bluuebunny/crossref_metadata_2025 huggingface dataset:
Real‐Time Monitoring of Luminal Esophageal Temperature During Left Atrial Radiofrequency Catheter Ablation for Atrial Fibrillation: Observations About Esophageal Heating During Ablation at the Pulmonary Vein Ostia and Posterior Left Atrium
Authors: PERZANOWSKI CHRISTIAN , TEPLITSKY LIANE , HRANITZKY PATRICK M. , BAHNSON TRISTRAM D.
Published: January 2006

Introduction: Left atrial radiofrequency catheter ablation (RFA) is gaining acceptance as treatment for drug‐refractory atrial fibrillation (AF). This therapy has been associated with esophageal injury and atrioesophageal fistula formation causing death.

Methods: We describe 3 patients undergoing catheter ablation for AF during real‐time monitoring of luminal esophageal temperature.

Results: We observed heating of the esophagus during short duration low power RFA, at either the left or right pulmonary vein ostia. Cryoablation at the pulmonary vein ostium in one patient resulted in esophageal cooling. Furthermore, we observed that fluoroscopic localization of the ablation catheter at a site apparently distant from the esophagus is not adequate to assure avoidance of ablation‐induced esophageal heating.

Conclusions: Real‐time monitoring of luminal esophageal position and temperature is feasible, enhances recognition of esophageal heating, and may add useful information beyond that provided by fluoroscopic assessment of esophageal position. There is a potential role for esophageal monitoring to help avoid thermal injury to the esophagus during catheter ablation for atrial fibrillation.
Chronic Myocardial Infarction is a Substrate for Bradycardia‐Induced Spontaneous Tachyarrhythmias and Sudden Death in Conscious Animals
Authors: KILLINGSWORTH CHERYL R. , WALCOTT GREGORY P. , GAMBLIN TRACY L. , GIROUARD L.V.T.,* STEVEN D. , SMITH WILLIAM M. , IDEKER RAYMOND E.
Published: January 2006

Introduction: Patients with bradycardia can have severe tachyarrhythmias but it is unclear whether bradycardia alone can induce arrhythmias or whether an additional substrate is necessary. While several animal models of ventricular tachycardia (VT) exist, no model has been reported to mimic the clinical condition of spontaneous VT and sudden cardiac death (SCD) in the presence of bradycardia and chronic myocardial infarction (MI) in large animals without manipulation of the autonomic nervous system. We tested the hypothesis that MI and bradycardia cause more spontaneous sustained VT than does bradycardia alone.

Methods and Results: Sheep (42–56 kg) underwent atrioventricular (AV) node catheter ablation alone (n = 5) or AV node ablation and 150 minutes of angioplasty balloon occlusion of the left anterior descending coronary artery (n = 9). An implantable cardioverter defibrillator delivered rescue shocks and demand pacing at 90 beats per minute for the first week and at 40 beats per minute thereafter. Electrograms were continuously radiotelemetered and recorded for 6 weeks. Acute post‐MI VT disappeared by day 4. The sudden bradycardia on day 8 triggered numerous premature ventricular contractions (PVCs) and episodes of sustained VT lasting >30 seconds during the next 5 weeks. There were 43 episodes of sustained VT and no spontaneous ventricular fibrillation (VF) with bradycardia alone. However, in the presence of both MI and bradycardia there were 970 episodes of VT/VF (P < 0.05) and three deaths at days 13, 15, and 34. The average 24‐hour count of PVCs was similar at day 7 between the two groups but by days 11 and 40, the PVC counts were 35 times and 4 times greater, respectively, in the presence of bradycardia and chronic MI compared to bradycardia alone. No significant difference in the incidence of PVCs was detected because of large individual variation between the two groups (P = 0.21). A high PVC count did not appear to predict SCD.

Conclusion: The combination of MI and bradycardia secondary to AV node ablation in sheep produces a higher incidence of VT than bradycardia alone, suggesting that this preparation can serve as a model for the study of VT and sudden cardiac death.
Defibrillation Energy Requirements in an ICD Population Receiving Cardiac Resynchronization Therapy
Authors: SCHUGER CLAUDIO , ELLENBOGEN KENNETH A. , FADDIS MITCHELL , KNIGHT BRADLEY P. , YONG PATRICK , SAMPLE ROSS ,   for the VENTAK CHF/CONTAK CD Study Investigators
Published: January 2006

Objectives: While defibrillation energy requirements (DERs) have been extensively studied in patients receiving conventional defibrillators, the DERs of patients receiving cardiac resynchronization therapy with defibrillation capability (CRT‐D) devices have not been well described. The purpose of this analysis was to characterize DERs (defined as true threshold or the presence of appropriate safety margins) in patients undergoing implant of a CRT‐D and to determine whether DERs in this population were similar to those reported for patients undergoing implantation of conventional defibrillators.

Methods: Data were analyzed retrospectively from the VENTAK CHF/CONTAK CD biventricular pacing study. An appropriate safety margin of at least 10 J was verified with at least two successful conversions with 21 J or less. Multivariate logistic regression was performed to determine baseline predictors of failed DER testing.

Results: Of 501 patients enrolled, 444 (89%) had successful DER test outcomes. Of the remaining 57 patients, 34 converted with energies ≥21J, and 23 had their testing terminated prematurely or were not tested, primarily due to patient condition. Larger left ventricular internal dimension in diastole (P = 0.003) and prolonged procedure time (P = 0.01) were significant predictors of higher energy requirements. Few significant complications arose from DER testing.

Conclusions: DER testing can be accomplished safely and successfully in the majority of CRT‐D patients. However, safety margins cannot be ascertained in a significant number of these patients. Left ventricular inner diameter in diastole (LVIDd) and prolonged procedure time may predict higher DERs, and could be used to anticipate the need for a high‐energy device or inclusion of a subcutaneous array.
Seasonal changes in clinical status in bipolar disorder: a prospective study in 1000 STEP‐BD patients
Authors: Friedman E. , Gyulai L. , Bhargava M. , Landen M. , Wisniewski S. , Foris J. , Ostacher M. , Medina R. , Thase M.
Published: January 2006

Objective:  To investigate seasonal and regional effects on bipolar I and II patients.

Method:  The Systematic Treatment Enhancement Program for Bipolar Disorder (STEP‐BD) patients were prospectively examined for monthly change in prevalence rates of depressed and recovered clinical status over the year. General Estimating Equation modeling was used to assess the effect of season on prevalence rates. Additionally, patients were stratified by bipolar subtype and by region.

Results:  A significantly higher prevalence rate of depression is observed in the northern sites, a significant prevalence by month effect is found only in the bipolar II patients.

Conclusion:  The prevalence of depression is greater in patients from the northern vs. southern STEP‐BD sites. Seasonal peak prevalence rates of depression differ by region. Bipolar II patients were more ill year‐round and demonstrated greater monthly fluctuation in prevalence rates of being ill than did bipolar I patients. We conclude that seasonal effects upon bipolar patients vary by region and bipolar subtype.
Self‐help treatments for disorders of recurrent binge eating: a systematic review
Authors: Stefano S. C. , Bacaltchuk J. , Blay S. L. , Hay P.
Published: January 2006

Objective:  To evaluate self‐help interventions for patients with binge eating disorder (BED) and bulimia nervosa (BN), tested in randomized controlled trials, and compared with waiting list or any other type of control group.

Methods:  A systematic review including quality appraisal was conducted of randomized controlled trials, using self‐help techniques in patients with BED and/or BN. Six databases were searched during the period between January 1994 and June 2004.

Results:  A total of 2686 articles were identified, 1701 abstracts were evaluated in detail and, nine studies fulfilled the inclusion criteria for this review. All studies indicated that patients treated with active interventions had a reduced number of binge eating episodes at end of treatment.

Conclusion:  The results support self‐help interventions but shall be interpreted with caution. Because of the small number of studies using self‐help techniques for BED and BN, further larger randomized, multi‐center controlled studies that apply standardized inclusion criteria, evaluation instruments and self‐help materials, are needed.
The effects of implant surface roughness and surgical technique on implant fixation in an in vitro model
Authors: Shalabi Manal M. , Wolke Johannes G. C. , Jansen John A.
Published: January 2006

Objectives: The aim of the present study was to determine the relationship between implant surface parameters, surgical approach and initial implant fixation.

Material and methods: Sixty tapered, conical, screw‐shaped implants with machined or etched surface topography were implanted into the explanted femoral condyle of goats. The implant sites were prepared either by a conventional technique, by undersized preparation, or by the osteotome technique. Peak insertion & removal torque, bone‐to‐implant contacts (BIC) and morphological bone appearance were assessed by scanning electron microscope (SEM) and micro‐computer tomography. (micro‐CT).

Results: Insertion and removal torque values were significantly higher for etched implants inserted with the undersized technique (115.2±31.1, 102.9±36.4 N cm) respectively. Also, the average BIC value was higher for the etched implants placed with the undersized technique (87.5±5.6), which was statistically significant compared with machined and etched implants inserted by conventional technique.

Conclusion: In conclusion, this study shows that the surgical technique has a decisive effect on implant fixation (represented in this study by installation torque value/removal torque value and histomorphometric evaluation) in trabecular bone. Nevertheless, additional in vivo studies have to be done to prove the importance of surgical protocol for the final implant–bone response.
Structural and radiological parameters for the characterization of jawbone
Authors: Stoppie Nele , Pattijn Veerle , Van Cleynenbreugel Tim , Wevers Martine , Sloten Jos Vander , Ignace Naert
Published: January 2006

Objectives: The aim of this study was to determine the Hounsfield values of selected bone sites on a computed tomography (CT) scan of the jaw and to investigate the relationship between this radiological parameter and structural parameters.

Materials and methods: A selection of 24 bone samples out of eight cadaver human jaws was made. The following parameters were measured: Hounsfield value in the jaw (HU1) determined by a first CT scan, Hounsfield value of the excised bone specimen (HU2) by a second CT scan, bone mineral density (BMD) by a dual‐energy X‐ray absorptiometry scan, bone volume (BV/TV) by the microfocus CT scan, first peak transmission time (TUS‐1) and first zero crossing transmission time (TUS‐2) by an ultrasound measurement and Young's modulus (EMECH) by a compression test.

Results: Thirteen specimens were composed of a mix of trabecular and a small amount of cortical bone, while another 11 specimens were composed of trabecular bone only. A good correlation was found between the HU value of the specimen (HU2) and BMD (ρ=0.99), BV/TV (ρ=0.97), TUS‐1 (ρ=−0.83), TUS‐2 (ρ=−0.87) and EMECH (ρ=0.83). For the pure trabecular bone specimens, the HU value of the excised bone specimen (HU2) was highly correlated (ρ=0.95) with the HU value of the total jaw scan (HU1). For mixed trabecular–cortical bone specimens, this relationship was weak (ρ=0.57).

Conclusion: With the current CT scan technology, predictions of the mechanical properties of trabecular jaw bone based on Hounsfield values were only valid for jaws with a thin layer of cortical bone. For jaws with a thicker cortical layer, the prediction of the mechanical properties decreased significantly.
Osteogenic differentiation induced by bone morphogenetic proteins can be suppressed by platelet‐released supernatant in vitro
Authors: Gruber Reinhard , Kandler Barbara , Fischer Michael B. , Watzek Georg
Published: January 2006

Abstract: Both bone morphogenetic proteins (BMPs) and growth factors released from activated platelets both occur at sites of bone regeneration but their functional relationship to regulate the temporal and spatial sequence of cellular events is not well defined. Here we investigated whether supernatants derived from activated platelets can modulate the response of the osteogenic cell line MC3T3‐E1 to BMPs, and whether BMPs have an effect on MC3T3‐E1 cells stimulated with platelet‐released supernatant. Platelet‐released supernatant suppressed BMP‐2‐, BMP‐6‐, and BMP‐7‐induced osteogenic differentiation of MC3T3‐E1 cells, as indicated by the significant decrease in alkaline phosphatase activity and lower levels of osteocalcin transcripts, whereas BMP‐2, BMP‐6, and BMP‐7 did not modulate migration and proliferation of MC3T3‐E1 cells, which were stimulated with platelet‐released supernatant. Osteogenic differentiation in response to BMPs was not affected after precultivation of MC3T3‐E1 cells with platelet‐released supernatant. These data suggest that activated platelets can provide a microenvironment that temporarily suppresses the differentiation of osteogenic cells in the presence of BMPs. Future strategies to stimulate bone regeneration should take the suppression of BMP‐induced osteogenic differentiation during the existence of the blood clot into account.
Orofacial/cerebral injuries and the use of mouthguards by professional athletes in Switzerland
Authors: Lieger Olivier , Von Arx Thomas
Published: January 2006

Abstract –  The objective of the present study was to measure the occurrence of orofacial and cerebral injuries in different sports and to survey the awareness of athletes and officials concerning the use of mouthguards during sport activities. Two hundred and sixty‐seven professional athletes and 63 officials participating in soccer, handball, basketball and ice hockey were interviewed. The frequency of orofacial and cerebral trauma during sport practice was recorded and the reason for using and not using mouthguards was assessed. A great difference in orofacial and cerebral injuries was found when comparing the different kinds of sports and comparing athletes with or without mouthguards. 45% of the players had suffered injuries when not wearing mouthguards. Most injuries were found in ice hockey, (59%), whereas only 24% of the soccer players suffered injuries when not wearing mouthguards. Sixty‐eight percentage of the players wearing mouthguards had never suffered any orofacial and cerebral injuries. Two hundred and twenty‐four athletes (84%) did not use a mouthguard despite general acceptance by 150 athletes (56%). Although the awareness of mouthguards among officials was very high (59%), only 25% of them would support the funding of mouthguards and 5% would enforce regulations. Athletes as well as coaches should be informed about the high risk of oral injuries when performing contact sports. Doctors and dentists need to recommend a more intensive education of students in sports medicine and sports dentistry, and to increase their willingness to become a team dentist.
Multidisciplinary approach to the rehabilitation of a crown‐root fracture with original fragment for immediate esthetics: a case report with 4‐year follow‐up
Authors: Öz İ. Attila , Haytaç M. Cenk , Toroǧlu M. Serdar
Published: January 2006

Abstract –  Dental practitioners frequently encounter dentoalveolar traumas. According to the severity of the trauma, a large spectrum of complications such as isolated tooth fracture, dentoalveolar fracture or fracture at maxillofacial region may occur. If the isolated tooth fracture occurs particularly at anterior region, the rehabilitation should satisfy both esthetic and functional problems. An unrestorable tooth should be extracted and this leads to more complex treatments such as implant or conventional prosthetic rehabilitations, which will restore the function, but impair the esthetics. Recently, powerful new generation dual‐cured resin composites have been produced for reattachment of original fractured fragments. In this case, we presented treatment of oblique crown‐root fracture of a maxillary central tooth from enamel‐cement junction by the reattachment technique. We used dual cured resin composite (Panavia F®) and a self‐tapping screw‐post (Dentatus®) for reattaching the crown fragment. Orthodontic treatment was applied for intruding and leveling the tooth. Four years after treatment, the tooth exhibited good esthetics, good periodontal health and normal function. However, minimal relapse occurred in spite of orthodontic treatment. In conclusion, the reattachment technique is an alternative method, which offers satisfactory esthetic and functional rehabilitation of the fractured teeth.
Mandibular fracture 2 weeks after third molar extraction
Authors: Komerik Nurgul , Karaduman Ayse Ilknur
Published: January 2006

Abstract –  This case report describes mandibular fracture after the surgical extraction of fully erupted lower third molar of a 53‐year‐old healthy male patient. The fracture occurred 15 days after the extraction while chewing. The fracture line extended from the apex of the mesiobuccal root socket to the inferior border of the mandible. Follow‐up of the patient was agreed as the patient was not willing to carry on further treatment. Bony union was observed radiologically 3 months later.
Long‐term effect of different treatment modalities for traumatized primary incisors presenting dark coronal discoloration with no other signs of injury
Authors: Holan Gideon
Published: January 2006

Abstract –  The aim was to compare the long‐term outcomes of root canal treatment with that of follow‐up‐only in traumatized primary incisors in which dark discoloration is the only sign of injury. Root canal treatment was performed in 48 dark discolored asymptomatic primary incisors following trauma. Twenty‐five of them [root canal treatment (RCT) group] were followed till eruption of their permanent successors. Ninety‐seven dark discolored asymptomatic primary incisors were left untreated and invited for periodic clinical and radiographic examination. Of these, 28 [follow‐up (FU) group] were followed till eruption of their permanent successors. The parameters examined included early extraction of the traumatized primary incisor, early or delayed eruption of the permanent successors, ectopic eruption of the permanent successor and signs of enamel hypopcalcification or hypoplasia in the permanent successor. Chi‐square test was used for statistical analysis. Seven of 25 (28%) of the RCT group and 32% (nine of 28) of the FU group required early extraction. Five of 25 (20%) of the RCT group and 21% (six of 28) of the FU group showed early or delayed eruption of the permanent successors. Sixteen of 25 (64%) of the RCT group and 79% (22 of 28) of the FU group showed ectopic eruption of the permanent successors. Enamel hypopcalcification or hypoplasia in the permanent successors was equally found (36%) in both groups (nine of 25 in the RCT group and 10 of 28 in the FU group). None of differences was statistically significant. Root canal treatment of primary incisors that had change their color into a dark‐gray hue following trauma with no other clinical or radiographic symptom is not necessary as it does not result in better outcomes in the primary teeth and their permanent successors.
Three‐dimensional bone microstructures of the mandibular angle using micro‐CT and finite element analysis: relationship between partially impacted mandibular third molars and angle fractures
Authors: Takada Hideki , Abe Shinichi , Tamatsu Yuichi , Mitarashi Satoshi , Saka Hideki , Ide Yoshinobu
Published: January 2006

Abstract –  The mandibular angle is one of the areas of the mandible that are prone to bone fractures, and the presence of an impacted third molar has been found to be associated with increased risk of angle fractures. The factors involved in bone fractures are the amount and direction of load, and the biomechanical and anatomical properties of bone. In the present study, micro‐focused X‐ray computed tomography was performed to observe and analyze the three‐dimensional (3D) bone microstructure of the mandibular angle, and finite element analysis was conducted to examine the relationship between angle fractures and the presence or absence of mandibular third molars. 3D bone microstructure showed no marked difference between mandibles with and without third molars. Finite element analysis showed that, in the mandible with a third molar, stress was concentrated around the root apex of the third molar, and was transmitted in a direction matching the clinical findings of angle fractures. The results obtained in this study suggest that the presence of an impacted third molar changes the concentration and transmission of stress in the mandible, thus increasing the risk of an angle fracture.
In vitro clonogenic capacity of periodontal ligament fibroblasts cultured with Emdogain
Authors: Ashkenazi Malka , Shaked Ilanit
Published: January 2006

Abstract –  The aim of the present study was to evaluate the efficiency of Emdogain (EMD) in preserving the size of the periodontal ligament progenitor pool (clonogenic capacity) and in promoting their proliferation. Periodontal ligament fibroblasts (PDLF) were obtained from explants of young permanent healthy tooth. After initial outgrowth (10 days to 2 weeks following explantation), the culture medium of experimental flasks was replaced with medium supplemented with 100 μg ml−1 EMD, whereas the other served as controls and were fed with regular medium. Following 5 weeks, the cells were washed (3×), harvested (trypsin + EDTA), and evaluated for their viability. Viable cells from each group were inoculated into six 96‐well plates at a concentration of one viable cell per two wells and were allowed to grow for 5 weeks. The percentage of cells with clonogenic capacity was determined as the number of colonies formed/number of cells seeded × 100 in the experimental and control groups. Three degrees of dish area coverage were utilized: up to 25%, between 25% and 75% and higher than 75%. This experiment was repeated four times from four different donors. A total of 2328 cells were evaluated, half of which, were cultured with EMD. The mean percentage of cells (from all donors) who exhibited any clonogenic capacity in the presence of EMD was comparable with that of cells cultured in the absence of EMD: 26.6 ± 14.3% when compared with 34.6 ± 20.6% respectively (P = 0.186). Similarly, the percentage of clones that proliferated to cover up to 25% of the well area was comparable in the two groups 7.5 ± 8.6 for EMD‐treated clones and 7.1 ± 7.8 for untreated clones (P = 0.674). The percentage of clones that proliferated to cover 25% up to 75% of the well area was greater EMD‐treated clones as compared with the untreated cells: 8.1 ± 6.7% vs 3.8 ± 3%. However this difference was not statistically significant (P = 0.277). In contrast, the percentage of clones that covered more than 75% of the well area was significantly lower in the EMD‐treated clones when compared with the untreated clones (10.9 ± 11.1 vs 23.8 ± 14.7; P = 0.022) . In conclusion, EMD decreased the percentage of PDLF with capabilities of arising colonies with 75–100% confluency probably by increasing their differentiation.
Morphometric and microscopic evaluation of the effect of solution of acetazolamide as an intracanal therapeutic agent in late reimplanted rat teeth
Authors: Mori Graziela Garrido , Garcia Roberto Brandão , Gomes de Moraes Ivaldo
Published: January 2006

Abstract –  The use of substances that inhibit root resorption may be an alternative for cases of unsuccessful reimplants. Hence, the purpose of this study was to test a solution of acetazolamide, a resorption inhibitor, as an intracanal therapeutic agent for late reimplanted teeth. Thirty rat maxillary right central incisors were avulsed and kept dry for 30 min. The teeth were instrumented, and the root surfaces treated with 1% hypochlorite solution followed by application of 2% sodium fluoride. Thereafter, the teeth were divided into two groups according to the intracanal dressing: Group I, solution of acetazolamide and Group II, calcium hydroxide paste. Teeth were then reimplanted in their respective sockets. The animals were killed at 15, 30, and 60 days after reimplantation and the samples processed for morphometric and microscopic analysis. The results showed that calcium hydroxide paste limited root resorption, even though not avoiding it. In contrast, no root resorption was observed after 60 days in the acetazolamide group, confirming the efficacy of the substance in inhibiting root resorption.
Radiofrequency haemorrhoid surgery: An alternative to newer treatment of haemorrhoids
Authors: Gupta Pravin J.
Published: January 2006

Background:  The author describes his experience of treatment of advanced haemorrhoidal disease using a technique called radiofrequency ablation and plication of haemorrhoids.

Patients and Methods:  Both male and female patients presenting with prolapsing haemorrhoids with indications for surgery were enrolled for the study. An Ellman radiofrequency generator was used for ablation of haemorrhoids. The surgical technique and clinical follow up of patients operated by this technique is presented. Patients were initially called at 7, 14 and 30 postoperative days and then at least 2 years after the procedure. Results in terms of mean hospital stay, postoperative pain, postoperative complications, period of incapacity for work and effectiveness of the procedure are presented.

Results:  1260 patients operated with this technique were assessed. The average duration of operation was 7 min (range 5–9 min). Mean hospital stay was 11 h (range 6–23 h). The immediate postoperative complication included secondary bleeding, retention of urine and perianal thrombosis. The mean period of incapacity for work was 8 days (range 6–14 days). The mean analgesic requirement was 20 tablets of Tramadol (range 14–33). At the last follow up, 2% of patients had recurrence of bleeding and 6% developed anal skin tags.

Conclusion:  The procedure of radiofrequency ablation and plication of haemorrhoids shows promising results in patients with advanced haemorrhoidal disease. Being safe, effective, and a swift technique, it can be proposed as an alternative to conventional surgical procedures.
Fatal spontaneous haemorrhage in Von Recklinghausen's disease
Authors: Tsang Chi‐Sum , Tan Tze‐Ching , Chan Alexander Chak‐Lam , Cheung Fung‐Ching
Published: January 2006

Spontaneous bleeding of neurofibroma is a rare complication in Von Recklinghausen's disease. We report a case of sudden death of a patient who had undergone laminectomy for excision of cervical neurofibroma.
Comparison of computerized tomography angiography and digital subtraction angiography in ruptured cerebral aneurysm surgery
Authors: Poon Tak‐Lap , Ho Wai‐Shing , Pang Kai‐Yuen , Wong Chi‐Keung
Published: January 2006

Objective:  The aim of the present study was to review the efficacy of 16‐row multislice computerized tomography angiography (CTA) in ruptured cerebral aneurysm surgery by comparison with conventional digital subtraction angiography (DSA).

Methods:  A systemic review of patients suffering from ruptured cerebral aneurysm was performed. We report the results obtained during the 19‐month period from April 2003 to October 2004. In total, 32 patients had undergone aneurysm surgeries, in which 11 patients had both DSA and CTA performed.

Results:  Among the 11 patients with both DSA and CTA performed, two aneurysms were missed in DSA in two patients. The sensitivity and specificity of CTA were 100%. The correlation of CTA with DSA in operative findings was 100%. Our CTA could detect the aneurysm size down to 2 mm in diameter.

Conclusion:  The diagnostic accuracy of 16‐row multislice CTA is promising and it compares well with DSA for detection and evaluation of ruptured cerebral aneurysms. It is safe and effective to establish treatment decision on the basis of CTA alone in the majority of cases.
Hybrid optical maskless lithography: Scaling beyond the 45nm node
Authors: Fritze M. , Bloomstein T. M. , Tyrrell B. , Fedynyshyn T. H. , Efremow N. N. , Hardy D. E. , Cann S. , Lennon D. , Spector S. , Rothschild M. , Brooker P.
Published: January 2006

Optical lithography at 193nm with resolution enhancements and immersion is widely expected to meet the needs of the 45nm node. Beyond this, at 32nm and below, the solution is not as clear. In this article we present simulation results and experimental demonstrations of an all-optical approach capable of high-throughput 32nm lithography (hybrid optical maskless lithography). In this method high-resolution dense gratings are defined in a first exposure using maskless interference lithography. A second “trim” exposure, using conventional projection lithography, customizes these gratings into useful patterns. Our simulations indicate that 32nm node patterning can be achieved using trim tools and masks of significantly lower resolution. We also present experimental feasibility results using 157nm “dry” interference in combination with projection 248nm or e-beam trim exposures. The technological requirements and extendibility of such a method beyond the 32nm node are also examined.
Integrated four-channel GaAs-based quantum dot laser module with photonic crystals
Authors: Scherer H. , Namje K. , Deubert S. , Löffler A. , Reithmaier J. P. , Kamp M. , Forchel A.
Published: January 2006

The integration of a four channel laser array with photonic crystals is demonstrated. The devices have been fabricated on GaAs quantum dot layers with an emission wavelength of 1.3μm. A double stage photonic crystal combiner is used to combine the emission of four tunable ridge-waveguide lasers with photonic crystal mirrors into a single output waveguide. The lasers can be operated separately or simultaneously, resulting in four separately selectable wavelengths in the output signal. Threshold currents of single lasers are around 30mA and sidemode suppression ratios up to 30dB have been achieved. Continuous operation of all four lasers is observed up to temperatures of 40°C.
Advanced photolithographic mask repair using electron beams
Authors: Liang Ted , Frendberg Eric , Lieberman Barry , Stivers Alan
Published: January 2006

Mask repair plays an important role in yielding advanced masks that support the lithography roadmap. It is also one of the more challenging parts of mask fabrication. Electron beam induced deposition and etching have shown great potential for mask repair applications. Our work has demonstrated that e-beam mask repair provides the superior resolution and damage-free process that is needed to support mask generations for the 32nm technology node and beyond. This article describes an installed e-beam mask repair tool at Intel Mask Operation and discusses the capabilities of this enabling technology based on results obtained from repairing masks with “defects” intentionally inserted into the design (programmed defect masks). Specifically, results are presented for quartz etch repair of alternating phase shift masks and TaBN absorber etch of extreme ultraviolet masks, two of the most difficult types of mask to repair using conventional methods.
Experimental optimization of the electron-beam proximity effect forward scattering parameter
Authors: Rooks M. , Belic N. , Kratschmer E. , Viswanathan R.
Published: January 2006

The electron-beam forward scattering parameter α characterizes the width of the incident beam plus an additional radius due to scattering of primary electrons in the resist. These “forward scattering” effects can be included in proximity-effect correction algorithms by using the point-spread energy function generated by a Monte Carlo simulation. Alternatively, correction algorithms may use a superposition of Gaussian functions to fit Monte Carlo simulations or to fit experimental data. Long-range (β>10μm) effects due to electrons backscattered from the substrate are well characterized by simulations; however, forward scattering effects are difficult to model or measure. Experimental methods of measuring α include the exposure of dot arrays, line arrays, or so-called “doughnut” patterns over a large range of doses. Proximity parameters are then inferred indirectly through fitting line and dot widths. We have instead used a simpler and faster technique based on the method of [Dubonos et al., Microelectron. Eng. 21, 293 (1993)] which uses a liftoff technique to choose the optimal value of the forward scattering parameter α. We have applied this technique to determine α for 100 kV exposure of poly(methyl methacrylate) and KRS resists. Negative resist presents more of a challenge, and so a method of optimizing α for negative resists is presented. This work includes the variation of α as a function of resist thickness, and compares these values to those inferred from Monte Carlo simulations. We also discuss the dependence of α on resist developer and the effects of distortions from the developer meniscus.
Self inspection of integrated circuits pattern defects using support vector machines
Authors: Feng Hanying , Ye Jun , Pease R. Fabian
Published: January 2006

At various steps of integrated circuit manufacturing, defects need to be inspected to ensure process integrity. It is desirable to detect the defects based on the captured optical image itself without comparing to any reference image. Such a methodology of defect inspection without any reference image is called defect self inspection. In this article, we investigate the defect self inspection using the support vector machines, a pattern classification methodology, and present detection sensitivity of this approach.
Performances by the electron optical system of low energy electron beam proximity projection lithography tool with a large scanning field
Authors: Kasahara Haruo , Shishido Tsutomu , Samoto Norihiko , Shimazu Nobuo
Published: January 2006

An electron optical system has been developed for a low energy electron beam proximity projection lithography tool that is capable of scanning a field of 40mm square with a beam current up to 20μA. By using a beam current of 18μA the system has successfully resolved a dense 46nm hole pattern with 90nm pitch near one corner of the field. This article introduces a double-pinhole technique to monitor and measure the telecentricity of the electron beam (or e-beam) of such a system. Other related areas covered in the article are the simulations of space charge effect and of deflection aberration: also discussed here is the linearity of the subdeflection system used for correcting the mask distortion.
Cross beam lithography (FIB+EBL) and dip pen nanolithography for nanoparticle conductivity measurements
Authors: Cabrini Stefano , Barsotti Robert J. , Carpentiero Alessandro , Businaro Luca , Zaccaria Remo Proietti , Stellacci Francesco , Di Fabrizio Enzo
Published: January 2006

Focused ion beam lithography is a very powerful technique for directly writing patterns on many substrates, it is a maskless and resistless technique that allows a very wide range of applications, providing a resolution down to 10nm. Using a system composed by a 30keV gallium ion beam column plus a 30keV electron beam, nanogaps for electrical measurements of nanoparticle were fabricated with a resolution down to the nanometer scale, by exploiting FIB milling (FIBM) and electron beam lithography (EBL). Starting from prepatterned samples a square pattern reduces the width of the gold wire and a narrow line pattern opens a gap of less than 7nm. Electrical measurements and AFM tapping mode imaging were performed on the gaps. We patterned the ends of the gold leads with dip pen nanolithography using mercapto-undecanol (MUD) to form a bond between the nanoparticle and the alcohol group attached to the gold surface. After this assembly, devices showed an increase in conductivity (10–100-fold increase). Measuring the device again one week later, we saw almost no change in conductivity, showing that we deposit a multiparticle cluster and measure its conductivity.
Direct-write e-beam patterning of stimuli-responsive hydrogel nanostructures
Authors: Tirumala Vijay R. , Divan Ralu , Ocola Leonidas E. , Mancini Derrick C.
Published: January 2006

The need for stimuli-responsive components in microfluidic systems has led to the development of hydrogel-based patterned microstructures. The most commonly practiced means for fabricating micropatterned hydrogels is based on in situ photopolymerization using 365nm UV light in a liquid medium. This approach has been found to be very successful for patterning hydrogel-based features with tens or hundreds of microns resolution, but its main drawback lies in having to contain the liquid prepolymer mixture within the device for irradiation. We instead propose an alternate approach that uses direct-write electron-beam radiation to cross-link a dry, spin-coated thin film of linear polymer. After exposure, the linear polymer is dissolved in water leaving behind the cross-linked regions. When immersed in water, the cross-linked regions assume the properties of hydrogel and undergo naturally thermoreversible swelling and shrinking. This direct-writing approach can be used to fabricate hydrogel-based nanostructures down to 100nm linewidth and also is amenable to easy integration into nano and bio devices. We focus on patterning a well-known thermoreversible hydrogel, poly (N-isopropylacrylamide), and use it to discuss various aspects of process methodology, fabrication, characterization, and stimuli-response properties of nanosized hydrogels in detail.
Scaling law in acceleration test of extreme ultraviolet lithography projection optics mirror contamination
Authors: Gomei Yoshio , Takase Hiromitsu , Aoki Takashi , Matsunari Shuichi , Terashima Shigeru , Kakutani Yukinobu , Niibe Masahito
Published: January 2006

A model to describe surface physics in extreme ultraviolet lithography (EUVL) optics mirror contamination is proposed. Photon-induced desorption is a key process in determining the surface areal density of the related adsorbed gas species when irradiating power is high. Scaling law for acceleration test is analyzed and experiment was performed by using synchrotron undulator radiation. It appears that oxidation on a Si capping layer is almost anti-linearly dependent on photon intensity and acceleration test can be conducted by increasing the H2O pressure linearly with photon intensity increase. In contrast, it was found that carbon deposition does not linearly scale to photon intensity. Special care is necessary in understanding results conducted in accelerated conditions as well as under different pulse duty conditions.
Thermal-induced formation of silver nanowires on titanium dioxide thin films
Authors: Chen Ta-Kun , Chen Wen-Tai , Yang Min-Chi , Wong Ming-Show
Published: January 2006

Silver nanowires are formed by the thermal reduction of an aqueous silver nitrate solution on the surface of TiO2 thin films. A variety of silver nanostructures including nanowires were prepared by variations in the crystallinity of TiO2 thin films and heat-treatment temperature. Under appropriate conditions, silver nanowires 30–100 nm in diameter and 1–50μm in length were produced. The nanowires are found only on anatase TiO2 thin films, and the yield of nanowires increases with the anatase crystallinity. While other substrate materials, including rutile TiO2 films, silicon wafers, indium tin oxide glasses, quartz coupons, chemical-vapor deposited diamond thin films, and alloy films, were used under comparable conditions, no silver nanowires were observed. The formation of silver nanowires seems to be related to the photocatalytic properties of anatase TiO2.
Enhancement of electroluminescence in GaN-based light-emitting diodes using an efficient current blocking layer
Authors: Jang Ho Won , Lee Jong-Lam
Published: January 2006

Enhancement of electroluminescence in GaN-based light-emitting diodes (LEDs) was achieved using an efficient current blocking layer formed by postannealing. When a LED chip with Ni∕Au pad on Ni∕Au transparent p contact was annealed at 500 °C, the electroluminescence of the LED chip increased by 55%. The specific contact resistivity of metal contact below the p pad significantly increased due to indiffusion of Au and Ni atoms from the p pad to the contact interfacial region. As a result, an efficient current blocking layer could be formed below the p pad, enhancing the light output and decreasing the reverse leakage current of the LED chip. This result suggests that a further increase in the extraction efficiency of GaN-based LEDs can be easily obtained using the postannealing.
Self-aligned platinum-silicide nanowires for biomolecule sensing
Authors: Ko Fu-Hsiang , Yeh Zen-Hou , Chen Chun-Chi , Liu Tzeng-Feng
Published: January 2006

A self-aligned platinum-silicide nanowire for biomolecule sensing is developed in this work. The 40nm nanowire is fabricated through a sequence of electron-beam writing on the polysilicon film, line shrinkage with alkaline solution, platinum film deposition, 550°C annealing, and aqua regia dissolution. The immobilization of single-stranded capture DNA onto the platinum-silicide nanowire is verified from the fluorescence-labeled technique. The field-effect transistor can distinguish the complementary, mismatched, and denatured DNA via the conductance difference. Although the nanowire sensor has not been integrated into a fluid channel system, we can sense the minimal target DNA concentration down to 100fM, and the signal is still 1000-fold larger than the noise signal.
Control of the receding meniscus in immersion lithography
Authors: Burnett H. , Shedd T. , Nellis G. , El-Morsi M. , Engelstad R. , Garoff S. , Varanasi K.
Published: January 2006

The implementation of immersion lithography requires a sophisticated fluid management system. The design of the fluid management system must simultaneously consider liquid heating, viscous shear, normal forces, air entrainment, and the control of the liquid/air interfaces. In particular, it is becoming clear that the behavior of the receding air/water interface is critical and must be carefully controlled in order to prevent the deposition of residual liquid due to film pulling or the interface instability referred to as meniscus overflow. This paper discusses these failure mechanisms that are associated with the receding meniscus and that have been experimentally observed. In addition, a simple yet physics-based engineering model of the receding meniscus failure is presented and the results of the model are compared to experimental data.
Development of a multi-electron-beam source for sub-10nm electron beam induced deposition
Authors: van Bruggen M. J. , van Someren B. , Kruit P.
Published: January 2006

A multibeam electron beam induced deposition (EBID) system is presented that aims at the fabrication of sub-10nm structures with EBID. This system consists of a multibeam source (MBS) module, delivering 100 virtual sources and a standard scanning electron microscope column to image the 100 sources onto a wafer. In this paper, the concept for the MBS is presented: starting with a single Schottky field emission gun, its broad beam is divided into 100 individually focused sub-beams. This is accomplished with an aperture plate with small current-limiting apertures on the side irradiated by the beam and larger holes on the other side, acting as aperture lenses due to the presence of a macroelectrode in front of it. With this concept, in addition to the miniature aperture lenses, a negative macrolens effect is established that can serve to compensate for both the third-order geometric and first-order chromatic aberration of the collimator lens in front of the aperture plate. A simple aberration model is presented to illustrate this, and first results are shown of a prototype MBS.
Deep subwavelength nanolithography using localized surface plasmon modes on planar silver mask
Authors: Srituravanich W. , Durant S. , Lee H. , Sun C. , Zhang X.
Published: January 2006

The development of a near-field optical lithography is presented in this paper. By accessing short modal wavelengths of localized surface plasmon modes on a planar metallic mask, the resolution can be significantly increased while using conventional UV light source. Taking into account the real material properties, numerical studies indicate that the ultimate lithographic resolution at 20nm is achievable through a silver mask by using 365nm wavelength light. The surface quality of the silver mask is improved by adding an adhesion layer of titanium during the mask fabrication. Using a two-dimensional hole array silver mask, we experimentally demonstrated nanolithography with half-pitch resolution down to 60nm, far beyond the resolution limit of conventional lithography using I-line (365nm) wavelength.
Topas-based lab-on-a-chip microsystems fabricated by thermal nanoimprint lithography
Authors: Bilenberg B. , Hansen M. , Johansen D. , Özkapici V. , Jeppesen C. , Szabo P. , Obieta I. M. , Arroyo O. , Tegenfeldt J. O. , Kristensen A.
Published: January 2006

We present a one-step technology for fabrication of Topas-based lab-on-a-chip (LOC) microsystems by the use of thermal nanoimprint lithography (NIL). The technology is demonstrated by the fabrication of two working devices: a particle separator and a LOC with integrated optics for absorbance measurements. These applications demonstrate the fabrication of millimeter to micrometer-sized structures in one lithographic step. The use of NIL makes the technology easily scalable into the nanometer regime by the use of a suitable lithographic technique in the fabrication of the stamp. Processing issues such as environmental stress cracking of the Topas and the requirements to anti-sticking layers on the stamp when imprinting into Topas are discussed.
Full wafer simulation of immersion fluid heating
Authors: El-Morsi M. , Nellis G. , Schuetter S. , Van Peski C. , Grenville A.
Published: January 2006

In immersion lithography, fluid is introduced into the region between the lens and wafer. The benefit of the immersion fluid is that it has an index of refraction greater than air, which leads to a higher numerical aperture and improved depth of focus. Since the liquid becomes an optical element in the imaging system, it must maintain a uniform optical quality. However, the liquid’s index of refraction can depend on its temperature, and the temperature of the fluid will rise due to the exposure energy. This article describes a detailed two-dimensional computational fluid dynamics model of the hydrodynamic and thermal aspects of fluid flow. The model focuses on the successive scanning processes that occur as multiple chips are exposed on a wafer and accounts for the resulting oscillatory wafer motion and the thermal loads related to absorption of the incident energy in the fluid, indirect heating of the fluid due to its contact with the wafer as well as viscous dissipation. The global storage of energy in the fluid and the wafer as multiple chips are exposed is considered. The effect of the wafer acceleration, lens-to-wafer spacing, and the thermo-optic coefficient of the immersion fluid are studied parametrically and the impact of these quantities on the temperature distribution is described.