Mutation Breeding of High Avermectin B1a-producing Strain by the Combination of High Energy Carbon Heavy Ion Irradiation and Sodium Nitrite Mutagenesis Based on High Throughput Screening

Xiaoqing Song,Yun Zhang,Xudong Zhu,Yonghong Wang,Ju Chu,Ying-ping Zhuang 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.5

Microbial mutation breeding has been widely used because it is one of the most efficient and practical breeding strategies in the fermentation industry. However, different mutagenesis methods cause various degrees of DNA damage to individual microorganisms, which lead to diverse characteristics of the mutants. In this study, the effects of four different mutagenesis methods on the mutation breeding of Streptomyces avermitilis for improving avermectin B1a production were investigated with an optimized liquid microtiter plate (MTP) culture system. First, an effective and feasible MTP system for mutant strain screening was evaluated through the optimization of the oxygen transfer rate and rapid titer determination. Then, high energy carbon heavy ion irradiation, diethyl sulfate, ultraviolet- (UV) irradiation combined with lithium chloride, and sodium nitrite were used as the mutagens for mutation breeding, respectively. Results showed that carbon heavy ion irradiation had the advantages of possessing the highest positive mutation rate and mean-production of positive mutant strains in the first generation. Sodium nitrite treatment resulted in mutant strains with better inherited stability than the other three methods. Through the combined treatment of carbon heavy ion irradiation and sodium nitrite treatment, an inheritstable mutant S. avermitilis S-233 with high avermectin B1a production was successfully obtained. The fermentation verification in a 500-liter (L) bioreactor demonstrated that the avermectin B1a produced by mutant S. avermitilis S-233 reached 6818 μg/mL, which was 23.8% higher than that of parent strains.

Pure-organic phosphine oxide luminescent materials

Song Xiaoqing,Xu Hui 한국정보디스플레이학회 2020 Journal of information display Vol.21 No.3

Phosphine-oxide-(PO)-based optoelectronic materials are attracting increasing attention owing to the unique advantages of P = O groups in modulating the molecular configuration, excited-state properties, and intermolecular interactions. P = O groups are also effective for the molecular design of high-performance luminescent materials. In this review, the research progress of pure-organic PO materials for light-emitting applications with high radiation is summarized. After a brief introduction about the luminescent mechanisms and the functions of P = O groups, this review focuses on the material design and structural-property relationships, especially the influences of P = O groups on the material performances, which are divided into three chapters according to the mechanisms of fluorescent (FL), thermally active delayed fluorescent (TADF), and charge-transfer-(CT)-based long-afterglow materials. It was shown that the electron-withdrawing effect and the insulating character of the P = O joint could improve the electrical properties and enhance inter – and intramolecular CT without remarkably changing the emission color, making it almost ‘ideal’ for blue emitters. The steric hindrance of 3D PO molecules further suppressed the quenching effects for emission efficiency improvement. These superiorities guarantee that the pure-organic PO system is one of the best fluorescent materials for diverse applications.

Boundary conditions and experimental observation of micro-explosion for water-ethanol diesel emulsified fuel droplets

( Xiaoqing Zhang ),( Tie Li ),( Jianpeng Song ),( Bin Wang ) 한국액체미립화학회 2017 한국액체미립화학회 학술강연회 논문집 Vol.2017 No.-

Droplet micro-explosion is a severe crushing phenomenon of emulsified fuel droplets during heating and evaporation. It is caused by overheating and vaporization of light components as the temperature rising to the extreme heat. Currently there are mainly two methods for solving the limit of superheat: Avedisian-Glassman kernel method and the intermolecular potential model. For the former, the nucleation rate obtained by this method is much smaller than the experimental observation, and also the surface tension for the activation energy of the molecule is not suitable for micro-size. While for the latter, it can only apply to pure liquid. Based on the Avedisian-Glassman kernel method and the intermolecular potential model, a solution for the three-component droplet micro-explosion limit of aqueous ethanol diesel emulsified fuels. Considering that the water and ethanol between the main bond energy is larger than other potential hydrogen bonding by one to two orders of magnitude, recombining the number density of molecules and the structure of molecular clusters, the hydrogen bond saturation is revised, further the activation energy of molecules can be calculated, the temperature boundary conditions for micro-explosion of water-ethanol diesel emulsified fuel droplets are obtained last. This method is not only applicable for pure liquids such as water and alcohols, but also for fuels with small liquid molecules and intermolecular potential energy with hydrogen bonds. The result of the superheat limit temperature of water under atmospheric pressure by using this method is consistent with the value of present literatures well. For more, the micro-explosion temperature boundary conditions for a kind of aqueous ethanol diesel emulsified fuel(HE30) droplet is calculated by using this method, and an observation experiment for micro-explosion is conducted to verify calculation results at last.

Damage Evolution and Integrity Assessment of Jointed Rock Mass Based on Synthetic Rock Mass Approach

Dan Huang,Xiaoqing Li,Wen-chao Song 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

The integrity coefficient Kv of bed rock is one of the important approaches to evaluate the stability of engineering rock mass, but this parameter is difficult in frequent field tests. The integrity coefficient is the quantitative index for evaluating the complete deformation of rock mass, while the damage variable represents the level of damage of the jointed rock mass, and both have similar physical meanings and represent the degree of deterioration of surrounding rock. Damage variables and damage constitutive models were constructed based on Weibull distribution damage model and Synthetic Rock Mass (SRM) model. The relationship between damage variables and numerical calculation and damage constitutive curves of different weathered granite rocks in Hongtuzhang tunnel was calculated. A new method for evaluating integrity coefficient of rock mass is proposed.

Differences in Clinical Characteristics and Surgical Outcomes of Patients with Ischemic and Hemorrhagic Pituitary Adenomas

Jingpeng Liu,Peng Huang,Xiaoqing Zhang,Yong Chen,Xin Zheng,Rufei Shen,Xuefeng Tang,Hui Yang,Song Li 대한신경외과학회 2023 Journal of Korean neurosurgical society Vol.66 No.1

Objective : Ischemia and hemorrhage of pituitary adenomas (PA) caused important clinical syndrome. However, the differences on clinical characteristics and surgical outcomes between these two kinds apoplexy were less reported. Methods : A retrospective analysis was made of patients with pituitary apoplexy between January 2013 and June 2018. Baseline and clinical characteristics before surgery were reviewed. All patients underwent transsphenoidal surgery and were followed up at least 1 year. Results : Total 67 cases (5.8%) among 1147 pituitary tumor patients were enrolled, which consisted of 28 (~2.4%) ischemic PA and 39 (~3.4%) hemorrhagic PA. There were more male patients in the ischemic group compared with hemorrhagic group (78.6% vs 53.8%, p=0.043). However, the mean age, tumor size and functional tumor ratio were significant higher in the hemorrhagic group. Headache was more common in ischemic PA (82.1%) than that of hemorrhagic PA (51.3%, p=0.011). Magnetic resonance imaging findings found that mucosal thickening and enhancement of the sphenoid sinus was observed in 15 ischemic PA patients (n=27, 55.6%), but none in patients with hemorrhagic PA (n=38, p<0.0001). It was worth noting that the rate of pre-surgical hypopituitarism in ischemic PA patients were seemed higher than that in hemorrhagic PA patients, but not significant. The two groups got a total tumor resection rate at 94.1% and 92.9%, independently. No significant difference on the operative time, blood loss in operation and complications in perioperative period was observed in two groups. After operation, cranial nerve symptoms recovered to normal at 81.8% of ischemic PA patients and 82.6% of hemorrhagic PA patients. Importantly, the incidence of postoperative hypopituitarism partially decreased in both groups, among which the rate of hypothyroidism in ischemic PA patients significantly decreased from 46.4% to 18.5% (p=0.044). Conclusion : Patients with ischemic PA presented different clinical characteristics to the hemorrhagic ones. Transsphenoidal surgery should be considered for the patients with neuro-ophthalmic deficits and might benefit for pituitary function recovery of the apoplectic adenoma patients, especially pituitary thyroid axis in ischemic PA patients.

Adaptive virtual impedance control based on second-order generalized integral for circulating current suppression

Zhang, Baifu,Han, Xiaoqing,Meng, Runquan,Ren, Chunguang,Wang, Lei,Song, Tianhao,Liu, Yizhao The Korean Institute of Power Electronics 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.1

The redundant design of multi-paralleled bidirectional power converters (BPCs) provides technical support for hybrid microgrid systems to consume more distributed generations (DGs) and DC loads. However, the multi-BPCs also provide paths for circulating current. In addition, the AC sub-grid may operate under unbalanced conditions due to the consumption of single-phase loads and power electronic devices. In addition, unbalanced three-phase voltage deteriorates the generation of circulating current. In this paper, an adaptive virtual impedance control method based on second-order generalized integration (SOGI) is proposed to suppress circulating current on the basic analysis of circulating current generation mechanism, the equivalent model establishment, and the suppression principle. The virtual impedance is dynamically adjusted in real-time based on the power oscillation caused by unbalanced voltage. Moreover, an integral term is added to the reactive power droop control to realize the tracking of voltage without static error. Finally, the effectiveness and feasibility of the proposed control algorithm are verified by experiments. The research results show that the proposed control method can optimize the damping characteristics, reduce the voltage difference between the BPCs, and improve the current sharing effect.