Frontiers in Microbiology
·
2023
·
IF 5.2
Liu Quanzhen,Wei Guoguang,Yang Pengfan,Wang Chengyong,Chen Kequan,Ouyang Pingkai,Zhang Alei
N-acetylneuraminic acid (Neu5Ac) possesses the ability to promote mental health and enhance immunity and is widely used in both medicine and food fields as a supplement. Enzymatic production of Neu5Ac using N-acetyl-D-glucosamine (GlcNAc) as substrate was significant. However, the high-cost GlcNAc limited its development. In this study, an in vitro multi-enzyme catalysis was built to produce Neu5Ac using affordable chitin as substrate. Firstly, exochitinase SmChiA from Serratia proteamaculans and N-acetylglucosaminosidase CmNAGase from Chitinolyticbacter meiyuanensis SYBC-H1 were screened and combined to produce GlcNAc, effectively. Then, the chitinase was cascaded with N-acetylglucosamine-2-epimerase (AGE) and N-neuraminic acid aldolase (NanA) to produce Neu5Ac; the optimal conditions of the multi-enzyme catalysis system were 37°C and pH 8.5, the ratio of AGE to NanA (1:4) and addition of pyruvate (70 mM), respectively. Finally, 9.2 g/L Neu5Ac could be obtained from 20 g/L chitin within 24 h along with two supplementations with pyruvate. This work will lay a good foundation for the production of Neu5Ac from cheap chitin resources.
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高影响因子
JOURNAL OF MOLECULAR LIQUIDS
·
2016
·
IF 2.74
Dongren Cai,Jinbei Yang,Hairong Da,Ling Li,Hongxing Wang,Ting Qiu
Densities, ρ and viscosities, η of N , N -dimethyl-N-(3-sulfopropyl)cyclohexylammo-nium tosylate ([CyN 1,1 PrSO 3 H][Tos]) with water and methanol were measured, at temperatures from 303.15 K to 328.15 K with 5 K interval and 0.1013 MPa, as a function of [CyN 1,1 PrSO 3 H][Tos] molality (or mass fraction). The isobaric thermal expansion coefficient , molecular volume, standard molar entropy, and lattice energy of the pure IL were obtained based on the density data of pure IL . The apparent molar volume , V φ , infinite dilution apparent molar expansibility, E φ ∞ and energy barrier, E were calculated from the experimental data. The Redlich-Mayer equation was used to evaluate infinite dilution apparent molar volume , V φ ∞ . In addition, viscosities can be described satisfactorily by Vogel-Fulcher-Tammann (VFT) equation. The V φ ∞ values of the IL in water are higher than those in methanol, which suggests that the ion-solvent interactions for [CyN 1,1 PrSO 3 H][Tos] + water binary system are stronger than those for [CyN 1,1 PrSO 3 H][Tos] + methanol. And the energy barrier values decrease with the drop of IL mass fraction in both systems, indicating that the viscosity changes of binary mixtures are more sensitive to the temperature at high composition of the IL.
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高影响因子
JOURNAL OF BIOACTIVE AND COMPATIBLE POLYMERS
·
2013
·
IF 2.207
Feng Xu,Ting-Ting Yan,Yan-Ling Luo
Novel amphiphilic block copolymers consisting of hydrophobic poly(D,L-lactide) segments and hydrophilic poly(N-isopropylacrylamide-co-N, N-dimethylacrylamide) blocks were designed and synthesized through a simple free radical copolymerization route based on a bifunctional initiator, followed by the ring-opening polymerization of D,L-lactide. The copolymers self-assembled into thermosensitive spherical-nanosized core–shell micelles in aqueous solution in the presence or the absence of the model drug prednisone. The chemical and physical characterizations of drug-loaded and unloaded micelles revealed a lower critical solution temperature of 40°C–47°C, and a critical micelle concentration less than 7.20 mg L−1, a transmission electron microscope mean particle size from 50 to 75 nm, and a narrow dynamic light scattering diameter below 180 nm. The prepared blank and drug-loaded micellar nanoparticles were thermodynamically stabile and employed in targeted drug delivery by responding to the higher temperature of the local microenvironment. Based on prednisone release kinetic studies, structural changes of the self-assembled micelles as well as temperature- or environment-induced diffusion controlled drug release and improved bioavailability. The copolymer micelles exhibited good biocompatibility as established by the MTT cytotoxicity assay. Therefore, an effective target therapy against lesion tissues is feasible using these polymeric micelles.
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ACS Omega
·
2020
·
IF 2.87
Panpan Zhang,Ke Zhang,Xi Chen,Shuliang Dou,Jiupeng Zhao,Yao Li
In this work, the effect of coagulation bath temperature in different solvent systems [1,4-butyrolactone (GBL)/N,N-dimethylacetamide (DMAC)] on the structure and dielectric properties of polyimide (PI) films was investigated for the first time. The solubility parameter was introduced to explain the formation process of porous PI films. The results showed that the changed tendency of the dielectric constant versus temperature is opposite for the single-solvent system and cosolvent system. For a single DMAC and GBL solvent, the dielectric constants of the films decreased with increasing temperature. In contrast, the dielectric constants increased with the increase in temperature for the GBL/DMAC cosolvent system. Moreover, the measured porosities were applied to estimate the dielectric constants of the PI films. This showed that the porosity increased with increasing temperature for a single-solvent system, while it decreased for a cosolvent system. Scanning electron microscopy images suggested that the variation trends are derived from the different influences of the temperature on the structure and morphology. Thus, this study reveals the effect of coagulation bath temperature on the structure and dielectric properties of porous PI films and provides the guidance for the design and optimization of architectures for high-performance porous films.
研究领域:
材料科学
·
高分子化学
·
电气工程
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高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2014
·Vol. 161
·期 9
·H493
·
IF 2.859
Kaina Zhang,Wenjing Lian,Shuang Liu,Hongyun Liu
The polymerization of N,N'-diethylacrylamide (DEA) into PDEA hydrogels could be initiated by glucose oxidase (GOD) in the presence of glucose, Fe2+ and oxygen. Based on this, the semi-interpenetrating polymer network (semi-IPN) films containing PDEA, hyaluronic acid (HA) and GOD were prepared on electrode surface. The electroactive probe ferrocenedicarboxylic acid (Fc(COOH)2) in solution demonstrated reversible pH-, temperature- and SO42−-sensitive cyclic voltammetric (CV) on-off behavior at the film electrodes. Taking pH-responsive property of the system as an example, at pH 4.5, the probe showed a large and well-defined CV peak pair, and the system was at the on state; while at pH 8.0, the CV peaks were greatly suppressed and the system was at the off state. The system could be further used to switch the electrochemical oxidation of glucose catalyzed by GOD in the films and mediated by Fc(COOH)2 in solution with pH, temperature and SO42− as the stimuli. Herein the enzyme GOD functioned in two ways: (1) in preparation of the films, GOD could induce radical polymerization of PDEA; (2) in the following electrochemical studies, GOD could catalyze the oxidation of glucose and helped to realize the switchable bioelectrocatalysis with amplification effect.
研究领域:
生物化学
·
材料科学
·
电化学
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高影响因子
ACS Nano
·
2022
·
IF 18.027
Yanan Wang,Minju Pu,Jiahui Yan,Jingwen Zhang,Huichao Wei,Liangmin Yu,Xuefeng Yan,Zhiyu He
Calcium overload is one of the early determinants of the core cellular events that contribute to the pathogenesis of acute kidney injury (AKI), which include oxidative stress, ATP depletion, calcium overload, and inflammatory response with self-amplifying and interactive feedback loops that ultimately lead to cellular injury and renal failure. Excluding adjuvant therapy, there are currently no approved pharmacotherapies for the treatment of AKI. Using an adipic dihydride linker, we modified the hyaluronic acid polymer chain with a potent antioxidant, bilirubin, to produce an amphiphilic conjugate. Subsequently, we developed a kidney-targeted and reactive oxygen species (ROS)-responsive drug delivery system based on the flash nanocomplexation method to deliver a well-known intracellular calcium chelator, 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid acetoxymethyl ester (BAPTA-AM, BA), with the goal of rescuing renal cell damage via rapidly scavenging of intracellularly overloaded Ca2+. In the ischemia–reperfusion (I/R) induced AKI rat model, a single dose of as-prepared formulation (BA 100 μg·kg–1) 6 h post-reperfusion significantly reduced renal function indicators by more than 60% within 12 h, significantly alleviated tissular pathological changes, ameliorated tissular oxidative damage, significantly inhibited apoptosis of renal tubular cells and the expression of renal tubular marker kidney injury molecule 1, etc., thus greatly reducing the risk of kidney failure. Mechanistically, the treatment with BA-loaded NPs significantly inhibited the activation of the ER stress cascade response (IRE1-TRAF2-JNK, ATF4-CHOP, and ATF6 axis) and regulated the downstream apoptosis-related pathway while also reducing the inflammatory response. The BA-loaded NPs hold great promise as a potential therapy for I/R injury-related diseases.
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高影响因子
JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2017
·
IF 2.323
Shiming Xu,Wei Wang,Xi Wu,Jungyong Hu,Mengnan Jiang
Vapor–liquid equilibrium data of binary working pairs play a crucial part in the research of absorption process and absorption refrigeration technology. In this paper, the VLE data of binary mixtures, R124-NMP and R124-DMF, were measured in a temperature range from 303.15 to 363.15 K, using a VLE measurement apparatus. The activity coefficient model of five-parameter nonrandom two liquid (NRTL) was selected to correlate all the VLE data acquired by measurement. The maximum relative deviation of the pressure between the measurement data and calculated data for R124-NMP and R124-DMF were 3.80% and 3.27% respectively, and the average relative deviation of the pressure were 1.25% and 1.17% respectively. The correlated results coincide well with the measurement data and show that the VLE characteristics of R124-NMP and R124-DMF mixtures have a negative deviation from Raoul’s law. Comparing three absorbents, DMF, DMAC and NMP, the activity coefficient of R124 in DMF is largest, that in DMAC is second, and that in NMP is smallest.
研究领域:
热力学
·
制冷与空调
·
化学工程
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JOURNAL OF CHEMICAL AND ENGINEERING DATA
·
2022
·
IF 3.119
Hao Li,Fengyi Zhang,Qianlong Zhang,Hongjuan Li,Zhiying Wang,Chunli Li,Jing Fang
For some strongly non-ideal solution systems, there are often errors in predicting the phase equilibrium relationship of a multi-component system using the interaction parameters obtained by the regression of the phase equilibrium data of the binary system. The interaction parameters between the components obtained by directly determining the phase equilibrium of the multivariate system will bring the calculated values closer to the experimental values. Liquid–liquid equilibrium (LLE) data were determined for the system of n-butanol + n-pentanol + n-hexanol + water at 313.15, 323.15, and 333.15K under atmospheric pressure. LLE compositions were determined by gas chromatography. LLE data were correlated by the UNIQUAC model and the non-random two-liquid (NRTL) model. Both models were appropriate for describing the LLE of this quaternary equilibrium system. They provided accurate thermodynamic parameters for the phase equilibrium of C4–6 mixed alcohols in Fischer–Tropsch synthesis water.
研究领域:
化学工程
·
热力学
·
相平衡建模
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Chinese Physics C
·
2023
·Vol. 47
·期 3
·034001
·
IF 3.6
Long He,Junhua Luo,Li Jiang
Measurement of the cross-sections of the 79Br(n, 2n)78Br, 81Br(n, p)81mSe, 81Br(n, α)78As, and 79Br(n, α)76As reactions was performed at specific neutron energies, precisely, 13.5±0.2, 14.1±0.2, 14.4±0.2, and 14.8±0.2 MeV, relative to the standard 93Nb(n, 2n)92mNb and 27Al(n, α)24Na reference reactions using offline γ-ray spectrometry and neutron activation. Monoenergetic neutrons were generated at the China Academy of Engineering Physics via a 3H(d, n)4He reaction using the K-400 Neutron Generator equipped with a solid 3H-Ti based target. The activity of the reaction produce was obtained using a high-purity germanium detector. The cross-sections of the (n, 2n), (n, p), and (n, α) reactions on the bromine isotopes were measured in the 13–15 MeV neutron energy range. The covariance analysis approach was employed for a thorough inspection of any uncertainties within the measured cross-section data. A discussion and comparison of the observed outcome were carried out with previously published data, especially with the results of the JENDL-4.0, JEFF-3.3, TENDL-2019, and ENDF/B-VIII.0 data libraries, along with the theoretical excitation function curve derived by employing the TALYS-1.95 program. Improved cross-section restrictions for the investigated processes in the 13–15 MeV neutron energy range will be obtained using the current findings, which will help to raise the caliber of associated databases. Furthermore, the parameters of relevant nuclear reaction models can be verified using this data.
研究领域:
核物理学
·
核工程
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高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Ding Tingji,Wang Ruihe,Xu Jiafang,Ma Jiayue,Wang Xiaohui,Xue Jiawen,Yang Xiaolong
During deepwater drilling operation, the wellbore temperature decreases with the increase of water depth, and increases rapidly with the increase of formation depth. Temperature sensitive polymers can change the molecular conformation with temperature, and then change its hydrophobicity , to adjust the network structure between solid particles and polymer in drilling fluid. In this paper, a novel temperature sensitive copolymer poly(N-vinylcaprolactam- co -N,N-diethyl acrylamide) (PNVDE) was synthesized. Its molecular structure, molecular weight and molecular weight distribution were characterized. The effects of salinity, pH value and copolymer concentrations on lower critical solution temperature (LCST) were studied. Based on the temperature sensitive property of the copolymer, the ability to control the low-temperature rheology of water-based drilling fluid (WBDF) was studied. The results showed that PNVDE can effectively control the rheology of deepwater WBDF in the range of 4~ 60 ℃. At the same time, the experiments of temperature and salt resistance showed that the copolymer has strong ability of temperature resistance and salt resistance, and can withstand the temperature alternation of drilling fluid. The synergistic effect of PNVDE and bentonite made the rheology of deepwater drilling fluid stable, which can be explained by “SASA Hydrogen Bond Network”.
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高影响因子
POLYMER SCIENCE SERIES B
·
2014
·Vol. 56
·期 6
·799-806
·
IF 0.633
Xu Yewei,Sun Yi,Huo Jichuan,Lei Yonglin,Zhang Lin
A new bis(benzimidazolyl) monomer containing biphenyl group, 4,4′-bis(2-benzimidazolyl) diphenyl, was successfully synthesized from 4,4′-biphenyldicarboxylic acid and 1,2-phenylenddiamine. The corresponding biphenyl-containing poly( N -arylenebenzimidazole)s were prepared using C-N coupling reaction that removed the N-H sites from the novel bis(benzimidazolyl) derivative with activated aromatic difluorides in sulfolane. The reaction was carried out at 210°C in the presence of anhydrous potassium carbonate. All resulting polymers showed essentially amorphous patterns. This was consistent with the calculated results. Differential scanning calorimetry and thermogravimetric measurements showed that the polymers had high glass transition temperatures (>253°C) and good thermal stability with high decomposition temperatures (>457°C). These novel polymers also showed easy solubility.
研究领域:
高分子化学
·
材料科学
·
有机合成
·
高性能聚合物
·
热分析
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高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2019
·
IF 4.175
Qiannan Wu,Qijing Bu,Shuo Li,Yanhong Lin,Xiaoxin Zou,Dejun Wang,Tengfeng Xie
Inevitable drawbacks on α-Fe 2 O 3 photoanodes , such as poor conductivity, short hole diffusion length , high electron-hole recombination rate, limit their photoelectrochemical (PEC) performance for water oxidation . The construction of heterojunction is an effective approach to improve the PEC performance of photoanodes. Herein, we report the design of the WO 3 /Ti–Fe 2 O 3 heterojunction photoanodes, which are synthesized by two simple hydrothermal method . The optimized WO 3 /Ti–Fe 2 O 3 photoanode shows remarkably improved photocurrent of 2.15 mA/cm 2 at 1.23 V versus reversible hydrogen electrode (RHE) without additional cocatalyst , which is higher than that of previous literatures. The improvement benefits from reduced charge transfer resistance in the bulk of Ti–Fe 2 O 3 photoanode and improved charge separation efficiency, which can been further confirmed by electrochemical impedance spectroscopy (EIS), the transient photovoltage (TPV) and the work function (WF) measurement. The present work also provide new opportunities in developing high performance photoanodes for PEC water splitting .
研究领域:
材料科学
·
物理化学
·
能源科学
·
半导体光电化学
·
纳米材料
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高影响因子
危险品化学品经营许可证（带存储）