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  • 1
    Electronic Resource
    Electronic Resource
    Stable Secondary Arrhythmias Late After Intraoperative Radiofrequency Ablation of Atrial Fibrillation: (2004)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 15 (2004), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: Intraoperative radiofrequency (RF) ablation is an effective treatment of atrial fibrillation (AF). However, secondary arrhythmias late after ablation may complicate the patient's course. We report on the incidence, mechanisms, and treatment of gap-related atrial flutter and other secondary arrhythmias during long-term follow-up. Methods and Results: In 129 patients who underwent intraoperative RF ablation with placement of left atrial linear lesions using minimally invasive surgical techniques, secondary arrhythmias were analyzed during long-term follow-up (20 ± 6 months). Transient atrial arrhythmias during the first 3 postoperative months were excluded. In 8 (6.2%) of 129 patients, sustained stable secondary arrhythmias were documented. Left atrial, gap-related atrial flutter was observed in 4 patients (3.1%). The flutter was treated by percutaneous RF ablation in 3 patients (2.3%) and with drugs in 1 patient (0.8%). In 2 patients (1.6%), right atrial isthmus-dependent atrial flutter occurred and was treated successfully by percutaneous RF ablation. In 2 patients (1.6%), ectopic right atrial tachycardias occurred and were treated with percutaneous RF ablation. Conclusion: Late after intraoperative RF ablation of atrial fibrillation, three types of stable secondary arrhythmias were observed in 6% of patients: left atrial gap-related atrial flutter, right atrial isthmus-dependent atrial flutter, and ectopic atrial tachycardia. Gaps after intraoperative RF ablation due to noncontinuous or nontransmural linear lesions may lead to stable left atrial macroreentrant tachycardias, requiring new interventional therapy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2004.04356.x
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  • 2
    Electronic Resource
    Electronic Resource
    Topographic Variability of the Esophageal Left Atrial Relation Influencing Ablation Lines in Patients with Atrial Fibrillation (2005)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 16 (2005), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: The close anatomic relationship of the posterior wall of the left atrium (LA) and the thermosensitive esophagus creates a potential hazard in catheter ablation procedures. Methods and Results: In 30 patients (pts) with atrial fibrillation (AF) undergoing catheter ablation, we prospectively studied the course and contact of the esophagus in relation to LA and the topographic proximity to ablation lines encircling the right-sided and left-sided pulmonary veins (PV) as well as to the posterior line connecting the encircling lines using the electromagnetic mapping system for reconstruction of LA and for tagging of the esophagus. This new technique of anatomic tagging of the esophagus was validated against the CT scan as a standard imaging procedure. The esophageal course was highly variable, extending from courses in direct vicinity to the left- or right-sided PV as well as in the midportion of the posterior LA. In order to avoid energy application in direct proximity to the esophagus, adjustments of the left and right PV encircling lines were necessary in 14/30 pts (47%) and 3/30 (10%). In 30 pts (100%), the mid- to inferior areas of the posterior LA revealed contact with the esophagus. Therefore, posterior and inferior linear ablation lines were abandoned and shifted to superior in 29 pts (97%). Conclusions: Anatomic tagging of esophagus revealed a highly variable proximity to different areas of the posterior LA suggesting individual adjustment of encircling and linear ablation lines in AF ablation procedures to avoid the life threatening complication of esophagus perforation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2005.40604.x
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  • 3
    Electronic Resource
    Electronic Resource
    Catheter Ablation of Ventricular Tachycardia in Remote Myocardial Infarction: (2003)
    350 Main Street , Malden , MA 02148-5018 , USA , and 9600 Garsington Road , Oxford OX4 2DQ , UK . : Blackwell Science Inc
    Journal of cardiovascular electrophysiology 14 (2003), S. 0 
    Details
    ISSN: 1540-8167
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Introduction: The aim of this study was to describe the arrhythmogenic substrate in postinfarction patients with ventricular tachycardia (VT) guiding the placement of individual strategic linear lesions transecting all potential isthmuses using target area maps with limited mapping points to allow short procedure times. Methods and Results: In 28 patients with pleomorphic, unstable, and/or incessant VT, electroanatomic voltage mapping was performed in conjunction with limited sinus rhythm mapping, pace mapping, and activation mapping. Radiofrequency (RF) energy was applied directly within the low-voltage areas of the chronically infarcted areas or in the border zone. Ablation lines typically were perpendicular to the course of the presumed central common pathways. The maps consisted of 63 ± 30 mapping points. An average lesion line length of 46 ± 21 mm was placed with 17 ± 7 RF pulses. Twenty-two (79%) of the 28 patients were rendered completely noninducible at the end of the procedure. Procedure time measured 134 ± 41 minutes. No major complications were observed. Six (27%) of 22 patients who were rendered completely noninducible experienced VT recurrence during follow-up versus 4 (67%) of 6 patients who were still inducible after ablation (P = 0.06). Conclusion: Individually tailored substrate description guiding the placement of linear lesion lines transecting potential isthmuses rendered 80% of the patients completely noninducible. The construction of regional target area maps allowed short procedure times, with a resulting low incidence of complications in these critically ill patients. (J Cardiovasc Electrophysiol, Vol. 14, pp. 675-681, July 2003)
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1540-8167.2003.02541.x
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  • 4
    Electronic Resource
    Electronic Resource
    Up-Regulation of NR2B Subunit of NMDA Receptors in Cerebellar Granule Neurons by Ca2+/Calmodulin Kinase Inhibitor KN93 (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Recordings of NMDA-activated currents from cerebellar granule neurons in culture revealed a developmental increase in current density accompanied by a slight decrease of the half-maximal effective concentration. At the same time, a decrease of NMDA receptors comprising NR2B subunits was demonstrated by the reduction in the antagonism of NMDA currents by ifenprodil. Ifenprodil antagonism increased after treatment for 24 h with KN93- and KN62-selective inhibitors of the Ca2+/calmodulin-dependent protein kinases (CaM kinases), indicating a selective increase of receptor containing NR2B subunit. This increase was observed at all ages tested: 4 days in vitro (DIV4), DIV6, and DIV13. Western blot analysis with specific NMDA receptor antibodies performed at DIV6 confirmed the electrophysiological data. At this age, the negative control KN92 was ineffective. The increasing ifenprodil antagonism after KN93 treatment was proportionally greater in cells at DIV13 than at DIV4. Treatment with NMDA (100 µM) of cerebellar cultures for 24 h produced a decrease in the NMDA-induced current density by almost 50% at all ages tested. Ifenprodil antagonism, however, was unchanged. We propose that the expression of NR2B subunits in cerebellar granule cells is selectively stimulated by the inhibition of CaM kinases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.70051898.x
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  • 5
    Electronic Resource
    Electronic Resource
    Developmental changes in localization of NMDA receptor subunits in primary cultures of cortical neurons (1998)
    Oxford, UK : Blackwell Science, Ltd
    European journal of neuroscience 10 (1998), S. 0 
    Details
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Immunoblot analysis, using antibodies against distinct N-methyl-d-aspartic acid (NMDA) receptor subunits, illustrated that the NR2A and NR2B subunit proteins have developmental profiles in cultured cortical neurons similar to those seen in vivo. NR1 and NR2B subunits display high levels of expression within the first week. In contrast, the NR2A subunit is barely detectable at 7 days in vitro (DIV) and then gradually increased to mature levels at DIV21. Immunocytochemical analysis indicated that NMDA receptor subunits cluster in the dendrites and soma of cortical neurons. Clusters of NR1 and NR2B subunits were observed as early as DIV3, while NR2A clusters were rarely observed before DIV10. At DIV18, NR2B clusters partially co-localize with those of NR2A subunits, but NR2B clusters always co-localize with those of NR1 subunits. Synapse formation, as indicated by the presence of presynaptic synaptophysin staining, was observed as early as 48–72 h after plating. However, in several neurons at ages less than DIV5 where synapses were scarce, NR2B and NR1 clusters were abundant. Furthermore, while NR2B subunit clusters were seen both at synaptic and extrasynaptic sites, NR2A clusters occurred almost exclusively in front of synaptophysin-labelled boutons. This result was supported by electrophysiological recording of NMDA-mediated synaptic activity [NMDA-excitatory postsynaptic currents (EPSCs)] in developing neurons. At DIV6, but not at DIV12, CP101, 606, a NR1/NR2B receptor antagonist, antagonized spontaneously occurring NMDA-EPSCs. Our data indicate that excitatory synapse formation occurs when NMDA receptors comprise NR1 and NR2B subunits, and that NR2A subunits cluster preferentially at synaptic sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1460-9568.1998.00169.x
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  • 6
    Electronic Resource
    Electronic Resource
    Separation of Primary Stress in Finite Element Analysis of Pressure Vessel with the Principle of Superposition (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 373-376 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A key problem in engineering application of “design by analysis” approach is how todecompose a total stress field obtained by the finite element analysis into different stress categoriesdefined in the ASME Code III and VIII-2. In this paper, we suggested an approach to separate primarystress with the principle of superposition, in which the structure does not need to be cut into primarystructure but analyzed as a whole only with decomposed load. Taking pressurized cylindrical vesselwith plate head as example, the approach is demonstrated and discussed in detail. The allowable loaddetermined by the supposed method is a little conservative than that determined by limited loadanalysis
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.353-358.373.pdf
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  • 7
    Electronic Resource
    Electronic Resource
    Encapsulated Titanium Oxide with Al〈sub〉2〈/sub〉O〈sub〉3〈/sub〉 and its Ultraviolet Shielding Properties (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 373-374 (Mar. 2008), p. 706-709 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this work, we encapsulated the titanium oxide particles with a layer of Al2O3 by asol-gel process and investigated the UV-shielding properties of the obtained Al2O3-TiO2 composites.In this method, Al(NO3)3 aqueous solution mixed with raw titanium oxide powder was hydrolyzedby adding NH3·H2O. The hydrated materials were calcined at 500°C and then the composite ofAl2O3-TiO2 was prepared. Different techniques including ICP-AES, XRD, SEM-EDS, and TEMwere used to characterize the raw TiO2 and encapsulated TiO2 particles. Chemical analysis showedthat TiO2 mass content in the raw titanium oxide particles is 98.25%, and Al2O3 is just 0.75%. Aftermodification, the percentage Al2O3 was increased to 4.48% due to the encapsulation of Al2O3. Traceelements analysis displayed that the concentration of the trace elements were much lower than theiroriginal content in the raw titanium oxide, which prove that proved that there was no impuritiesincorporated into in the sol-gel process. XRD analysis indicated that the modified titanium oxidepowders are mainly in phase of rutile, ca. 99.1%, and the profiles exhibit no peaks of crystallineAl2O3 suggesting the layer of Al2O3 exists in amorphous phase. SEM image suggests that the size isin 80~600nm of the raw TiO2 granula and became rougher on the surface, the packing of theagglomerations got looser after modification with Al2O3. HRTEM image shows that the TiO2particles was evenly coated with a packed layer ~8 nm in thickness. The UV-Vis absorbencyexperiments showed that the range of wavelength shielded was narrowed from 208-316 nm in theraw titanium oxide to 225-285 nm in the case of the Al2O3-TiO2. The average absorbency of UVwas improved from 1.07 to 1.98 at the same content 1.0 μg/mL in the suspended solution. Theresults reflected that Al2O3 modification process improve the titanium oxide particles UV-shieldingproperties in selectivity and performance
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/57/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.373-374.706.pdf
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  • 8
    Electronic Resource
    Electronic Resource
    A Proposed Thickness Distribution of Elbow Resisting Ratcheting (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Key engineering materials Vol. 353-358 (Sept. 2007), p. 377-380 
    Details
    ISSN: 1013-9826
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: With the analysis of thickness distributions of elbow by the equal-strength criterion andplastic deformation by pushing bending process, an ideal thickness distribution is proposed with theconsideration of elbow processing characteristics to improve its ratcheting resistance. Ratcheting ofelbows under internal pressure and reversed in-plane bending is analyzed with Chaboche model byfinite element method, which shows that elbows with the proposed thickness distribution have greatresistance to ratcheting compared with equal thickness elbows
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/55/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.353-358.377.pdf
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation and Characterization of Functional Geopolymer (2008)
    s.l. ; Stafa-Zurich, Switzerland
    Advanced materials research Vol. 47-50 (June 2008), p. 977-979 
    Details
    ISSN: 1662-8985
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The geopolymer has been prepared from fly ash, metakaolin and Quartz sand, by usingthe liquid sodium silicate as structural template and sodium hydroxide solution as activator. Theeffect of glass fiber on the properties of the geopolymer has been studied
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/01/41/transtech_doi~10.4028%252Fwww.scientific.net%252FAMR.47-50.977.pdf
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  • 10
    Electronic Resource
    Electronic Resource
    Preparation and Characterization of β-SiAlON Ceramics from High Aluminium Fly Ash via Carbothermal Reduction-Nitridation (2007)
    s.l. ; Stafa-Zurich, Switzerland
    Materials science forum Vol. 561-565 (Oct. 2007), p. 587-590 
    Details
    ISSN: 1662-9752
    Source: Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this work, β-sialon ceramics were prepared from high-aluminium fly ash viacarbothermal reduction-nitridation (CRN) and the physicochemical properties of the materials such asbulk density, apparent porosity, water absorption and flexural strength were also discussed. Theresults showed that the percentage of β-sialon phase in the product decreases as the temperatureincreases from 1400°C and the weight of the sintered specimen experienced an increase during1350°C~1450°C due to the nitridation reactions, and followed by a gradual decrease till 1550°C forthe decomposition of β-sialon. It is indicated that the optimum sintering temperature to obtain thehighest yield of β-sialon ~93% lies in 1400°C~1450°C. The SEM images revealed that the preparedβ-sialon sintered at 1400°C were mainly in shape of elongated prisms, typically ~5μm in length and0.5~1μm in width. As the temperature increased to 1500°C and above, β-sialon decomposed and thenew phases of SiC and AlN were formed at 1550°C as confirmed by XRD
    Type of Medium: Electronic Resource
    URL: http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.561-565.587.pdf
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