Silicon-Based Anode with High Capacity and Performance Produced by Magnesiothermic Coreduction of Silicon Dioxide and Hexachlorobenzene

Ma, Kai The Korean Electrochemical Society 2021 Journal of electrochemical science and technology Vol.12 No.3

Silicon (Si) has been considered as a promising anode material because of its abundant reserves in nature, low lithium ion (Li⁺) intercalation/de-intercalation potential (below 0.5 V vs. Li/Li⁺) and high theoretical capacity of 4200 mA h/g. In this paper, we prepared a silicon-based (Si-based) anode material containing a small amount of silicon carbide by using magnesiothermic coreduction of silica and hexachlorobenzene. Because of good conductivity of silicon carbide, the cycle performance of the silicon-based anode materials containing few silicon carbide is greatly improved compared with pure silicon. The raw materials were formulated according to a silicon-carbon molar ratio of 10:0, 10:1, 10:2 and 10:3, and the obtained products were purified and tested for their electrochemical properties. After 1000 cycles, the specific capacities of the materials with silicon-carbon molar ratios of 10:0, 10:1, 10:2 and 10:3 were still up to 412.3 mA h/g, 970.3 mA h/g, 875.0 mA h/g and 788.6 mA h/g, respectively. Although most of the added carbon reacted with silicon to form silicon carbide, because of the good conductivity of silicon carbide, the cycle performance of silicon-based anode materials was significantly better than that of pure silicon.

EFFECT OF THE STRUCTURE OF ISOMERS OF MERCAPTOVALERIC ACID ON OPTICAL PROPERTIES OF CdTe QUANTUM DOTS

KAI-GUO MA,JIN-YI BAI,TAN FANG,Haiqing Guo 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.5

4-Mercaptovaleric acid (4MVA) and 3-mercaptovaleric acid (3MVA), two branched isomers of 5-mercaptovaleric acid (MVA), were designed and synthesized. They were used as capping agents in the aqueous synthesis of CdTe quantum dots (QDs) by a modified hydrothermal method with sodium tellurite as Te source. Compared with MVA-CdTe, either 4MVA-QDs or 3MVA-QDs exhibited higher fluorescent quantum yield (QY) and sharper absorption peak, which confirmed the superiority of using branched mercapto acids in the aqueous synthesis of QDs for improved optical properties. The fluorescence of QDs capped with 4MVA was higher than that of QDs capped with 4-mercaptobutyric acid (MBA) but lower than that of QDs capped with 3-mercaptobutyric acid (3MBA), which further confirmed the advantage of designing methyl side group rather than methylene group in the main chain for desired optical properties. However, the lower fluorescence, less sharp absorption peak and faster growth rate of 3MVA-QDs than that of 3MBA-QDs indicated adverse effect of side group on the aqueous synthesis of QDs if the size of side group is very bulky. Our results are helpful for selecting and designing appropriate capping agents for QDs with excellent properties.

Manipulation of microdroplets at a T-junction: Coalescence and scaling law

Rui Ma,Qindan Zhang,Taotao Fu,Chunying Zhu,Kai Wang,Youguang Ma,Guangsheng Luo 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.65 No.-

The manipulation of a droplet at a microfluidic T-junction is achieved via adding reagents into the droplet with the same solution. Three types for droplet coalescence at the T-junction were observed: tail coalescence, slipping coalescence and unsteady coalescence behaviors with a new droplet formation. The final droplet size decreased (increased) with increasing the capillary number when the flow rate of the dispersed (continuous) phase was fixed. The final droplet size increased with increasing the capillary number of the added phase. The correlations for predicting the coalesced droplet size for tail and slipping coalescence were proposed.

Dynamic Compliance and its Compensation Control of HIVC Force Control System

Kai-xian Ba,Bin Yu,Wen-feng Li,Dong-kun Wang,Ya-liang Liu,Guo-liang Ma,Xiang-dong Kong 대한전기학회 2018 Journal of Electrical Engineering & Technology Vol.13 No.2

In this paper, the dynamic compliance and its compensation control of the force control system on the highly integrated valve-controlled cylinder (HIVC), the joint driver of the hydraulic drive legged robot, is researched. During the robot motion process, the outer loop dynamic compliance control is applied on the base of hydraulic control inner loop and most inner loop control are the force or torque closed loop control. While the dynamic compliance control effectiveness of outer loop can be affected by the inner loop self-dynamic-compliance. Based on this problem, the dynamic compliance series composition theory of HIVC force control system as well as the analysis of its self-dynamiccompliance is proposed. And then the paper comes up with the compliance-enhanced control, which is a compound compensation control method of dynamic compliance with multiple series branches. Finally, the experiment results indicate that the control method mentioned above can enhance the dynamic compliance of HIVC force control system observably. This provides the compensation control method of inner loop dynamic compliance for the outer loop compliance control requiring the high accuracy and high robustness for the robot.

Prospectively Electrocardiogram-Gated High-Pitch Spiral Acquisition Mode Dual-Source CT Coronary Angiography in Patients with High Heart Rates: Comparison with Retrospective Electrocardiogram-Gated Spiral Acquisition Mode

Kai Sun,Rui-Juan Han,Li-Jun Ma,Li-Jun Wang,Li-Gang Li,Jiu-Hong Chen 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.6

Objective: To assess the image quality and effective radiation dose of prospectively electrocardiogram (ECG)-gated high-pitch spiral acquisition mode (flash mode) of dual-source CT (DSCT) coronary angiography (CTCA) in patients with high heart rates (HRs) as compared with retrospectively ECG-gated spiral acquisition mode. Materials and Methods: Two hundred and sixty-eight consecutive patients (132 female, mean age: 55 ± 11 years) with mean HR > 65 beats per minute (bpm) were prospectively included in this study. The patients were divided into two groups. Collection was performed in group A CTCA using flash mode setting at 20-30% of the R-R interval, and retrospectively ECG-gated spiral acquisition mode in group B. The image noise, contrast-to-noise ratio (CNR), image quality scores, effective radiation dose and influencing factors on image quality between the two groups were assessed. Results: There were no significant differences in image quality scores and proportions of non-diagnostic coronary artery segments between two groups (image quality scores: 1.064 ± 0.306 [group A] vs. 1.084 ± 0.327 [group B], p = 0.063; proportion of non-diagnostic coronary artery segments: segment-based analysis 1.52% (group A) vs. 1.74% (group B), p = 0.345; patient-based analysis 7.5% (group A) vs. 6.7% (group B), p = 0.812). The estimated radiation dose was 1.0 ± 0.16 mSv in group A and 7.1 ± 1.05 mSv in group B (p = 0.001). Conclusion: In conclusion, in patients with HRs > 65 bpm without cardiac arrhythmia, the prospectively high-pitch spiral-acquisition mode with image-acquired timing set at 20-30% of the R-R interval provides a similar image quality and low rate of non-diagnostic coronary segments to the retrospectively ECG-gated low-pitch spiral acquisition mode, with significant reduction of radiation exposure. Objective: To assess the image quality and effective radiation dose of prospectively electrocardiogram (ECG)-gated high-pitch spiral acquisition mode (flash mode) of dual-source CT (DSCT) coronary angiography (CTCA) in patients with high heart rates (HRs) as compared with retrospectively ECG-gated spiral acquisition mode. Materials and Methods: Two hundred and sixty-eight consecutive patients (132 female, mean age: 55 ± 11 years) with mean HR > 65 beats per minute (bpm) were prospectively included in this study. The patients were divided into two groups. Collection was performed in group A CTCA using flash mode setting at 20-30% of the R-R interval, and retrospectively ECG-gated spiral acquisition mode in group B. The image noise, contrast-to-noise ratio (CNR), image quality scores, effective radiation dose and influencing factors on image quality between the two groups were assessed. Results: There were no significant differences in image quality scores and proportions of non-diagnostic coronary artery segments between two groups (image quality scores: 1.064 ± 0.306 [group A] vs. 1.084 ± 0.327 [group B], p = 0.063; proportion of non-diagnostic coronary artery segments: segment-based analysis 1.52% (group A) vs. 1.74% (group B), p = 0.345; patient-based analysis 7.5% (group A) vs. 6.7% (group B), p = 0.812). The estimated radiation dose was 1.0 ± 0.16 mSv in group A and 7.1 ± 1.05 mSv in group B (p = 0.001). Conclusion: In conclusion, in patients with HRs > 65 bpm without cardiac arrhythmia, the prospectively high-pitch spiral-acquisition mode with image-acquired timing set at 20-30% of the R-R interval provides a similar image quality and low rate of non-diagnostic coronary segments to the retrospectively ECG-gated low-pitch spiral acquisition mode, with significant reduction of radiation exposure.

Decellularized Human Umbilical Artery Exhibits Adequate Endothelialization in Xenogenic Transplantation

Kai Hsia,Tien-Shiang Wang,Chin-Su Liu,Chih-Kuan Su,Chien-Chin Chen,Chang-Ching Yeh,Hsinyu Lee,Chao-Ling Yao,Tsung-Yu Tseng,Shih-Hwa Chiou,Hsu Ma,Chih-Hsun Lin,Jen-Her Lu 한국생물공학회 2023 Biotechnology and Bioprocess Engineering Vol.28 No.3

Decellularized human umbilical arteries (dHUA) is an off-the-shelf graft that can potentially serve as vascular scaffolds in tissue engineering of small-diameter vascular grafts. This research aimed to investigate that dHUA could exhibit adequate endothelialization for a long term in xenogenic transplantation. 13 dHUAs were implanted in rat abdominal aortas up to 90 days. Rats were divided into three groups in terms of survival period: Group 1, one to seven days (n = 6); Group 2, 14 to 30 days (n = 4) and Group 3, 90 days (n = 3). The explants were analyzed by histological, immunohistochemistry and magnetic resonance angiography (MRA) examination. Allograft implantation of 12 decellularized rat abdominal aortas` were processed the same way as the rat in order to make a comparison for survival rates (Group 1, n = 5; Group 2, n = 4; Group 3, n = 3). The results demonstrated that the survival rates of xenograft and allograft implantation were estimated to be 59.2% vs. 58.3% in Group 1, 50.7% vs. 58.3% in Group 2 and 3. Grafts harvested from Group 2 were showed CD31, endothelial nitric oxide synthase expression at intima, and α-smooth muscle actin, CD45, CD68 and CD168 expression at the tunica externa. A layer structure with obvious endothelialization and fiber regeneration/orientation could be inspected from the explants of Group 3. MRA demonstrated the patency of dHUA on day 30 and 90. In conclusion, more than 50% dHUA maintained patency in the xenogenic model till 90 days after surgery. A mature vessel-like functional structure with intact endothelial layer was observed then. This warrants further study in the reinforcement of decellularized vascular scaffolds.

The generalized Fermat type difference equations

Kai Liu,Lei Ma,Xiaoyang Zhai 대한수학회 2018 대한수학회보 Vol.55 No.6

This paper is to consider the generalized Fermat difference equations with different types which ever considered by Li \cite{li}, Ishizaki and Korhonen \cite{IK}, Zhang \cite{zhangjie} and Liu \cite{liuk4,11,1177,liu}, respectively. Some new observations and results on these equations will be given.

Efficient Expression of Glucagon-like Peptide-1 Analogue with Human Serum Albumin Fusion Protein in Pichia pastoris Using the Glyceraldehyde-3-phosphate Dehydrogenase Promoter

Kai Qian,XiaoHai Gong,Bo Guan,SuPing Wu,JingJing Zhang,Jing Qian,YanFei Cai,Yun Chen,ZuoYing Duan,Xin Ma,HuaZhong Li,Jian Jin 한국생물공학회 2015 Biotechnology and Bioprocess Engineering Vol.20 No.4

Glucagon-like peptide-1 (GLP-1) was a potential therapeutic drug for type II diabetes, mainly because of the stimulatory effect on insulin secretion under condition of high blood glucose. We used PCR to obtain a recombination gene, GGH, in which two GLP-1 (GLP-1A2G) mutants were connected in series and then fused to the N terminal of human serum albumin. The fusion gene was inserted into pGAPZaA plasmid with Saccharomyces cerevisiae α- factor secretion signal sequence, and was expressed by the glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter. The engineered strain was constructed by integrating the recombinant plasmid pGAPZαA/GGH into the genome of Pichia pastoris GS115. Genome PCR and western blot showed that the recombinant P. pastoris successfully expressed the fusion protein GGH. The yield of GGH reached 78 mg/L after 72 h fermentation in a flask, using glucose as the optimal carbon source. Fed-batch fermentation was investigated in a 5 L bioreactor, and the expression level of GGH reached 246 mg/L in 52 h. The fusion protein GGH was purified in four steps, and the final purity was 96.1%. The in vitro bioactivity of GGH was the same as that expressed in P. pastoris by the AOX1 promoter. This study described an efficient way to express GGH fusion protein in P. pastoris using GAP promoter, fermentation was easier to control without carbon source change and fermentation time was 20 h less than AOX1 promotercontrolled GGH fermentation.

Power control of CiADS core with the intensity of the proton beam

Kai Yin,Wenjing Ma,Wenjuan Cui,Zhiyong He,Xinxin Li,Shiwu Dang,Feng Yang,Yuhui Guo,Limin Duan,Meng Li,Yikai Hou 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.4

This paper reports the control method for the core power of the China initiative Accelerator DrivenSystem (CiADS) facility. In the CiADS facility, an intense external neutron source provided by a protonaccelerator coupled to a spallation target is used to drive a sub-critical reactor. Without any control rodinside the sub-critical reactor, the core power is controlled by adjusting the proton beam intensity. Inorder to continuously change the beam intensity, an adjustable aperture is considered to be used at theLow Energy Beam Transport (LEBT) line of the accelerator. The aperture size is adjusted based on theProportional Integral Derivative (PID) controllers, by comparing either the setting beam intensity or thesetting core power with the measured value. To evaluate the proposed control method, a CiADS coremodel is built based on the point reactor kinetics model with six delayed neutron groups. The simulations based on the CiADS core model have indicated that the core power can be controlled stably byadjusting the aperture size. The response time in the adjustment of the core power depends mainly onthe adjustment time of the beam intensity

Performance Analysis for Distributed-Antenna OFDM Systems with Multiple CFOs Using Zero-Forcing Detection

Kai Deng,Wanzhi Ma 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.7

This paper theoretically analyzes the performance of distributed-antenna orthogonal frequency division multiplexing (OFDM) systems with multiple carrier frequency offsets (CFO) using zero-forcing (ZF) detection. Considering both the large-scale fading and the multipath fading of the wireless channel, we derive the average power of the inter-carrier interference (ICI) due to the CFOs and thus obtain the expression for the signal to interference and noise ratio (SINR). By analyzing the underlying characteristics of the ZF detection, we address the reason for the inaccuracy of the conventional SINR expression and propose a novel modified SINR expression with better precision, and hence obtain a closed-form expression for the bit error rate (BER) performance with the presence of multiple CFOs. It is shown by the analytical and simulation results that the analytical SINR obtained by the conventional expression appears lower than actually while the analytical SINR and BER obtained by the expressions presented in this paper are more accurate and closer to the corresponding simulation results.