Mesenchymal Stem Cells on a Decellularized Cartilage Matrix for Cartilage Tissue Engineering

Xi-Fu Zheng,Shi-Bi Lu,Wei-Guo Zhang,Shu-Yun Liu,Jing-Xiang Huang,Quan-Yi Guo 한국생물공학회 2011 Biotechnology and Bioprocess Engineering Vol.16 No.3

An ideal scaffold for cartilage tissue engineering should be biomimetic in not only its biochemical composition, but also in the morphological structure of the scaffold. In this study, we fabricated a scaffold with an oriented structure using a nanofibrous articular cartilage extracellular matrix (ACECM), in which the ACECM was used to mimic the biochemical composition and oriented structure of articular cartilage. Histology analysis showed that the scaffold contained cartilage ECM (GAGs and collagen II). Scanning electron microscopy (SEM) indicated that the scaffolds were composed of nanofibers and possessed vertical microtubules. Chondrogenic differentiation-induced mesenchymal stem cells (MSCs) were seeded on the scaffold in vitro. SEM showed that MSCs proliferated well and aligned along the vertical microtubules,which mimicked the orientation of deep zone articular cartilage. A cell proliferation assay and live/dead cell staining demonstrated that the ACECM possessed good cell affinity, which favored cell adherence and proliferation. The MSCs that had been labeled with the fluorescent dye PKH26 and seeded on scaffolds were implanted into nude mice. The differentiated cells/ACECM implants formed cartilage-like tissue 4 weeks after implantation, and stained positive for collagen type II and toluidine blue. In addition,the in vivo fluorescent images verified that the MSCs in the implants were the labeled MSCs. These results demonstrated that the oriented ACECM scaffolds hold great promise for use in cartilage tissue engineering applications.

High-Reliability Three-Phase Dual-Buck Grid-Connected Inverter without Shoot-Through Problem

Fu, Zhenbin,Feng, Zhihua,Chen, Xi,Zheng, Xinxin The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

When compared to traditional bridge-type inverters, the dual-buck inverter has a higher reliability due to the fact that its bridge legs do not have a shoot-through problem. In this paper, the working principle of the dual-buck inverter is analyzed. A comparison of the working modes under full-cycle and half-cycle control is discussed. With half-cycle control, the inverter can realize a higher efficiency. However, this results in current zero-crossing distortion. The corresponding control strategy of the dual-buck inverter is proposed in order to realize both high efficiency and low current harmonic distortion. In addition, the system stability is analyzed. Dead-time is unnecessary due to the advantages of the topology. Thus, the current harmonic distortion can be further reduced. An inverter with the proposed control strategy has the advantages of high reliability, high efficiency and low current harmonic distortion. Finally, simulation and experimental results are given to verify the theoretical analysis.

Frequency Synchronization of Three-Phase Grid-Connected Inverters Controlled as Current Supplies

Fu, Zhenbin,Feng, Zhihua,Chen, Xi,Zheng, Xinxin,Yin, Jing The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

In a three-phase system, three-phase AC signals can be translated into two-phase DC signals through a coordinate transformation. Thus, the PI regulator can realize a zero steady-state error for the DC signals. In the control of a three-phase grid-connected inverter, the phase angle of grid is normally detected by a phase-locked loop (PLL) and takes part in a coordinate transformation. A novel control strategy for a three-phase grid-connected inverter with a frequency-locked loop (FLL) based on coordinate transformation is proposed in this paper. The inverter is controlled as a current supply. The grid angle, which takes part in the coordinate transformation, is replaced by a periodic linear changing angle from $-{\pi}$ to ${\pi}$. The changing angle has the same frequency but a different phase than the grid angle. The frequency of the changing angle tracks the grid frequency by the negative feedback of the reactive power, which forms a FLL. The control strategy applies to non-ideal grids and it is a lot simpler than the control strategies with a PLL that are applied to non-ideal grids. The structure of the FLL is established. The principle and advantages of the proposed control strategy are discussed. The theoretical analysis is confirmed by experimental results.

Frequency Synchronization of Three-Phase Grid-Connected Inverters Controlled as Current Supplies

Zhenbin Fu,Zhihua Feng,Xi Chen,Xinxin Zheng,Jing Yin 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.5

In a three-phase system, three-phase AC signals can be translated into two-phase DC signals through a coordinate transformation. Thus, the PI regulator can realize a zero steady-state error for the DC signals. In the control of a three-phase grid-connected inverter, the phase angle of grid is normally detected by a phase-locked loop (PLL) and takes part in a coordinate transformation. A novel control strategy for a three-phase grid-connected inverter with a frequency-locked loop (FLL) based on coordinate transformation is proposed in this paper. The inverter is controlled as a current supply. The grid angle, which takes part in the coordinate transformation, is replaced by a periodic linear changing angle from –π to π. The changing angle has the same frequency but a different phase than the grid angle. The frequency of the changing angle tracks the grid frequency by the negative feedback of the reactive power, which forms a FLL. The control strategy applies to non-ideal grids and it is a lot simpler than the control strategies with a PLL that are applied to non-ideal grids. The structure of the FLL is established. The principle and advantages of the proposed control strategy are discussed. The theoretical analysis is confirmed by experimental results.

Review : The Current Status and Prospect of Sericultural Byproduct Industry in China

( Zhong Zheng Gui ),( Xi Jie Guo ),( Wu Fu An ),( Dai Jian Yi ) 한국잠사학회 2003 International Journal of Industrial Entomology Vol.7 No.1

High-Reliability Three-Phase Dual-Buck Grid-Connected Inverter without Shoot-Through Problem

Zhenbin Fu,Zhihua Feng,Xi Chen,Xinxin Zheng 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.2

When compared to traditional bridge-type inverters, the dual-buck inverter has a higher reliability due to the fact that its bridge legs do not have a shoot-through problem. In this paper, the working principle of the dual-buck inverter is analyzed. A comparison of the working modes under full-cycle and half-cycle control is discussed. With half-cycle control, the inverter can realize a higher efficiency. However, this results in current zero-crossing distortion. The corresponding control strategy of the dual-buck inverter is proposed in order to realize both high efficiency and low current harmonic distortion. In addition, the system stability is analyzed. Dead-time is unnecessary due to the advantages of the topology. Thus, the current harmonic distortion can be further reduced. An inverter with the proposed control strategy has the advantages of high reliability, high efficiency and low current harmonic distortion. Finally, simulation and experimental results are given to verify the theoretical analysis.

Two kinds of behavior of fruit peel coagulant in treating low carbon source wastewaters

Ying Fu,Qinghe Yue,Shuyuan Luo,Xi Tian,Jiewen Zheng,Yanting Yang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4

Based on present serious phenomenon of insufficient carbon source in municipal sewage in China, the two kinds of effect of hybrid-fruit-peel (HFP) coagulant (coagulation and external carbon source (ECS)) on treating low carbon source wastewater was studied, mainly compared with that of sodium acetate (NaAc). The feasibility of HFP as an ECS was researched, and then its coagulation behavior, sludge properties, nitrogen removal were studied mainly with aeration mode and sequencing batch reactor (SBR), respectively. The results showed the ration of biochemical oxygen demand (BOD5) to chemical oxygen demand (COD) released from HFP was 0.67−0.76, within the scope of easily biodegradable. Within a short aeration time, HFP posed obvious coagulation behavior. HFP sludge gave larger extracellular polymer (EPS) and lower dehydrogenase activity (DHA) than NaAc. For HFP, much larger size sludge flocs appeared, the connection among the flocs became closer, and the biofacies and number of microorganisms (Opercularia Coaractata, Nematode, Vorticella, etc.) increased significantly. HFP can be used as an excellent ECS for low carbon source wastewater, and probably also have the ability of slow-releasing carbon, and can be applied to municipal sewage or other wastewaters with insufficient carbon source.

Complete mitochondrial genome of the meadow moth, Loxostege sticticalis (Lepidoptera: Pyraloidea: Crambidae), compared to other Pyraloidea moths

Hong-Fang Ma,Xi-Xi Zheng,Ming-Hui Peng,Hai-Xu Bian,Miao-Miao Chen,Yan-Qun Liu,Xing-Fu Jiang,Li Qin 한국응용곤충학회 2016 Journal of Asia-Pacific Entomology Vol.19 No.3

The mitochondrial genome (mitogenome) is an important topic for comparative and evolutionary genomics, as well as phylogenetic and population genetics. However, there are limited data regarding the mitochondrial genome available of Pyraloidea, one of the largest superfamilies in Lepidoptera. In this report, we present the complete mitogenome of the meadow moth, Loxostege sticticalis L. (Lepidoptera: Pyraloidea: Crambidae), which is a serious economic pest of both crops and weedsworldwide, thereby enhancing the available genomic information for Pyraloidea. This circular genome is 15,218 bp in length, containing 13 protein-coding genes (PCGs), two rRNA genes (rRNAs), and 22 tRNA genes (tRNAs), with a typical gene orientation and order comparable to other sequenced Pyraloidea insects. The genome composition of the major strand exhibits highly AT bias (80.82%), with a slightly positive AT skew indicating the occurrence of more As than Ts. The L. sticticalis mitogenome has a total of 130 bp of intergenic spacer sequences spread over 15 regions, ranging in size from 1 to 48 bp, of which only two are common among the 23 total Pyraloidea moths that have data collected on the mitogenome (one is located between tRNAGln and ND2 with variation change in length and a limited sequence conservation, and the other is located between tRNASer(UCN) and ND1 with a conserved 6 bp motif ‘ATACTA’). The A + Trich region of 331 bp in the genome is comprised of non-repetitive sequences but contains an ATAGN motif followed by a poly-T stretch of 17 bp, a microsatellite-like (TA)11 element preceded by an ATTTA motif, and a poly-A stretch upstream tRNAMet. These conserved structures identified in the A + T-rich region are presented in all of the sequenced Pyraloidea species. We provide a mitogenome-based phylogeny of Pyraloidea species, in which L. sticticalis shares close ancestry to Ostrinia species with substantial evidence. Our phylogenetic analyses strongly divide Crambidae into two sister lineages, one consisting of Pyraustinae and Spilomelinae, while the other contains Crambinae, Acentropinae, Scopariinae, Schoenobiinae and Glaphyriinae. The mitogenome dataset also supports the basal split between Pyraustinae and Spilomelinae.