Optimization for Scenedesmus obliquus Cultivation: the Effects of Temperature, Light Intensity and pH on Growth and Biochemical Composition

Zhang, Yonggang,Ren, Li,Chu, Huaqiang,Zhou, Xuefei,Yao, Tianming,Zhang, Yalei The Korean Society for Microbiology and Biotechnol 2019 한국미생물·생명공학회지 Vol.47 No.4

Microalgae have been explored as potential host species for biofuel production. Environmental factors affect algal growth and cellular composition. The effects of several key environmental factors, such as temperature, light, and pH of the medium on the growth and biochemical composition of Scenedesmus obliquus were investigated in this study. The highest growth rate of microalgae was observed at an optimal temperature of 25℃, 150 μmol/(m²·s) light intensity, and pH 10.0. The biochemical composition analysis revealed that the carbohydrate content decreased at lower (20℃) or higher temperature (35℃), whereas the protein and lipid contents increase at these temperatures. The fluctuation of light intensity significantly affected the contents of protein, carbohydrate, and lipid. The protein levels varied greatly when the pH of the medium was below 7.0. The carbohydrate and lipid contents significantly increased at pH above 7.0.

Fecal Microbiota Transplantation (FMT) Alleviates Experimental Colitis in Mice by Gut Microbiota Regulation

Zhang Wanying,Zou Guiling,Li Bin,Du Xuefei,Sun Zhe,Sun Yu,Jiang Xiaofeng 한국미생물·생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.8

Inflammatory bowel disease (IBD) is an increasing global burden and a predisposing factor to colorectal cancer. Although a number of treatment options are available, the side effects could be considerable. Studies on fecal microbiota transplantation (FMT) as an IBD intervention protocol require further validation as the underlying mechanisms for its attenuating effects remain unclear. This study aims to demonstrate the ameliorative role of FMT in an ulcerative colitis (UC) model induced by dextran sulfate sodium (DSS) and elucidate its relative mechanisms in a mouse model. It was shown that FMT intervention decreased disease activity index (DAI) levels and increased the body weight, colon weight and colon length of experimental animals. It also alleviated histopathological changes, reduced key cytokine expression and oxidative status in the colon. A down-regulated expression level of genes associated with NF-κB signaling pathway was also observed. The results of 16S rRNA gene sequencing showed that FMT intervention restored the gut microbiota to the pattern of the control group by increasing the relative abundance of Firmicutes and decreasing the abundances of Bacteroidetes and Proteobacteria. The relative abundances of the genera Lactobacillus, Butyricicoccus, Lachnoclostridium, Olsenella and Odoribacter were upregulated but Helicobacter, Bacteroides and Clostridium were reduced after FMT administration. Furthermore, FMT administration elevated the concentrations of SCFAs in the colon. In conclusion, FMT intervention could be suitable for UC control, but further validations via clinical trials are recommended.

Traffic control technologies without interruption for component replacement of long-span bridges using microsimulation and site-specific data

Junyong Zhou,Xuefei Shi,Liwen Zhang,Zuo Sun 국제구조공학회 2019 Structural Engineering and Mechanics, An Int'l Jou Vol.70 No.2

The replacement of damaged components is an important task for long-span bridges. Conventional strategy for component replacement is to close the bridge to traffic, so that the influence of the surrounding environment is reduced to a minimum extent. However, complete traffic interruption would bring substantial economic losses and negative social influence nowadays. This paper investigates traffic control technologies without interruption for component replacement of long-span bridges. A numerical procedure of traffic control technologies is proposed incorporating traffic microsimulation and site-specific data, which is then implemented through a case study of cable replacement of a long-span cable-stayed bridge. Results indicate traffic load effects on the bridge are lower than the design values under current low daily traffic volume, and therefore cable replacement could be conducted without traffic control. However, considering a possible medium or high level of daily traffic volume, traffic load effects of girder bending moment and cable force nearest to the replaced cable become larger than the design level. This indicates a potential risk of failure, and traffic control should be implemented. Parametric studies show that speed control does not decrease but increase the load effects, and flow control using lane closure is not effectual. However, weight control and gap control are very effective to mitigate traffic load effects, and it is recommended to employ a weight control with gross vehicle weight no more than 65 t or/and a gap control with minimum vehicle gap no less than 40 m for the cable replacement of the case bridge.

Comparison of dry- and wet-heat induced changes in physicochemical properties of whey protein in absence or presence of inulin

Feng Gao,Xuefei Zhang,Hao Wang,Xiaomeng Sun,Jiaqi Wang,Cuina Wang 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.5

Changes in whey protein (10%, w/v) induced bydry-heating (60 C for 5 days at a relative humidity of63%), wet-heating (85 C for 30 min) or the two-combinedheating in absence or presence of inulin (8%, w/v) werestudied. Mixture of whey protein and inulin showed significantlyhigher absorbance at 290 nm than whey proteinalone in all heating conditions while only dry-heatedsamples showed significantly increased absorbance value at420 nm (p\0.05). Whey protein after heating showedsignificantly lower zeta potential and inulin decreased thevalue of all heated samples further (p\0.05) except forsamples after dry-heating. Heating decreased the freesulfhydryl group content of whey protein samples whilepresence of inulin decreased further (p\0.05). Dry-heatingdecreased while wet-heating increased the surfacehydrophobicity of whey protein. Inulin had no effect on thesurface hydrophobicity of heated whey protein under dryheatingbut decreased under wet-heating.

Systematical characterization of functional and antioxidative properties of heat-induced polymerized whey proteins

Feng Gao,Xuefei Zhang,Jiaqi Wang,Xiaomeng Sun,Cuina Wang 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.6

Effects of pH (6–8), protein concentration (6–11%, w/v), heating temperature (70–95 C) and time (5–30 min) on functional and antioxidative properties of heat-induced polymerized whey protein were systematically investigated. All samples were determined for solubility at pH 4.6, emulsion capacity and stability, and antioxidative properties involving 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,20-azinobis(2-ethylbenzothiazoline- 6-sulfonate) (ABTS) scavenging abilities. Heating resulted in significant loss in solubility, emulsion capacity and stability for whey protein, p\0.05. Heating decreased DPPH but enhanced ABTS scavenging ability for whey protein significantly, p\0.05. Changes caused by pH variation were much stronger than those observed for other factors. Both protein concentration and heating time had negative effects while heating temperature had positive effect on emulsion capacity of whey protein. Data indicates that functional and antioxidative properties of whey protein could be altered by factors including pH, protein concentration, heating temperature and time.

Efficient adsorption on Cr(VI) and electrochemical application of N, P co-doped carbon spheres

Luo Tian,Xing Xianjun,Zhang Xuefei,Yue Wang,Ma Xiufen 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.12

A nitrogen and phosphorus co-doped carbon sphere was synthesized and prepared by a two-step hydrothermal activation pyrolysis method using agricultural materials, in which forestry waste walnut shells, urea, and phosphoric acid were used as carbon, nitrogen, and phosphorus sources, respectively, for the efficient treatment of heavy metals Cr(VI) in wastewater. On this basis, a supercapacitor with high capacitive performance was investigated. The adsorption capacity of the N, P co-doped carbon sphere (N2PC) was optimal for Cr(VI), and the abundant functional groups on the surface of the carbon spheres significantly promoted the adsorption and reduction of Cr(VI). The adsorption capacity of the carbon material was up to 100.55 mg/g at 318 K, and the pseudo-second-order kinetic model and the Langmuir adsorption isotherm model were used to describe the adsorption process. Before and after adsorption, the material was applied to the electrode material of the supercapacitor, and the capacitive performance of the adsorbed material was satisfactory as well as with excellent cycling stability which 93% capacity retention even after 5000 cycles.

Blast vibration of a large-span high-speed railway tunnel based on microseismic monitoring

Li, Ao,Fang, Qian,Zhang, Dingli,Luo, Jiwei,Hong, Xuefei Techno-Press 2018 Smart Structures and Systems, An International Jou Vol.21 No.5

Ground vibration is one of the most undesirable effects induced by blast operation in mountain tunnels, which could cause negative impacts on the residents living nearby and adjacent structures. The ground vibration effects can be well represented by peak particle velocity (PPV) and corner frequency ($f_c$) on the ground. In this research, the PPV and the corner frequency of the mountain surface above the large-span tunnel of the new Badaling tunnel are observed by using the microseismic monitoring technique. A total of 53 sets of monitoring results caused by the blast inside tunnel are recorded. It is found that the measured values of PPV are lower than the allowable value. The measured values of corner frequency are greater than the natural frequencies of the Great Wall, which will not produce resonant vibration of the Great Wall. The vibration effects of associated parameters on the PPV and corner frequency which include blast charge, rock mass condition, and distance from the blast point to mountain surface, are studied by regression analysis. Empirical formulas are proposed to predict the PPV and the corner frequency of the Great Wall and surface structures due to blast, which can be used to determine the suitable blast charge inside the tunnel.

Surface oxidation of PAN‑based ultrahigh modulus carbon fibers (UHMCFs) and its effect on the properties of UHMCF/EP composites

Xinyu Wang,Xin Qian,Yonggang Zhang,Xuefei Wang,Shulin Song,Cheng Zhang 한국탄소학회 2021 Carbon Letters Vol.31 No.3

In this study, nitric acid oxidation with varied treatment temperature and time was conducted on the surfaces of polyacrylonitrile- based ultrahigh modulus carbon fibers. Scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and surface tension/dynamic contact angle instruments were used to investigate changes in surface topography and chemical functionality before and after surface treatment. Results showed that the nitric acid oxidation of ultrahigh modulus carbon fibers resulted in decreases in the values of the crystallite thickness Lc and graphitization degree. Meanwhile, increased treating temperature and time made the decreases more obviously. The surfaces of ultrahigh modulus carbon fibers became much more activity and functionality after surface oxidation, e.g., the total surface energy of oxidized samples at 80 °C for 1 h increased by 27.7% compared with untreated fibers. Effects of surface nitric acid oxidation on the mechanical properties of ultrahigh modulus carbon fibers and its reinforced epoxy composites were also researched. Significant decreases happened to the tensile modulus of fibers due to decreased Lc value after the nitric acid oxidation. However, surface treatment had little effect on the tensile strength even as the treating temperature and processing time increased. The highest interfacial shear strength of ultrahigh modulus carbon fibers/epoxy composites increased by 25.7% after the nitric acid oxidation. In the final, surface oxidative mechanism of ultrahigh modulus carbon fibers in the nitric acid oxidation was studied. Different trends of the tensile strength and tensile modulus of fibers in the nitric acid oxidation resulted from the typical skin–core structure.

Minimum Bandwidth Regenerating Codes Based on Cyclic VFR Codes

( Jing Wang ),( Shuxia Wang ),( Tiantian Wang ),( Xuefei Zhang ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.7

In order to improve the reliability and repair efficiency of distributed storage systems, minimum bandwidth regenerating (MBR) codes based on cyclic variable fractional repetition (VFR) codes are constructed in this thesis, which can repair failed nodes accurately. Specifically, in order to consider the imbalance of data accessed by the users, cyclic VFR codes are constructed according to that data with different heat degrees are copied in different repetition degrees. Moreover, we divide the storage nodes into groups, and construct MBR codes based on cyclic VFR codes to improve the file download speed. Performance analysis and simulation results show that, the repair locality of a single node failure is always 2 when MBR codes based on cyclic VFR codes are adopted in distributed storage systems, which is obviously superior to the traditional MBR codes. Compared with RS codes and simple regenerating codes, the proposed MBR codes based on cyclic VFR codes have lower repair locality, repair complexity and bandwidth overhead, as well as higher repair efficiency. Moreover, relative to FR codes, the MBR codes based on cyclic VFR codes can be applicable to more storage systems.

A Fast Voxel-based Method for Outlier Removal in Laser Measurement

Hao Chen,Yu Chen,Xu Zhang,Baiyuan Li,Xiaoqiang Liu,Xuefei Shi,Jie Shen 한국정밀공학회 2019 International Journal of Precision Engineering and Vol.20 No.6

Discrete data points are noncontinuous without structural information. In this paper, we propose a new fast outlier removal method via voxel-based surface propagation. The main technical components of our approach include (a) an efficient and simple spatial partitioning scheme and (b) a specially-designed surface propagation method. Numerical analyses indicate that our method is about 10 times faster than an existing method and significantly better than other two methods in terms of denoising accuracy. This provides an efficient solution to handling noisy laser-scanning data.