; however, the current dearth of well-established and scalable production methodologies in this domain remains conspicuous. In this investigation, we engineered a modified form of membrane-associated fatty acid photodecarboxylase sourced from Micractinium conductrix (McFAP). This endeavour resulted in creating an innovative assembled photoenzyme-membrane (protein load 5 mg cm ), subsequently integrated into an illuminated flow apparatus to achieve uninterrupted generation of alkane biofuels.

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Alcohol oxidases (AOxs) catalyze the aerobic oxidation of alcohols to the corresponding carbonyl products (aldehydes or ketones), producing only HO as the byproduct. The majority of known AOxs, however, have a strong preference for small, primary alcohols, limiting their broad applicability, e.g.

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A three-liquid-phase system (TLPS) was developed and used as a novel enzymatic one-pot multistep reaction (EOMR) system. In this system, lipase and phospholipase were enriched in a single liquid phase with a high recovery (ca. 98%) and then used for the simultaneous catalysis of mutually inhibiting and interfering reactions (hydrolysis of phospholipids and glyceride in crude oil).

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Triterpenoid compounds are one of the main functional components in jujube fruit. In this study, the optimal process for ultrasound-assisted extraction (UAE) of total triterpenoids from jujube fruit was determined using response surface methodology (RSM). The optimal conditions were as follows: temperature of 55.

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Cyclohexane was directly oxy-functionalised to ϵ-caprolactone through a cascade reaction sequence combining visible-light-driven photocatalysis with cyclohexanone monooxygenase (CHMO) whole-cell biocatalysis. Two available photocatalysts, Au-doped TiO (Au-TiO ) and graphitic carbonitride (g-C N ), were evaluated in the experiment and some optimisations to the cascade reaction were applied. In stepwise mode, the highest degree of conversion from cyclohexanol to ϵ-caprolactone can be up to 41 %, with use of g-C N .

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A bienzymatic cascade for selective sulfoxidation is presented. The evolved recombinant peroxygenase from Agrocybe aegeritra catalyses the enantioselective sulfoxidation of thioanisole whereas the choline oxidase from Arthrobacter nicotianae provides the H O necessary via reductive activation of ambient oxygen. The reactions are performed in choline chloride-based deep eutectic solvents serving as co-solvent and stoichiometric reductant at the same time.

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The use of natural deep eutectic solvents (NADES) as multifunctional solvents for limonene bioprocessing was reported. NADES were used for the extraction of limonene from orange peel wastes, as solvent for the chemoenzymatic epoxidation of limonene, and as sacrificial electron donor for the in situ generation of H O to promote the epoxidation reaction. The proof-of-concept for this multifunctional use was provided, and the scope and current limitations of the concept were outlined.

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Lead sulfate, lead oxides and lead metal are the main component of lead paste in spent lead acid battery. When lead sulfate was desulfurized and transformed into lead carbonate by sodium carbonate, lead metal and lead oxides remained unchanged. Lead carbonate is easily decomposed to lead oxide and carbon dioxide under high temperature.

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An in situ embedded synthesis strategy was developed for the preparation of a MoO3 /polypyrrole intercalative sampling adsorbent for the separation and analysis of trace volatile formaldehyde in aquatic products. Structural and morphological characteristics of the MoO3 /polypyrrole intercalative adsorbent were investigated by a series of characterization methods. The MoO3 /polypyrrole sampling adsorbent possessed a higher sampling capacity and selectivity for polar formaldehyde than commonly used commercial adsorbent Tenax TA.

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Toxic formaldehyde is sometimes used illegally as a food preservative, however, on-site rapid analysis of trace formaldehyde in aquatic products remains a challenge. In this work, a simple on-site rapid quantification method for trace volatile formaldehyde in aquatic products was developed by a derivative reaction-based surface enhanced Raman spectroscopy (SERS) technique coupled with a homemade portable purge-sampling device. Trace formaldehyde separated from complicated aquatic matrices via a purge-sampling procedure was reacted with a derivative reagent to produce a Raman-active analyte for consequent SERS analysis.

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A novel alumina nanowire (ANW) solid-phase microextraction (SPME) fiber coating was prepared by a simple and rapid anodization-chemical etching method for ultra-selective determination of volatile esters and alcohols from complicated food samples. Preparation conditions for ANW SPME fiber coating including corrosion solution concentration and corrosion time were optimized in detail for better surface morphology and higher surface area based on scanning electron microscope (SEM). Under the optimum conditions, homogeneous alumina nanowire structure of ANW SPME fiber coating was achieved with the average thickness of 20 μm around.

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Two novel polypyrrole (PPy) composite solid-phase microextraction (SPME) fiber coatings involving polypyrrole β-naphthalenesulfonic acid (PPy/β-NSA) and polypyrrole graphene (PPy/GR) composite SPME fiber coatings were prepared by a simple sol-gel technique for selectively sampling relatively polar biological volatile organic compounds (VOCs). Crucial preparation conditions of the PPy composite SPME fiber coatings were optimized and are discussed in detail. Physical tests suggested that the PPy composite SPME fiber coatings possessed a porous surface morphology, stable chemical and thermal properties.

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