Optimized Design Method for Profile Extrusion Die Based on NURBS Modeling

Guangdong Zhang,Xiang Huang,Shuanggao Li,Tong Deng 한국섬유공학회 2019 Fibers and polymers Vol.20 No.8

For optimization design of polymer extrusion dies, dimensional accuracy is critical to product quality of theextrudate. The extrusion dies used to be a regular geometrical profile, which is mostly composed by a straight line. Traditional optimization methods for extrusion die design used to have poor controllability when dealing with a curvedprofile. In this paper, the response surface optimization method is used to find out an optimal solution of the design of theextrusion die. Firstly, the Latin Hypercube Sampling method is used to generate the experiment samples for the design ofexperiments. Secondly, ANSYS Polyflow software is adopted to execute the computational fluid dynamics analysis. Thirdly,the Kriging method is used to generate the response surface. Finally, nonlinear programming by using Quadratic-Lagrangianalgorithm is applied to find out the optimal solution. It is worth noting that Non-uniform Rational B-Splines (NURBS)modeling is used to optimize flow channel of an extrusion die in order to obtain a qualified extrudate. Thus, design variablesfor the optimization involve control points of the NURBS curve of the inlet cross-section. Meanwhile, two new objectivefunctions, including minimization of point displacement and minimization of dimensional tolerance are proposed in theoptimization process. Compared with existing objective functions of flow balancing and homogeneous die swell, the newobjective functions of minimization of point displacement and minimization of dimensional tolerance have significantadvantages of strong adaptability, more precise shape of the extrudate and fast convergence, which significantly improveefficiency of the optimization design and thus lower manufacturing costs of the extrusion die.

A Modified PiggyBac Transposon System Mediated by Exogenous mRNA to Perform Gene Delivery in Bovine Mammary Epithelial Cells

Guangdong Hu,Jing Wang,Hui Huang,Fusheng Quan,Jian Kang,Yongyan Wu,Yuanpeng Gao,Feng Su,Minghao Shao,Yong Zhang 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.2

Transposons are widely used for geneticengineering in various model organisms. Recently, piggyBac(PB) has been developed as a transposable and efficientgene transfer tool in mammalian cells. In the present study,we developed three types of PB transposon systemscontaining a dual plasmid system (DPS), a single plasmidsystem (SPS), and a DNA-mRNA combined system (DRPS)and characterized their basic properties in HEK293 cells. The basic elements of the donor plasmid included aselectable-reporter gene expression cassette, two loxP sitesin the same orientation, a multiple cloning site, and twochicken β-globin insulator core elements. We further identifiedthe function of the selectable-reporter and examined PBintegration sites in the human genome. Moreover, wecompared the transposition efficacy and found that SPStransposed more efficiently, as compared to DPS; integrationinto the host genome was determined by measuring PBaseactivity. Results discovered the loss of PBase activity in theDRPS, indicating that this system is much more biologicallysafe, as compared to DPS and SPS. Finally, we employedthe DRPS to successfully perform a gene delivery intobovine mammary epithelial cells (BMECs). Taken together,the information from this study will improve the flexibilityof PB transposon systems and reduce the genotoxicity ofPBase in genetic engineering.

A study on stray capacitance of ferrite Common Mode Chokes for EMI filters

Guangdong Dong,Fanghua Zhang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

The stray capacitance of CM chokes consists of the material capacitance and the winding parasitic capacitances. The material capacitance is determined by the intrinsic material properties of the ferrite core. The influence of ferrite core material on stray capacitance of CM chokes are researched. The complex magnetic permeability (CMP) of a ferrite core is measured and the CMP characteristic is analyzed. The behavior of the material capacitance is inversely proportional to the square of turn N. Winding parasitic capacitances include turn-to-turn capacitance and turn-to-core capacitance. An analytical method is adopted to calculate the winding parasitic capacitances taking into the core physical construction and material properties. Based on the capacitance network model, the stray capacitance can be derived. The impedance characteristic of a CM choke is tested using impedance analyzer to extract the stray capacitance, and the analytical result is consistent with the measured result.

Equivalent Parallel Capacitance Cancellation of Common Mode Chokes Using Negative Impedance Converter for Common Mode Noise Reduction

Guangdong Dong,Fanghua Zhang 전력전자학회 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

Common mode (CM) chokes are a crucial part in EMI filters for mitigating the electromagnetic interference (EMI) of switched-mode power supplies (SMPS) and for meeting electromagnetic compatibility standards. However, the parasiticcapacitances of a CM choke deteriorate its high frequency filtering performance, which results in increases in the design cycle and cost of EMI filters. Therefore, this paper introduces a negative capacitance generated by a negative impedance converter (NIC) to cancel the influence of equivalent parallel capacitance (EPC). In this paper, based on a CM choke equivalent circuit, the EPCs of CM choke windings are accurately calculated by measuring their impedance. The negative capacitance is designed quantitatively and the EPC cancellation mechanisms are analyzed. The impedance of the CM choke in parallel with negative capacitances is tested and compared with the original CM choke using an impedance analyzer. Moreover, a CL type CM filter is added to a fabricated NIC prototype, and the insertion loss of the prototype is measured to verify the cancellation effect. The prototype is applied to a power converter to test the CM conducted noise. Both small signal and EMI measurement results show that the proposed technique can effectively cancel the EPCs and improve the CM filter's high frequency filtering performance.

Equivalent Parallel Capacitance Cancellation of Common Mode Chokes Using Negative Impedance Converter for Common Mode Noise Reduction

Dong, Guangdong,Zhang, Fanghua The Korean Institute of Power Electronics 2019 JOURNAL OF POWER ELECTRONICS Vol.19 No.5

Common mode (CM) chokes are a crucial part in EMI filters for mitigating the electromagnetic interference (EMI) of switched-mode power supplies (SMPS) and for meeting electromagnetic compatibility standards. However, the parasitic capacitances of a CM choke deteriorate its high frequency filtering performance, which results in increases in the design cycle and cost of EMI filters. Therefore, this paper introduces a negative capacitance generated by a negative impedance converter (NIC) to cancel the influence of equivalent parallel capacitance (EPC). In this paper, based on a CM choke equivalent circuit, the EPCs of CM choke windings are accurately calculated by measuring their impedance. The negative capacitance is designed quantitatively and the EPC cancellation mechanisms are analyzed. The impedance of the CM choke in parallel with negative capacitances is tested and compared with the original CM choke using an impedance analyzer. Moreover, a CL type CM filter is added to a fabricated NIC prototype, and the insertion loss of the prototype is measured to verify the cancellation effect. The prototype is applied to a power converter to test the CM conducted noise. Both small signal and EMI measurement results show that the proposed technique can effectively cancel the EPCs and improve the CM filter's high frequency filtering performance.

Mechanism analysis of switching direction transformation in an Er2O3 based RRAM device

Shuangsuo Mao,Guangdong Zhou,Bai Sun,Hosameldeen Elshekh,Xiaohua Zhang,Xiaohua Zhang,Feng Yang,Yong Zhao 한국물리학회 2019 Current Applied Physics Vol.19 No.12

The resistive random access memory (RRAM) based on resistive switching effect has considered to be the most advanced next generation memory, in which the switching direction determines the order of reading-writing. In this work, the rare-earth metal Er2O3 was used as functional layer, and Ag and indium-tin-oxide (ITO) are selected as top and bottom electrode to fabricate resistive switching device. Further, it is observed that the switching direction and memory window of resistive switching device can be regulated by exchanging top and bottom electrode. Moreover, the complementary switching memory behavior in Ag/Er2O3/ITO/Er2O3/Ag structure was also observed. Through mechanism analysis, it is expected that the barrier changes and metal-ions oxidation-reduction should be responsible for the conversion of switching direction and regulation of memory window. This work opens up a way to the development of next generation new concept memory.

Fascia Suture Technique Is a Simple Approach to Reduce Postmastectomy Seroma Formation

Yizi Cong,Jianqiao Cao,Guangdong Qiao,Song Zhang,Xinjie Liu,Xiaoming Fang,Haidong Zou,Shiguang Zhu 한국유방암학회 2020 Journal of breast cancer Vol.23 No.5

Purpose: Seroma formation is a common complication in breast cancer patients undergoing mastectomy, and it negatively affects patient recovery after surgery. The present study aimed to evaluate a simple method using fascia suture technique to fix the flap and reduce the incidence of seroma. Methods: A single-center, prospective, randomized controlled trial was carried out among 160 patients who had undergone mastectomy from May 2018 to September 2019. All patients were randomly divided into the fascia suture group (n = 80) or control group (n = 80) and were followed up for at least 3 months for the assessment of immediate and late complications after surgery. Results: No significant differences were observed between the 2 groups with regard to the basic characteristics. Duration of surgery in the fascia suture group was longer by about 6 minutes compared with that in the control group (114.93 ± 13.67 minutes vs. 108.81 ± 15.20 minutes, p = 0.008). The fascia suture group had a shorter duration of drain placement (10.99 ± 3.26 days vs. 13.85 ± 5.37 days, p < 0.001), a smaller volume of the total drainage (460.95 ± 242.92 mL vs. 574.83 ± 285.23 mL, p = 0.007), and the first 3-day drainage (224.96 ± 101.01 mL vs. 272.3 ± 115.47 mL, p = 0.006), compared with the control group. The incidence of seroma formation (G2 or G3) was significantly lower in the fascia suture group compared with the control group (28.8% vs. 12.5%, p = 0.033). Besides, there was no statistical difference between the 2 groups in the assessment of other complications, including postoperative pain, hematoma, surgical site infections, flap necrosis, and skin dimpling (all p > 0.050). Conclusion: The fascia suture technique is a simple and effective method for reducing seroma formation and should be used to prevent seroma formation after mastectomy.

Polymorphism of the Promoter Region of Hsp70 Gene and Its Relationship with the Expression of HSP70mRNA, HSF1mRNA, Bcl-2mrna and Bax-AMrna in Lymphocytes in Peripheral Blood of Heat Shocked Dairy Cows

Cai, Yafei,Liu, Qinghua,Xing, Guangdong,Zhou, Lei,Yang, Yuanyuan,Zhang, Lijun,Li, Jing,Wang, Genlin Asian Australasian Association of Animal Productio 2005 Animal Bioscience Vol.18 No.5

The blood samples were collected from dairy cows at the same milking stage. The single-strand conformation polymorphism (PCR-SSCP) method was used to analyze for polymorphism at the 5'flanking region of the hsp70 gene. The mRNA expression levels of HSP70, HSF1, Bcl-2 and Bax-$\alpha$ at different daily-mean-temperature were analyzed by relative quantitative RTPCR. The DNA content, cell phase and the ratio of apoptosis of lymphocytes in peripheral blood of dairy cattle at different daily-meantemperature were determined by FCM. The PCR-SSCP products of primer pair 1 showed polymorphisms and could be divided into four genotypes: aa, ab, ac, cc, with the cis-acting element (CCAAT box) included. Mutations in the hsp70 5'flanking region (468-752 bp) had different effects on mRNA expression of HSP70, HSF1, Bcl-2 and Bax-$\alpha$. The ac genotypic cows showed higher expressions of HSP70mRNA, HSF1mRNA and Bcl-2mRNA/Bax-$\alpha$mRNA and lower ratio of apoptosis. These mutation sites can be used as molecular genetic markers to assist selection for anti-heat stress cows.

A Brucella Omp16 Conditional Deletion Strain Is Attenuated in BALB/c Mice

( Feijie Zhi ),( Jiaoyang Fang ),( Weifang Zheng ),( Junmei Li ),( Guangdong Zhang ),( Dong Zhou ),( Yaping Jin ),( Aihua Wang ) 한국미생물 · 생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.1

Brucella spp. are facultative intracellular pathogens that invade, survive and proliferate in numerous phagocytic and non-phagocytic cell types, thereby leading to human and animal brucellosis. Outer membrane proteins (Omps) are major immunogenic and protective antigens that are implicated in Brucella virulence. A strain deleted of the omp16 gene has not been obtained which suggests that the Omp16 protein is vital for Brucella survival. Nevertheless, we previously constructed an omp16 conditional deletion strain of Brucella, ΔOmp16. Here, the virulence and immune response elicted by this strain were assessed in a mouse model of infection. Splenomegaly was significantly reduced at two weeks post-infection in ΔOmp16-infected mice compared to infection with the parental strain. The bacterial load in the spleen also was significantly decreased at this post-infection time point in ΔOmp16-infected mice. Histopathological changes in the spleen were observed via hematoxylineosin staining and microscopic examination which showed that infection with the ΔOmp16 strain alleviated spleen histopathological alterations compared to mice infected with the parental strain. Moreover, the levels of humoral and cellular immunity were similar in both ΔOmp16-infected mice and parental strain-infected mice. The results overall show that the virulence of ΔOmp16 is attenuated markedly, but that the immune responses mediated by the deletion and parental strains in mice are indistinguishable. The data provide important insights that illuminate the pathogenic strategies adopted by Brucella.

Omp16, a conserved peptidoglycan-associated lipoprotein, is involved in Brucella virulence in vitro

Feijie Zhi,Dong Zhou,Junmei Li,Lulu Tian,Guangdong Zhang,Yaping Jin,Aihua Wang 한국미생물학회 2020 The journal of microbiology Vol.58 No.9

Brucella, the bacterial agent of common zoonotic brucellosis, primarily infects specific animal species. The Brucella outer membrane proteins (Omps) are particularly attractive for developing vaccine and improving diagnostic tests and are associated with the virulence of smooth Brucella strains. Omp16 is a homologue to peptidoglycan-associated lipoproteins (Pals), and an omp16 mutant has not been generated in any Brucella strain until now. Very little is known about the functions and pathogenic mechanisms of Omp16 in Brucella. Here, we confirmed that Omp16 has a conserved Pal domain and is highly conserved in Brucella. We attempted to delete omp16 in Brucella suis vaccine strain 2 (B. suis S2) without success, which shows that Omp16 is vital for Brucella survival. We acquired a B. suis S2 Omp16 mutant via conditional complementation. Omp16 deficiency impaired Brucella outer membrane integrity and activity in vitro. Moreover, inactivation of Omp16 decreased bacterial intracellular survival in macrophage RAW 264.7 cells. B. suis S2 and its derivatives induced marked expression of IL-1β, IL-6, and TNF-α mRNA in Raw 264.7 cells. Whereas inactivation of Omp16 in Brucella enhanced IL-1β and IL-6 expression in Raw 264.7 cells. Altogether, these findings show that the Brucella Omp16 mutant was obtained via conditional complementation and confirmed that Omp16 can maintain outer membrane integrity and be involved in bacterial virulence in Brucella in vitro and in vivo. These results will be important in uncovering the pathogenic mechanisms of Brucella.