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Zhang HM, Sun Y, Li W, Peng JP, Song CL, Xing Y, Zhang Q, Guan J, Li Z, Zhao Y, Ji S, Wang L, He K, Chen X, Gu L, Ling L, Tian M, Li L, Xie XC, Liu J, Yang H, Xue QK, Wang J, Ma X. Detection of a superconducting phase in a two-atom layer of hexagonal Ga film grown on semiconducting GaN(0001). PHYSICAL REVIEW LETTERS 2015; 114:107003. [PMID: 25815961 DOI: 10.1103/physrevlett.114.107003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Indexed: 06/04/2023]
Abstract
The recent observation of the superconducting state at atomic scale has motivated the pursuit of exotic condensed phases in two-dimensional (2D) systems. Here we report on a superconducting phase in two-monolayer crystalline Ga films epitaxially grown on wide-band-gap semiconductor GaN(0001). This phase exhibits a hexagonal structure and only 0.552 nm in thickness, nevertheless, brings about a superconducting transition temperature Tc as high as 5.4 K, confirmed by in situ scanning tunneling spectroscopy and ex situ electrical magnetotransport and magnetization measurements. The anisotropy of critical magnetic field and Berezinski-Kosterlitz-Thouless-like transition are observed, typical for the 2D superconductivity. Our results demonstrate a novel platform for exploring atomic-scale 2D superconductors, with great potential for understanding the interface superconductivity.
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Sun Z, Wang Y, Ji S, Wang K, Zhao Y. Computer-aided analysis with Image J for quantitatively assessing psoriatic lesion area. Skin Res Technol 2015; 21:437-43. [PMID: 25661416 DOI: 10.1111/srt.12211] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/07/2014] [Indexed: 11/27/2022]
Abstract
BACKGROUND/AIMS Body surface area is important in determining the severity of psoriasis. However, objective, reliable, and practical method is still in need for this purpose. We performed a computer image analysis (CIA) of psoriatic area using the image J freeware to determine whether this method could be used for objective evaluation of psoriatic area. METHODS Fifteen psoriasis patients were randomized to be treated with adalimumab or placebo in a clinical trial. At each visit, the psoriasis area of each body site was estimated by two physicians (E-method), and standard photographs were taken. The psoriasis area in the pictures was assessed with CIA using semi-automatic threshold selection (T-method), or manual selection (M-method, gold standard). The results assessed by the three methods were analyzed with reliability and affecting factors evaluated. RESULTS Both T- and E-method correlated strongly with M-method, and T-method had a slightly stronger correlation with M-method. Both T- and E-methods had a good consistency between the evaluators. All the three methods were able to detect the change in the psoriatic area after treatment, while the E-method tends to overestimate. CONCLUSION The CIA with image J freeware is reliable and practicable in quantitatively assessing the lesional of psoriasis area.
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Wang D, Chen L, Liu H, Wang X, Cui G, Zhang P, Zhao D, Ji S. Topological states modulation of Bi and Sb thin films by atomic adsorption. Phys Chem Chem Phys 2015; 17:3577-83. [DOI: 10.1039/c4cp04502e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Based on first-principles calculations, we systematically investigated the topological surface states of Bi and Sb thin films of 1–5 bilayers in (111) orientation without and with H(F) adsorption, respectively.
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Ji S, Choi YS, Choi Y. Bacterial invasion and persistence: critical events in the pathogenesis of periodontitis? J Periodontal Res 2014; 50:570-85. [DOI: 10.1111/jre.12248] [Citation(s) in RCA: 91] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2014] [Indexed: 12/22/2022]
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Kang Y, Jang H, Kim Y, Choi B, Kim J, Lee J, Shin H, Kim S, Kay C, Park S, Ji S, Koo J, Jeon S, Lee S. The Feasibility Study of MRI-Based Dose Calculation With Look-up Table in Radiation Treatment Planning. Int J Radiat Oncol Biol Phys 2014. [DOI: 10.1016/j.ijrobp.2014.05.2496] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Ji S, Shao Q, Wang Y, Liu J. Efficacy comparison between minimally invasive and conventional surgery for lumbar disc herniation in Chinese Han population: a meta-analysis. Spinal Cord 2014; 52:734-9. [PMID: 24912547 DOI: 10.1038/sc.2014.98] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 04/29/2014] [Accepted: 05/11/2014] [Indexed: 11/09/2022]
Abstract
STUDY DESIGN The pooled data were analyzed using RevMan 5.2 software. OBJECTIVES The aim was to compare the efficacy of minimally invasive and conventional surgery for lumbar disc herniation (LDH) in Chinese Han population. SETTING China. METHODS An electronic search up to November 2013 was performed to retrieve all relevant articles. The overall standardized mean difference (SMD) for continuous outcomes and odds ratio (OR) for dichotomous variables as well as their 95% confidence intervals (CIs) were calculated to compare the efficacy of minimally invasive and conventional surgery. RESULTS A total of 23 studies involving 1913 patients treated by minimally invasive surgery and 2295 patients treated by conversational surgery were included in this meta-analysis. The overall estimate indicated that minimally invasive surgery could significantly decrease the hospitalization time (SMD = -2.03, 95% CI, -2.49 to 1.56, P < 0.0001), blood loss (SMD = -2.65, 95% CI -3.33 to 1.97, P < 0.0001), incision length (SMD = -3.57, 95% CI, -4.39 to 2.75, P < 0.0001), recurrence rate (odds ratio (OR) = 0.22, 95 CI: 0.08-0.60, P = 0.003) and complications (OR = 0.47, 95% CI: 0.25-0.92, P = 0.03) and increase the postoperative excellent rate (OR = 1.82, 95% CI, 1.44-2.31, P < 0.0001) compared with conventional surgery. In addition, the pooled data showed that there was no statistically significant difference in the operative time (SMD = -0.58, 95% CI, -1.32 to 0.15, P = 0.12) between LDH patients treated by minimally invasive and conventional surgery. CONCLUSION In conclusion, minimally invasive surgery was a more safe and effective treatment for treating LDH in Chinese Han population when compared with conventional surgery.
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Zhang H, Zhang X, Ji S, Hao C, Mu Y, Sun J, Hao J. Sohlh2 inhibits ovarian cancer cell proliferation by upregulation of p21 and downregulation of cyclin D1. Carcinogenesis 2014; 35:1863-71. [DOI: 10.1093/carcin/bgu113] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
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Meng F, Ma L, Ji S, Yang W, Cao B. Isolation and characterization of Bacillus subtilis strain BY-3, a thermophilic and efficient cellulase-producing bacterium on untreated plant biomass. Lett Appl Microbiol 2014; 59:306-12. [PMID: 24773580 DOI: 10.1111/lam.12276] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2013] [Revised: 03/24/2014] [Accepted: 04/15/2014] [Indexed: 11/28/2022]
Abstract
UNLABELLED Bioconversion of biomass, particularly crop wastes, into biofuels is being developed as an alternative approach in meeting the high energy demand. In this study, a thermophilic bacterial strain BY-3 that exhibits cellulolytic potential was isolated from faecal samples of Tibetan pigs; this strain was identified as Bacillus subtilis. The strain can produce cellulase when grown on various substrates, including carboxymethyl cellulose, rice straw, corn stover, soluble starch and wheat bran. The maximum cellulase activity of the strain was up to 4·323 ± 0·065 U ml(-1) when cultivated in the medium containing corn stover (30 g l(-1) ) for 24 h. The results demonstrated that corn stover is the most suitable substrate for cellulase production by the strain BY-3. The crude cellulase of strain BY-3 was most active at pH 5·5 and 60°C, and the enzyme in acetate buffer (50 mmol l(-1) ) demonstrated a good stability at 60°C for at least 1 h. The crude cellulase exhibited a strong antibacterial activity against Staphylococcus aureus. The strain can be used in cost-efficient cellulase production for bioconversion of agricultural residual biomass into biofuels. SIGNIFICANCE AND IMPACT OF THE STUDY The increased consumption of fossil fuels has caused serious energy crisis and environmental problem. Thus, an alternative energy source is necessary. Bioconversion of biomass, particularly agricultural residuals, into value-added bioproducts, such as biofuels and chemical solvents, has received considerable attention. In this study, the newly isolated thermophilic Bacillus subtilis strain BY-3 produces cellulase efficiently with the use of untreated corn stover as a sole carbon source. This strain possesses the thermostable cellulase that is active with diverse crop wastes with a broad pH range and is a highly promising candidate for agricultural waste management.
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Yan C, Liu J, Zang Y, Wang J, Wang Z, Wang P, Zhang ZD, Wang L, Ma X, Ji S, He K, Fu L, Duan W, Xue QK, Chen X. Experimental observation of Dirac-like surface states and topological phase transition in Pb(1-x)Sn(x)Te(111) films. PHYSICAL REVIEW LETTERS 2014; 112:186801. [PMID: 24856712 DOI: 10.1103/physrevlett.112.186801] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Indexed: 06/03/2023]
Abstract
The surface of a topological crystalline insulator (TCI) carries an even number of Dirac cones protected by crystalline symmetry. We epitaxially grew high-quality Pb(1-x)Sn(x)Te(111) films and investigated the TCI phase by in situ angle-resolved photoemission spectroscopy. Pb(1-x)Sn(x)Te(111) films undergo a topological phase transition from a trivial insulator to TCI via increasing the Sn/Pb ratio, accompanied by a crossover from n-type to p-type doping. In addition, a hybridization gap is opened in the surface states when the thickness of the film is reduced to the two-dimensional limit. The work demonstrates an approach to manipulating the topological properties of TCI, which is of importance for future fundamental research and applications based on TCI.
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Ji S, Chen Y, Ruan Z, Fu Y, Ji J, Fu Y, Wang H, Yu Y. Prevalence of carbapenem-hydrolyzing class D β-lactamase genes in Acinetobacter spp. isolates in China. Eur J Clin Microbiol Infect Dis 2013; 33:989-97. [PMID: 24374815 DOI: 10.1007/s10096-013-2037-z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2013] [Accepted: 12/12/2013] [Indexed: 10/25/2022]
Abstract
In order to assess the prevalence of carbapenem-hydrolyzing class D β-lactamase genes in Acinetobacter spp. isolates in China, we conducted a polymerase chain reaction (PCR)-based surveillance of OXA-type β-lactamase gene clusters for a total of 2,880 Acinetobacter spp. isolates collected from 23 Chinese provinces. All isolates were tested for susceptibility to 12 antimicrobial agents and showed high rates of resistance to all these agents except minocycline. We also found that the vast majority of carbapenem-resistant Acinetobacter spp. were OXA-23-like-producing isolates, predominantly Acinetobacter baumannii isolates. Besides, bla OXA-58-like and bla OXA-24-like genes were detected in 32 and 11 isolates, respectively, involving many provinces throughout China. Furthermore, these two carbapenem-resistance determinants were located on transferable plasmids in most cases, indicating an emerging threat for both OXA-58-like- and OXA-24-like-producing Acinetobacter spp. isolates in China. Interestingly, a novel homologue of the bla OXA-143 gene was identified in a susceptible Acinetobacter pittii isolate. Overall, these observations suggest that the bla OXA-23-harboring A. baumannii isolates are the most frequent carbapenem-resistant Acinetobacter spp. in China, and the bla OXA-24-like and bla OXA-58-like genes have emerged as potential threats of hospital outbreaks of multidrug-resistant Acinetobacter spp.
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Ji S, Tian Y, Sun R, Lu Y, Zhang L, Chen L, Duan S. Radiation-Induced Hippocampal Neurogenesis Impairment and Cognitive Deficits Is Associated With Inhibition of BDNF-Trk-B Signaling. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2013.06.1660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Ji J, Tian Y, Ji S, Zhang L, Zhu Y, Lu X. Ionizing Radiation Induces Cell Cycle G1 Arrest and Tumor Suppressor Gene P16, P21, P27 Expression in Keloid Fibroblasts. Int J Radiat Oncol Biol Phys 2013. [DOI: 10.1016/j.ijrobp.2013.06.1662] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Choi Y, Kim YC, Jo A, Ji S, Koo KT, Ko Y, Choi Y. Porphyromonas Gingivalisand Dextran Sulfate Sodium Induce Periodontitis Through the Disruption of Physical Barriers in Mice. EUR J INFLAMM 2013. [DOI: 10.1177/1721727x1301100212] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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Chang CZ, Zhang J, Feng X, Shen J, Zhang Z, Guo M, Li K, Ou Y, Wei P, Wang LL, Ji ZQ, Feng Y, Ji S, Chen X, Jia J, Dai X, Fang Z, Zhang SC, He K, Wang Y, Lu L, Ma XC, Xue QK. Experimental observation of the quantum anomalous Hall effect in a magnetic topological insulator. Science 2013; 340:167-70. [PMID: 23493424 DOI: 10.1126/science.1234414] [Citation(s) in RCA: 857] [Impact Index Per Article: 77.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The quantized version of the anomalous Hall effect has been predicted to occur in magnetic topological insulators, but the experimental realization has been challenging. Here, we report the observation of the quantum anomalous Hall (QAH) effect in thin films of chromium-doped (Bi,Sb)2Te3, a magnetic topological insulator. At zero magnetic field, the gate-tuned anomalous Hall resistance reaches the predicted quantized value of h/e(2), accompanied by a considerable drop in the longitudinal resistance. Under a strong magnetic field, the longitudinal resistance vanishes, whereas the Hall resistance remains at the quantized value. The realization of the QAH effect may lead to the development of low-power-consumption electronics.
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Xu J, Zhu W, Xu W, Yao W, Zhang B, Xu Y, Ji S, Liu C, Long J, Ni Q, Yu X. Up-Regulation of MBD1 Promotes Pancreatic Cancer Cell Epithelial-Mesenchymal Transition and Invasion by Epigenetic Down-Regulation of E-Cadherin. Curr Mol Med 2013. [DOI: 10.2174/156652413805076740] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Yao W, Cai X, Liu C, Qin Y, Cheng H, Ji S, Xu W, Wu C, Chen T, Xu J, Long J, Fang Z, Qu B, Hoth M, Ni Q, Zha X, Yu X. Profilin 1 potentiates apoptosis induced by staurosporine in cancer cells. Curr Mol Med 2013; 13:417-428. [PMID: 23331014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/12/2012] [Accepted: 10/15/2012] [Indexed: 06/01/2023]
Abstract
The correlation between the loss of Profilin 1 (Pfn1) with tumor progression indicated that Pfn1 is a tumor suppressor in human carcinoma. The molecular mechanisms underlying Pfn1 tumor suppression has yet to be elucidated. In this study, we showed that Pfn1 overexpression sensitizes cancer cells to apoptosis through the typical intrinsic apoptotic pathway. Mechanistically, the increased Pfn1 expression mediated the upregulation of p53R273H, one of the most common tumor-associated hotspot mutations of p53, with transactivation deletion in tumorigenesis and increased localization of p53R273H in cytoplasm. Further studies showed that mutant p53R273H was involved in apoptosis induced by Staurosporine (STS) via transcription-independent mitochondrial functions. We observed (i) the increased cytosolic localization of p53R273H, (ii) the activation of phosphorylation at Ser15, (iii) its mitochondrial localization; Pfn1 acted as a positive regulator of these processes. We also found that Pfn1 interacted with p53R273H and thus facilitated its exertion over the transcription-independent activity in the cytoplasm during drug action. Our results define a new function and mechanism of Pfn1 demonstrating that the combined effect with apoptotic agents led to a synergistic increase in apoptosis. In addition, p53R273H abrogating DNA binding was found to play a major role in the Pfn1- sensitized apoptosis through a transactivation-independent and cytosolic activity.
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Xu J, Zhu W, Xu W, Yao W, Zhang B, Xu Y, Ji S, Liu C, Long J, Ni Q, Yu X. Up-regulation of MBD1 promotes pancreatic cancer cell epithelial-mesenchymal transition and invasion by epigenetic down-regulation of E-cadherin. Curr Mol Med 2013; 13:387-400. [PMID: 23331011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Revised: 10/12/2012] [Accepted: 10/18/2012] [Indexed: 06/01/2023]
Abstract
Methyl-CpG binding domain protein 1 (MBD1) has been implicated in transcriptional regulation, heterochromatin formation, genomic stability, cell-cycle progression and development. It is also predicted that MBD1 might be involved in tumor development and progression. However, whether and how MBD1 is involved in tumorigenesis, especially in pancreatic cancer (PC), is currently unknown. We found that MBD1 was significantly up-regulated in PC tissues compared with the surrounding normal tissues according to RT-PCR data. Tissue microarray (TMA) based immunohistochemical study from 58 surgically resected PC specimens indicated that higher MBD1 expression correlated with lymph node metastasis and poor survival in PC patients. Gain- and loss-of-function studies in vitro validated MBD1 as a potent oncogene promoting PC cell invasion as well as epithelial-mesenchymal transition (EMT). Mechanistically, MBD1 is associated with Twist and NAD-dependent deacetylase sirtuin-1 (SIRT1), thereby forming the Twist-MBD1-SIRT1 complex on the CDH1 promoter, which resulted in reduced E-cadherin transcription activity and increased cell EMT ability. Significantly, targeting MBD1 reversed the EMT phenotype of PC and restored sensitivity to chemotherapy. Taken together, the results of our study revealed a novel function of MBD1 in PC invasion and metastasis by providing a molecular mechanism underlying MBD1-promoted EMT. Thus MBD1 may serve as a potential therapeutic target for PC.
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Yao W, Cai X, Liu C, Qin Y, Cheng H, Ji S, Xu W, Wu C, Chen T, Xu J, Long J, Fang Z, Qu B, Hoth M, Ni Q, Zha X, Yu X. Profilin 1 Potentiates Apoptosis Induced by Staurosporine in Cancer Cells. Curr Mol Med 2013. [DOI: 10.2174/156652413805076812] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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69
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Yao W, Cai X, Liu C, Qin Y, Cheng H, Ji S, Xu W, Wu C, Chen T, Xu J, Long J, Fang Z, Qu B, Hoth M, Ni Q, Zha X, Yu X. Profilin 1 Potentiates Apoptosis Induced by Staurosporine in Cancer Cells. Curr Mol Med 2013. [DOI: 10.2174/1566524011313030011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Xu J, Zhu W, Xu W, Yao W, Zhang B, Xu Y, Ji S, Liu C, Long J, Ni Q, Yu X. Up-Regulation of MBD1 Promotes Pancreatic Cancer Cell Epithelial-Mesenchymal Transition and Invasion by Epigenetic Down-Regulation of E-Cadherin. Curr Mol Med 2013. [DOI: 10.2174/1566524011313030008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Bedford A, Li Z, Li M, Ji S, Liu W, Huai Y, de Lange CFM, Li J. Epidermal growth factor-expressing Lactococcus lactis enhances growth performance of early-weaned pigs fed diets devoid of blood plasma. J Anim Sci 2012; 90 Suppl 4:4-6. [DOI: 10.2527/jas.53973] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
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Ji S, Yarmohammadi H, Hoyt H, Hansford R, Zviman M, Steinberg S, Judge D, Caffo B, Tomaselli G, Halperin H, Cheng A, Spragg D, Henrikson C, Sinha S, Marine J, Berger R, Calkins H, Nazarian S. Association of Atrial Myocardial Fibrosis with a Common Matrix Metalloproteinase-2 Promoter Polymorphism. Heart Rhythm 2012. [DOI: 10.1016/j.hrthm.2012.09.123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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73
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Ji S, Sun R, Zhang L, Tian Y. Whole Brain Irradiation-induced Decrease of Histone H3 Acetylation in Hippocampus of Rats. Int J Radiat Oncol Biol Phys 2012. [DOI: 10.1016/j.ijrobp.2012.07.1776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Cheng Z, Ji S, Stephens N, Fitzgerald R, Cenkowski S. P46 The impact of hydrogen sulfide on ovalbumin-sensitized canine trachealis smooth muscle. Nitric Oxide 2012. [DOI: 10.1016/j.niox.2012.08.047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Li W, Ding H, Li Z, Deng P, Chang K, He K, Ji S, Wang L, Ma X, Hu JP, Chen X, Xue QK. KFe2Se2 is the parent compound of K-doped iron selenide superconductors. PHYSICAL REVIEW LETTERS 2012; 109:057003. [PMID: 23006201 DOI: 10.1103/physrevlett.109.057003] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2012] [Indexed: 06/01/2023]
Abstract
We elucidate the existing controversies in the newly discovered K-doped iron selenide (K(x)Fe(2-y)Se(2-z)) superconductors. The stoichiometric KFe(2)Se(2) with √2 × √2 charge ordering was identified as the parent compound of K(x)Fe(2-y)Se(2-z) superconductor using scanning tunneling microscopy and spectroscopy. The superconductivity is induced in KFe(2)Se(2) by either Se vacancies or interacting with the antiferromagnetic K(2)Fe(4)Se(5) compound. In total, four phases were found to exist in K(x)Fe(2-y)Se(2-z): parent compound KFe(2)Se(2), superconducting KFe(2)Se(2) with √2 × √5 charge ordering, superconducting KFe(2)Se(2-z) with Se vacancies, and insulating K(2)Fe(4)Se(5) with √5 × √5 Fe vacancy order. The phase separation takes place at the mesoscopic scale under standard molecular beam epitaxy conditions.
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