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Lemke, Henrik T.,Bressler, Christian,Chen, Lin X.,Fritz, David M.,Gaffney, Kelly J.,Galler, Andreas,Gawelda, Wojciech,Haldrup, Kristoffer,Hartsock, Robert W.,Ihee, Hyotcherl,Kim, Jeongho,Kim, Kyung Hw American Chemical Society 2013 The journal of physical chemistry. A, Molecules, s Vol.117 No.4
<P>X-ray free electron lasers (XFELs) deliver short (<100 fs) and intense (∼10<SUP>12</SUP> photons) pulses of hard X-rays, making them excellent sources for time-resolved studies. Here we show that, despite the inherent instabilities of current (SASE based) XFELs, they can be used for measuring high-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2′-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics convoluted with the overall time resolution. The resulting time constant is ∼160 fs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpcafh/2013/jpcafh.2013.117.issue-4/jp312559h/production/images/medium/jp-2012-12559h_0008.gif'></P>
JOUNG, BOYOUNG,ZHANG, HONG,SHINOHARA, TETSUJI,MARUYAMA, MITSUNORI,HAN, SEONGWOOK,KIM, DAEHYEOK,CHOI, EUEx2010,KEUN,ON, YOUNGx2010,KEUN,LIN, SHIENx2010,FONG,CHEN, PENGx2010,SHENG Blackwell Publishing Inc 2011 Journal of cardiovascular electrophysiology Vol.22 No.4
<P> <B>Delayed Afterdepolarization in Sinoatrial Node. <I>Introduction:</I></B> Recent evidence indicates that spontaneous sarcoplasmic reticulum Ca release and Na‐Ca exchanger current activation contribute to the sinoatrial node (SAN) automaticity. These findings suggest that SAN activity may share mechanisms that underlie both automaticity and triggered activity. The aim of this study is to test the hypothesis that spontaneous, nonvoltage gated, intracellular Ca (Ca<SUB>i</SUB>) elevation may induce delayed afterdepolarization (DAD) in intact SAN during isoproterenol infusion.</P><P> <B> <I>Methods and Results:</I> </B> We simultaneously mapped Ca<SUB>i</SUB> and membrane potential in 31 isolated Langendorff‐perfused canine right atriums (RA). Isoproterenol increased heart rate and late diastolic Ca<SUB>i</SUB> elevation (LDCAE) of the superior SAN, leading to consistent SAN automaticity in all 31 RAs. However, DAD‐like diastolic depolarizations (DD) were transiently observed in 4 RAs during isoproterenol infusion. These DAD‐like DDs were preceded by LDCAE, but did not trigger a full action potential. The LDCAE preceding DAD‐like DDs had smaller amplitude (0.41 ± 0.08 AU vs 0.48 ± 0.07 AU, P = 0.001) and less steep slopes (3.7 ± 1.3 AU/s vs 4.8 ± 1.4 AU/s, P = 0.001) than that of sinus beats. The coupling interval of DAD‐like DDs was longer than that of the preceding normal beats (407 ± 48 ms vs 371 ± 44 ms, P = 0.002).</P><P> <B> <I>Conclusion:</I> </B> The isoproterenol‐induced LDCAE of superior SAN induced a full action potential in most cases. However, if the LDCAE was too small to trigger an action potential, then it induces only DAD‐like DD. The failure of DAD‐like DD to consistently trigger a sinus beat is a novel mechanism of atrial arrhythmogenesis. <I>(J Cardiovasc Electrophysiol, Vol. 22, pp. 448‐454)</I></P>
Transcriptomes of major renal collecting duct cell types in mouse identified by single-cell RNA-seq
Chen, Lihe,Lee, Jae Wook,Chou, Chung-Lin,Nair, Anil V.,Battistone, Maria A.,Pax306,unescu, Teodor G.,Merkulova, Maria,Breton, Sylvie,Verlander, Jill W.,Wall, Susan M.,Brown, Dennis,Burg, Maurice B. National Academy of Sciences 2017 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.114 No.46
<P><B>Significance</B></P><P>A long-term goal in mammalian biology is to identify the genes expressed in every cell type of the body. In the kidney, the expressed genes (i.e., transcriptome) of all epithelial cell types have already been identified with the exception of the cells that make up the renal collecting duct, which is responsible for regulation of blood pressure and body fluid composition. Here, single-cell RNA-sequencing was used in mouse to identify transcriptomes for the major collecting duct cell types: type A intercalated cells, type B intercalated cells, and principal cells. The information was used to create a publicly accessible online resource. The data allowed identification of genes that are selectively expressed in each cell type, which is informative for cell-level understanding of physiology and pathophysiology.</P><P>Prior RNA sequencing (RNA-seq) studies have identified complete transcriptomes for most renal epithelial cell types. The exceptions are the cell types that make up the renal collecting duct, namely intercalated cells (ICs) and principal cells (PCs), which account for only a small fraction of the kidney mass, but play critical physiological roles in the regulation of blood pressure, extracellular fluid volume, and extracellular fluid composition. To enrich these cell types, we used FACS that employed well-established lectin cell surface markers for PCs and type B ICs, as well as a newly identified cell surface marker for type A ICs, c-Kit. Single-cell RNA-seq using the IC- and PC-enriched populations as input enabled identification of complete transcriptomes of A-ICs, B-ICs, and PCs. The data were used to create a freely accessible online gene-expression database for collecting duct cells. This database allowed identification of genes that are selectively expressed in each cell type, including cell-surface receptors, transcription factors, transporters, and secreted proteins. The analysis also identified a small fraction of hybrid cells expressing aquaporin-2 and anion exchanger 1 or pendrin transcripts. In many cases, mRNAs for receptors and their ligands were identified in different cells (e.g., <I>Notch2</I> chiefly in PCs vs. <I>Jag1</I> chiefly in ICs), suggesting signaling cross-talk among the three cell types. The identified patterns of gene expression among the three types of collecting duct cells provide a foundation for understanding physiological regulation and pathophysiology in the renal collecting duct.</P>
X. S. Fang,J. P. Lin,Y. F. Liang,F. Ye,L. Q. Zhang,G. L. Chen 한국자기학회 2011 Journal of Magnetics Vol.16 No.2
0.30 ㎜ thick and 90 ㎜ wide thin foils made of Fe-6.5wt.%Si alloy were successfully fabricated by traditional rolling. The as-rolled sheets had good shapes and shining metal luster. The effects of annealing temperature on the magnetic properties of the sheets were investigated. Excellent Dc properties (Hc: 11.55 A/m, μm: 23710, and Bs: 1.439 T) were obtained at an annealing temperature of 1453 K for 1.5 h. At low frequencies (≤ 1 ㎑), heat treatment temperature has little effect on iron loss which remained at the level of 9.8 W/㎏. Annealing at 1273 K for 1.5 h is optimum for frequencies above 5 ㎑.
Numerical solution of singular integral equation for multiple curved branch-cracks
Chen, Y.Z.,Lin, X.Y. Techno-Press 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.1
In this paper, numerical solution of the singular integral equation for the multiple curved branch-cracks is investigated. If some quadrature rule is used, one difficult point in the problem is to balance the number of unknowns and equations in the solution. This difficult point was overcome by taking the following steps: (a) to place a point dislocation at the intersecting point of branches, (b) to use the curve length method to covert the integral on the curve to an integral on the real axis, (c) to use the semi-open quadrature rule in the integration. After taking these steps, the number of the unknowns is equal to the number of the resulting algebraic equations. This is a particular advantage of the suggested method. In addition, accurate results for the stress intensity factors (SIFs) at crack tips have been found in a numerical example. Finally, several numerical examples are given to illustrate the efficiency of the method presented.
Lin, P.,Li, S.C.,Xu, Z.H.,Li, L.P.,Huang, X.,He, S.J.,Chen, Z.W.,Wang, J. Techno-Press 2017 Geomechanics & engineering Vol.13 No.6
An innovative spiral variable-section capillary model is established for piping critical hydraulic gradient of cohesion-less soils causing water/mud inrush in tunnels. The relationship between the actual winding seepage channel and grain-size distribution, porosity, and permeability is established in the model. Soils are classified into coarse particles and fine particles according to the grain-size distribution. The piping critical hydraulic gradient is obtained by analyzing starting modes of fine particles and solving corresponding moment equilibrium equations. Gravities, drag forces, uplift forces and frictions are analyzed in moment equilibrium equations. The influence of drag force and uplift force on incipient motion is generally expounded based on the mechanical analysis. Two cases are studied with the innovative capillary model. The critical hydraulic gradient of each kind of sandy gravels with a bimodal grain-size-distribution is obtained in case one, and results have a good agreement with previous experimental observations. The relationships between the content of fine particles and the critical hydraulic gradient of seepage failure are analyzed in case two, and the changing tendency of the critical hydraulic gradient is accordant with results of experiments.
Numerical solution of singular integral equation for multiple curved branch-cracks
Y.Z. Chen,X.Y. Lin 국제구조공학회 2010 Structural Engineering and Mechanics, An Int'l Jou Vol.34 No.1
In this paper, numerical solution of the singular integral equation for the multiple curved branch-cracks is investigated. If some quadrature rule is used, one difficult point in the problem is to balance the number of unknowns and equations in the solution. This difficult point was overcome by taking the following steps: (a) to place a point dislocation at the intersecting point of branches, (b) to use the curve length method to covert the integral on the curve to an integral on the real axis, (c) to use the semi-open quadrature rule in the integration. After taking these steps, the number of the unknowns is equal to the number of the resulting algebraic equations. This is a particular advantage of the suggested method. In addition, accurate results for the stress intensity factors (SIFs) at crack tips have been found in a numerical example. Finally, several numerical examples are given to illustrate the efficiency of the method presented.