LUBRICATION SCIENCE, Issue 4 2005
M. A. Kalam
This paper presents the results of an experimental investigation into the wear and lubrication characteristics of a diesel engine using ordinary coconut oil (COIL)-blended fuels. The blended fuels consisted of 10, 20, 30, 40, and 50% COIL with diesel fuel (DF2). Pure DF2 was used for comparison purposes. The engine was operated with 50% throttle setting at a constant speed of 2000 rpm for a period of 100 h with each fuel. The same lubricating oil, equivalent to SAE 40, was used for all fuel systems. A multi-element oil analyser was used to measure wear metals (Fe, Cr, Cu, Al, and Pb), contaminant elements (Si, B, and V), and additive elements (Zn, Ca, P, and Mg) in the used lubricating oil. Fourier transform infrared analysis was performed to measure the degradation products (soot, oxidation, nitration, and sulphation products) in the used lubricant. Karl Fischer (ASTM D 1744) and potentiometric titrations (ASTM D 2896) were used to measure water concentration and total base number (TBN), respectively. An automatic viscometer (ASTM D 445) was used to measure lubricant viscosity. The results show that wear metals and contaminant elements increase with an increasing amount of COIL in DF2. An increasing amount of COIL in the blends reduces additive elements, with the reduction for blends of up to 30% COIL being quite similar to that for DF2. Soot and sulphation decrease with increasing COIL in the blended fuels due to reduced aromatics and sulphur in comparison to DF2. The water concentration increases for blended fuels with more than 30% COIL. The TBN and viscosity changes are found to be almost normal. The engine did not appear to have any starting and combustion problems when operating with the COIL-blended fuels. The lubricating oil analysis data from this study will help in the selection of tribological components and compatible lubricating oils for coconut oil- or biofuel-operated diesel engines. [source]

Electronic subretinal implants allow blind retinitis pigmentosa patients to read letters and recognize the direction of fine stripe patterns

ACTA OPHTHALMOLOGICA, Issue 2009
E ZRENNER
Purpose Restoration of letter reading and stripe pattern recognition in blind RP patients by placing subretinal implants transchoroidally near the macula, consisting of two arrays: 4x4 electrodes controlled retroauricularly via a subdermal line for direct stimulation ("DS array") and a "chip" (3x3x0,1 mm),1500 electrodes. Methods Letters and stripe pattern were presented to 3 patients via the light sensitive chip , by patterns steadily presented at a screen. On the DS array the sensation evoked by each individual pulse consists of whitish round dot, clearly separated from its neighbor. Patterns consisting of such 4 x 4 dots correspond to letters of approximately 5 cm diameter presented at 60 cm distance. Results Pat.1 correctly (20/24) recognized the direction of the letter "U", presented with the opening in four different directions (DS array). Pat.2 correctly (12/12) differentiated letters via DS array (e.g. COIL). With the light sensitive chip, he correctly (22/24) differentiated letters (e.g. LITZ; 8,5 cm high, 1.7 cm line width) steadily presented on a screen at 62 cm distance Pat.3 recognized (15/20 correct, 4AFC) the direction of lines or stripe patterns with the chip, as did Pat.1 (11/14, 2AFC) and Pat.2 (11/12 4AFC) up to 0.35 cycles/deg. Conclusion Active subretinal multielectrode implants with currents close to produce retinotopically correct patterns that allow for the first time recognition of individual letters and stripe patterns up to 0.35 cycles/deg clearly supporting the feasibility of light sensitive subretinal multi-electrode devices for restoration of useful vision. [source]

Transcatheter Closure of Congenital Ventricular Septal Defects: Experience with Various Devices

JOURNAL OF INTERVENTIONAL CARDIOLOGY, Issue 1 2003
RAMESH ARORA D.M.
Transcatheter closure of congenital ventricular septal defect (VSD) using various devices is gaining acceptance in selected cases of perimembranous and muscular defects, avoiding the inherent risks of cardiopulmonary bypass. The procedure was attempted in 137 patients having congenital defects using Rashkind Umbrella Device (RUD) in 29 patients, Amplatzer ventricular septal occluder (AVSO) in 107 patients, and Detachable Coil in one. All patients were selected using stringent criteria by detailed transthoracic echocardiography and/or transesophageal echocardiography. The location of VSD was perimembranous in 91 patients and was muscular trabecular in 46 patients. Seven patients had left ventricle (LV) to right atrium (RA) communication. Thirty-five patients with perimembranous and two with muscular VSD had aneurysm formation. The patients were 3 to 33 years old, and the diameter of VSD ranged from 3 to 12 mm. The pulmonary to systemic flow ratio was ,2:1 in 47 (34.3%) patients. The procedure was successful in 130 (94.8%) patients, with a success rate of 86.2% with RUD and 97.1% with AVSO. Residual shunt at 24 hours was seen in eight (32%) patients with RUD and in one patient (0.9%) with AVSO. Three (2.8%) developed transient bundle branch block, and two (1.9%) patients had complete heart block. New tricuspid stenosis and tricuspid regurgitation was observed in one patient each with AVSO. After immediate balloon dilatation, the mean pressure gradient across tricuspid valve decreased from 11 to 3 mmHg in the patient with tricuspid stenosis. On a follow-up of 1 to 66(mean 35.2 ± 10.7)months, the device was in position in all. None developed late conduction defect, aortic regurgitation, infective endocarditis, or hemolysis. At 9-month follow-up, the mean pressure gradient across the tricuspid valve was 3 mmHg in the patient with tricuspid stenosis. Complete occlusion of the shunt was achieved in 129 (99.2%) patients. One patient with RUD having persistent residual shunt underwent a second procedure with AVSO. Three out of 107 patients with AVSO had an unsuccessful procedure where the defect was perimembranous with a superior margin of defect less than 3 mm away from the aortic valve, and the specially designed perimembranous AVSO had to be retrieved because of hemodynamic compromise due to significant acute aortic regurgitation, whereas in all others, the defect was either ,3 mm away from the aortic valve or had aneurysm formation. All seven patients with LV to RA communication showed complete abolition of the shunt. Thus, in properly selected cases of perimembranous and muscular ventricular septal defects, the transcatheter closure is safe and efficacious using appropriate devices. The success rate is higher with AVSO compared with the previously used devices, as well as more successful for the muscular defects than those that are perimembranous in location. (J Interven Cardiol 2003;16:83,91) [source]

Extraction of the Inner Coil of a Pacemaker Lead Slid into the Pulmonary Artery

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2 2007
F.E.S.C., PIER GIORGIO GOLZIO M.D.
A patient required lead extraction for chronic draining sinus, due to abandoned leads. Preoperatively, the chest film showed a filament in the right pulmonary artery: it was the inner coil of an old atrial lead that, while remaining anchored to the auricle, slid outside the outer coil. By right subclavian approach, the old ventricular lead and the outer coil of the atrial lead were removed. Then, by right jugular approach, the freely floating end of theinner atrial coil was grasped by a pig-tail catheter, drawn back into the superior vena cava, exteriorized by a Lasso catheter, and finally extracted. [source]

RE,Coil: An Antimicrobial Peptide Regulator

ANGEWANDTE CHEMIE, Issue 51 2009
Maxim
Mal aktiv, mal inaktiv: Ein Peptidsystem, das für die Regulierung antimikrobieller Wirkungen entwickelt wurde, schaltet zwischen antimikrobiellen und inaktiven Formen um. Der Regulator besteht aus zwei ,-helicalen Sequenzen: Eine, das R-Knäuel, bindet an Mikroben-Membranen, fungiert als antimikrobielle Komponente und wird durch die andere, das E-Knäuel, ein membraninaktives Peptid, desaktiviert (siehe Bild). [source]

Configuration Studies on the Heliotron Fusion Energy Reactor with Split-Type Helical Coils

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 6-7 2010
N. Yanagi
Abstract Configuration optimization is examined for the heliotron fusion energy reactor FFHR in order to find sufficient clearances between the ergodic region outside the nested magnetic surfaces and blankets at the inboard side of the torus. The standard configuration of FFHR, which is similar to that of LHD, has a relatively large major radius of the helical coils in order to satisfy this requirement. It has been found, as an alternative design, that equivalent clearances are obtained with a shorter major radius both by employing a lower helical pitch parameter and splitting the helical coils in the poloidal cross-section at the outboard side. Splitting the helical coils also provides another configuration that ensures magnetic well formation in the fairly large nested magnetic surfaces with outward shifted configurations. Optimization is being carried out for these configurations by adjusting the pitch modulation parameter to improve the particle confinement (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Transarterial Coil Embolization of Patent Ductus Arteriosus in Small Dogs with 0.025-Inch Vascular Occlusion Coils: 10 Cases

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2004
Daniel F. Hogan
Patent ductus arteriosus (PDA) is the most common congenital cardiac disease in the dog and generally leads to severe clinical signs, including left-sided congestive heart failure. Historically, definitive treatment consisted of surgical ligation; however, the use of vascular occlusion devices by minimally invasive techniques has gained popularity in veterinary medicine during the past decade. Adequate vascular access is a major limiting factor for these minimally invasive techniques, precluding their use in very small dogs. The clinical management of PDA with 0.025-in vascular occlusion coils in a minimally invasive transarterial technique in 10 dogs is described. The dogs were small (1.38 ± 0.22 kg), were generally young (6.70 ± 5.74 months), and had small minimal ductal diameters (1.72 ± 0.81 mm from angiography). Vascular access was achieved, and coil deployment was attempted in all dogs with a 3F catheter uncontrolled release system. Successful occlusion, defined as no angiographic residual flow, was accomplished in 8 of 10 (80%) dogs. Successful occlusion was not achieved in 2 dogs (20%), and both dogs experienced embolization of coils into the pulmonary arterial tree. One of these dogs died during the procedure, whereas the other dog underwent a successful surgical correction. We conclude that transarterial PDA occlusion in very small dogs is possible with 0.025-in vascular occlusion coils by means of a 3F catheter system and that it represents a viable alternative to surgical ligation. The risk of pulmonary arterial embolization is higher with this uncontrolled release system, but this risk may decrease with experience. [source]

Transvenous Embolization of Small Patent Ductus Arteriosus with Single Detachable Coils in Dogs

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 3 2001
Matthias Schneider
Transvenous embolization of small patent ductus arteriosus (PDA; , 4 mm) with a single detachable coil was attempted in 24 dogs (median age 5.7 months, range, 2.6,65.5 months; median body weight 5.5 kg, range, 1.5,30.0 kg). Angiographic imaging of the duct and pressure measurements were made before and after embolization. The minimal ductal diameter was 2.7 ± 0.7 mm. In all dogs, a single coil was employed regardless of residual shunting. Ten dogs (PDA minimal diameter range, 1.5-2.2 mm) received a 5-mm coil, and 14 dogs (PDA minimal diameter range, 2.9-3.6 mm) received a 8-mm coil. After coil embolization the angiographic shunt grade decreased significantly (n = 20, P < .001). Residual shunts were assessed by angiography 15 minutes after and by Doppler echocardiography 1,3 days and 3 months after the intervention. In the dogs treated with the 5-mm coils the residual shunt rate was low (0%, 10%, and 0% for angiography and Doppler echocardiography at 1,3 days and 3 months, respectively), in contrast to the dogs treated with the 8-mm coils (91%, 79%, and 67% for angiography and Doppler echocardiography at 1,3 days and 3 months, respectively). After 3 months, no residual murmur was found in dogs treated with the 5-mm coils (0/7), in contrast to murmurs in 5 of 12 (42%) dogs treated with the 8-mm coils. Despite incomplete closure in these dogs, volume loading of the left heart decreased in all dogs. Pulmonic or aortic coil embolism did not occur. Analysis of initial results shows that single detachable coil embolization is possible in all dogs with a small PDA (, 4 mm), but only very small PDA (s 2.5) could be treated effectively, and for the moderate PDA (2.6-4.0 mm) longer coils or multiple coils may be necessary to achieve complete occlusion. [source]

Transcatheter Closure of Patent Ductus Arteriosus Using Occluding Spring Coils

JOURNAL OF VETERINARY INTERNAL MEDICINE, Issue 4 2000
A. A. Stokhof
The purpose of this study is to report our initial experience with the use of spring coils to close the patent ductus arteriosus in the dog. There are few large-patient series reported in the veterinary literature. Coil closure was attempted in 15 dogs (median weight, 6.5 kg; range, 1.2 to 38.7 kg) presenting with a patent ductus arteriosus between May 1997 and May 1999. Arterial catheterization followed by angiography was used to decide if coil placement was adequate. A 5- or 8-mm embolization coil, depending on the angiographic diameter of the ductus, was delivered, with 1 loop in the pulmonary arterial side and the remainder of the coil in the aortic side of the duct. Additional coils were used if a residual shunt was present, and closure was confirmed by aortography. Patients were discharged the day after the procedure. Successful coil closure, without residual shunt on angiography, was achieved in 11 of 13 dogs in which coils were released. In 6 dogs, a coil embolized to the pulmonary artery. Four of these dogs had successful closure with multiple coils, and 2 others had surgery. None of these dogs experienced adverse effects. In 2 dogs with conical patent ductus arteriosus >5 mm in minimal diameter, coil closure was not done. We conclude that the patent ductus arteriosus size and anatomical shape are crucial in deciding whether coil closure is the method of choice. In selected cases, coil closure represents an elegant alternative to surgical ligation. Although pulmonary embolism occurred commonly, it did not cause any obvious clinical problem. [source]

A New Transcutaneous Energy Transmission System With Hybrid Energy Coils for Driving an Implantable Biventricular Assist Device

ARTIFICIAL ORGANS, Issue 8 2009
Eiji Okamoto
Abstract:, We have developed a new transcutaneous energy transmission (TET) system for a totally implantable biventricular assist device (BVAD) system in the New Energy and Industrial Development Organization (NEDO) artificial heart project. The TET system mainly consists of an energy transmitter, a hybrid energy coil unit, an energy receiver, an internal battery system, and an optical telemetry system. The hybrid energy coil unit consists of an air-core energy transmission coil and an energy-receiving coil having a ferrite core. Internal units of the TET system are encapsulated in a titanium alloy casing, which has a size of 111 mm in width, 73 mm in length, and 25 mm in height. In in vitro experiments, the TET system can transmit a maximum electric energy of 60 Watts, and it has a maximum transmission efficiency of 87.3%. A maximum surface temperature of 46.1°C was measured at the ferrite core of the energy-receiving coil during an energy transmission of 20 Watts in air. The long-term performance test shows that the TET system has been able to operate stably for over 4 years with a decrease of energy-transmission efficiency from 85% to 80%. In conclusion, the TET system with the hybrid energy coil can overcome the drawback of previously reported TET systems, and it promises to be the highest performance TET system in the world. [source]

The Application of 199Hg NMR and 199mHg Perturbed Angular Correlation (PAC) Spectroscopy to Define the Biological Chemistry of HgII: A Case Study with Designed Two- and Three-Stranded Coiled Coils

CHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2007
Olga Iranzo Dr.
Abstract The use of de novo designed peptides is a powerful strategy to elucidate HgII,protein interactions and to gain insight into the chemistry of HgII in biological systems. Cysteine derivatives of the designed ,-helical peptides of the TRI family [Ac-G-(LaKbAcLdEeEfKg)4 -G-NH2] bind HgII at high pH values and at peptide/HgII ratios of 3:1 with an unusual trigonal thiolate coordination mode. The resulting HgII complexes are good water-soluble models for HgII binding to the protein MerR. We have carried out a parallel study using 199Hg NMR and 199mHg perturbed angular correlation (PAC) spectroscopy to characterize the distinct species that are generated under different pH conditions and peptide TRI,L9C/HgII ratios. These studies prove for the first time the formation of [Hg{(TRI,L9C)2 -(TRI,L9CH)}], a dithiolate,HgII complex in the hydrophobic interior of the three-stranded coiled coil (TRI,L9C)3. 199Hg NMR and 199mHg PAC data demonstrate that this dithiolate,HgII complex is different from the dithiolate [Hg(TRI,L9C)2], and that the presence of third ,-helix, containing a protonated cysteine, breaks the symmetry of the coordination environment present in the complex [Hg(TRI,L9C)2]. As the pH is raised, the deprotonation of this third cysteine generates the trigonal thiolate,HgII complex Hg(TRI,L9C)3, on a timescale that is slower than the NMR timescale (0.01,10,ms). The formation of the species [Hg{(TRI,L9C)2(TRI,L9CH)}] is the result of a compromise between the high affinity of HgII to form dithiolate complexes and the preference of the peptide to form a three-stranded coiled coil. [source]

The Molecular Basis of Self-Assembly of Dendron,Rod,Coils into One-Dimensional Nanostructures

CHEMISTRY - A EUROPEAN JOURNAL, Issue 28 2006
Eugene R. Zubarev Prof.
Abstract We describe here a comprehensive study of solution and solid-state properties of self-assembling triblock molecules composed of a hydrophilic dendron covalently linked to an aromatic rigid rod segment, which is in turn connected to a hydrophobic flexible coil. These dendron,rod,coil (DRC) molecules form well-defined supramolecular structures that possess a ribbonlike morphology as revealed by transmission-electron and atomic-force microscopy. In a large variety of aprotic solvents, the DRC ribbons create stable networks that form gels at concentrations as low as 0.2,% by weight DRC. The gels are thermally irreversible and do not melt at elevated temperatures, indicating high stability as a result of strong noncovalent interactions among DRC molecules. NMR experiments show that the strong interactions leading to aggregation involve mainly the dendron and rodlike blocks, whereas oligoisoprene coil segments remain solvated after gelation. Small-angle X-ray scattering (SAXS) profiles of different DRC molecules demonstrate an excellent correlation between the degree-of-order in the solid-state and the stability of gels. Studies on two series of analogous molecules suggest that self-assembly is very sensitive to subtle structural changes and requires the presence of at least four hydroxyl groups in the dendron, two biphenyl units in the rod, and a coil segment with a size comparable to that of the rodlike block. A detailed analysis of crystal structures of model compounds revealed the formation of stable one-dimensional structures that involve two types of noncovalent interactions, aromatic ,,, stacking and hydrogen bonding. Most importantly, the crystal structure of the rod,dendron compound shows that hydrogen bonding not only drives the formation of head-to-head cyclic structures, but also generates multiple linkages between them along the stacking direction. The cyclic structures are tetrameric in nature and stack into ribbonlike objects. We believe that DRC molecules utilize the same arrangement of hydrogen bonds and stacking of aromatic blocks observed in the crystals, explaining the exceptional stability of the nanostructures in extremely dilute solutions as well the thermal stability of the gels they form. This study provides mechanistic insights on self-assembly of triblock molecules, and unveils general strategies to create well-defined one-dimensional supramolecular objects. [source]

The origins and present status of the radio wave controversy in NMR

CONCEPTS IN MAGNETIC RESONANCE, Issue 4 2009
D.I. Hoult
Abstract The origins, history, and present status of the controversy surrounding a quantum description of the NMR signal as being due to radio waves are traced. With the Principle of Relativity and Coulomb's Law as formal starting points and the minimum of mathematics needed for understanding, the derivation of a classical electromagnetic theory of signal reception is first given. The agreement between that classical theory and a recent NMR experiment is then presented, leading to proof that, except for the highest field imaging experiments, there is no significant contribution of radio waves to the signal. Attention is drawn to the very different properties of the near and far energy, momenta, and fields inherent in the derivation. The role of the Correspondence Principle in formulating a quantum description is then emphasized and it is shown that the standard NMR interpretation of Dicke's theory of coherent spontaneous emission,that the latter is responsible for the NMR signal,cannot be correct. Finally, the author speculates on some of the intriguing relationships found in the classical electrodynamics of NMR signal reception and attempts to relate them to a common quantum electrodynamic precept of near field interaction: that the free induction decay voltage present at the terminals of an open-circuit receiving coil is based on an exchange of virtual photons between the nuclei in a sample and the free electrons in a receiving coil. © 2009 Crown in the right of Canada. Concepts Magn Reson Part A 34A: 193,216, 2009. [source]

A simple method to calculate the signal-to-noise ratio of a circular-shaped coil for MRI

CONCEPTS IN MAGNETIC RESONANCE, Issue 6 2006
K. Ocegueda
Abstract The introduction of the ultrafast imaging sequences has renewed the interest in development of RF coils. The theoretical frame of the SNR of MRI coils is a challenge because it requires a deep mathematical background to master the associated concepts. Here, a simpler method is proposed based on Legendre polynomials. This approximation method, together with a quasi-static approach, was used to derive a signal-to-noise ratio expression for a circular-shaped coil. Legendre polynomials were used instead of a weighting function to simplify the vector potential of the power loss, and an SNR formula was then derived. The simplified version of the SNR formula of a circular coil was compared with the weighting function-derived SNR expression using the quasi-static approach. SNR-vs.-depth plots were computed to theoretically compare both SNR formulas. Results showed a strong agreement between SNR values for the circular-shaped coil. This approach can be used as a tool to derive SNR expressions for more complex geometries. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part A 28A: 422,429, 2006 [source]

Use of mutually inductive coupling in probe design,

CONCEPTS IN MAGNETIC RESONANCE, Issue 4 2002
D.I. Hoult
Abstract An analysis is presented of mutually inductive coupling in probe design. It is assumed that near field couplings predominate and that lumped constants may therefore be employed. Using three published designs as examples, analytic techniques are presented for assessing B1 field strength, losses, and signal-to-noise ratio in increasingly complex situations. The perturbing effect of the B1 field from a matching coil is examined and it is shown that if the coil is too close to the sample there can be an asymmetry introduced in the rotating frame B1 field. It is then shown that such asymmetries are potentially a general feature of inductively coupled, loaded coils. The importance of suppressing unwanted resonances is highlighted if tuning and matching are to be orthogonal, a potential advantage of mutually inductive matching. Finally, a lumped-constant simulation is briefly described for those situations where an analytic approach becomes too cumbersome. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 262,285, 2002 [source]

Solenoidal microcoil design,Part II: Optimizing winding parameters for maximum signal-to-noise performance

CONCEPTS IN MAGNETIC RESONANCE, Issue 3 2001
Kevin R. Minard
Abstract In high-field proton NMR, the signal-to-noise ratio (SNR) achieved with a close-fitting solenoidal microcoil is adversely affected by radio frequency (RF) losses in the coil, its leads, the capacitor used to tune it, and finally, the sample. In Part II, a rigorous description of these various losses is presented, and their severity is related to the details of coil design. Results not only provide a rational basis for defining a microcoil's optimal wire diameter and the number of turns, but also for evaluating how the SNR varies with coil size and NMR frequency in high-field proton NMR studies involving either conducting or non-conducting samples. © 2001 John Wiley & Sons, Inc. Concepts Magn Reson 13: 190,210, 2001 [source]

Extrapolation of the W7-X Magnet System to Reactor Size

CONTRIBUTIONS TO PLASMA PHYSICS, Issue 8 2010
F. Schauer
Abstract The fusion experiment Wendelstein 7-X (W7-X), presently under construction at the Greifswald branch institute of IPP, shall demonstrate the reactor potential of a HELIAS stellarator. HELIAS reactors with three, four and five periods have been studied at IPP since many years. With a plasma axis induction of 5 T, corresponding to about 10 T maximal induction at the coil, it was shown that such reactors are feasible. Now the possibility is being investigated to increase the conductor induction up to the 12 T , range, corresponding to > 5.5 T at the plasma axis. This improves the stellarator confinement properties but does not change the basic physics with respect to the previously analyzed machines. In particular the 5periodic HELIAS type, HSR5, is considered which evolves from W7-X by linear scaling of the main dimensions by a factor of four. Recent progress in superconductor technology and the extensive development work performed for ITER are taken into account. The latter is particularly relevant since by coincidence the circumferences of the HSR5 and the ITER toroidal field coils are practically the same. For the presented 12 T reactor version, the HSR50a, also the conductor and structural requirements are comparable to the corresponding ITER specifications. Therefore, advantage can be taken of these similarities for the stellarator reactor magnet design. The input was provided by the new code "MODUCO" which was developed for interactive coil layout. It is based on Bézier curve approximations and includes the computation of magnetic surfaces and forces (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Numerical investigation of heat transport and fluid flow during the seeding process of oxide Czochralski crystal growth Part 1: non-rotating seed

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2007
M. H. Tavakoli
Abstract For the seeding process of oxide Czochralski crystal growth, the flow and temperature field of the system as well as the seed-melt interface shape have been studied numerically using the finite element method. The configuration usually used initially in a real Czochralski crystal growth process consists of a crucible, active afterheater, induction coil with two parts, insulation, melt, gas and non-rotating seed crystal. At first the volumetric distribution of heat inside the metal crucible and afterheater inducted by the RF coil was calculated. Using this heat source the fluid flow and temperature field were determined in the whole system. We have considered two cases with respect to the seed position: (1) before and (2) after seed touch with the melt. It was observed that in the case of no seed rotation (,seed = 0), the flow pattern in the bulk melt consists of a single circulation of a slow moving fluid. In the gas domain, there are different types of flow motion related to different positions of the seed crystal. In the case of touched seed, the seed-melt interface has a deep conic shape towards the melt. It was shown that an active afterheater and its location with respect to the crucible, influences markedly the temperature and flow field of the gas phase in the system and partly in the melt. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Study on minute surface structures of the depressed-type early gastric cancer with magnifying endoscopy

DIGESTIVE ENDOSCOPY, Issue 3 2001
Kouji Tobita
Background: Gastric surface patterns and morphology of minute surface vessels in depressed lesions were analyzed using a magnifying endoscope with high resolving power to contribute to qualitative diagnosis of gastric cancer. Methods: Subjects were diagnosed with depressed-type early gastric cancer (pT1), there were 63 lesions, 38 differentiated-type lesions, and 25 undifferentiated-type lesions. There were also 40 benign depressed lesions found. After routine observations with an endoscope, amplifying observations of lesions were made by EG-410CR (Fuji Photo Optical; Saitama, Japan) (CR). The images were compared with macroscopic patterns and histopathological patterns of the surgical specimens and endoscopic mucosal resection specimens. Results: Surface patterns of gastric depressed lesions were classified as irregular protrusion, normal papilla, pseudopapilla and amorphia. Irregular protrusion was found only in cancerous lesions. Characteristic minute vessels were observed in amorphia. Their patterns were classified into the following six types: sand, fence, round net, flat net, branch and coil. Irregular protrusion and minute vessels in amorphia (round net, flat net, branch and coil) were specific to cancers. There was a tendency for round net and flat net patterns to be found often in differentiated cancers and for branch and coil patterns to be found often in undifferentiated cancers. Conclusion: This magnifying endoscopic classification is considered useful for the qualitative diagnosis of depressed-type early gastric cancer. [source]

A zone-control induction heating (ZCIH) system for semiconductor processing

ELECTRICAL ENGINEERING IN JAPAN, Issue 1 2010
Hideaki Fujita
Abstract This paper proposes a new induction heating technology capable of controlling a precise exothermic distribution, which is termed zone-control induction heating (ZCIH). The ZCIH system consists of two or more sets of a high-frequency inverter unit and a work coil. The inverter units control the phase angle of the coil current to be in phase with each other. The ZCIH has the capability of operation with the mutual inductance, and enables locating the coils as close as possible. As a result, the ZCIH technology makes it possible to achieve rapid heating performance with extremely precise exothermic distribution. This paper presents experimental results of a 150-kW six-zone ZCIH system for semiconductor heat processing. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(1): 37,45, 2010; Published online in Wiley InterScience (www.interscience. wiley.com). DOI 10.1002/eej.20908 [source]

Application of the equivalent multipole moment method with polar translations to forward calculation of neuromagnetic fields

ELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 4 2008
Shoji Hamada
Abstract This paper describes an application of the equivalent multipole moment method (EMMM) with polar translations to calculation of magnetic fields induced by a current dipole placed in a human head model. Although the EMMM is a conventional Laplacian field solver based on spherical harmonic functions, the polar translations enable it to treat eccentric and exclusive spheres in arbitrary arrangements. The head model is composed of seven spheres corresponding to skin, two eyeballs, skull, cerebral spinal fluid, gray matter, and white matter. The validity of the calculated magnetic fields and the magnetic flux linkages with a loop coil located near the model is successfully confirmed by the reciprocity theorem derived by Eaton. © 2008 Wiley Periodicals, Inc. Electron Comm Jpn, 91(4): 34,44, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10079 [source]

Repeated high-frequency transcranial magnetic stimulation over the dorsolateral prefrontal cortex reduces cigarette craving and consumption

ADDICTION, Issue 4 2009
Revital Amiaz
ABSTRACT Aims To evaluate the effect of repeated high-frequency transcranial magnetic stimulation (rTMS) of the left dorsolateral prefrontal cortex (DLPFC), combined with either smoking or neutral cues, on cigarette consumption, dependence and craving. Design Participants were divided randomly to real and sham stimulation groups. Each group was subdivided randomly into two subgroups presented with either smoking-related or neutral pictures just before the daily TMS intervention. Ten daily rTMS sessions were applied every week-day and then a maintenance phase was conducted in which rTMS sessions were less frequent. Setting Single-site, out-patient, randomized, double-blind, sham-controlled. Participants Forty-eight chronic smokers who smoked at least 20 cigarettes per day and were motivated to quit smoking. Healthy males and females were recruited from the general population using advertisements in newspapers and on internet websites. Intervention Ten daily rTMS sessions were administered using a standard figure-8 coil over the DLPFC. Stimulation included 20 trains/day at 100% of motor threshold. Each train consisted of 50 pulses at 10 Hz with an inter-train interval of 15 seconds. Measurements Cigarette consumption was evaluated objectively by measuring cotinine levels in urine samples and subjectively by participants' self-reports. Dependence and craving were evaluated by standard questionnaires. Findings Ten daily rTMS sessions over the DLPFC reduced cigarette consumption and nicotine dependence. Furthermore, treatment blocked the craving induced by daily presentation of smoking-related pictures. However, these effects tended to dissipate over time. Conclusions Multiple high-frequency rTMS of the DLPFC can attenuate nicotine craving. [source]

Electrospun Silk Fibroin Mats for Tissue Engineering

ENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 3 2008
A. Alessandrino
Abstract Processing Silk Fibroin (SF) with electrospinning (ES) offers a very attractive opportunity for producing a variety of 2D and 3D matrices with great potential for tissue regeneration and repair due to the superior biocompatibility and mechanical properties of SF. Different combinations of ES parameters were explored to investigate the best experimental set-up related to the dimension and uniformity of the fibers in the electrospun silk fibroin (ES-SF) mats. Using SEM it was found that the ES-SF mats contain uniform fibers with a diameter in the nanometric range obtained by electrospinning a 7.5,% w/v SF solution in formic acid, with an electric field of 2.4,kV/cm and a spinneret-collector distance of 10,cm. FT-IR and DSC analyses were performed to investigate the structure of the ES-SF mats before and after immersion in methanol for different times (5, 10, and 15,min). The methanol treatment was able to promote the crystallization of SF by conformational transition of random coil and other poorly ordered conformations (turns and bends) to the ,-sheet structure. The degree of crystallinity was enhanced as shown by the trend of both the FT-IR crystallinity index and the melting/decomposition peak temperature (from DSC). To study the cytocompatibility of ES-SF mats, tests with L929 murine fibroblasts were carried out. Samples were seeded with the cells and incubated for 1, 3, and 7,days at 37,°C. At each time point, SEM investigations and Alamar blue tests were performed. The SEM images showed cell adhesion and proliferation just after 1,day and cell confluence at 7,days. Alamar blue test demonstrated that there were very low differences between cell viability on ES-SF mats and the tissue culture plastic control. [source]

Slow Repetitive TMS for Drug-resistant Epilepsy: Clinical and EEG Findings of a Placebo-controlled Trial

EPILEPSIA, Issue 2 2007
Roberto Cantello
Summary:,Purpose: To assess the effectiveness of slow repetitive transcranial magnetic stimulation (rTMS) as an adjunctive treatment for drug-resistant epilepsy. Methods: Forty-three patients with drug-resistant epilepsy from eight Italian Centers underwent a randomized, double-blind, sham-controlled, crossover study on the clinical and EEG effects of slow rTMS. The stimulus frequency was 0.3 Hz. One thousand stimuli per day were given at the resting motor threshold intensity for 5 consecutive days, with a round coil at the vertex. Results:"Active" rTMS was no better than placebo for seizure reduction. However, it decreased interictal EEG epileptiform abnormalities significantly (p < 0.05) in one-third of the patients, which supports a detectable biologic effect. No correlation linked the rTMS effects on seizure frequency to syndrome or anatomic classification, seizure type, EEG changes, or resting motor threshold (an index of motor cortex excitability). Conclusions: Although the antiepileptic action was not significant (p > 0.05), the individual EEG reactivity to "active" rTMS may be encouraging for the development of more-powerful, noninvasive neuromodulatory strategies. [source]

High-resolution MRI Enhances Identification of Lesions Amenable to Surgical Therapy in Children with Intractable Epilepsy

EPILEPSIA, Issue 8 2004
Monisha Goyal
Summary:,Purpose: Many children with refractory epilepsy can achieve better seizure control with surgical therapy. An abnormality on magnetic resonance imaging (MRI), along with corroborating localization by other modalities, markedly increases chances of successful surgical outcome. We studied the impact of high-resolution MRI on the surgical outcome of intractable epilepsy. Methods: High-resolution MRI using four-coil phased surface array was obtained as part of the comprehensive presurgical protocol for children with focal onset intractable seizures evaluated by our epilepsy center during the first half of 2002. Results: Thirteen consecutive children, ages 5 to 18 years, entered this prospective study. For four patients with a lesion on a recent MRI examination with a standard head coil, management did not change with high-resolution MRI. Standard MRI in the other nine patients did not identify a lesion. However, high-resolution MRI with the phased-array surface coil found previously undiagnosed focal abnormalities in five of nine patients. These abnormalities included hippocampal dysplasia, hippocampal atrophy, and dual pathology with frontal cortical dysplasia. In four of nine patients, no identifiable lesion was identified on the high-resolution MRI. All patients underwent invasive monitoring. In three of five patients, newly diagnosed lesions correlated with EEG abnormalities, and resection was performed. Conclusions: In our center, high-resolution MRI identified lesions not detected by standard MRI in more than half the children (56%). Technical advances such as four-coil phased surface array MRI can help identify and better delineate lesions, improving the diagnosis of patients who are candidates for surgical treatment of refractory epilepsy. [source]

Task-induced modulation of motor evoked potentials in upper-leg muscles during human gait: a TMS study

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 11 2002
Mireille Bonnard
Abstract The aim of this study was to determine the relative involvement of the corticospinal (CS) pathway in voluntarily controlled walking compared to unconstrained walking. In the voluntarily controlled walking condition, subjects had to walk at the same speed as in unconstrained walking with a mechanical constraint, which is known to affect specifically the upper-leg muscles. The motor cortex was activated transcranially using a focal magnetic stimulation coil in order to elicit motor evoked potentials (MEPs) in the rectus femoris (RF) and the biceps femoris (BF). The magnetic stimulation was delivered at the end of the swing (at 90% of the cycle duration), when the EMG backgrounds were similar in the two experimental conditions. For each subject in each condition, MEPs were measured for several stimulus intensities in order to establish the input/output (I/O) curve (MEPs amplitude plotted against stimulus strength). The results showed a significant increase in the MEPs amplitude of both the RF and BF in voluntarily controlled walking compared to unconstrained walking, which is the first evidence of cofacilitation of MEPs in antagonist upper-leg muscles during human gait. In conclusion, although a lot of studies have emphasized a privileged input of the corticospinal pathway to the distal lower-leg muscles, this study shows that, if a locomotory task requires fine control of the proximal upper-leg muscles, a selective facilitation of MEPs is observed in these muscles. [source]

Design of an estimator of the kinematics of AC contactors

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 7 2009
Jordi-Roger Riba Ruiz
Abstract This paper develops an estimator of the kinematics of the movable parts of any AC powered contactor. This estimator uses easily measurable electrical variables such as the voltage across the coil terminals and the current flowing through the main coil of the contactor. Hence, a low cost microcontroller would be able to implement a control algorithm in order to reduce the undesirable phenomenon of contact bounce, which causes severe erosion of the contacts and dramatically reduces the electrical life and reliability of the contacts. To develop such an estimator is essential to have at our disposal a robust model of the contactor. Therefore, a rigorous parametric model that allows us to predict the dynamic response of the AC contactor is proposed. It solves the mechanic and electromagnetic coupled differential equations that govern the dynamics of the contactor by applying a Runge,Kutta-based solver. Several approaches have been described in the technical literature. Most of them are based on high cost computational finite elements method or on simplified parametric models. The parametric model presented here takes into account the fringing flux and deals with shading rings interaction from a general point of view, thus avoiding simplified assumptions. Copyright © 2008 John Wiley & Sons, Ltd. [source]

An experimental study on the transformer coil leakage current

EUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 3 2006
Mohamed A. A. Wahab
This paper is concerned with the transformer coil dc leakage current under different conditions. These conditions include in-air, and in-oil leakage, currents with or without artificial coil deposits. In-oil leakage, currents are investigated when the coil is immersed in new or used transformer oil at different temperatures. The results showed that the leakage current increases with the increase in the applied voltage and oil temperatures. The rate of increase in leakage current with temperature depends on the transformer oil and coil conditions. The in-oil leakage currents are higher than those obtained in air. The leakage currents measured in used oil are higher than those resulted in new oil. Copper deposits cause higher values of leakage current than iron deposits for the same medium, applied voltage and temperature. Deposits increase the leakage current for different coil surrounding media. A linear model for the leakage current as a function of the applied voltage under different conditions has been found and its validity has been justified by statistical consideration. The parameters of this model account for various experimental conditions. Copyright © 2006 John Wiley & Sons, Ltd. [source]

LIN54 is an essential core subunit of the DREAM/LINC complex that binds to the cdc2 promoter in a sequence-specific manner

FEBS JOURNAL, Issue 19 2009
Fabienne Schmit
Recently, the conserved human LINC/DREAM complex has been described as an important regulator of cell cycle genes. LINC consists of a core module that dynamically associates with E2F transcription factors, p130 and the B-MYB transcription factor in a cell cycle-dependent manner. In this study, we analyzed the evolutionary conserved LIN54 subunit of LINC. We found that LIN54 is required for cell cycle progression. Protein interaction studies demonstrated that a predicted helix,coil,helix motif is required for the interaction of LIN54 with p130 and B-MYB. In addition, we found that the cysteine-rich CXC domain of LIN54 is a novel DNA-binding domain that binds to the cdc2 promoter in a sequence-specific manner. We identified two binding sites for LIN54 in the cdc2 promoter, one of which overlaps with the cell cycle homology region at the transcriptional start site. Gel shift assays suggested that, in quiescent cells, the binding of LIN54 at the cell cycle homology region is stabilized by the binding of E2F4 to the adjacent cell cycle-dependent element. Our data demonstrate that LIN54 is an important and integral subunit of LINC. Structured digital abstract ,,MINT-7239362: LIN54 (uniprotkb:Q6MZP7) physically interacts (MI:0915) with p130 (uniprotkb:Q08999) by anti tag coimmunoprecipitation (MI:0007) ,,MINT-7239376: LIN54 (uniprotkb:Q6MZP7) physically interacts (MI:0915) with B-Myb (uniprotkb:P10244) by anti tag coimmunoprecipitation (MI:0007) [source]

Crystal structures of Nipah and Hendra virus fusion core proteins

FEBS JOURNAL, Issue 19 2006
Zhiyong Lou
The Nipah and Hendra viruses are highly pathogenic paramyxoviruses that recently emerged from flying foxes to cause serious disease outbreaks in humans and livestock in Australia, Malaysia, Singapore and Bangladesh. Their unique genetic constitution, high virulence and wide host range set them apart from other paramyxoviruses. These characteristics have led to their classification into the new genus Henpavirus within the family Paramyxoviridae and to their designation as Biosafety Level 4 pathogens. The fusion protein, an enveloped glycoprotein essential for viral entry, belongs to the family of class I fusion proteins and is characterized by the presence of two heptad repeat (HR) regions, HR1 and HR2. These two regions associate to form a fusion-active hairpin conformation that juxtaposes the viral and cellular membranes to facilitate membrane fusion and enable subsequent viral entry. The Hendra and Nipah virus fusion core proteins were crystallized and their structures determined to 2.2 Å resolution. The Nipah and Hendra fusion core structures are six-helix bundles with three HR2 helices packed against the hydrophobic grooves on the surface of a central coiled coil formed by three parallel HR1 helices in an oblique antiparallel manner. Because of the high level of conservation in core regions, it is proposed that the Nipah and Hendra virus fusion cores can provide a model for membrane fusion in all paramyxoviruses. The relatively deep grooves on the surface of the central coiled coil represent a good target site for drug discovery strategies aimed at inhibiting viral entry by blocking hairpin formation. [source]