bluuebunny/crossref_metadata_2025_split huggingface dataset:
Three-phase voltage outages compensator with cascaded multilevel converter
Authors: Iwaszkiewicz Jan , Bogusławski Piotr , Krahel Antoni , Łowiec Eugeniusz 
Published: September 2012

Three-phase voltage outages compensator with cascaded multilevel converterThe paper presents a laboratory prototype of the three-phase transformerless voltage outages compensator with an energy storage based on high voltage supercapacitors. The system described is able to protect an isolated grid e.g. in industry against short voltage interruptions, dips and sags. An idea of a control method as well as a digital controller has been presented, too.
Research of selected electric and magnetic properties of railway rail
Authors: Kiraga Kamil , Szychta Elżbieta 
Published: September 2012

Research of selected electric and magnetic properties of railway rail
The article presents measurement methods serving to determine electric and magnetic properties of rails (60E1) used to construct railroad turnouts. Knowledge of a rail's electric and magnetic properties is necessary to analyse the phenomena in the rail's internal structure when under impact of a powerful electromagnetic field. The electric and magnetic properties will also help to develop a simulation model of turnout induction heating in 2D and 3D space.
Analysis of three-phases matrix reactance frequency converter with two pulsations of control signal
Authors: Korotyeye Igor , Zięba Beata 
Published: September 2012

Analysis of three-phases matrix reactance frequency converter with two pulsations of control signalThis paper presents a method of calculation of steady-state processes in three-phases matrix-reactance frequency converters (MRFC's), in which voltages and currents are transformed by control signals with two pulsations. A solution of nonstationary differential equations with periodic coefficients that describe this system is obtained by using Galerkin's method and an extension of equations of one variable of time to equations of two variables of time. The results of calculations are presented in an example of three-phases MRFC with buck-boost topology and compared with a numerical method embedded in the program Mathematica.
Modified algorithms of direct power control of AC/DC converter co-operating with the grid
Authors: Kulikowski Krzysztof 
Published: September 2012

Modified algorithms of direct power control of AC/DC converter co-operating with the grid
This paper briefly describes direct power control methods for two- and three-level AC/DC converters and their modified DPC 3 × 2-δ and the DPC 5 × 2-δ algorithms. It also presents two new control methods DPC-3Am (direct power control 3 areas with modification) and the DPC-3L-3Am (direct power control 3 levels 3 areas with modification). The research results were used to compare the described methods. The comparison was based on an average value of switching frequency and current distortion coefficient. Experimental investigations into the methods have shown that the use of the modified DPC methods reduces the number of switchings by more than 70% compared with the standard DPC method.
Analysis and control of dual stator winding induction motor
Authors: Pieńkowski Krzysztof 
Published: September 2012

Analysis and control of dual stator winding induction motor
The paper presents the mathematical models of dual stator squirrel-cage induction motor, formulated in phase coordinate system and in general transformed space vector form. The two types of models of dual stator induction motor are considered. The control systems of field-oriented control (IFOC and DFOC) and direct torque control (DTC) of the dual stator induction motor have been described and discussed.
Thermal-hydraulic issues of flow boiling and condensation in organic Rankine cycle heat exchangers
Authors: Mikielewicz Jarosław , Mikielewicz Dariusz 
Published: September 2012

Thermal-hydraulic issues of flow boiling and condensation in organic Rankine cycle heat exchangers
In the paper presented are the issues related to the design and operation of micro heat exchangers, where phase changes can occur, applicable to the domestic micro combined heat and power (CHP) unit. Analysed is the stability of the two-phase flow in such unit. A simple hydraulic model presented in the paper enables for the stability analysis of the system and analysis of disturbance propagation caused by a jump change of the flow rate. Equations of the system dynamics as well as properties of the working fluid are strongly non-linear. A proposed model can be applicable in designing the system of flow control in micro heat exchangers operating in the considered CHP unit.
Models for water steam condensing flows
Authors: Wróblewski Włodzimierz , Dykas Sławomir , Chmielniak Tadeusz 
Published: September 2012

Models for water steam condensing flows
The paper presents a description of selected models dedicated to steam condensing flow modelling. The models are implemented into an in-house computational fluid dynamics code that has been successfully applied to wet steam flow calculation for many years now. All models use the same condensation model that has been validated against the majority of available experimental data. The state equations for vapour and liquid water, the physical model as well as the numerical techniques of solution to flow governing equations have been presented. For the single-fluid model, the Reynolds-averaged Navier-Stokes equations for vapour/liquid mixture are solved, whereas the two-fluid model solves separate flow governing equations for the compressible, viscous and turbulent vapour phase and for the compressible and inviscid liquid phase. All described models have been compared with relation to the flow through the Laval nozzle.
Pressure drop during condensation of refrigerants in pipe minichannels
Authors: Bohdal Tadeusz , Charun Henryk , Sikora Małgorzata 
Published: September 2012

Pressure drop during condensation of refrigerants in pipe minichannelsThe present paper describes results of experimental investigations of pressure drop during the condensation of R134a, R404a and R407C refrigerants in pipe minichannels with internal diameter 0.31-3.30 mm. The results concern investigations of the mean and local pressure drop in single minichannels. The results of experimental investigations were compared with the calculations according to the correlations proposed by other authors. A pressure drop during the condensation of refrigerants is described in a satisfactory manner with Friedel and Garimella correlations. On the basis of the experimental investigations, the authors proposed their own correlation for calculation of local pressure drop during condensation in single minichannels.
CFD simulation of DEBORA boiling experiments
Authors: Rzehak Roland , Krepper Eckhard 
Published: September 2012

CFD simulation of DEBORA boiling experimentsIn this work we investigate the present capabilities of computational fluid dynamics for wall boiling. The computational model used combines the Euler/Euler two-phase flow description with heat flux partitioning. This kind of modeling was previously applied to boiling water under high pressure conditions relevant to nuclear power systems. Similar conditions in terms of the relevant non-dimensional numbers have been realized in the DEBORA tests using dichlorodifluoromethane (R12) as the working fluid. This facilitated measurements of radial profiles for gas volume fraction, gas velocity, bubble size and liquid temperature as well as axial profiles of wall temperature. After reviewing the theoretical and experimental basis of correlations used in the ANSYS CFX model used for the calculations, we give a careful assessment of the necessary recalibrations to describe the DEBORA tests. The basic CFX model is validated by a detailed comparison to the experimental data for two selected test cases. Simulations with a single set of calibrated parameters are found to give reasonable quantitative agreement with the data for several tests within a certain range of conditions and reproduce the observed tendencies correctly. Several model refinements are then presented each of which is designed to improve one of the remaining deviations between simulation and measurements. Specifically we consider a homogeneous MUSIG model for the bubble size, modified bubble forces, a wall function for turbulent boiling flow and a partial slip boundary condition for the liquid phase. Finally, needs for further model developments are identified and promising directions discussed.
Chaotic air pressure fluctuations during departure of air bubbles from two neighbouring nozzles
Authors: Mosdorf Romuald , Wyszkowski Tomasz 
Published: September 2012

Chaotic air pressure fluctuations during departure of air bubbles from two neighbouring nozzlesIn the experiment, bubbles were generated from two brass nozzles with inner diameters of 1.1 mm. They were submerged in the glass tank filled with distilled water. There have been measured the air pressure fluctuations and the signal from the laser-phototransistor sensor. For analysis of the pressure signal the correlation (the normalized cross - correlation exponent) and non-linear analyses have been used. It has been shown that hydrodynamic interactions between bubbles can lead to bubble departure synchronization. In this case the bubble departures become periodic. The results of calculation of correlation dimension and the largest Lyapunov exponent confirm that hydrodynamic bubble interactions observed for 4 mm spacing between nozzels cause the periodic bubble departures from two neighbouring nozzles.
Target DNA Sequence Directly Regulates the Frequency of Activation-Induced Deaminase-Dependent Mutations
Authors: Chen Zhangguo , Viboolsittiseri Sawanee S. , O’Connor Brian P. , Wang Jing H. 
Published: September 2012

Abstract
Activation-induced deaminase (AID) catalyses class switch recombination (CSR) and somatic hypermutation (SHM) in B lymphocytes to enhance Ab diversity. CSR involves breaking and rejoining highly repetitive switch (S) regions in the IgH (Igh) locus. S regions appear to be preferential targets of AID. To determine whether S region sequence per se, independent of Igh cis regulatory elements, can influence AID targeting efficiency and mutation frequency, we established a knock-in mouse model by inserting a core Sγ1 region into the first intron of proto-oncogene Bcl6, which is a non-Ig target of SHM. We found that the mutation frequency of the inserted Sγ1 region was dramatically higher than that of the adjacent Bcl6 endogenous sequence. Mechanistically, S region-enhanced SHM was associated with increased recruitment of AID and RNA polymerase II, together with Spt5, albeit to a lesser extent. Our studies demonstrate that target DNA sequences influence mutation frequency via regulating AID recruitment. We propose that the nucleotide sequence preference may serve as an additional layer of AID regulation by restricting its mutagenic activity to specific sequences despite the observation that AID has the potential to access the genome widely.
Dectin-1 and IL-17A Suppress Murine Asthma Induced by Aspergillus versicolor but Not Cladosporium cladosporioides Due to Differences in β-Glucan Surface Exposure
Authors: Mintz-Cole Rachael A. , Gibson Aaron M. , Bass Stacey A. , Budelsky Alison L. , Reponen Tiina , Hershey Gurjit K. Khurana 
Published: September 2012

Abstract
There is considerable evidence supporting a role for mold exposure in the pathogenesis and expression of childhood asthma. Aspergillus versicolor and Cladosporium cladosporioides are common molds that have been implicated in asthma. In a model of mold-induced asthma, mice were repeatedly exposed to either A. versicolor or C. cladosporioides spores. The two molds induced distinct phenotypes, and this effect was observed in both BALB/c and C57BL/6 strains. C. cladosporioides induced robust airway hyperresponsiveness (AHR), eosinophilia, and a predominately Th2 response, whereas A. versicolor induced a strong Th17 response and neutrophilic inflammation, but very mild AHR. Neutralization of IL-17A resulted in strong AHR and eosinophilic inflammation following A. versicolor exposure. In Dectin-1–deficient mice, A. versicolor exposure resulted in markedly attenuated IL-17A and robust AHR compared with wild-type mice. In contrast, C. cladosporioides induced AHR and eosinophilic inflammation independent of IL-17A and Dectin-1. A. versicolor, but not C. cladosporioides, spores had increased exposure of β-glucans on their surface and were able to bind Dectin-1. Thus, the host response to C. cladosporioides was IL-17A– and Dectin-1–independent, whereas Dectin-1– and IL-17A–dependent pathways were protective against the development of asthma after exposure to A. versicolor.
SB1578, a Novel Inhibitor of JAK2, FLT3, and c-Fms for the Treatment of Rheumatoid Arthritis
Authors: Madan Babita , Goh Kee Chuan , Hart Stefan , William Anthony D. , Jayaraman Ramesh , Ethirajulu Kantharaj , Dymock Brian W. , Wood Jeanette M. 
Published: September 2012

Abstract
SB1578 is a novel, orally bioavailable JAK2 inhibitor with specificity for JAK2 within the JAK family and also potent activity against FLT3 and c-Fms. These three tyrosine kinases play a pivotal role in activation of pathways that underlie the pathogenesis of rheumatoid arthritis. SB1578 blocks the activation of these kinases and their downstream signaling in pertinent cells, leading to inhibition of pathological cellular responses. The biochemical and cellular activities of SB1578 translate into its high efficacy in two rodent models of arthritis. SB1578 not only prevents the onset of arthritis but is also potent in treating established disease in collagen-induced arthritis mice with beneficial effects on histopathological parameters of bone resorption and cartilage damage. SB1578 abrogates the inflammatory response and prevents the infiltration of macrophages and neutrophils into affected joints. It also leads to inhibition of Ag-presenting dendritic cells and inhibits the autoimmune component of the disease. In summary, SB1578 has a unique kinase spectrum, and its pharmacological profile provides a strong rationale for the ongoing clinical development in autoimmune diseases.
Hepatic Stellate Cells Undermine the Allostimulatory Function of Liver Myeloid Dendritic Cells via STAT3-Dependent Induction of IDO
Authors: Sumpter Tina L. , Dangi Anil , Matta Benjamin M. , Huang Chao , Stolz Donna B. , Vodovotz Yoram , Thomson Angus W. , Gandhi Chandrashekhar R. 
Published: September 2012

Abstract
Hepatic stellate cells (HSCs) are critical for hepatic wound repair and tissue remodeling. They also produce cytokines and chemokines that may contribute to the maintenance of hepatic immune homeostasis and the inherent tolerogenicity of the liver. The functional relationship between HSCs and the professional migratory APCs in the liver, that is, dendritic cells (DCs), has not been evaluated. In this article, we report that murine liver DCs colocalize with HSCs in vivo under normal, steady-state conditions, and cluster with HSCs in vitro. In vitro, HSCs secrete high levels of DC chemoattractants, such as MΙP-1α and MCP-1, as well as cytokines that modulate DC activation, including TNF-α, IL-6, and IL-1β. Culture of HSCs with conventional liver myeloid (m) DCs resulted in increased IL-6 and IL-10 secretion compared with that of either cell population alone. Coculture also resulted in enhanced expression of costimulatory (CD80, CD86) and coinhibitory (B7-H1) molecules on mDCs. HSC-induced mDC maturation required cell–cell contact and could be blocked, in part, by neutralizing MΙP-1α or MCP-1. HSC-induced mDC maturation was dependent on activation of STAT3 in mDCs and, in part, on HSC-secreted IL-6. Despite upregulation of costimulatory molecules, mDCs conditioned by HSCs demonstrated impaired ability to induce allogeneic T cell proliferation, which was independent of B7-H1, but dependent upon HSC-induced STAT3 activation and subsequent upregulation of IDO. In conclusion, by promoting IDO expression, HSCs may act as potent regulators of liver mDCs and function to maintain hepatic homeostasis and tolerogenicity.
Staphylococcus aureus Induces Type I IFN Signaling in Dendritic Cells Via TLR9
Authors: Parker Dane , Prince Alice 
Published: September 2012

Abstract
The importance of type I IFN signaling in the innate immune response to viral and intracellular pathogens is well established, with an increasing literature implicating extracellular bacterial pathogens, including Staphylococcus aureus, in this signaling pathway. Airway epithelial cells and especially dendritic cells (DCs) contribute to the production of type I IFNs in the lung. We were interested in establishing how S. aureus activates the type I IFN cascade in DCs. In vitro studies confirmed the rapid uptake of S. aureus by DCs followed promptly by STAT1 phosphorylation and expression of IFN-β. Signaling occurred using heat-killed organisms and in the absence of PVL and α-toxin. Consistent with the participation of endosomal and not cytosolic receptors, signaling was predominantly mediated by MyD88, TLR9, and IRF1 and blocked by cytochalasin D, dynasore, and chloroquine. To determine the role of TLR9 signaling in the pathogenesis of S. aureus pneumonia, we infected WT and Tlr9−/− mice with MRSA USA300. Tlr9−/− mice had significantly improved clearance of S. aureus from the airways and lung tissue. Ifnar−/− mice also had improved clearance. This enhanced clearance in Tlr9−/− mice was not due to differences in the numbers of recruited neutrophils into the airways, but instead correlated with decreased induction of TNF. Thus, we identified TLR9 as the critical receptor mediating the induction of type I IFN signaling in DCs in response to S. aureus, illustrating an additional mechanism through which S. aureus exploits innate immune signaling to facilitate infection.
Autotaxin through Lysophosphatidic Acid Stimulates Polarization, Motility, and Transendothelial Migration of Naive T Cells
Authors: Zhang Yafeng , Chen Yi-Chun Maria , Krummel Matthew F. , Rosen Steven D. 
Published: September 2012

Abstract
Blood-borne lymphocytes home to lymph nodes by interacting with and crossing high endothelial venules (HEVs). The transendothelial migration (TEM) step is poorly understood. Autotaxin (ATX) is an ectoenzyme that catalyzes the conversion of lysophosphatidylcholine (LPC) to lysophosphatidic acid (LPA), a bioactive lipid and a close relative of sphingosine 1-phosphate. HEVs produce and secrete ATX into the blood. A prior study implicated ATX in the overall homing process, but the step in which it functions and its mechanism of action have not been defined. In this article, we show that HA130, an inhibitor of the enzymatic activity of ATX, slows T cell migration across lymph node HEVs in vivo. Ex vivo, ATX plus LPC or LPA itself induces the polarization of mouse naive T cells and stimulates their motility on an ICAM-1 substratum. Under physiologic shear conditions in a flow chamber, LPA or ATX/LPC strongly enhances TEM of integrin-arrested T cells across an endothelial monolayer. HA130 blunts the TEM-promoting activity of ATX, paralleling its in vivo effects. T cells possess Mn+2-activatable receptors for ATX, which are localized at the leading edge of polarized cells. ATX must bind to these receptors to elicit a maximal TEM response, providing a mechanism to focus the action of LPA onto arrested lymphocytes in flowing blood. Our results indicate that LPA produced via ATX facilitates T cell entry into lymph nodes by stimulating TEM, substantiating an additional step in the homing cascade. This entry role for LPA complements the efflux function of sphingosine 1-phosphate.
Mesenchymal Stem Cell Transplantation Improves Regional Cardiac Remodeling Following Ovine Infarction
Authors: Zhao Yunshan , Li Tieluo , Wei Xufeng , Bianchi Giacomo , Hu Jingping , Sanchez Pablo G. , Xu Kai , Zhang Pei , Pittenger Mark F. , Wu Zhongjun J. , Griffith Bartley P. 
Published: September 2012

AbstractProgressive cardiac remodeling, including the myopathic process in the adjacent zone following myocardial infarction (MI), contributes greatly to the development of cardiac failure. Cardiomyoplasty using bone marrow-derived mesenchymal stem cells (MSCs) has been demonstrated to protect cardiomyocytes and/or repair damaged myocardium, leading to improved cardiac performance, but the therapeutic effects on cardiac remodeling are still under investigation. Here, we tested the hypothesis that MSCs could improve the pathological remodeling of the adjacent myocardium abutting the infarct. Allogeneic ovine MSCs were transplanted into the adjacent zone by intracardiac injection 4 hours after infarction. Results showed that remodeling and contractile strain alteration were reduced in the adjacent zone of the MSC-treated group. Cardiomyocyte hypertrophy was significantly attenuated with the normalization of the hypertrophy-related signaling proteins phosphatidylinositol 3-kinase α (PI3Kα), PI3Kγ, extracellular signal-regulated kinase (ERK), and phosphorylated ERK (p-ERK) in the adjacent zone of the MSC-treated group versus the MI-alone group. Moreover, the imbalance of the calcium-handling proteins sarcoplasmic reticulum Ca2+ adenosine triphosphatase (SERCA2a), phospholamban (PLB), and sodium/calcium exchanger type 1 (NCX-1) induced by MI was prevented by MSC transplantation, and more strikingly, the activity of SERCA2a and uptake of calcium were improved. In addition, the upregulation of the proapoptotic protein Bcl-xL/Bcl-2-associated death promoter (BAD) was normalized, as was phospho-Akt expression; there was less fibrosis, as revealed by staining for collagen; and the apoptosis of cardiomyocytes was significantly inhibited in the adjacent zone by MSC transplantation. Collectively, these data demonstrate that MSC implantation improved the remodeling in the region adjacent to the infarct after cardiac infarction in the ovine infarction model.
Variability in the Generation of Induced Pluripotent Stem Cells: Importance for Disease Modeling
Authors: Vitale Alejandra M. , Matigian Nicholas A. , Ravishankar Sugandha , Bellette Bernadette , Wood Stephen A. , Wolvetang Ernst J. , Mackay-Sim Alan 
Published: September 2012

Abstract
In the field of disease modeling, induced pluripotent stem cells (iPSCs) have become an appealing choice, especially for diseases that do not have an animal model. They can be generated from patients with known clinical features and compared with cells from healthy controls to identify the biological bases of disease. This study was undertaken to determine the variability in iPSC lines derived from different individuals, with the aim of determining criteria for selecting iPSC lines for disease models. We generated and characterized 18 iPSC lines from eight donors and considered variability at three levels: (a) variability in the criteria that define iPSC lines as pluripotent cells, (b) variability in cell lines from different donors, and (c) variability in cell lines from the same donor. We found that variability in transgene expression and pluripotency marker levels did not prevent iPSCs from fulfilling all other criteria for pluripotency, including teratoma formation. We found low interindividual and interclonal variability in iPSCs that fulfilled the most stringent criteria for pluripotency, with very high correlation in their gene expression profiles. Interestingly, some cell lines exhibited reprogramming instability, spontaneously regressing from a fully to a partially reprogrammed state. This was associated with a low percentage of cells expressing the pluripotency marker stage-specific embryonic antigen-4. Our study shows that it is possible to define a similar “ground state” for each cell line as the basis for making patient versus control comparisons, an essential step in order to identify disease-associated variability above individual and cell line variability.