Search

Esterase/lipase-catalyzed selective hydrolysis of d, l-menthyl esters has become one of the promising approaches for producing l-menthol, one of the most important flavoring chemicals with extensive uses.

d-pantolactone is an intermediate in the synthesis of d-pantothenic acid, which is known as vitamin B5. The commercial synthesis of d-pantolactone is carried out through the selective resolution of dl-pantolactone catalyzed by lactone hydrolase. In contrast to a kinetic resolution approach, the deracemization of dl-pantolactone is a simpler, greener, and more sustainable way to obtain d-pantolactone with high optical purity. Herein, an efficient three-enzyme cascade was developed for the deracemization of dl-pantolactone, using l-pantolactone dehydrogenase from Amycolatopsis methanolica (AmeLPLDH), conjugated polyketone reductase from Zygosaccharomyces parabailii (ZpaCPR), and glucose dehydrogenase from Bacillus subtilis (BsGDH). The AmeLPLDH was used to catalyze the dehydrogenated l-pantolactone into ketopantolactone; the ZpaCPR was used to further catalyze the ketopantolactone into d-pantolactone; and glucose dehydrogenase together with glucose fulfilled the function of coenzyme regeneration. All three enzymes were co-expressed in E. coli strain BL21(DE3), which served as the whole-cell biocatalyst. Under optimized conditions, 36 h deracemization of 1.25 M dl-pantolactone d-pantolactone led to an e.e.p value of 98.6%, corresponding to productivity of 107.7 g/(l·d).

Scientific research ability (SRA) is now the main technical index used to assess comprehensive strength of a university. At the same time, it will have an impact on college and university rankings as well as enrollment. However, at the moment, college and university evaluation standards for research capacity are not unified, and there are various evaluation criteria, making it impossible to measure with unified standards. The main reason is that the evaluation factors are not consistent. Based on the characteristics of Guangxi Normal University of Science and Technology (GNUST), this paper develops the evaluation system of GNUST and introduced an improved neural network to assess the SRA of the faculty and the staff of GNUST. The simulation results show that the 15 technical indicators used in this paper are effective.

Yong Li,1,2,* Senbo Zhu,2,* Junchao Luo,2 Yu Tong,2 Yixuan Zheng,1 Lichen Ji,2 Zeju He,2 Qiangan Jing,1 Jiaqing Huang,2 Yinjun Zhang,1 Qing Bi2 1College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, 310014, People’s Republic of China; 2Laboratory Medicine Center, Department of Laboratory Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, 310014, People’s Republic of China*These authors contributed equally to this workCorrespondence: Yinjun Zhang, College of Biotechnology and Bioengineering, Zhejiang University of Technology, Hangzhou, Zhejiang, 310014, People’s Republic of China, Tel +86-13735494556, Email zhangyj@zjut.edu.cn Qing Bi, Laboratory Medicine Center, Department of Laboratory Medicine, Zhejiang Provincial People’s Hospital, Affiliated People’s Hospital, Hangzhou Medical College, Hangzhou, Zhejiang, 310014, People’s Republic of China, Tel +86-13588302991, Email bqzjsrmyy@163.comIntroduction: Osteoarthritis (OA) is a common chronic joint disease characterized by articular cartilage degeneration. OA usually manifests as joint pain, limited mobility, and joint effusion. Currently, the primary OA treatment is non-steroidal anti-inflammatory drugs (NSAIDs). Although they can alleviate the disease’s clinical symptoms and signs, the drugs have some side effects. Selenium nanoparticles (SeNPs) may be an alternative to relieve OA symptoms.Materials and Results: We confirmed the anti-inflammatory effect of selenium nanoparticles (SeNPs) in vitro and in vivo experiments for OA disease in this study. In vitro experiments, we found that SeNPs could significantly reduce the expression of nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2), the major inflammatory factors, and had significant anti-inflammatory and anti-arthritic effects. SeNPs can inhibit reactive oxygen species (ROS) production and increased glutathione peroxidase (GPx) activity in interleukin-1beta (IL-1β)-stimulated cells. Additionally, SeNPs down-regulated matrix metalloproteinase-13 (MMP-13) and thrombospondin motifs 5 (ADAMTS-5) expressions, while up-regulated type II collagen (COL-2) and aggrecan (ACAN) expressions stimulated by IL-1β. The findings also indicated that SeNPs may exert their effects through suppressing the NF-κB p65 and p38/MAPK pathways. In vivo experiments, the prevention of OA development brought on by SeNPs was demonstrated using a DMM model.Discussion: Our results suggest that SeNPs may be a potential anti-inflammatory agent for treating OA.Keywords: osteoarthritis, NF-κB p65 signaling pathway, p38/MAPK signaling pathway, selenium nanoparticles

Pedestrian reidentification has recently emerged as a hot topic that attains considerable attention since it can be applied to many potential applications in the surveillance system. However, high-accuracy pedestrian reidentification is a stimulating research problem because of variations in viewpoints, color, light, and other reasons. This work addresses the interferences and improves pedestrian reidentification accuracy by proposing two novel algorithms, pedestrian multilabel learning, and investigating hybrid learning metrics. First, unlike the existing models, we construct the identification framework using two subnetworks, namely, part detection subnetwork and feature extraction subnetwork, to obtain pedestrian attributes and low-level feature scores, respectively. Then, a hybrid learning metric that combines pedestrian attributes and low-level feature scores is proposed. Both low-level features and pedestrian attributes are utilized, thus enhancing the identification rate. Our simulation results on both datasets, i.e., CUHK03 and VIPeR, reveal that the identification rate is improved compared to the existing pedestrian reidentification methods.

Finger citron pomace is a cheap and renewable by-product of the citrus processing industry, representing up to 60% of the fruit biomass. In this study, a pectinase-based and ultrasonic-assisted method was firstly used to extract pectic oligosaccharides (POS) from finger citron pomace. Using the orthogonal experiment design (OED), the maximum conversion rate of up to 64.5% from pomace to POS was obtained under the extraction conditions of 0.25 mg mL-1 pectinase and 50 mg mL-1 pectin at 45 °C and pH 4.5 for 2 h. The extracted POS was then fractionated and purified to homogeneous oligosaccharides (FCPOS-1) with a molecular weight of 2.15 kDa, and the analyses of monosaccharide composition, FTIR, NMR and ESI-MS indicated that FCPOS-1 consisted of GalA and a small amount of mannose, galactose and arabinose. Multiple antioxidant activity assays in vitro revealed that FCPOS-1 possessed remarkable antioxidant properties, especially scavenging activity against DPPH radicals up to 94.07%. FCPOS-1 has the potential to be an effective natural antioxidant for applications in the food and pharmaceutical industries.

Lipases are known for their high catalytic activity, unique substrate selectivity, and acyl chain length specificity. To investigate the acyl chain length specificity and catalytic properties of lipase, we developed a novel gas chromatography (GC) method by determining multiple substrates of saturated fatty acid ethyl esters with acyl chain lengths ranging from C4 to C18. The commercial immobilized lipase Novozym 435 (Candida antarctica lipase B) was selected as the model lipase. Acyl chain length specificity of Novozym 435 was determined with multiple substrates for three reactions (hydrolysis, esterification, and alcoholysis). Apparent Michaelis constant (Km) and Vmax for the reactions catalyzed by Novozym 435 were calculated, and the effect of organic solvent on lipase-catalyzed esterification and alcoholysis was further studied. The main advantages of this GC analytical method are using inexpensive reagents, simple detection operation, and a useful tool for simultaneously determining the acyl chain length specificity of lipase in catalytic hydrolysis, esterification, and alcoholysis reactions.

When a train enters a tunnel, the passengers in the train will feel tinnitus. The main reason is that the pressure in the tunnel enters the vehicle through the adjusting system of the train, which will cause discomfort to the passengers. In this paper, according to the quasi-periodicity and repeatability of mass data in the process of train running in tunnels, a control method based on the IOTs big data is proposed, and an adaptive iterative learning control algorithm based on the IOTs big data is established. The fan operation frequency of ventilation system is regulated by adaptive iterative learning control algorithm, and can adjust the new air and exhaust gas of the ventilation system in real time to restrain the pressure fluctuation in the train. Finally, the simulation results show that the adaptive iterative learning control algorithm based on the Internet of Things can significantly reduce the amplitude of pressure fluctuation in the tunnel and the change rate of the ventilator, and improve the passenger comfort program. Moreover, the real-time measured data also show that the proposed closed-loop adaptive iterative learning control algorithm based on the Internet of Things is obviously superior to active control.

In this study, a novel lipase M5 derived from Aspergillus oryzae WZ007 was prone to exhibit high hydrolytic activity and stereoselectivity towards racemic substrate (R,S)-ethyl 2-bromoisovalerate. (R)-ethyl 2-bromoisovalerate was obtained by enzymatic resolution, which is the key chiral intermediate for highly efficient enantiomerically fluvalinate. The results showed that the enzymatic reaction was carried out in 120mM racemic substrate for 3 hours, the enantiomeric excess reached 98.6%, the conversion was 51.7%, and E value above 120. Therefore, the novel lipase M5 has the ability to efficiently produce (R)-ethyl 2-bromoisovalerate, which greatly reduces the industrial production cost of the highly efficient counterpart of fluvalinate.

An intracellular esterase (BCE) from Bacillus cereus WZZ006 was purified to homogeneity with an 89.5-fold purification, specific activity of 1.79 U/mg, and 26.7% recovery. The estimated molecular weight of BCE was 96 kDa which was analyzed by SDS-PAGE and MALDI-TOF-MS. Activity staining denotes that BCE has an unexplored new carboxyl esterase characteristic. BCE enzyme activity was maximum at pH 8.5 and also at 50 °C with pNP-caproate as a substrate. This indicates that the studied BCE as a thermoalkaliphilic esterase. The kinetic properties like Km, Vmax, kcat and kcat/Km value for BCE was found to be 0.98 mM, 0.03 mM/min, 69.47 min−1 and 70.89 mM−1 min−1, respectively. Synthesis of (S)-5-chloro-1-oxo-2,3-dihydro-2-hydroxy-1H-indole-2-carboxylic acid methyl ester ((S)-CODHCM) by BCE can be shortened to 3 h compared to 36 h with whole-cell catalysis. The e.e.s achieved was 93.83%, and conversion around 52.78% with E being 39.95. These features render BCE as a promising biocatalyst for the synthesis of a key chiral intermediate for indoxacarb.

The present study aims to increase pyruvate production by engineering Yarrowia lipolytica through modifying the glycerol metabolic pathway. Results: Wild-type Yarrowia lipolytica (Po1d) was engineered to produce six different strains, namely ZS099 (by over-expressing PYK1), ZS100 (by deleting DGA2), ZS101 (by over-expressing DAK1, DAK2, and GCY1), ZS102 (by over-expressing GUT1 and GUT2), ZS103 (by over-expressing GUT1) and ZSGP (by over-expressing POS5 and deleting GPD2). Production of pyruvate from engineered and control strains was determined using high-performance liquid chromatography (HPLC). Subsequently, the fermentation conditions for producing pyruvate were optimized, including the amount of initial inoculation, the addition of calcium carbonate (CaCO(3)), thiamine and glycerol. Finally, for scaled-up purposes, a 20-L fermentor was used. It was observed that pyruvate production increased by 136% (8.55 g/L) in ZSGP strain compared to control (3.62 g/L). Furthermore, pyruvate production by ZSGP reached up to 110.4 g/L in 96 h in the scaled-up process. We conclude that ZSGP strain of Y. lipolytica can be effectively used for pyruvate production at the industrial level. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13205-022-03158-7.

Aspergillus niger has been used for homologous and heterologous expressions of many protein products. In this study, the α-L-rhamnosidase from A. niger (Rha-N1, GenBank XP_001389086.1) was homologously expressed in A. niger 3.350 by Agrobacterium tumefaciens-mediated transformation. The enzyme activity of Rha-N1 was 0.658 U/mL, which was obtained by cultivation of engineered A. niger in a 5-L bioreactor. Rha-N1 was purified by affinity chromatography and characterized. The optimum temperature and optimum pH for Rha-N1 were 60 °C and 4.5, respectively. Enzyme activity was promoted by Al

Finger citron pomace is a cheap and renewable by-product of the citrus processing industry, representing up to 60% of the fruit biomass. In this study, a pectinase-based and ultrasonic-assisted method was firstly used to extract pectic oligosaccharides (POS) from finger citron pomace. Using the orthogonal experiment design (OED), the maximum conversion rate of up to 64.5% from pomace to POS was obtained under the extraction conditions of 0.25 mg mL

To purify an esterase which can selectively hydrolyze (R,S)-ethyl indoline-2-carboxylate to produce (S)-indoline-2-carboxylic acid and characterize its enzymatic properties. An intracellular esterase from Bacillus aryabhattai B8W22 was isolated and the purified protein was identified as a carboxylesterase by MALDI-TOF mass spectrometry. The enzyme (named BaCE) was 59.03-fold purification determined to be of approximately 35 kDa. Its specific activity was 0.574 U/mL with 20% yield. The enzyme showed maximum activity at pH 8.5 and 30 °C and was stable at 20–30 °C using pNPB as the substrate. The Km, Vmax, kcat and kcat/Km of the esterase were 0.52 mM, 6.39 μM/min, 26.87 min−1 and 51.67 mM/min, respectively. The esterase demonstrated high enantioselectivity toward (S)-ethyl indoline-2-carboxylate with 96.55% e.e.p at 44.39% conversion, corresponding to an E value of 133.45. In this study, a new esterase BaCE with an apparent molecular mass of 35 kDa was purified to homogeneity for the first time. The esterase from Bacillus aryabhattai B8W22 was isolated with a purification more than 59-fold and a yield of 20% by anion exchange chromatography and hydrophobic interaction chromatography. And its biochemical characterization were described in detail with pNPB as substrate. It displayed high enantioselectivity toward (S)-ethyl indoline-2-carboxylate. We next plan to highly express esterase BaCE in Escherichia coli, and apply it to industrial production of (S)-indoline-2-carboxylic acid.

Chin-brick tea polysaccharide conjugates (TPC-C) were prepared to study their emulsion capabilities. Interfacial tension and the effects of some factors, such as storage time, metal ion concentrations (Na+, Ca2+), pH (2.0-8.0), and heat treatment (70-100 °C) on the emulsions stabilized by TPC-C were studied. The interfacial tension of TPC-C (10.88 mN/m) was lower than that of gum arabic (15.18 mN/m) at a concentration of 0.08%. As the TPC-C concentration increased from 0.1 to 3.0 wt %, the mean particle diameter (MPD) (d32) of emulsions stabilized by TPC-C decreased from 1.88 to 0.16 μm. Furthermore, at a concentration of 0.5 wt % or higher, the MPD (d32) of emulsions stabilized by TPC-C at 25 and 60 °C for 10 days was between 0.20 and 0.50 μm. In the tested pH conditions from 2.0 to 8.0, the MPD (d32) of emulsions stabilized by 2.0 wt % TPC-C was less than 0.20 μm. At Na+ concentration conditions between 0.10 and 0.50 mol/L, the MPD (d32) of emulsions was between 0.19 and 0.20 μm, and the zeta potential values varied from -34.10 to -32.60 mV. However, with an increasing Ca2+ concentration from 0.01 to 0.05 mol/L, the MPD (d32) of emulsions was between 0.20 and 21.65 μm, and the zeta potential raised sharply from -34.10 to -28.46 mV. The emulsions stabilized by TPC-C have a decent storage stability after a high-temperature heat treatment. Overall, tea polysaccharide conjugates strongly stabilized the emulsions, which support their new application as natural emulsifiers.

Typical cover techniques adopted in the conventional secure communication schemes are the additive masking and modulation by multiplication. In order to enhance security, in this paper, the new masking and decryption methods were given by iterative learning control algorithm for secure communication. In order to enhance security, the paper proposed the nonlinear masking method to apply to the traditional items and used the iterative learning control algorithm to decrypt. The algorithm reconstructed the information signal completely and analyzed the robustness and convergence of learning algorithm about the initial error and output error. The convergence conditions were given and the simulations shown in the algorithm can reconstruct the signal in secure communication.

In this paper, a novel method of image extraction is proposed. Firstly, the image information is embedded into the parameters of the chaotic system, and then the image is overlapped and embedded to complete the image hiding. This process is equivalent to a dynamic system with unknown time-varying parameters. Secondly, the D-type iterative learning control algorithm is used to extract the information hidden in the image, because iterative learning can be used to estimate the time-varying parameter system completely in the time interval. Finally, the numerical simulation shows that the algorithm can effectively extract the hidden information under various attacks.

To explore the effect of self-made protective clothing in tracheal intubation for the patients with respiratory infectious diseases.Self-made protective clothing were made by adult model plastic raincoat with sleeve lets and goggles. A prospective randomized controlled study was conducted. Patients with severe respiratory infectious diseases who needed tracheal intubation admitted to the department of intensive medicine of the Third Affiliated Hospital of Gansu University of Chinese Medicine from January 1st 2018 to March 31st 2020 were enrolled. According to the random number table method, they were divided into two groups. The control group was wearing standard protective clothing, while the test group was wearing self-made protective clothing for endotracheal intubation. The wearing time, infection rate of operators and costs of protective clothing were compared between the two groups. The patients were sprayed with trypanosome blue diluent before tracheal intubation, and the whole body of the operator was photographed with fluorescence before wearing self-made protective clothing and after doing tracheal intubation to take off the self-made protective clothing, in order to evaluate the permeability resistance of self-made protective clothing.A total of 86 patients were enrolled. There were 46 cases in the test group, included 28 cases of influenza A (H1N1) virus infection, 11 cases of influenza B virus infection and 7 cases of adenovirus infection. There were 40 cases in the control group, included 15 cases of H1N1 virus infection, 10 cases of influenza B virus infection, 10 cases of adenovirus infection and 5 cases of unknown pathogen. There was no significant difference in respiratory etiology between the two groups (χSelf-made protective clothing has short wearing time, low cost and equivalent isolation effect compared with standard protective clothing, which is worthy of clinical promotion.