IMPROVED PERTURBATION BOUND FOR ROBUST STABILITY IN LINEAR SYSTEM

Zhang Zhao,Zhao Chan Gan,Hu Heng Zhang 대한전자공학회 1992 대한전자공학회 Conference Vol.1992 No.2

IMPROVED PERTURBATION BOUND FOR ROBUST STABILITY IN LINEAR SYSTEM

Zhao, Zhang,Gan, Zhao Chan,Zhang, Hu Heng 대한전자공학회 1992 HICEC:Harbin International Conference on Electroni Vol.1 No.1

The problem of robust stability of linear systems is investigated in time domain in this paper. For an asymptotically stable linear system, the maximum allowable perturbation bound (under which the system remains stable) is obtained by using Lyapunov method. A numerical example is given to show the perturbation bound obtained is better than ones in some literatures.

3D numerical model for wave-induced seabed response around breakwater heads

Zhao, H.Y.,Jeng, D.S.,Zhang, Y.,Zhang, J.S.,Zhang, H.J.,Zhang, C. Techno-Press 2013 Geomechanics & engineering Vol.5 No.6

This paper presents a three-dimensional (3D) integrated numerical model where the wave-induced pore pressures in a porous seabed around breakwater heads were investigated. Unlike previous research, the Navier-Stokes equation is solved with internal wave generation for the flow model, while Biot's dynamic seabed behaviour is considered in the seabed model. With the present model, a parametric study was conducted to examine the effects of wave and soil characteristics and breakwater configuration on the wave-induced pore pressure around breakwater heads. Based on numerical examples, it was found that the wave-induced pore pressures at breakwater heads are greater than that beneath a breakwater. The wave-induced seabed response around breakwater heads become more important with: (i) a longer wave period; (ii) a seabed with higher permeability and degree of saturation; and (iii) larger angle between the incident waves and breakwater. Furthermore, the relative difference of wave-induced pore pressure between fully-dynamic and quasi-static solutions are larger at breakwater heads than that beneath a breakwater.

Preparation and Adsorption Properties of PA6/PSMA-OA Molecularly Imprinted Composite Membranes in Supercritical CO₂

Zhang, Qing,Zhang, Xingyuan,Zhang, Wencheng,Pan, Jian,Liu, Ling,Zhang, Haitao,Zhao, Dong,Li, Zhi Korean Chemical Society 2011 Bulletin of the Korean Chemical Society Vol.32 No.9

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical $CO_2$ ($ScCO_2$). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of $ScCO_2$ from $35^{\circ}C$ to $50^{\circ}C$ and pressure of $ScCO_2$ 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.

TGF-β promotes pericyte-myofibroblast transition in subretinal fibrosis through the Smad2/3 and Akt/mTOR pathways

Zhao Zhenzhen,Zhang Yumeng,Zhang Chaoyang,Zhang Jingting,Luo Xueting,Qiu Qinghua,Luo Dawei,Zhang Jingfa 생화학분자생물학회 2022 Experimental and molecular medicine Vol.54 No.-

Subretinal fibrosis remains a major obstacle to the management of neovascular age-related macular degeneration. Choroidal pericytes were found to be a significant source of subretinal fibrosis, but the underlying mechanisms of pericyte-myofibroblast transition (PMT) remain largely unknown. The goal of this study was to explore the role and potential mechanisms by which PMT contributes to subretinal fibrosis. Choroidal neovascularization (CNV) was induced by laser photocoagulation in transgenic mice with the collagen1α1-green fluorescent protein (Col1α1-GFP) reporter, and recombinant adeno-associated virus 2 (rAAV2)-mediated TGF-β2 (rAAV2-TGF-β2) was administered intravitreally to further induce PMT. Primary mouse choroidal GFP-positive pericytes were treated with TGF-β2 in combination with siRNAs targeting Smad2/3, the Akt inhibitor MK2206 or the mTOR inhibitor rapamycin to examine cell proliferation, migration, and differentiation into myofibroblasts. The involvement of the Akt/mTOR pathway in PMT in subretinal fibrosis was further investigated in vivo. Intraocular TGF-β2 overexpression induced GFP-positive pericyte infiltration and PMT in subretinal fibrosis, which was mimicked in vitro. Knockdown of Smad2/3 or inhibition of Akt/mTOR decreased cell proliferation, PMT and migration in primary mouse pericytes. Combined inhibition of Smad2/3 and mTOR showed synergistic effects on attenuating α-smooth muscle actin (α-SMA) expression and cell proliferation. In mice with laser-induced CNV, the administration of the Akt/mTOR inhibitors suppressed pericyte proliferation and alleviated the severity of subretinal fibrosis. Our results showed that PMT plays a pivotal role in subretinal fibrosis, which was induced by TGF-β2 through the Smad2/3 and Akt/mTOR pathways. Thus, inhibiting PMT may be a novel strategy for the treatment of subretinal fibrosis.

A brain somatic RHEB doublet mutation causes focal cortical dysplasia type II

Shanshan Zhao,Zhenghui Li,Muxian Zhang,Lingliang Zhang,Honghua Zheng,Jinhuan Ning,Yanyan Wang,Feng-Peng Wang,Xiaobin Zhang,Hexia Gan,Yuanqing Wang,Xian Zhang,Hong Luo,Guojun Bu,Huaxi Xu,Yi Yao,Yun-wu 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-

Focal cortical dysplasia type II (FCDII) is a cerebral cortex malformation characterized by local cortical structure disorganization, neuronal dysmorphology, and refractory epilepsy. Brain somatic mutations in several genes involved in the PI3K/AKT/mTOR pathway are associated with FCDII, but they are only found in a proportion of patients with FCDII. The genetic causes underlying the development FCDII in other patients remain unclear. Here, we carried out whole exome sequencing and targeted sequencing in paired brain–blood DNA from patients with FCDII and identified a brain somatic doublet mutation c.(A104T, C105A) in the Ras homolog, mTORC1 binding (RHEB) gene, which led to the RHEB p.Y35L mutation in one patient with FCDII. This RHEB mutation carrier had a dramatic increase of ribosomal protein S6 phosphorylation, indicating mTOR activation in the region of the brain lesion. The RHEB p.Y35L mutant protein had increased GTPλS-binding activity compared with wild-type RHEB. Overexpression of the RHEB p. Y35L variant in cultured cells also resulted in elevated S6 phosphorylation compared to wild-type RHEB. Importantly, in utero electroporation of the RHEB p.Y35L variant in mice induced S6 phosphorylation, cytomegalic neurons, dysregulated neuron migration, abnormal electroencephalogram, and seizures, all of which are found in patients with FCDII. Rapamycin treatment rescued abnormal electroencephalograms and alleviated seizures in these mice. These results demonstrate that brain somatic mutations in RHEB are also responsible for the pathogenesis of FCDII, indicating that aberrant activation of mTOR signaling is a primary driver and potential drug target for FCDII.

Metastasis associated genomic aberrations in stage II rectal cancer

Hong Zhao,Zhi-Zhou Shi,Rui Jiang,Dong-Bing Zhao,Hai-Tao Zhou,Jian-Wei Liang,Xin-Yu Bi,Jian-Jun Zhao,Zhi-Yu Li,Jian-Guo Zhou,Zhen Huang,Ye-Fan Zhang,Jian Wang,Xin Xu,Yan Cai,Ming-Rong Wang,Yu Zhang 한국유전학회 2016 Genes & Genomics Vol.38 No.11

Genomic aberrations of rectal carcinoma, especially DNA copy number changes associated with metastasis were largely unclear. We aim to identify the metastasis associated biomarkers in stage II rectal cancer. Formalin-fixed, paraffin-embedded primary tumor tissues of stage II rectal carcinoma were analyzed by array-based comparative genomic hybridization, and genomic aberrations were identified by Genomic Workbench and SAM software. Copy number changes and mRNA expressions were validated by Real-time PCR in an independent rectal cancer samples. The results showed that the most frequent gains in stage II rectal cancer were at 1q21.2-q23.1, 3p21.31, 11q12.2-q23.3, 12q24.11-q24.31, 12q13.11-q14.1 and losses in 18q11.2-q23, 17q21.33-q22, 13q31.1-q31.3, 21q21.1-q21.3, 8p23.3-p23.1 and 4q22.1-q23. Twenty-two amplifications and five homozygous deletions were also identified. We further found that S100A1 (1q21.3-q23.1), MCM7 (7q22.1) and JUND (19p13.11) were amplified and overexpressed in stage II rectal cancer. Interestingly, the genomic aberrations affected 14 signaling pathways including VEGF signaling pathway and fatty acid metabolism. Most importantly, loss of 13q31.1-q34 and gain of 1q44 were associated with distant metastasis. Our results indicated that these metastasis associated genomic changes may be useful to reveal the pathogenesis of rectal cancer metastasis and identify candidate biomarkers.

Preparation and Adsorption Properties of PA6/PSMA-OA Molecularly Imprinted Composite Membranes in Supercritical CO_2

Qing Zhang,Wencheng Zhang,Jian Pan,Ling Liu,Haitao Zhang,Dong Zhao,Zhi Li,Xingyuan Zhang 대한화학회 2011 Bulletin of the Korean Chemical Society Vol.32 No.9

Oleanolic acid (OA) as template molecule, polyamide-6 (PA6) as basement membrane and poly(styrene-comaleic acid) (PSMA) were used to prepare PA6/PSMA-OA molecularly imprinted composite membranes by phase inversion method in supercritical CO_2 (ScCO_2). The template molecule (OA), [poly(styrene-co-maleic anhydride) (PSMAH), PSMA, molecularly imprinted membranes (MIMs) imprinting OA and MIMs after elution were all characterized by Fourier transform infrared spectroscopy (FTIR). The conditions that were the mass ratio between PSMA and OA from 3:1 to 8:1, temperature of ScCO_2 from 35 ºC to 50 ºC and pressure of ScCO_2 12 MPa to 17 MPa were studied. It was obtained the largest adsorption rate and purity of OA after adsorption of the resultant MIMs, 50.41% and 96.15% respectively. After using PA6 film and non-woven fabrics as basement membrane respectively, it was found that smaller aperture of PA6 was used as basement membrane, a higher adsorption rate and a higher purity of OA after adsorption of the MIMs were obtained, and so were the stability and reproducibility of the resultant MIMs. After template molecules being removed, the MIMs had effective selectivity hydrogen bonding to separately bind in the binary components to the template molecules-oleanolic acid.

Enhanced D-ribose production by genetic modification and medium optimization in Bacillus subtilis 168

Chen Zhao,Xiang-Ying Zhao,Jian-Jun Liu,Jun-Jiao Zhang,Jia-Xiang Zhang,Li-He Zhang 한국화학공학회 2018 Korean Journal of Chemical Engineering Vol.35 No.5

D-ribose, a five-carbon sugar with diverse applications, is mainly produced by transketolase (tkt)-deficient Bacillus subtilis (B. Subtilis). We constructed B.subtilis SFR-3A by replacing the corresponding sites of B. subtilis 168 with the mutation site of tkt in the “wild” D-ribose high-producing strain B. subtilis SFR-4, resulting in 5.29 g/L of Dribose. In the meantime, B.subtilis SFR-159 was constructed by completely removing the tkt gene of B. subtilis 168 with a higher production of 6.21 g/L. Through medium optimization, batch fermentation of SFR-3A and SFR-159 gave the best result of 27.56 g/L and 29.89 g/L, which corresponds to productivity of 0.51 g/L/h and 0.41 g/L/h, respectively. In this work, SFR-3A showed more latent capacity over SFR-159 as to productivity and had greater potential to serve as a platform for D-ribose production.

ROOM-TEMPERATURE FERROMAGNETISM IN SnO 2 NANOFIBERS AND NANOTUBES PREPARED BY ELECTROSPINNING

JIAN-GUO ZHAO,WEI-YING ZHANG,ZHAO-JUN LIU,ZHONG-LI LIU,YA-JUAN ZHANG,ER-QING XIE,XIU-YUN AN,YONG-FENG CHEN,CHANG-YOU ZHANG 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.2

SnO 2 nano¯bers and nanotubes were synthesized by electrospinning method. Magnetizationmeasurement indicates that the SnO 2 nano¯bers and nanotubes annealed in air at 500?C exhibitthe room-temperature ferromagnetism and the ferromagnetism of nanotubes is stronger than thenano¯bers. Selected area electron di®raction, X-ray di®raction and Raman measurements showthat all the samples possess a typical rutile structure and no other impurity phases are observed. The results of the Raman spectra also indicate that there are lots of defects existing in thefabricated samples. The observed room-temperature ferromagnetism in SnO 2 nano¯bers andnanotubes possibly originates from oxygen vacancies. The ¯eld cooled (FC) and zero-¯eld-cooled(ZFC) magnetization curves indicate that the Curie temperature T C is above 300 K.