Arnold-Chiari Type II Malformation: A Case Report and Review of Prenatal Sonographic Findings

Directory of Open Access Journals (Sweden)

Maryam Nik Nejadi

2008-01-01

Full Text Available The Arnold-Chiari malformation is a congenital abnormality of CNS, characterized by downwarddisplacement the parts of the cerebellum, fourth ventricle, pons and medulla oblongata into thespinal canal. This malformation is one of causative factor of death in neonates and infants. Athorough understanding of the direct and indirect sonographic findings is necessary for diagnosis ofChiari II malformation in the developing fetus.In this case report, we present a Chiari malformation II detected at 23 weeks of gestation by routinelysonographic screening. The Role of prenatal sonography in recognition of the malformation andprognostic value of these features are discussed.

A Retrospective 2D Morphometric Analysis of Adult Female Chiari Type I Patients with Commonly Reported and Related Conditions

Directory of Open Access Journals (Sweden)

Maggie S. Eppelheimer

2018-01-01

Full Text Available Purpose: Researchers have sought to better understand Chiari type I malformation (CMI through morphometric measurements beyond tonsillar position (TP. Soft tissue and bone structures within the brain and craniocervical junction have been shown to be different for CMI patients compared to healthy controls. Yet, several morphological characteristics have not been consistently associated with CMI. CMI is also associated with different prevalent conditions (PCs such as syringomyelia, pseudotumor, Ehlers-Danlos syndrome (EDS, scoliosis, and craniocervical instability. The goal of this study was two-fold: (1 to identify unique morphological characteristics of PCs, and (2 to better explain inconsistent results from case-control comparisons of CMI.Methods: Image, demographic, and PC information was obtained through the Chiari1000, a self-report web-accessed database. Twenty-eight morphometric measurements (MMs were performed on the cranial MR images of 236 pre-surgery adult female CMI participants and 140 female healthy control participants. Custom software was used to measure 28 structures within the posterior cranial fossa (PCF compartment, craniocervical junction, oral cavity, and intracranial area on midsagittal MR images for each participant.Results: Morphometric analysis of adult females indicated a smaller McRae line length in CMI participants with syringomyelia compared to those without syringomyelia. TP was reduced in CMI participants with EDS than those without EDS. Basion to posterior axial line was significantly longer in CMI participants with scoliosis compared to those without scoliosis. No additional MMs were found to differ between CMI participants with and without a specific PC. Four morphometric differences were found to be consistently different between CMI participants and healthy controls regardless of PC: larger TP and a smaller clivus length, fastigium, and corpus callosum height in CMI participants.Conclusion: Syringomyelia, EDS

Combined Spinal-Epidural Analgesia for Laboring Parturient with Arnold-Chiari Type I Malformation: A Case Report and a Review of the Literature

Directory of Open Access Journals (Sweden)

Clark K. Choi

2013-01-01

Full Text Available Anesthetic management of laboring parturients with Arnold-Chiari type I malformation poses a difficult challenge for the anesthesiologist. The increase in intracranial pressure during uterine contractions, coughing, valsalva maneuvers, and expulsion of the fetus can be detrimental to the mother during the process of labor and delivery. No concrete evidence has implicated high cerebral spinal fluid pressure on maternal and fetal complications. The literature on the use of neuraxial techniques for managing parturients with Arnold-Chiari is extremely scarce. While most anesthesiologists advocate epidural analgesia for management of labor pain and spinal anesthesia for cesarean section, we are the first to report the use of combined spinal-epidural analgesia for managing labor pain in a pregnant woman with Arnold-Chiari type I malformation. Also, we have reviewed the literature and presented information from case reports and case series to support the safe usage of neuraxial techniques in these patients.

Acromesomelic dysplasia (Marotaeux type associated with craniovertebral junction anomaly: A report of a rare case and review of literature

Directory of Open Access Journals (Sweden)

Jayesh C Sardhara

2014-01-01

Full Text Available Acromesomelic dysplasia Maroteaux type (AMDM is a rare autosomal recessive osteochondrodysplasia. The responsible gene, AMDM gene, in human beings, has been mapped on 9p13-q12 chromosome by homozygous mapping and pathogenic mutation was later identified in natriuretic receptor B (NPR-B which has been implicated in the regulation of skeletal growth. Till now, around 40 to 50 cases of AMDM have been described in the world literature. Association of the congenital craniovertebral (CV junction anomaly has not been reported. Here we are presenting a case of AMDM, with CV junction anomaly. A 10-year boy presented with short stature (122 cm with short distal limbs, symptomatic for thoracic kyphoscoliosis with back pain. On examination there were no neurological deficits. On radiological investigation, he was found to have short and broad phalanges and toes, thoracic kyphoscoliosis, abnormal pelvic ring, mild ventriculomegaly, cervical syringomyelia and tonsillar descent below foramen magnum, hydrocephalus, os odontoideum with Klippel-Feil anomaly. This was diagnosed as AMDM with congenital os odontoideum, Klippel-Feil anomaly with Arnold-Chiari malformation (ACM type-1. The patient underwent posterior fossa decompression by removal of foramen magnum ring along with C1 arch for ACM type-1. Kyphosis was left for conservative treatment till further observation and required orthopedic correction in his further age. To the best of our knowledge this is a very rare entity of AMDM with congenital CV junction anomaly.

Headache in children with Chiari I malformation.

Science.gov (United States)

Toldo, Irene; Tangari, Marta; Mardari, Rodica; Perissinotto, Egle; Sartori, Stefano; Gatta, Michela; Calderone, Milena; Battistella, Pier Antonio

2014-05-01

Headache is the most common symptom of Chiari 1 malformation, a condition characterized by the herniation of cerebellar tonsils through the foramen magnum. However, the headache pattern of cases with Chiari 1 malformations is not well defined in the literature, especially in children. The aim of this retrospective chart review was to evaluate the frequency and the characteristics of headache in children with Chiari 1 malformation at initial evaluation and during follow up. Forty-five cases with tonsillar ectopia were selected among 9947 cases under 18 years of age who underwent neuroimaging between 2002 and 2010. A semistructured clinical interview (mean follow-up: 5.2 years) was conducted. Headache was classified according to the second edition of the International Classification of Headache Disorders. Possible associations between clinical picture, in particular headache pattern, but also other signs and symptoms attributable to Chiari 1 malformation, and the extent of tonsillar ectopia were found for 3 different groups: those with borderline (headache, and 9/33 (27%) of those patients (5 with mild and 4 with severe tonsillar ectopia) reported headache attributed to Chiari 1 malformation. In our studied pediatric population, the most common symptom for cases diagnosed with Chiari 1 malformation was headache, and headache attributed to Chiari 1 malformation was the most common headache pattern in patients with Chiari 1 malformation. The presence of headache attributed to Chiari 1 malformation along with 3 other signs or symptoms of Chiari 1 malformation were highly predictive of severe tonsillar ectopia. © 2014 American Headache Society.

Management of uncommon secondary trigeminal neuralgia related to a rare Arnold Chiari type I malformation

Directory of Open Access Journals (Sweden)

Zafar Ali Khan

2017-12-01

Full Text Available Background Trigeminal neuralgia (TN may sometimes present secondary to an intra-cranial cause. Arnold Chiari Malformation (ACM is downward herniation of the cerebellar tonsils through the foramen magnum that may be a cause of TN like pain in very rare cases. Aims The aim of this brief report is to suggest the proper management of uncommon secondary trigeminal neuralgia related to a rare Arnold Chiari type I malformation. Methods A male patient presented electric shock like stabbing pain on the right side of the face for more than ten years. The symptoms were typical of trigeminal neuralgia except that there was loss of corneal reflex on the right side and the patient also complained of gait & sleep disturbances. Complex and multilevel diagnosis was made. Results A multiplanar imaging through brain acquiring T1/T2W1 revealed ACM Type I Malformation with caudal displacement of cerebellar tonsils through foramen magnum. Conclusion Dental surgeons and oral and Maxillofacial Surgeons should exclude intra-cranial causes by Magnetic Resonance Imaging(MRI in patients of TN presenting with loss of corneal reflex, gait and sleep disturbances due to night time pain episodes.

Cranial CT signs of the Chiari II malformation

International Nuclear Information System (INIS)

Naidich, T.P.; Pudlowski, R.M.

1980-01-01

Serial CT scans of 32 patients with proved Chiari II malformations and 19 patients with hydrocephalus and meningomyelocele (presumed to have Chiari II malformation) were reviewed and compared with CT scans from 30 patients with non-chiari aqueductal stenosis to develop criteria for identifying the Chiari II malformation and for differentiating it from other forms of hydrocephalus. Correlation with post-mortem specimens of Chiari II brains provided a pathologic basis for the CT signs observed. (orig.) [de

PTA and stenting for various types of Budd-Chiari syndrome

International Nuclear Information System (INIS)

Zhang Xinbao

2011-01-01

Objective: To investigate and evaluate PTA and stenting for various types of Budd-Chiari syndrome (BCS). Methods: 89 patients with BCS were diagnosed and treated during 7 years. The interventional procedures included: Percutaneous balloon dilatation (PBD) of inferior vena cava (IVC), PBD and stent placement for IVC, hepatic vein angioplasty via trans jugular vein, hepatic vein angioplasty via transhepatic and trans jugular approach, accessory hepatic vein angioplasty, percutaneous dual balloon dilatation for IVC and hepatic vein, and percutanous dual stent placement for IVC and hepatic vein. Results: The achievement ratio of PTA and stent placement was 96% and the mortality was 0%. The serious complication of PTA and stent placement of BCS was penetration into the pericardium, endovascular stent migration into right atrium. Conclusion: 1. PTA is a reliable procedures in treating type I a, II and III BCS, and TIPPS is useful for type I b BCS. But PTA and stenting is necessary for patients with type IV BCS. 2. Thrombolysis is needed for patients with type III, IV BCS. 3. Guiding of Color Doppler Ultrasound can improve the success of percutanous hepatic vein and reduce complications. (authors)

Surgical treatment of type I Chiari malformation: the role of Magendie’s foramen opening e tonsils manipulation

Directory of Open Access Journals (Sweden)

Claudio Henrique Fernandes Vidal

2015-02-01

Full Text Available The treatment for type 1 Chiari malformation (CM 1 is one of the most controversial topics in the neurosurgical field. The present study evaluated two of the most applied surgical techniques to treat CM 1. Method 32 patients were evaluated and divided in two groups: group 1 had 16 patients that were submitted to decompression of occipital bone and dura mater of the craniovertebral junction (CVJ; group 2 also had 16 patients and in addition to the previous procedure, they were submitted to Magendie’s foramen opening e tonsils manipulation. The comparison between the groups included neurological exam and cerebrospinal fluid flow imaging during pre and postoperative periods. Results Both techniques were equivalents in terms of neurological improvement of the patients (p > 0.05, but the group 2 had more surgical complications, with relative risk of 2.45 (CI 1.55-3.86 for adverse events. Whatever the cerebrospinal fluid flow at CVJ, the patients of the group 1 achieved greater amount of flow than the group 2 (p < 0.05 during the postoperative period. Conclusion The cranial and dural decompression of the CVJ without arachnoidal violation was the best surgical intervention for treatment of CM 1, between these two compared techniques.

Budd-Chiari syndrome complicating hydatid liver disease

International Nuclear Information System (INIS)

Robotti, G.C.; Meister, F.; Schroeder, R.; Bern Univ.; Bern Univ.

1985-01-01

In two female patients a diagnosis of Budd-Chiari syndrome secondary to hepatic echinococcosis was established by CT. One patient developed acute Budd-Chiari syndrome secondary to E. granulosus lesions of the liver. The second patient presented with a picture of chronic Budd-Chiari syndrome secondary to alveolar echinococcosis. CT findings of Budd-Chiari syndrome included ascites, low density areas in the liver parenchyma, hypertrophy of the caudate lobe, non visualisation of the hepatic veins, occlusion of the retrohepatic inferior vena cava and enlarged retroperitoneal veins. (orig.) [de

Surgical treatment of Chiari malformation complicated with basilar impression

Directory of Open Access Journals (Sweden)

Yuan MA

2011-02-01

Full Text Available Objective To evaluate the therapeutic effect of small craniotomic posterior fossa decompression combined with occipital-cervical bone graft fusion and internal fixation on Chiari malformation complicated with basilar impression.Methods The clinical data of 16 cases(7 males and 9 females,aged 17 to 65 years,mean 36.4 of Chiari malformation complicated with basilar impression from 2006 to 2010 were retrospectively analyzed.The diagnoses for all the patients were confirmed by radiology.Small craniotomic posterior fossa decompression was performed in all patients,cerebellar tonsils were resected,and then one-stage occipital-cervical bone graft fusion using autogenous iliac bone and internal wiring fixation were performed.Neck support was used for 3 months after surgery.Results Symptoms were significantly improved in all cases after surgical operation.No patient died or infected.Cerebrospinal fluid leakage was found at draining site in one case.Transient pain of scapular and chest was found in one case and disappeared spontaneously.A 6-months follow-up showed that 6 patients were cured,9 improved and 1 unchanged according to Symon and Lavender standard.Postoperative MRI showed the reconstructed cisterna magna was clear in all patients,no cerebellar ptosis was found,and the occipital-cervical graft bone was fused.Conclusion In patients with Chiari malformation complicated with basilar impression,small craniotomic posterior fossa decompression combined with one-stage occipital-cervical bone graft fusion and internal wiring fixation has a clear and definite effect,it can increase the volume of posterior fossa and alleviate the ventral brain stem compression simultaneously,and reconstruct the stability of cranio-cervical junction.

Imaging of Budd-Chiari syndrome

International Nuclear Information System (INIS)

Buckley, O.; O' Brien, J.; Snow, A.; Stunell, H.; Torreggiani, W.C.; Lyburn, I.; Munk, P.L.

2007-01-01

Budd-Chiari syndrome occurs when venous outflow from the liver is obstructed. The obstruction may occur at any point from the hepatic venules to the left atrium. The syndrome most often occurs in patients with underlying thrombotic disorders such as polycythemia rubra vera, paroxysmal nocturnal hemoglobinuria and pregnancy. It may also occur secondary to a variety of tumours, chronic inflammatory diseases and infections. Imaging plays an important role both in establishing the diagnosis of Budd-Chiari syndrome as well as evaluating for underlying causes and complications such as portal hypertension. In this review article, we discuss the role of modern imaging in the evaluation of Budd-Chiari syndrome. (orig.)

Imaging of Budd-Chiari syndrome

Energy Technology Data Exchange (ETDEWEB)

Buckley, O.; O' Brien, J.; Snow, A.; Stunell, H.; Torreggiani, W.C. [Adelaide and Meath Hospital, Incorporating the National Children' s Hospital (AMNCH), Department of Radiology, Dublin 24 (Ireland); Lyburn, I. [Cheltenham Hospital, Department of Radiology, Cheltenham (United Kingdom); Munk, P.L. [Vancouver General Hospital, Department of Radiology, Vancouver (Canada)

2007-08-15

Budd-Chiari syndrome occurs when venous outflow from the liver is obstructed. The obstruction may occur at any point from the hepatic venules to the left atrium. The syndrome most often occurs in patients with underlying thrombotic disorders such as polycythemia rubra vera, paroxysmal nocturnal hemoglobinuria and pregnancy. It may also occur secondary to a variety of tumours, chronic inflammatory diseases and infections. Imaging plays an important role both in establishing the diagnosis of Budd-Chiari syndrome as well as evaluating for underlying causes and complications such as portal hypertension. In this review article, we discuss the role of modern imaging in the evaluation of Budd-Chiari syndrome. (orig.)

Anesthesia management for pregnant patient with Arnold-Chiari malformation type I: A case report

Directory of Open Access Journals (Sweden)

Şaban Yalçın

2012-06-01

Full Text Available The Arnold-Chiari I malformation (ACM is a congenitalanomaly characterized by downward herniation of thecerebellar tonsils into the spinal canal. The anomaly maypresent in a variety of ways with vague symptoms suchas head and limb pains, vertigo, hypoesthesia, weaknessin the extremities. Diagnosis is often difficult and thereforedelayed. Measurement of intracranial pressure in thesepatients is an important measure thus precautions shoulbe taken for avoidance of increased intracranial pressure.In this case report, we discussed the anesthetic managementof a pregnant patient with Arnold Chiari I malformationwho underwent an emergency caesarean section.

Chiari I malformation associated with turner syndrome

Directory of Open Access Journals (Sweden)

Kamble Jayaprakash Harsha

2017-01-01

Full Text Available Turner syndrome (TS is a rare genetic disease due to the absence of one X chromosome. Patients with TS have more subtle neurological/neuropsychiatric problems, while headache is an uncommon clinical presentation which needs attention. We report a 12-year-old child presenting with typical cough headache. Her magnetic resonance imaging revealed Chiari I malformation associated with TS. To the best of our knowledge, Chiari I malformation associated with TS is not described in literature. We report the first case of TS associated with Chiari I malformation. Interestingly, Chiari I malformation is also associated with Noonan's syndrome, which is a close morphological mimicker of TS, raising the possibility of sharing similar pathogenesis in both conditions.

Sleep Disordered Breathing in Children and Adolescents with Chiari Malformation Type I

Science.gov (United States)

Losurdo, Anna; Dittoni, Serena; Testani, Elisa; Di Blasi, Chiara; Scarano, Emanuele; Mariotti, Paolo; Paternoster, Giovanna; Di Rocco, Concezio; Massimi, Luca; Della Marca, Giacomo

2013-01-01

Study Objectives: Chiari malformation Type I (CM-I) has been associated with sleep disordered breathing (SDB). The aim of this study was to evaluate the prevalence of SDB in CM-I and its clinical correlates in a population of children and adolescents. Methods: Fifty-three consecutive children and adolescents affected by CM-I were enrolled (27 girls and 26 boys, mean age 10.3 ± 4.3, range: 3-18 years). All patients underwent neurological examination, MRI, and polysomnography (PSG). Otorhinolaryngologic clinical evaluation was performed in patients with polysomnographic evidence of sleep-related upper airway obstruction. Results: Mean size of the herniation was 9.5 ± 5.4 mm. Fourteen patients had syringomyelia, 5 had hydrocephalus, 31 presented neurological signs, 14 had epileptic seizures, and 7 reported poor sleep. PSG revealed SDB in 13 subjects. Patients with SDB, compared to those without SDB, had a higher prevalence hydrocephalus (p = 0.002), syringomyelia (p = 0.001), and neurological symptoms (p = 0.028). No significant difference was observed in age, gender, prevalence of epilepsy, and size of the herniation. Obstructive SDB was associated with syringomyelia (p = 0.004), whereas central SDB was associated with hydrocephalus (p = 0.034). Conclusions: In our population of CM-I patients the prevalence of SDB was 24%, lower than that reported in literature. Moreover, our findings suggest that abnormalities in cerebrospinal fluid dynamics in CM-I, particularly syringomyelia and hydro-cephalus, are associated with SDB. Citation: Losurdo A; Dittoni S; Testani E; Di Blasi C; Scarano E; Mariotti P; Paternoster G; Di Rocco C; Massimi L; Della Marca G. Sleep disordered breathing in children and adolescents with Chiari malformation Type I. J Clin Sleep Med 2013;9(4):371-377. PMID:23585753

Asymptomatic Chiari Type I malformation: should patients be advised against participation in contact sports?

Science.gov (United States)

Spencer, Robert; Leach, Paul

2017-08-01

Chiari type I malformation (CM-I) is characterised by caudal displacement of the cerebellar tonsils through the foramen magnum, crowding the craniocervical junction. It is being increasingly diagnosed in asymptomatic patients due to the widespread availability of MRI, and there are case reports of these patients suffering sudden death or neurological injury following head or neck trauma, raising the issue of whether they should be prohibited from contact sport participation, given the likelihood of frequent trauma. General neurosurgical opinion is that patients who are symptomatic and those with an associated spinal cord syrinx should be offered foramen magnum decompression, however asymptomatic patients without syringomyelia are not offered this in the majority of cases. The authors performed a full review of the published literature, including all case reports, case series, studies and literature reviews regarding CM-I and either contact sports or trauma, excluding patients that had undergone surgical intervention and those becoming symptomatic in circumstances other than head or neck trauma. 21 case reports of CM-I patients deteriorating following trauma were identified, including four cases of sudden death following head or neck injury. However, studies of large samples of CM-I patients are yet to capture an incident of sudden death or acute neurological deterioration, suggesting that the risk is very low. CM-I patients may have an increased risk of concussion and post-concussion syndrome compared to the background population however. Overall, the authors feel that there should be no restriction of sports participation for CM-I patients, but a discussion to make them and their families aware of the possible increased risks is important.

Budd-Chiari syndrome secondary to toxic pyrrolizidine alkaloid exposure.

Science.gov (United States)

Wu, Janet S W; Poon, W T; Ma, C K; Chen, M L; Pang, K S; Mak, Tony W L; Chan, H B

2013-12-01

In this report, we describe a case of pyrrolizidine alkaloid-related Budd-Chiari syndrome in Hong Kong. A 10-month-old boy presented with ascites, right pleural effusion, and hepatomegaly after consumption of herbal drinks for 3 months. His clinical (including imaging) features were compatible with Budd-Chiari syndrome. Budd-Chiari syndrome is a rare disease entity in paediatric patients. In our case, extensive workup performed to look for the underlying cause of Budd-Chiari syndrome was unrevealing, except for toxic pyrrolizidine alkaloid exposure in his herbal drinks.

Orofacial clinical features in Arnold Chiari type I malformation: A case series.

Science.gov (United States)

de Arruda, José-Alcides; Figueiredo, Eugênia; Monteiro, João-Luiz; Barbosa, Livia-Mirelle; Rodrigues, Cleomar; Vasconcelos, Belmiro

2018-04-01

Arnold Chiari malformation (ACM) is characterized by an anatomical defect at the base of the skull where the cerebellum and the spinal cord herniate through the foramen magnum into the cervical spinal canal. Among the subtypes of the condition, ACM type I (ACM-I) is particularly outstanding because of the severity of symptoms. This study aimed to analyze the orofacial clinical manifestations of patients with ACM-I, and discuss their demographic distribution and clinical features in light of the literature. A case series with patients with ACM-I treated between 2012 and 2015 was described. The sample consisted of patients who were referred by the Department of Neurosurgery to the Oral and Maxillofacial Surgery Service of Hospital da Restauração in Brazil for the assessment of facial symptomatology. A questionnaire was applied to evaluate the presence of painful orofacial findings. Data are reported using descriptive statistical methods. Mean patient age was 39.3 years and the sample consisted mostly of male patients. A high prevalence of headache (50%) and pain in the neck (66.7%) and masticatory muscles (50%) was found. Only one patient reported difficulty in performing mandibular movements and two reported jaw clicking sounds. Mean mouth opening was 40.83 mm. ACM-I patients may exhibit orofacial symptoms which may mimic temporomandibular joint disorders. This study brings interesting information that could help clinicians and oral and maxillofacial surgeons to understand this uncommon condition and also help with the diagnosis of patients with similar physical characteristics by referring them to a neurosurgeon. Key words: Arnold-Chiari malformation, facial pain, diagnosis, orofacial.

Syringomyelia and Craniocervical Junction Abnormalities in Chihuahuas

OpenAIRE

Kiviranta, A.‐M.; Rusbridge, C.; Laitinen‐Vapaavuori, O.; Hielm‐Björkman, A.; Lappalainen, A.K.; Knowler, S.P.; Jokinen, T.S.

2017-01-01

Background: Chiari-like malformation (CM) and syringomyelia (SM) are widely reported in Cavalier King Charles Spaniels and Griffon Bruxellois dogs. Increasing evidence indicates that CM and SM also occur in other small and toy breed dogs, such as Chihuahuas. Objectives: To describe the presence of SM and craniocervical junction (CCJ) abnormalities in Chihuahuas and to evaluate the possible association of CCJ abnormalities with SM. To describe CM/SM-related clinical signs and neuro...

Difficult intubation in a parturient with syringomyelia and Arnold–Chiari malformation: Use of Airtraq™ laryngoscope

Science.gov (United States)

Mustapha, Bensghir; Chkoura, K.; Elhassani, M.; Ahtil, R.; Azendour, H.; Kamili, N. Drissi

2011-01-01

Anesthetic technique in parturient with syringomyelia and Arnold–Chiari malformation is variable depending on the teams. Difficult intubation is one of the risks when general anesthesia is opted. Different devices have been used to manage the difficult intubation in pregnant women. We report the use of Airtraq™ laryngoscope after failed standard laryngoscopy in a parturient with syringomyelia and Arnold–Chiari type I malformation. PMID:22144932

Difficult intubation in a parturient with syringomyelia and Arnold-Chiari malformation: Use of Airtraq™ laryngoscope

Directory of Open Access Journals (Sweden)

Bensghir Mustapha

2011-01-01

Full Text Available Anesthetic technique in parturient with syringomyelia and Arnold-Chiari malformation is variable depending on the teams. Difficult intubation is one of the risks when general anesthesia is opted. Different devices have been used to manage the difficult intubation in pregnant women. We report the use of Airtraq™ laryngoscope after failed standard laryngoscopy in a parturient with syringomyelia and Arnold-Chiari type I malformation.

Shunt malfunction causing acute neurological deterioration in 2 patients with previously asymptomatic Chiari malformation Type I. Report of two cases.

Science.gov (United States)

Elliott, Robert; Kalhorn, Stephen; Pacione, Donato; Weiner, Howard; Wisoff, Jeffrey; Harter, David

2009-08-01

Patients with symptomatic Chiari malformation Type I (CM-I) typically exhibit a chronic, slowly progressive disease course with evolution of symptoms. However, some authors have reported acute neurological deterioration in the setting of CM-I and acquired Chiari malformations. Although brainstem dysfunction has been documented in patients with CM-II and hydrocephalus or shunt malfunction, to the authors' knowledge only 1 report describing ventriculoperitoneal (VP) shunt malfunction causing neurological deterioration in a patient with CM-I exists. The authors report on their experience with the treatment of previously asymptomatic CM-I in 2 children who experienced quite different manifestations of acute neurological deterioration secondary to VP shunt malfunction. Presumably, VP shunt malfunction created a positive rostral pressure gradient across a stenotic foramen magnum, resulting in tetraparesis from foramen magnum syndrome in 1 patient and acute ataxia and cranial nerve deficits from syringobulbia in the other. Although urgent shunt revisions yielded partial recovery of neurological function in both patients, marked improvement occurred only after posterior fossa decompression.

Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 in a dog

Directory of Open Access Journals (Sweden)

Harumichi Itoh

2017-03-01

Full Text Available Craniocervical junction abnormalities with atlantoaxial subluxation caused by ventral subluxation of C2 were diagnosed in a 6-month-old female Pomeranian with tetraplegia as a clinical sign. Lateral survey radiography of the neck with flexion revealed atlantoaxial subluxation with ventral subluxation of C2. Computed tomography revealed absence of dens and atlanto-occipital overlapping. Magnetic resonance imaging showed compression of the spinal cord and indentation of caudal cerebellum. The diagnosis was Chiari-like malformation, atlantoaxial subluxation with ventral displacement of C2, atlanto-occipital overlapping, and syringomyelia. The dog underwent foramen magnum decompression, dorsal laminectomy of C1, and ventral fixation of the atlantoaxial joint. Soon after the operation, voluntary movements of the legs were recovered. Finally, the dog could stand and walk without assistance. The dog had complicated malformations at the craniocervical junction but foramen magnum decompression and dorsal laminectomy for Chiari-like malformation, and ventral fixation for atlantoaxial subluxation resulted in an excellent clinical outcome.

Spinning, hurting, still, afraid: Living life spaces with Type I Chiari Malformation.

Science.gov (United States)

Andrews, Gavin J

2018-01-31

Human geography's varied engagement with the brain has involved considerations of the way people know and respond to their environments, and their place-based experiences with emotions, mental illnesses and disorders, intellectual disabilities and particular neurological conditions. This paper argues however that this scholarship could be augmented by, and existing expertise be directed towards, considering physical brain abnormalities and injuries. As a case in point it considers the spatial experience of living with Type 1 Chiari Malformation. Through interviews with four sufferers, the research articulates three domains that they have had to re-negotiate - home space, social space and medical space - emphasizing supportive and challenging aspects of each, as well as meaningful and affective qualities to encounters. The paper concludes with some pointers towards the future study of physical brain abnormalities and injuries and the kinds of knowledge it might create to increase awareness and inform care. Copyright © 2018 Elsevier Ltd. All rights reserved.

Evolutionary hypothesis for Chiari type I malformation.

Science.gov (United States)

Fernandes, Yvens Barbosa; Ramina, Ricardo; Campos-Herrera, Cynthia Resende; Borges, Guilherme

2013-10-01

Chiari I malformation (CM-I) is classically defined as a cerebellar tonsillar herniation (≥5 mm) through the foramen magnum. A decreased posterior fossa volume, mainly due to basioccipital hypoplasia and sometimes platybasia, leads to posterior fossa overcrowding and consequently cerebellar herniation. Regardless of radiological findings, embryological genetic hypothesis or any other postulations, the real cause behind this malformation is yet not well-elucidated and remains largely unknown. The aim of this paper is to approach CM-I under a broader and new perspective, conjoining anthropology, genetics and neurosurgery, with special focus on the substantial changes that have occurred in the posterior cranial base through human evolution. Important evolutionary allometric changes occurred during brain expansion and genetics studies of human evolution demonstrated an unexpected high rate of gene flow interchange and possibly interbreeding during this process. Based upon this review we hypothesize that CM-I may be the result of an evolutionary anthropological imprint, caused by evolving species populations that eventually met each other and mingled in the last 1.7 million years. Copyright © 2013 Elsevier Ltd. All rights reserved.

Acute trauma-induced Budd-Chiari syndrome

International Nuclear Information System (INIS)

Izard, G.; Houri, R.; Randrianasolo, S.; Gailleton, R.

1995-01-01

The diagnosis of Budd-Chiari syndrome is based on clinical signs including liver enlargement and ascites and findings of complementary examinations: echography, echo-Doppler, cat scanning (CT-scan), magnetic resonance imaging, angiography, pressure readings, laparoscopy and biopsy. Trauma is rarely reported as a cause of acute Budd-Chiari syndrome. In some cases, the trauma is so violent the supra-hepatic veins are ruptured and the dramatic outcome leaves no time for the syndrome to develop. In others, the resulting haematomas form a compression block of the supra hepatic vessels. The mechanism of the trauma in our case appears to have been unreported to date. Four days after a violent motorcycle accident, a 33-year-old man developed an acute Budd-Chiari syndrome probably due to partial and temporary thrombosis of the left and middle supra hepatic veins. A side-to-side porto-cava anastomosis with a calibrated venous graft was performed in an emergency procedure. Outcome was quite favourable and after a 4 year follow-up, the patient is in good health. (authors). 13 refs

Terminal hemimyelocystocele associated with Chiari II malformation

Directory of Open Access Journals (Sweden)

Umamaheswara Reddy V.

2014-06-01

Full Text Available Terminal myelocystocele (TMC results from failure of embryonic CSF to drain outside the neural tube creating CSF reservoir within a dorsal meningocele. Association of Chiari II malformation with diastematomyelia and myelocystocele is extremely rare. Myelocystoceles do not have neural tissue so they have good prognosis after treatment, however when associated with hydromelia and Chiari malformation they present with neurological deficits. We present details of a 2 year old female who presented to us with this rare anomaly.

Do the cerebellar tonsils move during flexion and extension of the neck in patients with Chiari I malformation? A radiological study with clinical implications.

Science.gov (United States)

Tubbs, R Shane; Kirkpatrick, Christina M; Rizk, Elias; Chern, Joshua J; Oskouian, Rod J; Oakes, W Jerry

2016-03-01

In the past, diagnosis of the Chiari I malformation has primarily been made on midsagittal MRI. We hypothesized that based on the frequent presentation of opisthotonos in patients with hindbrain hernia (primarily Chiari II malformation but sometimes Chiari I malformation) that the hyperextension might be a compensatory technique used by such patients to bring the cerebellar tonsils up out of the cervical spine. This prospective study reviewed imaging of patients with Chiari I malformation who underwent flexion/extension MRI for evaluation of their hindbrain herniation. Age-matched controls were used for comparison. In general, there was elevation of the cerebellar tonsils with extension and increased descent with flexion of the cervical spine. In 72 % of patients, flexion of the neck resulted in descent of the cerebellar tonsils. In 64 % of patients, extension of the neck resulted in ascent of the cerebellar tonsils. In the 14 patients with an associated syrinx, 71 % were found to have caudal movement of the cerebellar tonsils with neck flexion, and only 43 % were observed to have any movement of the cerebellar tonsils in neck extension compared to patients without a syrinx where ascent of the tonsils was seen in only nine during neck extension. Two patients were observed to have the reverse finding of ascent of the cerebellar tonsils with neck flexion and descent of the cerebellar tonsils with neck extension. Five patients had no movement of the cerebellar tonsils in either flexion or extension of the neck, and one of these had a small syrinx. Although minimal and not in all patients, we observed elevation of the herniated cerebellar tonsils with extension of the cervical spine in patients with Chiari I malformation. This finding provides evidence as to why some patients with hindbrain herniation present with opisthotonos and supports earlier findings that CSF flow is reduced at the craniocervical junction in flexion in patients with Chiari I malformation.

Chiari-like malformation and syringomyelia in cavalier King Charles spaniels

NARCIS (Netherlands)

Rusbridge, C.

2007-01-01

This thesis is the cumulation of over a decade of study into the pathogenesis and treatment Chiari-like malformation and syringomyelia (CM/SM) in the cavalier King Charles spaniel (CKCS). Chiari-like malformation is a condition where the brain is too big for the skull and is crushed and pushed out

CT findings in Arnold-Chiari malformation

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Y.; Nakamura, S. (Aichi Prefecture Colony, Kasugai (Japan). Central Hospital); Yamada, H.; Kageyama, N.

1981-12-01

CT scans of Arnold-Chiari malformations demonstrate many abnormal findings that are considered to be specific for this type of malformation. Fifty patients with Arnold-Chiari malformations were studied, and their CT findings were analyzed. This number included 14 preshunted neonatal cases and 36 post-shunted infantile cases. Craniolacunia was recognized only in the neonatal cases, but other skull changes, including scaphocephaly and petrous scalloping, were found more frequently in the infantile cases. The posterior fossa abnormality was composed of several specific changes, such as a non-visualized fourth ventricle, a lateral or upward growth of the cerebellum, or a beaking deformity of the midbrain. These findings were far more common in the infantile cases. However, in 7 neonatal cases on which CT cisternography was performed, these posterior fossa changes were well recognized in the majority of cases. Hydrocephalus was found in all cases. In half of the post-shunted infantile cases, the lateral ventricles were markedly collapsed. Characteristic features of the lateral ventricles, such as a protruding of the caudate nuclei, a pointing of the frontal and/or occipital horns, an absent septum pellucidum, or dominently dilated occipital horns, were commonly found in both neonatal and infantile cases. The subarachnoid space was remarkably widened at the retrothalamic cistern and/or the interhemispheric fissure in many cases.

Subdural Fluid Collection and Hydrocephalus After Foramen Magnum Decompression for Chiari Malformation Type I: Management Algorithm of a Rare Complication.

Science.gov (United States)

Rossini, Zefferino; Milani, Davide; Costa, Francesco; Castellani, Carlotta; Lasio, Giovanni; Fornari, Maurizio

2017-10-01

Chiari malformation type I is a hindbrain abnormality characterized by descent of the cerebellar tonsils beneath the foramen magnum, frequently associated with symptoms or brainstem compression, impaired cerebrospinal fluid circulation, and syringomyelia. Foramen magnum decompression represents the most common way of treatment. Rarely, subdural fluid collection and hydrocephalus represent postoperative adverse events. The treatment of this complication is still debated, and physicians are sometimes uncertain when to perform diversion surgery and when to perform more conservative management. We report an unusual occurrence of subdural fluid collection and hydrocephalus that developed in a 23-year-old patient after foramen magnum decompression for Chiari malformation type I. Following a management protocol, based on a step-by-step approach, from conservative therapy to diversion surgery, the patient was managed with urgent external ventricular drainage, and then with conservative management and wound revision. Because of the rarity of this adverse event, previous case reports differ about the form of treatment. In future cases, finding clinical and radiologic features to identify risk factors that are useful in predicting if the patient will benefit from conservative management or will need to undergo diversion surgery is only possible if a uniform form of treatment is used. Therefore, we believe that a management algorithm based on a step-by-step approach will reduce the use of invasive therapies and help to create a standard of care. Copyright © 2017 Elsevier Inc. All rights reserved.

Budd-Chiari syndrome: CT and MRI findings

International Nuclear Information System (INIS)

Xu Kai; Li Lingsun

2008-01-01

Budd-Chiari syndrome is an uncommon but often fatal disorder resulting from obstruction of hepatic venous outflow tract at the level of the hepatic veins, the inferior vena cava. The CT and MRI characteristics of Budd-Chiari syndrome are reviewed in this article especially for displaying the exact site and extent of the obstruction. In addition to this direct sign, the indirect findings of venous obstruction such as the presence of intra-and extrahepatic collateral veins, caudate lobe enlargement, inhomogeneous liver enhancement, and regenerative nodules can also be demonstrated. Awareness of these findings is important for early diagnosis and appropriate treatment. (authors)

Fetal diffusion tensor quantification of brainstem pathology in Chiari II malformation

Energy Technology Data Exchange (ETDEWEB)

Woitek, Ramona; Prayer, Daniela; Weber, Michael; Schoepf, Veronika; Furtner, Julia; Asenbaum, Ulrika; Kasprian, Gregor [Medical University of Vienna, Department of Biomedical Imaging and Image-guided Therapy, Vienna (Austria); Amann, Gabriele [Medical University of Vienna, Department of Clinical Pathology, Vienna (Austria); Seidl, Rainer [Medical University of Vienna, Department of Paediatrics and Adolescent Medicine, Vienna (Austria); Bettelheim, Dieter [Medical University of Vienna, Department of Obstetrics and Gynecology, Vienna (Austria); Brugger, Peter C. [Medical University of Vienna, Center for Anatomy and Cell Biology, Vienna (Austria)

2016-05-15

This prenatal MRI study evaluated the potential of diffusion tensor imaging (DTI) metrics to identify changes in the midbrain of fetuses with Chiari II malformations compared to fetuses with mild ventriculomegaly, hydrocephalus and normal CNS development. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from a region of interest (ROI) in the midbrain of 46 fetuses with normal CNS, 15 with Chiari II malformations, eight with hydrocephalus and 12 with mild ventriculomegaly. Fetuses with different diagnoses were compared group-wise after age-matching. Axial T2W-FSE sequences and single-shot echo planar DTI sequences (16 non-collinear diffusion gradient-encoding directions, b-values of 0 and 700 s/mm{sup 2}, 1.5 Tesla) were evaluated retrospectively. In Chiari II malformations, FA was significantly higher than in age-matched fetuses with a normal CNS (p =.003), while ADC was not significantly different. No differences in DTI metrics between normal controls and fetuses with hydrocephalus or vetriculomegaly were detected. DTI can detect and quantify parenchymal alterations of the fetal midbrain in Chiari II malformations. Therefore, in cases of enlarged fetal ventricles, FA of the fetal midbrain may contribute to the differentiation between Chiari II malformation and other entities. (orig.)

Fetal diffusion tensor quantification of brainstem pathology in Chiari II malformation

International Nuclear Information System (INIS)

Woitek, Ramona; Prayer, Daniela; Weber, Michael; Schoepf, Veronika; Furtner, Julia; Asenbaum, Ulrika; Kasprian, Gregor; Amann, Gabriele; Seidl, Rainer; Bettelheim, Dieter; Brugger, Peter C.

2016-01-01

This prenatal MRI study evaluated the potential of diffusion tensor imaging (DTI) metrics to identify changes in the midbrain of fetuses with Chiari II malformations compared to fetuses with mild ventriculomegaly, hydrocephalus and normal CNS development. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated from a region of interest (ROI) in the midbrain of 46 fetuses with normal CNS, 15 with Chiari II malformations, eight with hydrocephalus and 12 with mild ventriculomegaly. Fetuses with different diagnoses were compared group-wise after age-matching. Axial T2W-FSE sequences and single-shot echo planar DTI sequences (16 non-collinear diffusion gradient-encoding directions, b-values of 0 and 700 s/mm 2 , 1.5 Tesla) were evaluated retrospectively. In Chiari II malformations, FA was significantly higher than in age-matched fetuses with a normal CNS (p =.003), while ADC was not significantly different. No differences in DTI metrics between normal controls and fetuses with hydrocephalus or vetriculomegaly were detected. DTI can detect and quantify parenchymal alterations of the fetal midbrain in Chiari II malformations. Therefore, in cases of enlarged fetal ventricles, FA of the fetal midbrain may contribute to the differentiation between Chiari II malformation and other entities. (orig.)

Audio-vestibular signs and symptoms in Chiari malformation type i. Case series and literature review.

Science.gov (United States)

Guerra Jiménez, Gloria; Mazón Gutiérrez, Ángel; Marco de Lucas, Enrique; Valle San Román, Natalia; Martín Laez, Rubén; Morales Angulo, Carmelo

2015-01-01

Chiari malformation is an alteration of the base of the skull with herniation through the foramen magnum of the brain stem and cerebellum. Although the most common presentation is occipital headache, the association of audio-vestibular symptoms is not rare. The aim of our study was to describe audio-vestibular signs and symptoms in Chiari malformation type i (CM-I). We performed a retrospective observational study of patients referred to our unit during the last 5 years. We also carried out a literature review of audio-vestibular signs and symptoms in this disease. There were 9 patients (2 males and 7 females), with an average age of 42.8 years. Five patients presented a Ménière-like syndrome; 2 cases, a recurrent vertigo with peripheral features; one patient showed a sudden hearing loss; and one case suffered a sensorineural hearing loss with early childhood onset. The most common audio-vestibular symptom indicated in the literature in patients with CM-I is unsteadiness (49%), followed by dizziness (18%), nystagmus (15%) and hearing loss (15%). Nystagmus is frequently horizontal (74%) or down-beating (18%). Other audio-vestibular signs and symptoms are tinnitus (11%), aural fullness (10%) and hyperacusis (1%). Occipital headache that increases with Valsalva manoeuvres and hand paresthesias are very suggestive symptoms. The appearance of audio-vestibular manifestations in CM-I makes it common to refer these patients to neurotologists. Unsteadiness, vertiginous syndromes and sensorineural hearing loss are frequent. Nystagmus, especially horizontal and down-beating, is not rare. It is important for neurotologists to familiarise themselves with CM-I symptoms to be able to consider it in differential diagnosis. Copyright © 2014 Elsevier España, S.L.U. y Sociedad Española de Otorrinolaringología y Patología Cérvico-Facial. All rights reserved.

Budd-Chiari Syndrome in a Patient with Hepatitis C

Directory of Open Access Journals (Sweden)

Joseph Frankl

2016-01-01

Full Text Available Chronic Budd-Chiari syndrome can present with cirrhosis and signs and symptoms similar to those of other chronic liver diseases. We present a case of Budd-Chiari syndrome discovered during attempted transjugular intrahepatic portosystemic shunting in a patient with decompensated cirrhosis believed to be secondary to hepatitis C. Although the patient had hepatocellular carcinoma, the Budd-Chiari syndrome was a primary disease due to hepatic venous webs. Angioplasty was performed in this case, which resolved the patient’s symptoms related to portal hypertension. Follow-up venography 5 months after angioplasty demonstrated continued patency of the hepatic veins. A biopsy was obtained in the same setting, which showed centrilobular fibrosis indicating that venous occlusion was indeed the cause of cirrhosis. It is important to consider a second disease when treating a patient with difficult to manage portal hypertension.

Budd Chiari Syndrome in a Fifteen-Year Old Girl with Systemic ...

African Journals Online (AJOL)

It is believed that in this patient, Budd Chiari Syndrome resulted from hepatic veinous thrombosis due to the presence of Lupus anticoagulants. As the young girl was suffering from antiphospholipid syndrome secondary to lupus, this milder form of Budd-Chiari Syndrome was later treated in India with surgical shunts.

Diagnosis and therapy of Budd-Chiari syndrome

International Nuclear Information System (INIS)

Bachmann, R.; Strunk, H.; Hofer, U.; Schild, H.; Brensing, K.A.

1998-01-01

Purpose: Budd-Chiari syndrome is a fairly uncommon disease in Europe. This often leads to its late diagnosis. The syndrome is characterised by portal hypertension and splanchnic congestion due to obstruction of hepatic venous outflow. This paper describes the treatment of three patients with Budd-Chiari syndrome by interventional therapeutic techniques and discusses alternative treatment modalities. Patients and Methods: The first patient presented with veno-occlusive disease and was treated by the placement of a transjugular intrahepatic portosystemic stentshunt. The second patient showed an occlusion of the major hepatic veins. After percutaneous recanalisation, a stent was placed in the right hepatic vein which remained patent. The third patient had a membranous obstruction of the right hepatic vein which was treated by percutaneous balloon dilatation. Results: In all patients the clinical symptoms resolved completely after treatment and no complications were encountered. Conclusions: The authors conclude that interventional therapeutic techniques offer a wide variety of possibilities for the treatment of patients with Budd-Chiari syndrome and are safe, effective and relatively inexpensive. However, further studies are required to assess the long-term results and survival rates of these patients. (orig.) [de

Anesthetic management in a child with Arnold-Chiari malformation and bilateral vocal cord paralysis.

NARCIS (Netherlands)

Setz, A.C.W.; Boer, H.D. de; Driessen, J.J.; Scheffer, G.J.

2005-01-01

We report a case of a child who was scheduled for an emergency ventriculoperitoneal shunt procedure. The patient had a type II Arnold-Chiari malformation (ACM) and associated hydrocephalus and presented with near complete respiratory obstruction from bilateral abductor vocal cord palsy. Early

[Association Budd Chiari syndrome, antiphospholipid syndrome and Grave's disease].

Science.gov (United States)

Mouelhi, Leila; Chaieb, Mouna; Debbeche, Radhouane; Salem, Mohamed; Sfar, Imene; Trabelsi, Sinda; Gorgi, Yosr; Najjar, Taoufik

2009-02-01

Antiphospholipid syndrome is revealed by Budd Chiari syndrome in 5% of the cases. Antiphospholipid syndrome is characterized by venous or arterial thrombosis, foetal loss and positivity of antiphospholipid antibodies, namely lupus anticoagulant, anticardiolipin antibodies and anti-beta2-glycoprotein I. Anticardiolipin antibodies was reported in auto-immune thyroid disorders, particularly in Grave's disease. Antiphospholipid syndrome associated to Grave's disease was reported in only three cases. To describe a case report of association of Grave's disease and antiphospholipid syndrome. We report the first case of Grave's disease associated with antiphospholipid syndrome, revealed by Budd Chiari syndrome. Our observation is particular by the fact that it is about a patient presenting a Grave's disease associated with antiphospholipid syndrome revealed by Budd Chiari syndrome. This triple association has never been reported in literature. Although association between antiphospholipid syndrome and Grave's disease was previously described, further studies evaluating the coexistence of these two affections in the same patient would be useful.

Is Chiari malformation a cause of systemic hypertension and sinus bradycardia? A case report and literature review

Directory of Open Access Journals (Sweden)

Majid Ghasemi

2011-01-01

Type I Chiari malformation is a disease mostly caused by congenital displacement of cerebellar tonsils through the fo-ramen magnum. The most common symptom is headache, rarely reported with hypertension or sinus bradycardia.

Surgical treatment of Arnold-Chiari malformation type I in an adult patient

Directory of Open Access Journals (Sweden)

Marković Marko

2008-01-01

Full Text Available Background. Herniation of the cerebellar tonsils through the foramen magnum into the cervical spinal canal with obliteration of the cerebellomedullary cistern is the primary feature of Arnold-Chiari type I malformation (ACM I. It is considered to be congenital malformation, although there have been reported cases of an acquired form. Case report. We presented a female patient, 45-year old, with ACM I without syringomyelia as a rare and unusual clinical image, as well as the effect of decompressive surgery in the treatment of this malformation. The patient was admitted to the Department of Neurosurgery with clinical signs of truncal ataxia worsening during the last six years. Moderate quadriparesis with predominant lower extremity involvement and the signs of the cranial nerves damages occured during the last seven months before admission, with progressive clinical course up to the date of admission. Neurosurgical treatment that included suboccipital medial craniectomy with resection of posterior arch C1 vertebrae and C2 laminectomy resulted in a significant clinical improvement and a much better quality of life. Conclusion. Posterior craniovertebral decompression with microsurgical reduction of the cerebellar tonsils and placement of an artificial dural graft is a treatment of choice in severe forms of ACM I without syringomyelia. .

Expert consensus on the classification of subtype in Budd-Chiari syndrome

Directory of Open Access Journals (Sweden)

Expert committee on Vane Cava Obstruction,Specialized CommitteeofEndovascology,ChineseMedicalDoctorAssociation

2017-07-01

Full Text Available From 2012 to 2015 the Department of Interventional Radiology of the Affiliated Hospital of Xuzhou Medical University undertook the clinical special research subject ”Study on the standardization of interventional diagnosis and treatment of Budd- Chiari syndrome”（No. BL2012021）， a program supported by the Department of Science and Technology of Jiangsu Province. Based on the clinical results of three years research and the scientific summary of the experience from more than 2150 cases accumulated in more than 20 years， the Department of Interventional Radiology of the Affiliated Hospital of Xuzhou Medical University presided over a demonstration meeting about “the standardization of interventional diagnosis and treatment of Budd- Chiari syndrome” on January 14， 2016 in Xuzhou City of Jiangsu Province， China. The scholars from the Expert Committee on Vena Cava Obstruction of Specialized Committee of Endovascology， Chinese Medical Doctor Association， as well as the experts from the related medical fields， including interventional radiology， vascular surgery， pathology and diagnostic imaging， who have been engaged in the study of Budd- Chiari syndrome， attended the meeting， and in the meeting the participants made a full and thorough discussion on the classification and subtypes of Budd - Chiari syndrome. The scholars and experts have unanimously reached a consensus on the subtype definition of Budd- Chiari syndrome: the Budd Chiari syndrome is suggested to be classified into the hepatic vein occlusion subtype， the inferior vena cava occlusion subtype and mixed occlusion subtype， including 10 subtype entities in total. The hepatic vein occlusion subtype includes membranous occlusion of hepatic vein/accessory hepatic vein， segmental occlusion of hepatic vein， extensive occlusion of hepatic vein， and hepatic vein occlusion associated with thrombus formation. The inferior vena cava occlusion subtype

Radiation-induced liver injury showing low intensity on T2-weighted images noted in Budd-Chiari syndrome

Energy Technology Data Exchange (ETDEWEB)

Mori, Harushi [Tokyo Univ. (Japan). Graduate School of Medicine; Yoshioka, Hiroshi; Saida, Yukihisa; Itai, Yuji [Tsukuba Univ., Ibaraki (Japan). Inst. of Clinical Medicine; Mori, Kensaku [Tsukuba Univ., Ibaraki (Japan). Hospital; Ahmadi, T. [Shahid Beheshti Univ. of Medical Sciences, Teheran (Iran, Islamic Republic of); Okumura, Toshiyuki [Ibaraki Prefectural Central Hospital, Tomobe (Japan)

2002-04-01

Although it is documented that radiation can cause density or intensity changes on computed tomography or MR imaging in the irradiated hepatic parenchyma, few researchers have reported or understood the MR presentation of changes in hepatic parenchyma following radiotherapy in the patient with Budd-Chiari syndrome. The purpose of this study was to investigate the MR appearance of hepatic radiation injury in Budd-Chiari syndrome and to consider the underlying pathophysiology. The MR examinations of two patients with Budd-Chiari syndrome was compared with those of 11 patients without Budd-Chiari syndrome. The two groups, both of which suffered from hepatocellular carcinoma, underwent 50-72 Gy of proton-beam irradiation during a period of 14-43 days. Examinations including T1- and T2-weighted imaging, superparamagnetic iron oxide-enhanced imaging, and dynamic study were performed 3-10 weeks after the end of irradiation. Radiation-induced hepatic injury was observed as a low-intensity area on T2-weighted images and on delayed phase images of dynamic study in the Budd-Chiari patients, and as iso- or high-intensity areas on both images in the patients without Budd-Chiari syndrome. US-guided needle biopsy from the irradiated area in one patient with Budd-Chiari syndrome revealed mostly necrotic tissue and fibrous tissue. These MR features of hepatic radiation injury in Budd-Chiari syndrome were considered to be due to severe hepatic fibrosis. (author)

Results of Chiari pelvic osteotomy for acetabular dysplasia in adults; Association with bone scintigraphic findings

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Nobuo; Ozono, Kenji; Sugano, Nobuhiko; Takaoka, Kunio; Ono, Hiroo (Osaka Univ. (Japan). Faculty of Medicine)

1993-02-01

In an attempt to determine indications of Chiari pelvic osteotomy in acetabular dysplasia, postoperative outcome of hip joint (64 joints) was examined on the basis of findings of bone scintigraphy. The subjects were 61 patients with osteoarthrosis of hip joint who underwent preoperative bone scintigraphy. The follow-up period ranged from 2 years to 9 years and 7 months with a mean of 4 years and 9 months. According to X-ray findings, 37 osteoarthrosis joints were staged as early and 27 as progressive. Preoperative bone scintigraphic findings fell into three: (I) normal or slight hot type (33 joints), (II) hot type at the weighting part (16 joints), and (III) double hot type in the weighting part and inside part (15 joints). None of the patients had severe surgical complications such as deep-seated infection, neuroparalysis and pseudojoint. According to the clinical staging for hip joint function, 7 (47%) of 64 joints were judged as poor after osteotomy, belonging to type III. Deterioration of osteoarthrosis was seen in 11 joints (41%) on X-ray films. Of these, 9 had type III. In conclusion, Chiari pelvic osteotomy should not be indicated when type III is shown on bone scintigrams. (N.K.).

Two Cases of Arnold-Chiari Malformation with Respiratory Failure

Directory of Open Access Journals (Sweden)

Sinem Iliaz

2014-03-01

Full Text Available Arnold–Chiari malformation is defined as downward displacement of the brainstem and cerebellum through the foramen magnum. It has different clinical presentations and four subtypes. It is known that downward migration of posterior fossa components through the foramen magnum and associated lower cranial nerve palsy and brainstem compression can cause respiratory failure. Acute respiratory failure could mark the onset of the disease. Posterior fossa decompression performed to treat primary disease can improve the central sleep abnormalities. As respiratory failure is rarely seen, this paper presents two cases of Arnold–Chiari malformation with respiratory failure.

The Chiari III malformation: an unusual and asymptomatic variant in an 11-year old child

International Nuclear Information System (INIS)

Sirikci, Akif; Bayazit, Yildirim A.; Bayram, Metin

2001-01-01

Chiari III malformation is an extremely rare condition, and is characterized by the hindbrain herniation into a low occipital or high cervical encephalocele together with the pathologic and imaging features of the Chiari II malformation. In this report, an unusual variant of the Chiari III malformation was diagnosed in an 11-year-old girl. She had an encephalocele operation when she was a newborn, and has been asymptomatic since then. The clinical and imaging findings of this case were presented

The Chiari III malformation: an unusual and asymptomatic variant in an 11-year old child

Energy Technology Data Exchange (ETDEWEB)

Sirikci, Akif E-mail: sirikci@yahoo.com; Bayazit, Yildirim A.; Bayram, Metin

2001-09-01

Chiari III malformation is an extremely rare condition, and is characterized by the hindbrain herniation into a low occipital or high cervical encephalocele together with the pathologic and imaging features of the Chiari II malformation. In this report, an unusual variant of the Chiari III malformation was diagnosed in an 11-year-old girl. She had an encephalocele operation when she was a newborn, and has been asymptomatic since then. The clinical and imaging findings of this case were presented.

Factor V G1691A (Leiden is a major etiological factor in Egyptian Budd-Chiari syndrome patients

Directory of Open Access Journals (Sweden)

Tawhida Y. Abdel Ghaffar

2011-12-01

Full Text Available Objective: Budd-Chiari syndrome is a multifactorial disease in which several prothrombotic disorders may predispose patients to the development of thrombosis at this uncommon location (hepatic veins. The aim of this study was to determine the prevalence and characteristics of inherited thrombophilia in Egyptian Budd-Chiari syndrome patients.Materials and Methods: The study included 47 Budd-Chiari syndrome patients (20 children and 27 adults. Genotyping of Factor V G1691A (Leiden, prothrombin G20210A (PT, and methylenetetrahydrofolate reductase C677T were performed using real-time PCR and fluorescence melting curve detection analysis.Results: Factor V Leiden was observed in 29 patients (61.7%. It is the only factor that caused Budd-Chiari syndrome in 18 of the patients and in 5 of the patients with inferior vena cava involvement. Myeloproliferative disease was noted in 12 (25.5% patients, antiphospholipid syndrome in 5 (10.6%, and Behcet’s disease in 3 (6.4%. Interestingly, 3 of the children with Budd-Chiari syndrome had lipid storage disease.Conclusion: Factor V Leiden was a major etiological factor in Egyptian Budd-Chiari syndrome patients, which may have been related to the high frequency of this mutation in the study region. Factor V Leiden was also a strong thrombophilic factor and the leading cause of inferior vena cava thrombosis in these patients. Lipid storage disease should be included as a risk factor for Budd-Chiari syndrome.

Bilateral pulmonary thromboembolism and Budd-Chiari syndrome in a patient with Crohn's disease on oral contraceptives Tromboembolismo de pulmón bilateral y síndrome de Budd-Chiari en paciente con enfermedad de Crohn y toma de anticonceptivos orales

Directory of Open Access Journals (Sweden)

M. Valdés Mas

2009-09-01

Full Text Available Budd-Chiari syndrome can be defined as an interruption or diminution of the normal blood flow out of the liver. Patients with Budd-Chiari syndrome present with varying degrees of symptomatology that can be divided into the following categories: fulminant, acute, subacute and chronic. The subacute form is the most common presentation. A majority of patients with Budd-Chiari syndrome have an underlying hypercoagulability state. We present the case of a young woman with Crohn's disease on oral contraceptives who developed bilateral pulmonary thromboembolism and Budd-Chiari syndrome.El síndrome de Budd-Chiari consiste en la interrupción o disminución de flujo de las venas suprahepáticas. Tiene una gran variabilidad clínica en cuanto a su forma de presentación siendo la más frecuente la forma subaguda. La gran mayoría de los pacientes responden a estados de hipercoagulabilidad. Presentamos el caso de una paciente joven con enfermedad de Crohn que estaba en tratamiento con anticonceptivos orales y desarrolló un cuadro clínico de tromboembolismo de pulmón bilateral y síndrome de Budd-Chiari.

Radiological evolution of peri-odontoid pannus in a patient with Chiari I malformation: a case-based review.

Science.gov (United States)

Sanders, Felipe Hada; Wang, Joy M H; Oskouian, Rod J; Tubbs, R Shane; Oakes, W Jerry

2017-08-01

The Chiari I malformation (CIM) is commonly encountered by neurosurgeons and can have different etiologies and clinical presentations. We report a CIM patient who presented with symptoms of ventral brain stem compression and was found to have a large peri-odontoid pannus. Posterior fossa decompression was performed with a planned second-stage odontoidectomy. However, at the 6-month follow-up, postoperative images demonstrated a mostly resolved pannus and improvement of the brain stem compression symptoms, and the patient progressed uneventfully without the need for odontoidectomy. This case illustrates the resolution of a significant and symptomatic peri-odontoid pannus in a patient with CIM without craniocervical fusion or odontoidectomy. Such a case indicates that not all peri-odontoid pannus formations in CIM patients are due to hypermobility at the craniocervical junction.

Unusual Ventilatory Response to Exercise in Patient with Arnold-Chiari Type 1 Malformation after Posterior Fossa Decompression

Directory of Open Access Journals (Sweden)

Keely Smith

2016-01-01

Full Text Available We present a case of a 17-year-old Hispanic male with Arnold-Chiari Type 1 [AC-Type 1] with syringomyelia, status post decompression, who complains of exercise intolerance, headaches, and fatigue with exertion. The patient was found to have diurnal hypercapnia and nocturnal alveolar hypoventilation. Cardiopulmonary testing revealed blunting of the ventilatory response to the rise in carbon dioxide (CO2 resulting in failure of the parallel correlation between increased CO2 levels and ventilation; the expected vertical relationship between PETCO2 and minute ventilation during exercise was replaced with an almost horizontal relationship. No new pathology of the brainstem was discovered by MRI or neurological evaluation to explain this phenomenon. The patient was placed on continuous noninvasive open ventilation (NIOV during the day and CPAP at night for a period of 6 months. His pCO2 level decreased to normal limits and his symptoms improved; specifically, he experienced less headaches and fatigue during exercise. In this report, we describe the abnormal response to exercise that patients with AC-Type 1 could potentially experience, even after decompression, characterized by the impairment of ventilator response to hypercapnia during exertion, reflecting a complete loss of chemical influence on breathing with no evidence of abnormality in the corticospinal pathway.

Junctional epidermolysis bullosa(non-herlitz type)

International Nuclear Information System (INIS)

Bhinder, M. A.; Arshad, M. W.; Shabbir, M. I.; Zahoor, M. Y.; Shehzad, W.; Tariq, M.

2017-01-01

Junctional epidermolysis bullosa (JEB) is a recessively inherited skin blistering disease and is caused due to abnormalities in proteins that hold layers of the skin. Herlitz JEB is the severe form and non-Herlitz JEB is the milder form. This report describes a case of congenitally affected male child aged 5 years, with skin blistering. He has mitten-like hands and soft skin blistering on hands, legs and knees. Symptoms almost disappeared at the age of 3 years but reappeared with increased severity after 6 months. Histopathological examination showed epidermal detachment with intact basal cell layer and sparse infiltrate of lymphocytes with few eosinophils in the dermis. There was no blistering on the moist lining of the mouth and digestive tract. Localized symptoms with less lethality and histopathological examination indicated the presence of non-Herlitz type of JEB. This is the first report which confirms the presence of non-Herlitz junctional epidermolysis bullosa in Pakistan. (author)

Junctional Epidermolysis Bullosa (Non-Herlitz Type).

Science.gov (United States)

Bhinder, Munir Ahmad; Arshad, Muhammad Waqar; Zahoor, Muhammad Yasir; Shehzad, Wasim; Tariq, Muhammad; Shabbir, Muhammad Imran

2017-05-01

Junctional epidermolysis bullosa (JEB) is a recessively inherited skin blistering disease and is caused due to abnormalities in proteins that hold layers of the skin. Herlitz JEB is the severe form and non-Herlitz JEB is the milder form. This report describes a case of congenitally affected male child aged 5 years, with skin blistering. He has mitten-like hands and soft skin blistering on hands, legs and knees. Symptoms almost disappeared at the age of 3 years but reappeared with increased severity after 6 months. Histopathological examination showed epidermal detachment with intact basal cell layer and sparse infiltrate of lymphocytes with few eosinophils in the dermis. There was no blistering on the moist lining of the mouth and digestive tract. Localized symptoms with less lethality and histopathological examination indicated the presence of non-Herlitz type of JEB. This is the first report which confirms the presence of non-Herlitz junctional epidermolysis bullosa in Pakistan.

Quantitative trait loci (QTL study identifies novel genomic regions associated to Chiari-like malformation in Griffon Bruxellois dogs.

Directory of Open Access Journals (Sweden)

Philippe Lemay

Full Text Available Chiari-like malformation (CM is a developmental abnormality of the craniocervical junction that is common in the Griffon Bruxellois (GB breed with an estimated prevalence of 65%. This disease is characterized by overcrowding of the neural parenchyma at the craniocervical junction and disturbance of cerebrospinal fluid (CSF flow. The most common clinical sign is pain either as a direct consequence of CM or neuropathic pain as a consequence of secondary syringomyelia. The etiology of CM remains unknown but genetic factors play an important role. To investigate the genetic complexity of the disease, a quantitative trait locus (QTL approach was adopted. A total of 14 quantitative skull and atlas measurements were taken and were tested for association to CM. Six traits were found to be associated to CM and were subjected to a whole-genome association study using the Illumina canine high density bead chip in 74 GB dogs (50 affected and 24 controls. Linear and mixed regression analyses identified associated single nucleotide polymorphisms (SNPs on 5 Canis Familiaris Autosomes (CFAs: CFA2, CFA9, CFA12, CFA14 and CFA24. A reconstructed haplotype of 0.53 Mb on CFA2 strongly associated to the height of the cranial fossa (diameter F and an haplotype of 2.5 Mb on CFA14 associated to both the height of the rostral part of the caudal cranial fossa (AE and the height of the brain (FG were significantly associated to CM after 10 000 permutations strengthening their candidacy for this disease (P = 0.0421, P = 0.0094 respectively. The CFA2 QTL harbours the Sall-1 gene which is an excellent candidate since its orthologue in humans is mutated in Townes-Brocks syndrome which has previously been associated to Chiari malformation I. Our study demonstrates the implication of multiple traits in the etiology of CM and has successfully identified two new QTL associated to CM and a potential candidate gene.

Quantitative analysis of Chiari-like malformation and syringomyelia in the Griffon Bruxellois dog.

Directory of Open Access Journals (Sweden)

Susan P Knowler

Full Text Available This study aimed to develop a system of quantitative analysis of canine Chiari-like malformation and syringomyelia on variable quality MRI. We made a series of measurements from magnetic resonance DICOM images from Griffon Bruxellois dogs with and without Chiari-like malformation and syringomyelia and identified several significant variables. We found that in the Griffon Bruxellois dog, Chiari-like malformation is characterized by an apparent shortening of the entire cranial base and possibly by increased proximity of the atlas to the occiput. As a compensatory change, there appears to be an increased height of the rostral cranial cavity with lengthening of the dorsal cranial vault and considerable reorganization of the brain parenchyma including ventral deviation of the olfactory bulbs and rostral invagination of the cerebellum under the occipital lobes.

The odontoid process invagination in normal subjects, Chiari malformation and Basilar invagination patients: Pathophysiologic correlations with angular craniometry.

Science.gov (United States)

Ferreira, Jânio A; Botelho, Ricardo V

2015-01-01

Craniometric studies have shown that both Chiari malformation (CM) and basilar invagination (BI) belong to a spectrum of malformations. A more precise method to differentiate between these types of CVJM is desirable. The Chamberlain's line violation (CLV) is the most common method to identify BI. The authors sought to clarify the real importance of CLV in the spectrum of craniovertebral junction malformations (CVJM) and to identify possible pathophysiological relationships. We evaluated the CLV in a sample of CVJM, BI, CM patients and a control group of normal subjects and correlated their data with craniocervical angular craniometry. A total of 97 subjects were studied: 32 normal subjects, 41 CM patients, 9 basilar invagination type 1 (BI1) patients, and 15 basilar invagination type 2 (BI2) patients. The mean CLV violation in the groups were: The control group, 0.16 ± 0.45 cm; the CM group, 0.32 ± 0.48 cm; the BI1 group, 1.35 ± 0.5 cm; and the BI2 group, 1.98 ± 0.18 cm. There was strong correlation between CLV and Boogard's angle (R = 0.82, P = 0.000) and the clivus canal angle (R = 0.7, P = 0.000). CM's CLV is discrete and similar to the normal subjects. BI1 and BI2 presented with at least of 0.95 cm CLV and these violations were strongly correlated with a primary cranial angulation (clivus horizontalization) and an acute clivus canal angle (a secondary craniocervical angle).

Effect of cross-type bias in a two-dimensional array of short Josephson junctions

DEFF Research Database (Denmark)

Filatrella, G.; Pedersen, Niels Falsig; Wiesenfeld, K.

1998-01-01

We investigate numerically the effect of cross-type bias on two-dimensional arrays of short Josephson junctions. We have demonstrated that, for the simplest circuit, this type of bias is able to phase lock the junctions yielding a substantial improvement over ordinary biasing schemes. (C) 1998...

Comparison of Porcine and Bovine Collagen Dural Substitutes in Posterior Fossa Decompression for Chiari I Malformation in Adults.

Science.gov (United States)

Lee, Christine K; Mokhtari, Tara; Connolly, Ian D; Li, Gordon; Shuer, Lawrence M; Chang, Steven D; Steinberg, Gary K; Hayden Gephart, Melanie

2017-12-01

Posterior fossa decompression surgeries for Chiari malformations are susceptible to postoperative complications such as pseudomeningocele, external cerebrospinal fluid (CSF) leak, and meningitis. Various dural substitutes have been used to improve surgical outcomes. This study examined whether the collagen matrix dural substitute type correlated with the incidence of postoperative complications after posterior fossa decompression in adult patients with Chiari I malformations. A retrospective cohort study was conducted of 81 adult patients who underwent an elective decompressive surgery for treatment of symptomatic Chiari I malformations, with duraplasty involving a dural substitute derived from either bovine or porcine collagen matrix. Demographics and treatment characteristics were correlated with surgical outcomes. A total of 81 patients were included in the study. Compared with bovine dural substitute, porcine dural substitute was associated with a significantly higher risk of pseudomeningocele occurrence (odds ratio, 5.78; 95% confidence interval, 1.65-27.15; P = 0.01) and a higher overall complication rate (odds ratio, 3.70; 95% confidence interval, 1.23-12.71; P = 0.03) by univariate analysis. There was no significant difference in the rate of meningitis, repeat operations, or overall complication rate between the 2 dural substitutes. In addition, estimated blood loss was a significant risk factor for meningitis (P = 0.03). Multivariate analyses again showed that porcine dural substitute was associated with pseudomeningocele occurrence, although the association with higher overall complication rate did not reach significance. Dural substitutes generated from porcine collagen, compared with those from bovine collagen, were associated with a higher likelihood of pseudomeningocele development in adult patients undergoing Chiari I malformation decompression and duraplasty. Copyright © 2017 Elsevier Inc. All rights reserved.

Role of Cysternography in the management of Chiari I malformation related syringomyelia

International Nuclear Information System (INIS)

Das, B.K.; Pradhan, P.K.; Arora, P.; Bihari, S.; Arya, A.; Jain, V.K.; Banerjee, D.; Chhabra, D.K.

2002-01-01

Aim: In syringomyelia related to Chiari I malformation there is significant alteration of CSF flow dynamics . However, no systematic study has been reported revealing the changes of flow dynamics and its role in assessing the outcome of treatment. The aim of this prospective study was to characterize the changes of CSF flow dynamics in MRI proven Chiari I malformation and correlate the findings with the outcome of posterior decompression and duraplasty. Material and Method : Fifteen patients with MRI proven Chiari I malformation without associated hydrocephalus or fixed AAD requiring trans oral decompression were included in this study. 185 MBq ( 5 mCi ) Tc99m-DTPA was instilled in lumbar region and the ascent of the tracer was followed at 2 hrs, 4 hrs, 6 hrs and 24 hrs by Gamma Camera imaging. The time and pattern of ascent to Foramen magnum(FM), cranial subarachnoidal spaces, delay or hold up of tracer or filling of syrinx were noted. Results: Out of 15 patients six (40%) showed timely tracer ascent with normal CSF flow to the cerebral convexities(group I) whereas 9 patients (60%) had delayed ascent and abnormal intra cranial CSF flow. In these 9 patients two distinctive groups could be identified. Six patients (group II) had mild delay whereas three patients (group III) showed almost complete block of CSF flow at the FM level. Comparison of clinical status as measured by modified JOAS disability grading system before and six months after surgical intervention showed significant improvement in group III and moderate improvement in group II. Group I patients had a low disability grade before and showed minor improvement after intervention. Conclusions: (i) Cysternography can be helpful in predicting the outcome of surgical intervention in Chiari I malformation related syringomyelia. (ii) Pre and post operative clinical scores correlate with the cysternography findings. (iii) The traditional belief that FM block causes Chiari I malformation related syringomyelia

MRI tight posterior fossa sign for prenatal diagnosis of Chiari type II malformation

Energy Technology Data Exchange (ETDEWEB)

Ando, Kumiko; Ishikura, Reiichi; Ogawa, Masayo; Takada, Yoshihiro; Yamamoto, Satoshi; Fujiwara, Masayuki; Hirota, Shozo [Hyogo College of Medicine, Department of Radiology, Nishinomiya, Hyogo (Japan); Shakudo, Miyuki [Osaka City General Hospital, Department of Radiology, Osaka (Japan); Tanaka, Hiroyuki [Hyogo College of Medicine, Department of Gynecology, Nishinomiya (Japan); Minagawa, Kyoko [Hyogo College of Medicine, Department of Pediatrics, Nishinomiya (Japan)

2007-12-15

Chiari type II malformation (CMII) is one of three hindbrain malformations that display hydrocephalus. We have observed that cerebrospinal fluid (CSF) signal in the posterior fossa, which is always apparent on normal fetal MR images, is not visible in a fetus with CMII. We use the term 'tight posterior fossa' for this MR imaging finding, and evaluate the diagnostic value of this finding on fetal MR images. Included in the study were 21 fetuses which underwent brain MR imaging at 1.5 T using two-dimensional balanced turbo-field-echo (2-D balanced-TFE) in the axial and sagittal planes. Postnatal diagnoses were CMII (n=5), CNS abnormalities other than CMII (n=8), and no abnormality (n=8). A tight posterior fossa was defined as an absent or slit-like water signal space around the hindbrain in the posterior fossa on both sagittal and axial MR images. All CMII fetuses displayed a tight posterior fossa on MR images. Hydrocephalus was visualized in all CMII fetuses and myelomeningocele in four fetuses, but hindbrain herniation was visualized only in two of five fetuses. The CSF signal surrounding the hindbrain was clearly visible in all the other 16 fetuses, including five with hydrocephalus not associated with CMII, although it was slightly narrower in a fetus with a cloverleaf skull than in the normal fetuses. Tight posterior fossa in the presence of hydrocephalus is a useful and characteristic finding of CMII on fetal MRI. (orig.)

MRI tight posterior fossa sign for prenatal diagnosis of Chiari type II malformation

International Nuclear Information System (INIS)

Ando, Kumiko; Ishikura, Reiichi; Ogawa, Masayo; Takada, Yoshihiro; Yamamoto, Satoshi; Fujiwara, Masayuki; Hirota, Shozo; Shakudo, Miyuki; Tanaka, Hiroyuki; Minagawa, Kyoko

2007-01-01

Chiari type II malformation (CMII) is one of three hindbrain malformations that display hydrocephalus. We have observed that cerebrospinal fluid (CSF) signal in the posterior fossa, which is always apparent on normal fetal MR images, is not visible in a fetus with CMII. We use the term 'tight posterior fossa' for this MR imaging finding, and evaluate the diagnostic value of this finding on fetal MR images. Included in the study were 21 fetuses which underwent brain MR imaging at 1.5 T using two-dimensional balanced turbo-field-echo (2-D balanced-TFE) in the axial and sagittal planes. Postnatal diagnoses were CMII (n=5), CNS abnormalities other than CMII (n=8), and no abnormality (n=8). A tight posterior fossa was defined as an absent or slit-like water signal space around the hindbrain in the posterior fossa on both sagittal and axial MR images. All CMII fetuses displayed a tight posterior fossa on MR images. Hydrocephalus was visualized in all CMII fetuses and myelomeningocele in four fetuses, but hindbrain herniation was visualized only in two of five fetuses. The CSF signal surrounding the hindbrain was clearly visible in all the other 16 fetuses, including five with hydrocephalus not associated with CMII, although it was slightly narrower in a fetus with a cloverleaf skull than in the normal fetuses. Tight posterior fossa in the presence of hydrocephalus is a useful and characteristic finding of CMII on fetal MRI. (orig.)

Investigation of fluid-structure interaction with various types of junction coupling

Science.gov (United States)

Ahmadi, A.; Keramat, A.

2010-10-01

In this study of water hammer with fluid-structure interaction (FSI) the main aim was the investigation of junction coupling effects. Junction coupling effects were studied in various types of discrete points, such as pumps, valves and branches. The emphasis was placed on an unrestrained pump and branch in the system, and the associated relations were derived for modelling them. Proposed relations were considered as boundary conditions for the numerical modelling which was implemented using the finite element method for the structural equations and the method of characteristics for the hydraulic equations. The results can be used by engineers in finding where junction coupling is significant.

Scoliosis and Syringomyelia With Chiari Malformation After Lumbar Shunting

Directory of Open Access Journals (Sweden)

Hsin-Hung Chen

2010-07-01

Full Text Available Unsteady gait was noted in a 2-year-old boy with a lumboperitoneal (LP shunt that had been inserted 1 year earlier for increased head circumference caused by communicating hydrocephalus. Scoliosis was also noted during postoperative follow-up. Magnetic resonance imaging revealed new hindbrain tonsillar herniation and an extensive syrinx from C3 to L1. The malfunctioning LP shunt was removed and posterior fossa decompression with ventriculoperitoneal shunt insertion was performed. The unsteady gait recovered completely and scoliosis improved. Magnetic resonance imaging demonstrated resolution of the syrinx and tonsillar herniation. Acquired Chiari I malformation after LP shunt is well documented; usually, patients have no symptoms. This is the first report to have all the cause and effect mechanisms among syringomyelia, scoliosis and Chiari I malformation in 1 patient. We review the literature and discuss the possible mechanisms.

Hemifacial spasm in a patient with neurofibromatosis and Arnold-Chiari malformation: a unique case association Espasmo hemifacial em paciente com neurofibromatose e malformação de Arnold-Chiari: uma associação rara

Directory of Open Access Journals (Sweden)

Andre Carvalho Felício

2007-09-01

Full Text Available BACKGROUND: The association of hemifacial spasm (HFS, Chiari type I malformation (CIM and neurofibromatosis type 1 (NF1 has not been described yet. CASE REPORT: We report the case of a 31-year-old woman with NF1 who developed a right-sided HFS. On magnetic resonance imaging (MRI a CIM was seen without syringomyelia. The patient has been successfully treated with botulinum toxin type A injections for 5 years without major side effects. CONCLUSION:Clinical features of HFS, CMI and NF1 are highlighted together with their possible relationship. Also, therapeutic strategies are also discussed.INTRODUÇÃO: A associação entre espasmo hemifacial (EHF, malformação de Chiari tipo I (MCI e neurofibromatose tipo I (NFI ainda não foi descrita. RELATO DO CASO: Relatamos o caso de mulher com 31 anos com NFI que desenvolveu EHF à direita. Na ressonância magnética (RM foi observada MCI sem seringomielia associada. A paciente foi tratada com sucesso com toxina botulínica tipo A por 5 anos sem efeitos colaterais. CONCLUSÃO: Ressaltamos as características clínicas do EHF, MCI e NFI assim como uma possível relação entre elas. Além disto, discutimos também estratégias terapêuticas.

Budd-Chiari syndrome and liver transplantation

Science.gov (United States)

Akamatsu, Nobuhisa; Sugawara, Yasuhiko; Kokudo, Norihiro

2015-01-01

Summary Budd-Chiari syndrome involves obstruction of hepatic venous outflow tracts at various levels from small hepatic veins to the inferior vena cava and is the result of thrombosis or its fibrous sequelae. There is a conspicuous difference in its etiology in the West and the East. Myeloproliferative disease predominates in the West and obstruction of the vena cava predominates in the East. The clinical presentation and clinical manifestations are so varied that it should be suspected in any patient with acute or chronic liver dysfunction. It should be treated with step-wise management. First-line therapy should be anticoagulation with medical treatment of the underlying illness, and interventional revascularization and TIPS are indicated in the event of a lack of response to medical therapy. Liver transplantation may be indicated as a rescue treatment or for fulminant cases with promising results. This step-by-step strategy has achieved a 5-year transplant-free survival rate of 70% and a 5-year overall survival rate of 90%. Living donor liver transplantation can also be used for patients with Budd-Chiari syndrome if deceased donor livers are scarce, but it requires a difficult procedure particularly with regard to venous outflow reconstruction. PMID:25674385

The Association between Sleep-Disordered Breathing and Magnetic Resonance Imaging Findings in a Pediatric Cohort with Chiari 1 Malformation

Directory of Open Access Journals (Sweden)

Reshma Amin

2015-01-01

Full Text Available BACKGROUND: The prevalence of sleep-disordered breathing (SDB reported in the literature for Chiari malformation type 1 (CM1 is uniformly high (24% to 70%. In Canada, there is limited access to pediatric polysomnography (PSG. Therefore, the identification of clinical features would be invaluable for triaging these children.

Hemiplegia cruzada associada a impressão basilar, malformação de Arnold-Chiari e siringomielia: relato de caso Cruciate hemiplegia associated with basilar impression, Arnold-Chiari malformation and syringomyelia: case report

Directory of Open Access Journals (Sweden)

José Alberto Gonçalves da Silva

1996-12-01

Full Text Available Os autores apresentam um caso de hemiplegia cruzada associada a impressão basilar, malformação de Arnold-Chiari e siringomielia. Discutem as propostas anatômicas e a fiopatogenia desta síndrome de ocorrência bastante rara.The authors report a case of cruciate hemiplegia associated with basilar impression, Chiari malformation and syringomyelia. The neuroanatomical controversy, the surgical treatment and the good outcome of the patient are discussed.

Relationship between Cough-Associated Changes in CSF Flow and Disease Severity in Chiari I Malformation: An Exploratory Study Using Real-Time MRI.

Science.gov (United States)

Bezuidenhout, A F; Khatami, D; Heilman, C B; Kasper, E M; Patz, S; Madan, N; Zhao, Y; Bhadelia, R A

2018-05-10

Currently no quantitative objective test exists to determine disease severity in a patient with Chiari I malformation. Our aim was to correlate disease severity in symptomatic patients with Chiari I malformation with cough-associated changes in CSF flow as measured with real-time MR imaging. Thirteen symptomatic patients with Chiari I malformation (tonsillar herniation of ≥5 mm) were prospectively studied. A real-time, flow-sensitized pencil-beam MR imaging scan was used to measure CSF stroke volume during rest and immediately following coughing and relaxation periods (total scan time, 90 seconds). Multiple posterior fossa and craniocervical anatomic measurements were also obtained. Patients were classified into 2 groups by neurosurgeons blinded to MR imaging measurements: 1) nonspecific Chiari I malformation (5/13)-Chiari I malformation with nonspecific symptoms like non-cough-related or mild occasional cough-related headache, neck pain, dizziness, paresthesias, and/or trouble swallowing; 2) specific Chiari I malformation (8/13)-patients with Chiari I malformation with specific symptoms and/or objective findings like severe cough-related headache, myelopathy, syringomyelia, and muscle atrophy. The Spearman correlation was used to determine correlations between MR imaging measurements and disease severity, and both groups were also compared using a Mann-Whitney U test. There was a significant negative correlation between the percentage change in CSF stroke volume (resting to postcoughing) and Chiari I malformation disease severity ( R = 0.59; P = .03). Mann-Whitney comparisons showed the percentage change in CSF stroke volume (resting to postcoughing) to be significantly different between patient groups ( P = .04). No other CSF flow measurement or anatomic measure was significantly different between the groups. Our exploratory study suggests that assessment of CSF flow response to a coughing challenge has the potential to become a valuable objective noninvasive

Posterior Fossa Decompression with Duraplasty in Chiari-1 Malformations

International Nuclear Information System (INIS)

Rehman, L.; Akbar, H.; Bokhari, I.; Babar, A. K.; Hahim, A. S. M.; Arain, S. H.

2015-01-01

Objective: To evaluate the symptomatic outcome after PFD (Posterior Fossa Decompression) with duraplasty in Chiari-1 malformations. Study Design: Case series. Place and Duration of Study: Department of Neurosurgery, JPMC, Karachi, from July 2008 to September 2012. Methodology: This included 21 patients of Chiari 1 malformations admitted in department through OPD with clinical features of headache, neck pain, numbness, neurological deficit, and syringomyelia. Diagnosis was confirmed by MRI. PFD followed by C1 laminectomy with duraplasty was done in all cases and symptomatic outcome was assessed in follow-up clinic. Results: Among 21 patients, 13 were females and 8 were males. Age ranged from 18 to 40 years. All the patients had neck pain and numbness in hands. Only 3 patients had weakness of all four limbs and 12 with weakness of hands. Symptoms evolved over a mean of 12 months. Syringomyelia was present in all cases. All patients underwent posterior fossa decompression with duraplasty with an additional C1 laminectomy and in 2 cases C2 laminectomy was done. Syringo-subarachnoid shunt was placed in one patient and ventriculo-peritoneal shunt was placed in 2 patients. Pain was relieved in all cases. Weakness was improved in all cases and numbness was improved in 19 cases. Syringomyelia was improved in all cases. Postoperative complications included CSF leak in 2 patients and wound infection in one patient. However, there was no mortality. Conclusion: Posterior fossa decompression with duraplasty is the best treatment option for Chiari-1 malformations because of symptomatic improvement and less chances of complications. (author)

Etiology, management, and outcome of the Budd-Chiari syndrome

NARCIS (Netherlands)

S. Darwish Murad (Sarwa); A. Plessier (Aurelie); M. Hernandez-Guerra (Manuel); F. Fabris (Federica Margherita); C.E. Eapen (Chundamannil Eapen); M.J. Bahr (Matthias); J. Trebicka (Jonel); I. Morard (Isabelle); L. Lasser (Luc); J. Heller (Jörg); A. Hadengue (Antoine); P. Langlet (Philippe); H. Miranda (Helena); M. Primignani (Massimo); E. Elias (Elwyn); F.W.G. Leebeek (Frank); F.R. Rosendaal (Frits); J.C. Garcia-Pagan (Juan Carlos); D.C. Valla (Dominique Charle); H.L.A. Janssen (Harry)

2009-01-01

textabstractBackground: The Budd-Chiari syndrome (BCS) is hepatic venous outflow obstruction. What is known about the syndrome is based on small studies of prevalent cases. Objective: To characterize the causes and treatment of incident BCS. Design: Consecutive case series of patients with incident

Budd–Chiari Syndrome in Young Chinese: Clinical Characteristics, Etiology and Outcome of Recanalization from a Single Center

Energy Technology Data Exchange (ETDEWEB)

Zhou, Wen-Jie, E-mail: 776260859@qq.com; Cui, Yan-Feng, E-mail: cuiyanfeng366@126.com; Zu, Mao-Heng, E-mail: cjr.zumaoheng@vip.163.com; Zhang, Qing-Qiao, E-mail: 1427286069@qq.com; Xu, Hao, E-mail: xuhao585@yeah.net [Affiliated Hospital of Xuzhou Medical College, Department of Interventional Radiology (China)

2016-04-15

PurposeWe aimed to characterize the clinical profile, etiology, and outcomes of young Chinese patients with Budd–Chiari syndrome treated with recanalization.MethodsA total of 35 consecutive young patients (≤25 years of age) with primary Budd–Chiari syndrome treated with recanalization at our center were enrolled in this study between March 2011 and December 2014. Data on baseline information, etiology tests, therapeutic recanalization strategies, and follow-up were collected.ResultsThe most common clinical feature was ascites, present in 33 cases (94 %). Hepatic vein obstruction was present in 60 % (21/35) of patients, inferior vena cava obstruction in 3 % (1/35), and combined obstruction in 37 % (13/35). The most common risk factor for thrombosis was hyperhomocysteinemia (14/35, 40 %). Recanalization was technically successful in 32 of 35 patients (91 %), and clinically successful in 28 of these 32 patients (88 %). The cumulative 1- and 3-year primary patency rates were 75.2 and 54.3 %, respectively. The cumulative 1- and 3-year secondary patency rates were 89.3 and 89.3 %, respectively. The cumulative 1- and 3-year survival rates were 96.9 and 93.8 %, respectively.ConclusionIn this study, the most common type of lesion was hepatic vein obstruction, the most common thrombotic risk factor was hyperhomocysteinemia, and recanalization resulted in good mid-term outcomes in young Chinese patients with Budd–Chiari syndrome.

Relationship between pharyngitis and peri-odontoid pannus: A new etiology for some Chiari I malformations?

Science.gov (United States)

Tubbs, R Shane; Griessenauer, Christoph J; Hendrix, Philipp; Oakes, Peter; Loukas, Marios; Chern, Joshua J; Rozzelle, Curtis J; Oakes, W Jerry

2015-07-01

The pathophysiology underlying Chiari I malformations (CIMs) provides room for debate with several theories attempting to address this issue. We retrospectively reviewed many of our past patients with pediatric CIMs (specifically, those with peri-odontoid pannus), and present a hypothesis for the development of the malformation in some of said patients. Our experience with the pediatric CIM has shown that almost 1 in 20 patients who present with symptoms is found to have a peri-odontoid pannus. These masses ranged in size from 4 to 11 mm in diameter. Forty percent had a history of clinically significant pharyngitis or pharyngeal abscess. Pannus formation around the dens (odontoid) resulted in ventral compression of the craniocervical junction in each of these patients. Highlighting the hypermobility that causes such lesions, following fusion, the pannus and symptoms in several patients were diminished. Impairment of normal cerebrospinal fluid circulation out of the fourth ventricle and across the craniocervical junction appears to be a plausible endpoint in this discussion and a suitable explanation for some patients with CIM. Still, the mechanisms by which cerebrospinal fluid circulation is compromised may be variable and are not well understood. This is the first study dedicated to the evaluation of pannus formation in the CIM population. We hypothesize that pharyngeal inflammatory conditions contribute to the formation and progression of hindbrain herniation in a small subset of patients with CIMs. © 2015 Wiley Periodicals, Inc.

Alternative types of molecule-decorated atomic chains in Au–CO–Au single-molecule junctions

Directory of Open Access Journals (Sweden)

Zoltán Balogh

2015-06-01

Full Text Available We investigate the formation and evolution of Au–CO single-molecule break junctions. The conductance histogram exhibits two distinct molecular configurations, which are further investigated by a combined statistical analysis. According to conditional histogram and correlation analysis these molecular configurations show strong anticorrelations with each other and with pure Au monoatomic junctions and atomic chains. We identify molecular precursor configurations with somewhat higher conductance, which are formed prior to single-molecule junctions. According to detailed length analysis two distinct types of molecule-affected chain-formation processes are observed, and we compare these results to former theoretical calculations considering bridge- and atop-type molecular configurations where the latter has reduced conductance due to destructive Fano interference.

Pericardial tamponade complicated by interventional management for Budd-Chiari syndrome: clinical analysis and treatment

International Nuclear Information System (INIS)

Zhang Luxi; Zu Maoheng; Wu Jinping; Xu Hao; Jiao Xudong; Chen Zhengkan

2011-01-01

Objective: To discuss the cases and treatment of pericardial tamponade (PT) occurred in the interventional management for Budd-Chiari syndrome (BCS). Methods: During the period from 1990 to 2006, interventional treatment was performed in 812 patients with BCS. Pericardial tamponade occurred in nine patients during the period of interventional treatment. The clinical data, including angiographic findings, clinical symptoms, management and outcomes, of the nine patients were retrospectively analyzed. The possible causes of pericardial tamponade were discussed. Results: Of the nine patients occurring pericardial tamponade, successful treatment was obtained in eight and death occurred in one. The lesions of BCS in the nine cases included inferior vena cava obstruction type (n=7), hepatic venous obstruction type (n=1) and mixed type (n=1). Pericardial tamponade was caused by mistakenly puncturing into pericardium (n=5), mistakenly puncturing together with laceration of pericardium by balloon (n=3), and breaking of pericardium by displaced stent (n=1). Conventional pericardicentesis was employed in one case, surgery was carried out in three cases, and infra-xiphoid catheterization and drainage using Seldinger technique was performed in two cases. Conservative treatment was adopted in one case and aspiration through the wrongly inserted catheter was tried in one case. In the remaining one case, aspiration through the wrongly inserted catheter together with infra-xiphoid catheterization and drainage by using Seldinger technique was carried out. Conclusion: The pericardial tamponade is an severe complication occurred in the interventional management for Budd-Chiari syndrome, although it is rarely seen. Preoperative prevention, prompt detection and rational treatment are the keys avoid serious consequences. (authors)

Dysfunction of the neuromuscular junction in spinal muscular atrophy types 2 and 3.

Science.gov (United States)

Wadman, Renske I; Vrancken, Alexander F J E; van den Berg, Leonard H; van der Pol, W Ludo

2012-11-13

Spinal muscular atrophy (SMA) is pathologically characterized by degeneration of anterior horn cells. Recent observations in animal models of SMA and muscle tissue from patients with SMA suggest additional abnormalities in the development and maturation of the neuromuscular junction. We therefore evaluated neuromuscular junction function in SMA with repetitive nerve stimulation. In this case-control study, repetitive nerve stimulation was performed in 35 patients with SMA types 2, 3, and 4, 20 healthy controls, and 5 controls with motor neuron disease. Pathologic decremental responses (>10%) during 3-Hz repetitive nerve stimulation were observed in 17 of 35 patients (49%) with SMA types 2 and 3, but not in healthy controls or controls with motor neuron disease. None of the patients or controls had an abnormal incremental response of >60%. The presence of an abnormal decremental response was not specific for the type of SMA, nor was it associated with compound muscle action potential amplitude, clinical scores, or disease duration. Two of 4 patients with SMA type 3 who tried pyridostigmine reported increased stamina. These data suggest dysfunction of the neuromuscular junction in patients with SMA types 2 and 3. Therefore, drugs that facilitate neuromuscular transmission are candidate drugs for evaluation in carefully designed, placebo-controlled, clinical trials.

Disproportionate rise in serum CA 125 in case of budd chiari syndrome: an unusual presentation

OpenAIRE

Prasad D. Game; Madhuri P. Holay; Satyanarayan Durgam; Sandeep Kharkar

2015-01-01

Ca 125 is used as a diagnostic and prognostic biomarker for ovarian cancer. The level of CA 125 is also elevated in benign conditions like Budd Chiari syndrome, liver cirrhosis and heart failure. But very high level of CA 125 is rarely associated with benign conditions and this can mislead the physician. Here we present a case of budd chiari syndrome in postpartum period associated with very high level of CA 125 which is an unusual presentation. [Int J Res Med Sci 2015; 3(8.000): 2129-2131

The incidence of Arnold–Chiari malformation in neurological practice

Directory of Open Access Journals (Sweden)

E. A. Kantimirova

2015-01-01

Full Text Available Arnold-Chiari malformation (ACM is a group of congenital hindbrain malformations affecting the structural relationships between the cerebellum, brain stem, top cervical spinal cord, and bones of the skull base. In clinical practice, ACM types 0 and 1 are more common and types 2, 3, and 4 belong to rare severe (often fatal congenital malformations.Objective: to study gender differences in the incidence of ACM types 0 and 1 in outpatient neurological practice.Patients and methods. A total 2039 case records of outpatients who had visited a neurologist of the Krasnoyarsk University clinic in 2008–2014 were analyzed. Neurological and neuroradiological (1.5 Tesla brain magnetic resonance imaging, phase-contrast spinal cerebral fluid flow imaging diagnostic techniques were used. 3.4% (70/2039 of cases were randomized according to the criteria of inclusion and exception. An entire sample included 70 ACM patients (median age, 25 [17; 34] years (30 (42.8–7.1% men and 40 (57.2–7.1% women.Results. There was an increase in the incidence of ACM type 1 in the women than in the men. Conclusion. It is necessary to develop a new strategy for the prophylactic medical examination of patients with ACM to improve primary and specialized outpatient health care.

Syringomyelia and Craniocervical Junction Abnormalities in Chihuahuas.

Science.gov (United States)

Kiviranta, A-M; Rusbridge, C; Laitinen-Vapaavuori, O; Hielm-Björkman, A; Lappalainen, A K; Knowler, S P; Jokinen, T S

2017-11-01

Chiari-like malformation (CM) and syringomyelia (SM) are widely reported in Cavalier King Charles Spaniels and Griffon Bruxellois dogs. Increasing evidence indicates that CM and SM also occur in other small and toy breed dogs, such as Chihuahuas. To describe the presence of SM and craniocervical junction (CCJ) abnormalities in Chihuahuas and to evaluate the possible association of CCJ abnormalities with SM. To describe CM/SM-related clinical signs and neurologic deficits and to investigate the association of CM/SM-related clinical signs with signalment, SM, or CCJ abnormalities. Fifty-three client-owned Chihuahuas. Prospective study. Questionnaire analyses and physical and neurologic examinations were obtained before magnetic resonance and computed tomography imaging. Images were evaluated for the presence of SM, CM, and atlantooccipital overlapping. Additionally, medullary kinking, dorsal spinal cord compression, and their sum indices were calculated. Scratching was the most common CM/SM-related clinical sign and decreased postural reaction the most common neurologic deficit in 73 and 87% of dogs, respectively. Chiari-like malformation and SM were present in 100 and 38% of dogs, respectively. Syringomyelia was associated with the presence of CM/SM-related clinical signs (P = 0.034), and medullary kinking and sum indices were higher in dogs with clinical signs (P = 0.016 and P = 0.007, respectively). Syringomyelia and CCJ abnormalities are prevalent in Chihuahuas. Syringomyelia was an important factor for the presence of CM/SM-related clinical signs, but many dogs suffered from similar clinical signs without being affected by SM, highlighting the clinical importance of CCJ abnormalities in Chihuahuas. Copyright © 2017 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.

Junction-type photonic crystal waveguides for notch- and pass-band filtering

KAUST Repository

Shahid, Naeem

2011-01-01

Evolution of the mode gap and the associated transmission mini stop-band (MSB) as a function of photonic crystal (PhC) waveguide width is theoretically and experimentally investigated. The change of line-defect width is identified to be the most appropriate way since it offers a wide MSB wavelength tuning range. A high transmission narrow-band filter is experimentally demonstrated in a junction-type waveguide composed of two PhC waveguides with slightly different widths. The full width at half maximum is 5.6 nm; the peak transmission is attenuated by only ∼5 dB and is ∼20 dB above the MSBs. Additionally, temperature tuning of the filter were also performed. The results show red-shift of the transmission peak and the MSB edges with a gradient of dλ/dT = 0.1 nm/°C. It is proposed that the transmission MSBs in such junction-type cascaded PhC waveguides can be used to obtain different types of filters. © 2011 Optical Society of America.

Linker-dependent Junction Formation Probability in Single-Molecule Junctions

Energy Technology Data Exchange (ETDEWEB)

Yoo, Pil Sun; Kim, Taekyeong [HankukUniversity of Foreign Studies, Yongin (Korea, Republic of)

2015-01-15

We compare the junction formation probabilities of single-molecule junctions with different linker molecules by using a scanning tunneling microscope-based break-junction technique. We found that the junction formation probability varies as SH > SMe > NH2 for the benzene backbone molecule with different types of anchoring groups, through quantitative statistical analysis. These results are attributed to different bonding forces according to the linker groups formed with Au atoms in the electrodes, which is consistent with previous works. Our work allows a better understanding of the contact chemistry in the metal.molecule junction for future molecular electronic devices.

Co-existence of Chiari malformation type I and Epstein-Barr virus meningoencephalitis in a 3-year-old child: case report and review of the literature

International Nuclear Information System (INIS)

Solomou, E.K.; Kotsarini, C.; Badra, F.A.; Krepis, A.; Papanastasiou, D.; Patriarcheas, G.

2005-01-01

In the present report we describe an unusual case of a 3-year-old girl who was admitted to our hospital with Epstein-Barr virus meningoencephalitis. Brain magnetic resonance imaging revealed diffuse abnormalities in white matter and Chiari I malformation with cervical and thoracic hydro-syringomyelia. (orig.)

Le syndrome de Budd-Chiari: une complication rare de la ...

African Journals Online (AJOL)

L'atteinte hépatique au cours de la sarcoïdose est une localisation fréquente, habituellement asymptomatique. La cholestase anictérique et l'hypertension portale représentent ses principales complications. Le syndrome de Budd-Chiari est une complication peu connue qui demeure exceptionnelle. Nous rapportons un ...

Surgical decompression for symptomatic Chiari II malformation in neonates with myelomeningocele

NARCIS (Netherlands)

Vandertop, W. P.; Asai, A.; Hoffman, H. J.; Drake, J. M.; Humphreys, R. P.; Rutka, J. T.; Becker, L. E.

1992-01-01

Between January, 1981, and July, 1991, 17 infants under 1 month of age were admitted to The Hospital for Sick Children with the signs and symptoms of a Chiari II malformation. These patients' presentation included swallowing difficulty (71%), stridor (59%), apneic spells (29%), aspiration (12%),

Budd-chiari syndrome caused by diaphragmatic hernia of the liver: a case report

Energy Technology Data Exchange (ETDEWEB)

Song, Jae Min; Yoon, Jung Won; Kim, Jae Wook; Chung, Woo Kyoung; Chung, Hee Sun; Kim, Joo Hyung; Choi, Jun Ho; Kim, Seung Ho [Armed Forces Capital Hospital, Seongnam (Korea, Republic of)

2007-01-15

Budd-Chiari syndrome is an uncommon disorder, and it is caused by obstruction of the hepatic venous out-flow or inferior vena cava above the hepatic vein. It may result from a large number of conditions, including primary congenital obstructions of the hepatic veins or inferior vena cava by webs or bands. Secondary causes include trauma, polycythemia vera, chronic leukemia, pregnancy, tumors and use of oral contraceptives. No definitive etiologic factors have been identified in two thirds of all cases. We recently experienced a case of Budd-Chiari syndrome caused by diaphragmatic hernia in 21-year-old man. Postoperative follow up CT showed normal venous flow after reintroduction of the liver into the abdominal cavity and closure of the diaphragm defect.

Budd-chiari syndrome caused by diaphragmatic hernia of the liver: a case report

International Nuclear Information System (INIS)

Song, Jae Min; Yoon, Jung Won; Kim, Jae Wook; Chung, Woo Kyoung; Chung, Hee Sun; Kim, Joo Hyung; Choi, Jun Ho; Kim, Seung Ho

2007-01-01

Budd-Chiari syndrome is an uncommon disorder, and it is caused by obstruction of the hepatic venous out-flow or inferior vena cava above the hepatic vein. It may result from a large number of conditions, including primary congenital obstructions of the hepatic veins or inferior vena cava by webs or bands. Secondary causes include trauma, polycythemia vera, chronic leukemia, pregnancy, tumors and use of oral contraceptives. No definitive etiologic factors have been identified in two thirds of all cases. We recently experienced a case of Budd-Chiari syndrome caused by diaphragmatic hernia in 21-year-old man. Postoperative follow up CT showed normal venous flow after reintroduction of the liver into the abdominal cavity and closure of the diaphragm defect

Otto Mennicke (1876-) and the first description of skull base anomalies causing cerebellar tonsillar ectopia: one of the first mentions of the Chiari I malformation.

Science.gov (United States)

Fries, Fabian N; Hendrix, Philipp; Brinker, Titus J; Loukas, Marios; Tubbs, R Shane

2017-05-01

Although Hans Chiari made significant and meaningful contributions to our understanding and classification of hindbrain herniations, others have also contributed to this knowledge. One figure who has been lost to history is Otto Mennicke. Herein, we discuss his role in our understanding of tonsillar ectopia and his life and connection to Hans Chiari. Our knowledge of what is now known as the Chiari malformations has been shaped by several clinicians including Otto Mennicke.

Surgical treatment of Chiari malformation: review and progress

Directory of Open Access Journals (Sweden)

ZHANG Yuan-zheng

2012-08-01

Full Text Available The surgical treatment of Chiari malformation (CM began in 1932. With the advance of medical technology, the surgical technique of CM is also in constant improvement. But due to its pathogenesis has not yet clear, there is no accepted optimal method, and different levels of the operation is still controversial. The author reviewed the concept, pathogenesis, diagnosis and surgical treatment of CM. The hot topics and new technological application were also reviewed in this article.

Cost-Effectiveness of Postoperative Ketamine in Chiari Decompression.

Science.gov (United States)

McDowell, Michael M; Alhourani, Ahmad; Pearce-Smith, Beverly A; Mazurkiewicz, Anna; Friedlander, Robert M

2018-02-01

In Chiari I patients, postoperative pain and discomfort frequently slow the transition back to the home setting. We sought to determine the effect of standardized ketamine infusion protocols on hospital length of stay (LOS). This retrospective cohort study reviewed 100 consecutive adult patients undergoing Chiari I decompression. Fifty-nine patients were placed on a 2-3 mg/hr ketamine drip until postoperative day 1. This group was compared with a group who received 2-3 mg/hr of ketamine until postoperative day 2 (19 patients) and patients who did not receive ketamine at all (22 patients). Clinical characteristics, opioid use, LOS, and relative hospitalization costs were assessed. All narcotic amounts were converted into milligram equivalents of morphine. LOS of the short-ketamine group was 46.5 hours when compared with the long-ketamine group (66.8 hours) and no-ketamine group (56.9 hours). There was a statistically significant difference when comparing the short-ketamine group with the long-ketamine group and no-ketamine group together (P ketamine protocol was used (P ketamine group, 196 mg in the long-ketamine group, and 187 mg in the no-ketamine group (P = 0.65). No adverse events from ketamine were noted. Ketamine at subanesthetic levels may be an effective tool to facilitate early return home postoperatively and may significantly reduce medical costs. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of the complications in interventional treatment for Budd-Chiari syndrome

International Nuclear Information System (INIS)

Niu Zhike; Lv Guanghua; Du Fei; Guo Yanxia; Guan Lan

2010-01-01

Objective: To discuss the causes and the prevention measures of the complications occurred after interventional therapy for different type of Budd-Chiari syndrome (BCS). Methods: Based on the type of BCS, the corresponding interventional management was adopted in 204 patients with BCS. The interventional procedures included PTA and stent placement of inferior vena cava (IVC), percutaneous transhepatic recanalization and dilation (PTRD) of hepatic vein, percutaneous trans jugular or trans inferior vena cava recanalization, dilation and stent placement of hepatic vein and trans jugular intrahepatic portal-systemic stenting shunt (TIPSS). Results: The successful rate of interventional therapy was 95.5% (21 / 22) for type Ia, 81.8% (9/11) for type Ib, 97.3% (109/112) for type IIa, 92.9% (13/14) for type IIb, 88.9% (8/9) for type IIIa, 100% (2/2) type IIIb, 92% (23/25) for type IVa and 88.9% (8/9) for type IVb BCS. The main complications occurred during or after the operation included acute cardiac insufficiency (n=2), pulmonary arterial embolization (n=4), disseminated intravascular coagulation (n=1), extravasation of contrast medium (n=3), arrhythmia (n=2), and cardiac tamponade (n=1). Conclusion: Interventional therapy is simple, safe and effective for the treatment of BCS, but its indications should be strictly considered and all kinds of effective prevention measures should be taken to avoid or to reduce the possible complications. (authors)

Long-term follow-up of patients with Herlitz-type junctional epidermolysis bullosa

NARCIS (Netherlands)

Yuen, W. Y.; Duipmans, J. C.; Molenbuur, B.; Herpertz, I.; Mandema, J. M.; Jonkman, M. F.

Background Junctional epidermolysis bullosa, type Herlitz (JEB-H) is a rare, autosomal recessive disease caused by absence of the epidermal basement membrane adhesion protein laminin-332. It is characterized by extensive and devastating blistering of the skin and mucous membranes, leading to death

Anesthesia for a patient of acromesomelic dysplasia with associated hydrocephalus, Arnold Chiari malformation and syringomyelia

Directory of Open Access Journals (Sweden)

Rudrashish Haldar

2013-01-01

Full Text Available Acromesomelic dysplasias are autosomal recessive osteochondrodysplasias. Acromesomelic dysplasia Maroteaux-type (AMDM, also known as St Helena dysplasia, is of two types: The classical and the mild variety. About 50 cases of AMDM have been reported till date, most of them being the classical variety. There is scarcity of literature on anesthesia for such patients. We are reporting a case of general anesthetic management of AMDM, associated with hydrocephalus, Arnold Chiari malformation type-1 and syringomyelia. The patient was a 10-year-old short-statured boy who presented with symptomatic thoracic kyphoscoliosis, gibbus deformity and back pain. On examination, there was no neurological deficit. Radiology revealed thoracic kyphoscoliosis, mild ventriculomegaly and upper cervical syringomyelia. The patient underwent posterior fossa decompression in the prone position under general anesthesia. We will discuss the anesthetic considerations for such patients and review the pertinent literature.

Resonance Transport of Graphene Nanoribbon T-Shaped Junctions

International Nuclear Information System (INIS)

Xiao-Lan, Kong; Yong-Jian, Xiong

2010-01-01

We investigate the transport properties of T-shaped junctions composed of armchair graphene nanoribbons of different widths. Three types of junction geometries are considered. The junction conductance strongly depends on the atomic features of the junction geometry. When the shoulders of the junction have zigzag type edges, sharp conductance resonances usually appear in the low energy region around the Dirac point, and a conductance gap emerges. When the shoulders of the junction have armchair type edges, the conductance resonance behavior is weakened significantly, and the metal-metal-metal junction structures show semimetallic behaviors. The contact resistance also changes notably due to the various interface geometries of the junction

Phase diagrams of particles with dissimilar patches: X-junctions and Y-junctions

International Nuclear Information System (INIS)

Tavares, J M; Teixeira, P I C

2012-01-01

We use Wertheim’s first-order perturbation theory to investigate the phase behaviour and the structure of coexisting fluid phases for a model of patchy particles with dissimilar patches (two patches of type A and f B patches of type B). A patch of type α = {A,B} can bond to a patch of type β = {A,B} in a volume v αβ , thereby decreasing the internal energy by ε αβ . We analyse the range of model parameters where AB bonds, or Y-junctions, are energetically disfavoured (ε AB AA /2) but entropically favoured (v AB ≫ v αα ), and BB bonds, or X-junctions, are energetically favoured (ε BB > 0). We show that, for low values of ε BB /ε AA , the phase diagram has three different regions: (i) close to the critical temperature a low-density liquid composed of long chains and rich in Y-junctions coexists with a vapour of chains; (ii) at intermediate temperatures there is coexistence between a vapour of short chains and a liquid of very long chains with X- and Y-junctions; (iii) at low temperatures an ideal gas coexists with a high-density liquid with all possible AA and BB bonds formed. It is also shown that in region (i) the liquid binodal is reentrant (its density decreases with decreasing temperature) for the lower values of ε BB /ε AA . The existence of these three regions is a consequence of the competition between the formation of X- and Y-junctions: X-junctions are energetically favoured and thus dominate at low temperatures, whereas Y-junctions are entropically favoured and dominate at higher temperatures. (paper)

Diagnosis of Chiari III malformation by second trimester fetal MRI with postnatal MRI and CT correlation

International Nuclear Information System (INIS)

Smith, Alice B.; Glenn, Orit A.; Gupta, Nalin; Otto, Carl

2007-01-01

We report a case of Chiari III malformation diagnosed by fetal MRI. Ultrasound (US) performed at a gestational age of 18 weeks demonstrated a posterior skull base cyst. Repeat US at 19 weeks demonstrated neural tissue in the cyst, consistent with an encephalocele. MR imaging at 23 weeks confirmed the presence of an occipital encephalocele, demonstrated additional bony defect in the upper cervical spine, and identified abnormal morphology and position of the brainstem consistent with the diagnosis of Chiari III. Postnatal MRI and CT confirmed the fetal MRI findings and demonstrate the utility of fetal MRI in the early evaluation of songraphically detected posterior fossa abnormalities. (orig.)

Diagnosis of Chiari III malformation by second trimester fetal MRI with postnatal MRI and CT correlation

Energy Technology Data Exchange (ETDEWEB)

Smith, Alice B.; Glenn, Orit A. [University of California, San Francisco, Department of Radiology, San Francisco, CA (United States); Gupta, Nalin [University of California, San Francisco, Department of Neurosurgery, San Francisco, CA (United States); Otto, Carl [California Pacific Medical Center, Department of Perinatology, San Francisco, CA (United States)

2007-10-15

We report a case of Chiari III malformation diagnosed by fetal MRI. Ultrasound (US) performed at a gestational age of 18 weeks demonstrated a posterior skull base cyst. Repeat US at 19 weeks demonstrated neural tissue in the cyst, consistent with an encephalocele. MR imaging at 23 weeks confirmed the presence of an occipital encephalocele, demonstrated additional bony defect in the upper cervical spine, and identified abnormal morphology and position of the brainstem consistent with the diagnosis of Chiari III. Postnatal MRI and CT confirmed the fetal MRI findings and demonstrate the utility of fetal MRI in the early evaluation of songraphically detected posterior fossa abnormalities. (orig.)

Siringomielia y malformación de Arnold-Chiari

Directory of Open Access Journals (Sweden)

Jairo Muñoz Escobar

1971-01-01

Full Text Available Presentamos en este informe, nuestra experiencia en ocho casos de siringomielia en dos de ellos asociada a malformación de Arnold Chiari, que hemos analizado desde el punto de vista clínico y de los hallazgos de radiología simple y contrastada. Analizamos igualmente las técnicas quirúrgicas empleadas y los resultados obtenidos en siete casos que fueron intervenidos quirúrgicamente. Finalmente comparamos nuestros hallazgos y resultados con los mencionados en la literatura y hacemos algunos comentarios sobre fisio-patología.

Complicated Pseudomeningocele Repair After Chiari Decompression: Case Report and Review of the Literature.

Science.gov (United States)

De Tommasi, Claudio; Bond, Aaron E

2016-04-01

Pseudomeningocele is a recognised complication after posterior fossa decompression for Chiari malformation. Its management can be challenging and treatment options vary in literature. A difficult-to-treat case of a pseudomeningocele after posterior fossa decompression for a Chiari I malformation is presented. A 34-year-old woman underwent an initial decompression followed by multiple revision surgeries after the development of a symptomatic pseudomeningocele and a low-grade infection. Complications associated with standard treatment modalities, including lumbar drainage and dural repair, are discussed. A review of the existing literature is presented. The reported case ultimately required complete removal of all dural repair materials to eliminate the patient's low-grade infection, a muscular flap, and placement of a ventricular-peritoneal shunt for definitive treatment after a trial of a lumbar drain led to herniation and development of a syrinx. Copyright © 2016 Elsevier Inc. All rights reserved.

Use of Morphometric Mapping to Characterise Symptomatic Chiari-Like Malformation, Secondary Syringomyelia and Associated Brachycephaly in the Cavalier King Charles Spaniel.

Directory of Open Access Journals (Sweden)

Susan P Knowler

Full Text Available To characterise the symptomatic phenotype of Chiari-like malformation (CM, secondary syringomyelia (SM and brachycephaly in the Cavalier King Charles Spaniel using morphometric measurements on mid-sagittal Magnetic Resonance images (MRI of the brain and craniocervical junction.This retrospective study, based on a previous quantitative analysis in the Griffon Bruxellois (GB, used 24 measurements taken on 130 T1-weighted MRI of hindbrain and cervical region. Associated brachycephaly was estimated using 26 measurements, including rostral forebrain flattening and olfactory lobe rotation, on 72 T2-weighted MRI of the whole brain. Both study cohorts were divided into three groups; Control, CM pain and SM and their morphometries compared with each other.Fourteen significant traits were identified in the hindbrain study and nine traits in the whole brain study, six of which were similar to the GB and suggest a common aetiology. The Control cohort had the most elliptical brain (p = 0.010, least olfactory bulb rotation (p = 0.003 and a protective angle (p = 0.004 compared to the other groups. The CM pain cohort had the greatest rostral forebrain flattening (p = 0.007, shortest basioccipital (p = 0.019, but a greater distance between the atlas and basioccipital (p = 0.002 which was protective for SM. The SM cohort had two conformation anomalies depending on the severity of craniocervical junction incongruities; i the proximity of the dens (p <0.001 ii increased airorhynchy with a smaller, more ventrally rotated olfactory bulb (p <0.001. Both generated 'concertina' flexures of the brain and craniocervical junction.Morphometric mapping provides a diagnostic tool for quantifying symptomatic CM, secondary SM and their relationship with brachycephaly. It is hypothesized that CM pain is associated with increased brachycephaly and SM can result from different combinations of abnormalities of the forebrain, caudal fossa and craniocervical junction which compromise

Budd-chiari syndrome by membranous obstruction of inferior vena cava: comparison of sonography and computed tomography

International Nuclear Information System (INIS)

Lee, Dong Ho; Lim, Jae Hoon; Ko, Young Tae; Yoon, Yup; Lim, Joo Won

1992-01-01

Membranous obstruction of the hepatic inferior vena cava (MOVC) is one of the common causes of Budd-Chiari syndrome. The aim of this study is to ascertain and compare the characteristic sonographic and CT findings of Budd-Chiari syndrome caused by MOVC. We studied 10 patients of Budd-Chiari syndrome caused by MOVC thorough sonography and CT. MOVC was confirmed by operation and/or inferior vena cavography. The cases included 9 men and one woman. With sonography, IVC obstruction was diagnosed in 9 cases. The cause of IVC obstruction was web in 5 cases and fibrous cord in 3 cases. The cause was unspecified in one case. Obliteration of the hepatic veins and intrahepatic collateral vessels were delineated in 9 cases. With color doppler sonography, the directions of blood flow of the hepatic veins through the intervenous communication were fairly well demonstrated in all 5 cases. With CT, IVC obstruction was diagnosed in 7 cases. The obliteration of the hepatic segment of the IVC were segmental in 6 cases and diffuse in one case. CT demonstrated communicating vessels between the hepatic veins in 3 cases. Furthermore, systemic collateral vessels (azygos and hemiazygos veins, veins along the abdominal wall, and internal mammary veins) were demonstrated in all cases. Liver cirrhosis was combined in all cases and hepatoma developed in 4 cases. Sonography is useful to detect the MOVC and to demonstrate hepatic venous obstruction and intrahepatic collateral vessels. Color doppler sonography is easily performed to show the direction of the blood flow through interconnecting vessels. CT shows the obliterated segment of the IVC clearly and multiple prominent systemic collaterals. In conclusion, Budd-Chiari syndrome caused by MOVC is accurately diagnosed by combined color doppler sonography and CT

Equivalent Josephson junctions

International Nuclear Information System (INIS)

Boyadzhiev, T.L.; ); Semerdzhieva, E.G.; Shukrinov, Yu.M.; Fiziko-Tekhnicheskij Inst., Dushanbe

2008-01-01

The magnetic field dependences of critical current are numerically constructed for a long Josephson junction with a shunt- or resistor-type microscopic inhomogeneities and compared to the critical curve of a junction with exponentially varying width. The numerical results show that it is possible to replace the distributed inhomogeneity of a long Josephson junction by an inhomogeneity localized at one of its ends, which has certain technological advantages. It is also shown that the critical curves of junctions with exponentially varying width and inhomogeneities localized at the ends are unaffected by the mixed fluxon-antifluxon distributions of the magnetic flux [ru

[The usefullness of percutaneous transluminal balloon angioplasty in the management of budd-Chiari syndrome].

Science.gov (United States)

Kim, Se Hwan; Yu, Kyung Sool; Baek, Seung Min; Lee, Seung Yup; Kim, Hyun Su; Tak, Won Young; Kweon, Young Oh; Kim, Sung Kook; Choi, Yong Hwan; Chung, Joon Mo

2002-06-01

Membranous obstruction is the most common cause of Budd-Chiari syndrome in Orientals. Recently, percutaneous transluminal balloon angioplasty (PTBA) has been successfully applied as a treatment of membranous obstruction. We evaluated etiologies and clinical manifestations in our cases and the usefulness of PTBA. Twelve cases of Budd-Chiari syndrome were analyzed. 50.3 years was the average age of the cases (ranging from 37 to 67 years). Major symptoms or signs were superficial collateral vessels on the chest or the abdomen in 6 cases, ascites in 3, abdominal pain in 4, hepatomegaly in 4, splenomegaly in 3, melena or hematemesis in 2, and leg edema in 2. Upper gastrointestinal endoscopy showed esophageal varices in 6 cases and two of these 6 cases had gastric varices. Of 8 cases with liver cirrhosis, 4 were classified as Child-Pugh class A and 4 as B. Four patients with cirrhosis had concurrent hepatocellular carcinoma including 1 patient who was HBs Ag positive. Etiologies were membranous obstruction in 11 cases and protein C deficiency in 1 case. The main site of obstruction was IVC in 8 and hepatic vein in 4. PTBA was successfully performed in 8 cases of membranous obstruction. During the mean follow-up period of 27.6 months (12-40 months), there were no reobstructions except in 2 cases. The most common cause of Budd-Chiari syndrome in our cases was membranous obstruction of IVC. Percutaneous transluminal balloon angioplasty is a very useful treatment method.

Clinical and radiological outcome of craniocervical osteo-dural decompression for Chiari I-associated syringomyelia.

Science.gov (United States)

Spena, Giannantonio; Bernucci, Claudio; Garbossa, Diego; Valfrè, Walter; Versari, Pietro

2010-07-01

The aim of this study was to analyze the long-term clinical and radiological outcomes of craniocervical decompression for patients affected by Chiari I-related syringomyelia. We performed a retrospective analysis of a group of patients affected by Chiari I-associated syringomyelia treated by craniocervical decompression (CCD). Surgical and technical aspects and preoperative factors predicting outcome were discussed. A total of 36 patients were reviewed. There were 17 men and 19 women (female/male ratio 1.11), and the mean age was 40.4 (range 18-68). The most important preoperative symptoms were related to myelopathy (pain, weakness, atrophy, spasticity, sensory loss, and dysesthesias). Most syrinxes were in the cervico-thoracic region (61.1%), and the majority of patients had tonsillar descent between the foramen magnum and C1. All patients underwent a craniectomy less than 3 cm in diameter followed by a duroplasty with dura substitute. No arachnoid manipulation was necessary. Three patients (8.1%) experienced cerebrospinal fluid leaks that resolved without complications. At a mean follow up of 40 months (range 16-72) 80.5% of patients exhibited improvement over their preoperative neurological examination while 11.1% stabilized. The syrinx shrank in 80.5% of patients. Chi-square test showed that preoperative syrinx extension and degree of tonsillar descent did not correlate with clinical and neuroradiological postoperative evolution. Treating syringomyelia associated in Chiari I malformation with CCD leads to a large percentage of patients with satisfying results and no irreversible complications.

Quantum Junction Solar Cells

KAUST Repository

Tang, Jiang

2012-09-12

Colloidal quantum dot solids combine convenient solution-processing with quantum size effect tuning, offering avenues to high-efficiency multijunction cells based on a single materials synthesis and processing platform. The highest-performing colloidal quantum dot rectifying devices reported to date have relied on a junction between a quantum-tuned absorber and a bulk material (e.g., TiO 2); however, quantum tuning of the absorber then requires complete redesign of the bulk acceptor, compromising the benefits of facile quantum tuning. Here we report rectifying junctions constructed entirely using inherently band-aligned quantum-tuned materials. Realizing these quantum junction diodes relied upon the creation of an n-type quantum dot solid having a clean bandgap. We combine stable, chemically compatible, high-performance n-type and p-type materials to create the first quantum junction solar cells. We present a family of photovoltaic devices having widely tuned bandgaps of 0.6-1.6 eV that excel where conventional quantum-to-bulk devices fail to perform. Devices having optimal single-junction bandgaps exhibit certified AM1.5 solar power conversion efficiencies of 5.4%. Control over doping in quantum solids, and the successful integration of these materials to form stable quantum junctions, offers a powerful new degree of freedom to colloidal quantum dot optoelectronics. © 2012 American Chemical Society.

Sleep-Related Breathing Disorders in Chiari Malformation Type 1: A Prospective Study of 90 Patients.

Science.gov (United States)

Ferré, Álex; Poca, Maria A; de la Calzada, Maria D; Moncho, Dulce; Romero, Odile; Sampol, Gabriel; Sahuquillo, Juan

2017-06-01

The aim of the present study is to describe the prevalence of sleep disorders in a large group of patients with Chiari malformation type 1 (CM-1) and determine the presence of risk factors associated with these abnormalities. Prospective study with consecutive patient selection. We included 90 adult patients with CM-1, defined by the presence of a cerebellar tonsillar descent (TD) ≥3 mm. Clinical, neuroradiological studies, and nocturnal polysomnography (PSG) was carried out. In addition, patients were also subclassified into 2 CM subtypes: CM-1, with the obex above the foramen magnum (FM) and CM-1.5, in which along with a TD ≥3 mm, the obex was located below the FM. We observed a high prevalence (50%) of sleep-related breathing disorders (SRBDs) with predominant hypopnea. Only six patients showed a central apnea index of ≥5. Hypoventilation was observed in only three patients. SRBD severity was associated with male sex, older age, excess weight, and the presence of hydrocephalus. No differences in clinical or PSG parameters were found when comparing CM subtypes (CM-1 and CM-1.5). Sleep architecture study showed decreased sleep efficiency with an increase in arousal and waking after sleep onset. The presence of SRBDs was found to be associated with poorer sleep architecture parameters. This study confirms a high prevalence of SRBDs in patients with CM-1 and CM-1.5, with a predominant obstructive component. Nocturnal PSG recordings should be systematically conducted in these patients, especially those who are male, older, or overweight or those who present hydrocephalus. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

Loss models for long Josephson junctions

DEFF Research Database (Denmark)

Olsen, O. H.; Samuelsen, Mogens Rugholm

1984-01-01

A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement.......A general model for loss mechanisms in long Josephson junctions is presented. An expression for the zero-field step is found for a junction of overlap type by means of a perturbation method. Comparison between analytic solution and perturbation result shows good agreement....

Subacute Budd-Chiari syndrome associated with polycythemia vera and factor V Leiden mutation

NARCIS (Netherlands)

Simsek, S; Verheesen, RV; Haagsma, EB; Lourens, J

We describe a 48-year-old caucasian woman with a subacute Budd-Chiari syndrome attributed to the presence of polycythaemia vera, heterozygosity for the factor V Leiden mutation and the use of an oral contraceptive pill. Two diagnostic pitfalls were encountered. First, on CT scanning of the abdomen

Un libello di citazioni. I “Frammenti morali, scientifici, eruditi e poetici” e la polemica fra Pietro Verri e l’abate Chiari

Directory of Open Access Journals (Sweden)

Valeria Tavazzi

2012-12-01

Full Text Available After recreating the occurrence of the dispute between Pietro Verri and abbot Chiari – due to Verri's favour to Goldoni in theatrical competitions – this article analyses a work entirely composed of quotations: Frammenti morali, scientifici, eruditi e poetici del signor abbate D. Pietro Chiari. This text was assembled by Verri to show that his adversary's epistles in verse were sloppy and full of incongruities. The use of quotations, as an instrument of attack and defence, is investigated by analysing some passages that preceeded the quarrel, the Frammenti, and Chiari's answer in the novel La filosofessa italiana . In addition, there emerge some aspects of the character of young Verri that might be of interest, especially within the context of his relationship with Goldoni, and in relation to Goldoni's dedication to Verri in Festino.

Chiari malformation and central sleep apnea syndrome: efficacy of treatment with adaptive servo-ventilation

Directory of Open Access Journals (Sweden)

Jorge Marques do Vale

2014-10-01

Full Text Available The Chiari malformation type I (CM-I has been associated with sleep-disordered breathing, especially central sleep apnea syndrome. We report the case of a 44-year-old female with CM-I who was referred to our sleep laboratory for suspected sleep apnea. The patient had undergone decompressive surgery 3 years prior. An arterial blood gas analysis showed hypercapnia. Polysomnography showed a respiratory disturbance index of 108 events/h, and all were central apnea events. Treatment with adaptive servo-ventilation was initiated, and central apnea was resolved. This report demonstrates the efficacy of servo-ventilation in the treatment of central sleep apnea syndrome associated with alveolar hypoventilation in a CM-I patient with a history of decompressive surgery.

Budd-Chiari and inferior caval vein syndromes due to membranous obstruction of the liver veins. Successful treatment with angioplasty and transcaval TIPS

DEFF Research Database (Denmark)

Holland-Fischer, Peter

2004-01-01

The case is presented of a 25-year-old Caucasian patient with Budd-Chiari syndrome due to membranous obstruction of the liver veins and inferior caval vein syndrome as a result of secondary hyperplasia of the caudate lobe of the liver, obstructing the caval vein. Diagnosis was established...... that angioplasty and TIPS are safe and efficient procedures to reduce liver engorgement and complications of portal hypertension in selected patients with Budd-Chiari syndrome....

Unusual Association Between Spontaneous Lateral Sphenoid Encephalocele and Chiari Malformation Type I: Endoscopic Repair Through a Transpterygoid Approach.

Science.gov (United States)

Starnoni, Daniele; Daniel, Roy Thomas; George, Mercy; Messerer, Mahmoud

2017-01-01

Spontaneous meningoencephaloceles of the lateral sphenoid sinus are rare entities, and their peculiar location represents a surgical challenge due to the importance of a wide exposure and skull base reconstruction. They are thought to arise from the congenital base defect of the lateral sphenoid or in some cases have been postulated to represent a rare manifestation of altered cerebrospinal fluid (CSF) dynamics. We report the first case in the literature of a Chiari malformation type I (CMI) and a lateral sphenoid encephalocele, revising the theoretic etiology and surgical technique of endoscopic repair. A 50-year-old woman with a surgical history of symptomatic CMI presented with episodes of spontaneous CSF rhinorrhea. Radiologic investigations revealed a left mesial temporal encephalocele herniating into the lateral recess of the sphenoid sinus and radiologic features of altered CSF dynamics, which may have played an etiologic role. An endoscopic transpterygoid excision of the encephalocele and multilayer skull base repair were performed. The association of spontaneous lateral sphenoid encephaloceles with CMI is distinctly unusual. Predisposing factors and disruption of CSF dynamics may play a major role in the development of these rare complications in patients with CMI. Because of their distinct location, transethmoid or transpterygoid endoscopic approaches represent an excellent surgical technique to treat these lesions thanks to their wide and direct visualization of the entire skull base defect following the encephalocele excision, allowing an adequate multilayer repair and lateral sphenoid recess occlusion. Copyright © 2016 Elsevier Inc. All rights reserved.

Sleep apnea and REM sleep behavior disorder in patients with Chiari malformations Apnéia do sono e distúrbio do comportamento da fase do sono com REM em pacientes com malformações de Chiari

Directory of Open Access Journals (Sweden)

Paulo Sérgio A. Henriques-Filho

2008-06-01

Full Text Available BACKGROUND: Chiari malformations (CM may result in the appearance of REM sleep behavior disorder (RBD and sleep apnea syndrome (SAS that can be considered markers of brain stem dysfunction. PURPOSE: To evaluate the frequency of RBD and SAS in patients with CM type I and II. METHOD: Were evaluated 103 patients with CM by means of full night polysomnography. Were scoring different sleep stages, frequency of abnormal movements (through video monitoring and abnormal respiratory events. RESULTS: Of the 103 patients, 36 showed CM type I and 67 CM type II. Episodes of RBD were observed in 23 patients. Abnormal apnea-hypopnea index (AHI was observed in 65 patients. CONCLUSION: The high rate of RBD suggests that this parassomnia and the increased frequency of central sleep apnea episodes, may be considered as a marker of progressive brain stem dysfunction.INTRODUÇÃO: Malformações de Chiari (MC podem gerar o aparecimento de distúrbio comportamental da fase do sono com REM (DCR e síndrome da apnéia do sono (SAS, sugerindo a ocorrência de disfunção do tronco cerebral. OBJETIVO: Avaliar a freqüência de DCR e SAS em pacientes com MC I ou II. MÉTODO: Utilizou-se a polissonografia de noite inteira para a avaliação de 103 pacientes. Classificaram-se as diferentes fases do sono e analisou-se a freqüência de movimentos anormais (monitorada por vídeo e de eventos respiratórios anormais. RESULTADOS: Dos 103 pacientes analisados, 36 eram portadores de MC I e 67 de MC II. Episódios de DCR foram observados em 23 pacientes. O índice de apnéia/hipopnéia foi considerado anormal em 65 pacientes. CONCLUSÃO: A alta freqüência de DCR e o aumento da freqüência de episódios de apnéia central do sono podem ser considerados manifestação de disfunção progressiva do tronco cerebral.

Clinical evaluation of interventional treatment for Budd-Chiari syndrome

International Nuclear Information System (INIS)

Zhong Hongshan; Xu Ke; Xiao Liang

2009-01-01

Objective: To evaluate the interventional treatment of Budd-Chiari syndrome (BCS) with regard to different types of the disease. Methods: One hundred and fifty-nine consecutive cases with BCS underwent interventional treatments with regard to different types of the diseases, including percutaneous angioplasty (PTA), transcatheter thrombolysis, endovascular stent implantation and modified transjugular intrahepatic portosystemic shunt (MTIPS). Among them, 147 cases that underwent complete follow-up were enrolled in this study. Simple obstruction of HV, membranous obstruction of IVC, membranous obstruction of IVC combined with thrombosis in the distal lumen and segmental obstruction of IVC constituted 13.6% (20), 66.0% (97), 6.1% (9)and 14.3% (21/147), respectively. The technical success rate of each type was determined. They were followed up for (67.3±9.0) months (16 h-104 months). Overall primary patency rate was evaluated. The late effect on liver function was analyzed according to the Child-Pugh score. Results: The primary patency rate of PTA was 65.6% (86/131) and the secondary, patency rate was 96.9% (124/128). The primary patency rate of stent implantation was 78.9% (15/19) and the secondary patency rate was 92.3% (24/26). One patient of type IIIa that received recanalization, catheter-directed thrombolysis and PTA in IVC died of hemoptysis 72 h after the procedure. One patients of type I b who received MTIPS died of DIC 16 hrs after the procedure. And one patient of type Ib who received MTIPS died of liver failure 13 months after the procedure. Twelve patients died in 7-79 months after the interventional procedure due to unrelated causes. At the end of follow-up, the liver function of the patients was improved. Conclusions: Optimal application of various vascular interventional techniques has a satisfactory primary and secondary patency rate and improves the long-term liver function. (authors)

Stent Angioplasty of Closed Mesocaval Shunt in a Patient with Budd-Chiari Syndrome

International Nuclear Information System (INIS)

Sancak, Tanzer; Karagulle, Ayse Tuba; Bilgic, Sadik; Sanlidilek, Umman; Yerdel, Mehmet Ali

2002-01-01

Budd-Chiari syndrome (BCS) is an uncommon disorder caused by hepatic venous outflow obstruction. It is characterized by ascites, hepatomegaly and abdominal pain. Percutaneous intervention shave recently been used for the treatment of BCS. We present a case of BCS with a closed mesocaval shunt which was reopened with a self-expandable metallic stent

Method of manufacturing Josephson junction integrated circuits

International Nuclear Information System (INIS)

Jillie, D.W. Jr.; Smith, L.N.

1985-01-01

Josephson junction integrated circuits of the current injection type and magnetically controlled type utilize a superconductive layer that forms both Josephson junction electrode for the Josephson junction devices on the integrated circuit as well as a ground plane for the integrated circuit. Large area Josephson junctions are utilized for effecting contact to lower superconductive layers and islands are formed in superconductive layers to provide isolation between the groudplane function and the Josephson junction electrode function as well as to effect crossovers. A superconductor-barrier-superconductor trilayer patterned by local anodization is also utilized with additional layers formed thereover. Methods of manufacturing the embodiments of the invention are disclosed

Unique cell type-specific junctional complexes in vascular endothelium of human and rat liver sinusoids.

Directory of Open Access Journals (Sweden)

Cyrill Géraud

Full Text Available Liver sinusoidal endothelium is strategically positioned to control access of fluids, macromolecules and cells to the liver parenchyma and to serve clearance functions upstream of the hepatocytes. While clearance of macromolecular debris from the peripheral blood is performed by liver sinusoidal endothelial cells (LSECs using a delicate endocytic receptor system featuring stabilin-1 and -2, the mannose receptor and CD32b, vascular permeability and cell trafficking are controlled by transcellular pores, i.e. the fenestrae, and by intercellular junctional complexes. In contrast to blood vascular and lymphatic endothelial cells in other organs, the junctional complexes of LSECs have not yet been consistently characterized in molecular terms. In a comprehensive analysis, we here show that LSECs express the typical proteins found in endothelial adherens junctions (AJ, i.e. VE-cadherin as well as α-, β-, p120-catenin and plakoglobin. Tight junction (TJ transmembrane proteins typical of endothelial cells, i.e. claudin-5 and occludin, were not expressed by rat LSECs while heterogenous immunreactivity for claudin-5 was detected in human LSECs. In contrast, junctional molecules preferentially associating with TJ such as JAM-A, B and C and zonula occludens proteins ZO-1 and ZO-2 were readily detected in LSECs. Remarkably, among the JAMs JAM-C was considerably over-expressed in LSECs as compared to lung microvascular endothelial cells. In conclusion, we show here that LSECs form a special kind of mixed-type intercellular junctions characterized by co-occurrence of endothelial AJ proteins, and of ZO-1 and -2, and JAMs. The distinct molecular architecture of the intercellular junctional complexes of LSECs corroborates previous ultrastructural findings and provides the molecular basis for further analyses of the endothelial barrier function of liver sinusoids under pathologic conditions ranging from hepatic inflammation to formation of liver metastasis.

Angiographic and hemodynamic evaluation of the mesoatrial shunt in patients with Budd-Chiari syndrome and inferior vena caval obstruction

International Nuclear Information System (INIS)

Redmond, P.L.; Kadir, S.; Cameron, J.L.; Kaufman, S.L.; White, R.I. Jr.

1986-01-01

Obstruction of the inferior vena cava (IVC) is not uncommon in patients with the Budd-Chiari syndrome. The caval obstruction may be due to thrombus or compression by an enlarged caudate lobe. Conventional portosystemic shunts are not possible in the presence of an obstructed IVC; the mesoatrial shunt is indicated in these patients. Between 1973 and 1986, the authors studied 13 patients (ten female, three male) with Budd-Chiari syndrome and IVC obstruction in whom mesoatrial shunts were subsequently constructed. Polycythemia rubra vera was the most common predisposing condition. Preoperative evaluation included US, scintigraphy, CT, and angiography (hepatic arteriography, hepatic venography and pressure measurements, inferior vena cavography, arterial portography). Postoperatively shunts were assessed angiographically and hemodynamically, and several patients underwent CT. The shunts were catheterized via a brachial or femoral venous approach, which allowed pressures along the shunt from the superior mesenteric vein to the right atrium to be measured. The mesoatrial shunt is a relatively new procedure which is indicated in patients with the Budd-Chiari syndrome complicated by IVC obstruction. Shunt patency may be demonstrated arteriographically or with CT, but hemodynamic evaluation with measurement of pressure gradients is required to assess shunt function

Retroperitoneal myxoid liposarcoma of the renal capsule causing Budd-Chiari syndrome

International Nuclear Information System (INIS)

Gruetzner, G.; Fuerst, G.; Kuhn, F.P.; Kliche, K.O.

1991-01-01

A retroperitoneal myxoid liposarcoma of the renal capsule must be differentiated from renal cell carcinomas, angiomyolipomas, fibrogenous lipomas, fibrolipomas and mixed tumours containing fat tissue. Myxoid liposarcomas can lead to intracavale tumourthromboses, which is often the case with renal cell carcinomas and revealed clinical with Budd-Chiari syndrome. Computed tomography and magnetic resonance imaging give additional information in the diagnosis of intracaval tumourthromboses and show the exact expansion of the topographic-anatomical structure. (orig.) [de

Dynamics of pi-junction interferometer circuits

DEFF Research Database (Denmark)

Kornkev, V.K.; Mozhaev, P.B.; Borisenko, I.V.

2002-01-01

The pi-junction superconducting circuit dynamics was studied by means of numerical simulation technique. Parallel arrays consisting of Josephson junctions of both 0- and pi-type were studied as a model of high-T-c grain-boundary Josephson junction. The array dynamics and the critical current depe...

Fabrication of sandwich-type MgB{sub 2}/Boron/MgB{sub 2} Josephson junctions with rapid annealing method

Energy Technology Data Exchange (ETDEWEB)

Zhang, Song; Wang, Xu; Ma, Junli; Cui, Ruirui; Deng, Chaoyong, E-mail: cydeng@gzu.edu.cn

2015-11-15

Sandwich-type MgB{sub 2}/Boron/MgB{sub 2} Josephson junctions were fabricated using magnetron sputtering system. The rapid-anneal process was adopted to replace traditional way of annealing, trying to solve the problem of interdiffusion and oxidation with multilayer films. The boron film was used as barrier layer to avoid the introduction of impurities and improve reproducibility of the junctions. The bottom MgB{sub 2} thin films deposited on c-plane sapphire substrate exhibits a critical temperature T{sub C} of 37.5 K and critical current density J{sub C} at 5 K of 8.7 × 10{sup 6} A cm{sup −2}. From the XRD pattern, the bottom MgB{sub 2} thin film shows c-axis orientation, whereas the top MgB{sub 2} became polycrystalline as Boron barrier layer grown thicker. Therefore, all junction samples show lower T{sub C} than single MgB{sub 2} thin film. The junctions exhibit excellent quasiparticle characteristics with ideal dependence on temperature and Boron barrier thickness. Subharmonic gap structure was appeared in conductance characteristics, which was attributed to the multiple Andreev reflections (MAR). The result demonstrates great promise of this new fabrication technology for MgB{sub 2} Josephson junction fabrication. - Highlights: • Sandwich-type MgB{sub 2}/Boron/MgB{sub 2} Josephson junctions were fabricated. • The junctions were annealed after deposition with the rapid-anneal process. • The highest critical current is 25.3 mA at 5 K and remains non-zero near 25 K. • Subharmonic gap features can be observed in the dI/dV – V curves.

[Oropharyngeal dysphagia associated with Chiari I malformation and syringomyelia J].

Science.gov (United States)

Cortés-Medina, Julio César; Cárdenas-Lara, Armando; Guerrero-Rascón, Carlos Alberto; Rodríguez-Bautista, Heber

2014-01-01

Dysphagia associated with neurological disease is an important clinical manifestation in the diagnosis of injury that justifies the compression of the brainstem and lower cranial nerves. To emphasize the study of dysphagia in a patient with Chiari I malformation associated with syringomyelia in the absence of primary gastroenterological symptoms. We describe the case of a 62 year-old woman with oropharyngeal dysphagia of six years of evolution, cervicobrachialgia, ptosis and facial diplexia. Magnetic resonance imaging is an essential element for establishing the etiologic diagnosis of neurogenic dysphagia.

Diagnosis and Management of Budd Chiari Syndrome: An Update

International Nuclear Information System (INIS)

Copelan, Alexander; Remer, Erick M.; Sands, Mark; Nghiem, Hanh; Kapoor, Baljendra

2015-01-01

Imaging plays a crucial role in the early detection and assessment of the extent of disease in Budd Chiari syndrome (BCS). Early diagnosis and intervention to mitigate hepatic congestion is vital to restoring hepatic function and alleviating portal hypertension. Interventional radiology serves a key role in the management of these patients. The interventionist should be knowledgeable of the clinical presentation as well as key imaging findings, which often dictate the approach to treatment. This article concisely reviews the etiology, pathophysiology, and clinical presentation of BCS and provides a detailed description of imaging and treatment options, particularly interventional management

Diagnosis and Management of Budd Chiari Syndrome: An Update

Energy Technology Data Exchange (ETDEWEB)

Copelan, Alexander, E-mail: alexander.copelan@beaumont.edu [William Beaumont Hospital, Diagnostic Radiology Department (United States); Remer, Erick M., E-mail: remere1@ccf.org; Sands, Mark, E-mail: sandsm@ccf.org [Cleveland Clinic, Imaging Institute (United States); Nghiem, Hanh, E-mail: HNghiem@beaumont.edu [William Beaumont Hospital, Diagnostic Radiology Department (United States); Kapoor, Baljendra, E-mail: kapoorb@ccf.org [Cleveland Clinic, Imaging Institute (United States)

2015-02-15

Imaging plays a crucial role in the early detection and assessment of the extent of disease in Budd Chiari syndrome (BCS). Early diagnosis and intervention to mitigate hepatic congestion is vital to restoring hepatic function and alleviating portal hypertension. Interventional radiology serves a key role in the management of these patients. The interventionist should be knowledgeable of the clinical presentation as well as key imaging findings, which often dictate the approach to treatment. This article concisely reviews the etiology, pathophysiology, and clinical presentation of BCS and provides a detailed description of imaging and treatment options, particularly interventional management.

A Case of Acute Budd-Chiari Syndrome Complicating Primary Antiphospholipid Syndrome Presenting as Acute Abdomen and Responding to Tight Anticoagulant Therapy

Directory of Open Access Journals (Sweden)

Naofumi Chinen

2016-01-01

Full Text Available A 34-year-old woman with primary antiphospholipid syndrome was admitted to the Gastroenterology Department of our hospital with fever, acute abdomen, watery diarrhea, and extremely high levels of inflammatory parameters. She had a history of left lower limb deep vein thrombosis and pulmonary embolism and was taking warfarin potassium. Acute gastroenteritis was suspected and an antibiotic was administered, but symptoms progressed. Abdominal ultrasonography showed occlusion of the left hepatic vein and the middle hepatic vein and her D-dimer level was high. Accordingly, Budd-Chiari syndrome was diagnosed and high-dose intravenous infusion of heparin was initiated. Her abdominal symptoms improved and the levels of inflammatory parameters and D-dimer decreased rapidly. It is known that antiphospholipid syndrome can be complicated by Budd-Chiari syndrome that usually occurs as subacute or chronic onset, but acute onset is rare. It is difficult to diagnose acute Budd-Chiari syndrome complicating antiphospholipid syndrome and this complication generally has a poor outcome. However, the present case can get early diagnosis and successful treatment with tight anticoagulant therapy.

Constructing carbon nanotube junctions by Ar ion beam irradiation

International Nuclear Information System (INIS)

Ishaq, Ahmad; Ni Zhichun; Yan Long; Gong Jinlong; Zhu Dezhang

2010-01-01

Carbon nanotubes (CNTs) irradiated by Ar ion beams at elevated temperature were studied. The irradiation-induced defects in CNTs are greatly reduced by elevated temperature. Moreover, the two types of CNT junctions, the crossing junction and the parallel junction, were formed. And the CNT networks may be fabricated by the two types of CNT junctions. The formation process and the corresponding mechanism of CNT networks are discussed.

Comparative evaluation of ultrasonography, computed tomography and magnetic resonance imaging in the follow-up of Budd-Chiari syndrome

Energy Technology Data Exchange (ETDEWEB)

Legmann, P; Levesque, M; De, Broucker F; F,; Hay, J M; Maillard, J N

1988-01-01

A comparative evaluation of ultrasonography, computed tomography and MRI in 8 patients operated for Budd-Chiari syndrome is reported. The results obtained, evaluated separately for each technique and then compared between each other and with the data of superior coelio-mesenteric angiography and inferior cavography, show that the MRI data is very clearly superior to the data obtained by ultrasonography and computed tomography. MRI allows simultaneous assessment of the hepatic parenchyma, evaluation of portal hypertension and the porto-caval anastomosis, which are all essential elements in the follow-up Budd-Chiari syndrome. However, in the light of the literature, the authors stress that ultrasonography associated with pulsed Doppler also ensures satisfactory vascular and parenchymal assessment of this disease in the majority of cases.

Comparative evaluation of ultrasonography, computed tomography and magnetic resonance imaging in the follow-up of Budd-Chiari syndrome

International Nuclear Information System (INIS)

Legmann, P.; Levesque, M.; Broucker, F. de; Hay, J.M.; Maillard, J.N.

1989-01-01

The authors report a comparative evaluation of ultrasonography, computed tomography and MRI in 8 patients operated for Budd-Chiari syndrome. The results obtained, evaluated separately for each technique and then compared between each other and with the data of superior coelio-mesenteric angiography and inferior cavography, showed that MRI data is very clearly superior to the data obtained by ultrasonography and computed tomography. MRI allows simultaneous assessment of the hepatic parenchyma, and evaluation of portal hypertension and the porto-caval anastomosis, which are all essential elements in the follow-up Budd-Chiari syndrome. However, in the light of the literature, the authors stress that ultrasonography associated with pulsed Doppler also ensures satisfactory vascular and parenchymal assessment of this disease in the majority of cases [fr

Charge transport in 2DEG/s-wave superconductor junction with Dresselhaus-type spin-orbit coupling

International Nuclear Information System (INIS)

Sawa, Y.; Yokoyama, T.; Tanaka, Y.

2007-01-01

We study spin-dependent charge transport in superconducting junctions. We consider ballistic two-dimensional electron gas (2DEG)/s-wave superconductor junctions with Dresselhaus-type spin-orbit coupling (DSOC). We calculate the conductance normalized by that in the normal state of superconductor in order to study the effect of DSOC in 2DEG on conductance, changing the height of insulating barrier. We find the DSOC suppresses the conductance for low insulating barrier, while it can slightly enhance the conductance for high insulating barrier. It has a reentrant dependence on DSOC for middle strength insulating barrier. The effect of DSOC is weaken as the insulating barrier becomes high

Acute Presentation of Chiari I Malformation with Hemiparesis in a Pediatric Patient.

Science.gov (United States)

Miranda, Stephen P; Kimmell, Kristopher T; Silberstein, Howard J

2016-01-01

Chiari I malformation (CM-I) is defined by cerebellar tonsillar herniation through the foramen magnum. Patients typically present with chronic complaints, including headache, dizziness, and numbness, although there are few reports in the literature of pediatric patients presenting acutely with neurological deficit caused by CM-I. We report a child who presented acutely with hemiparesis and magnetic resonance imaging findings consistent with CM-I and spinal cord edema. A 3-year old boy with normal development presented with difficulty walking and increased drooling. His mother stated he was running into objects and had balance issues for several days. Neurological examination showed ataxia with falling to the right after a few steps and weakness of the right arm and leg. His medical history was remarkable only for mild asthma, although he had recently been treated for an upper respiratory viral infection. Computed tomography of the head demonstrated no brainstem mass. Magnetic resonance imaging of the head and cervical spine showed tonsillar ectopia approximately 2 cm below the craniocervical junction with increased T2 signal in the spinal cord from C1 to C3 consistent with syringomyelia and cord edema. The patient underwent suboccipital craniectomy with removal of the posterior arch of C1 and dural patch graft. His postoperative course was unremarkable, with complete resolution of his symptoms at his 1-month follow-up visit. This case highlights an unusual presentation of CM-I with neurological deficit related to spinal cord edema, possibly precipitated by the "water-hammer" effect of this patient's coughing fits. Providers should be aware of the acute presentations of CM-I. Copyright © 2016 Elsevier Inc. All rights reserved.

Achados cirúrgicos em 260 casos de impressão basilar e/ou malformação de Arnold-Chiari

Directory of Open Access Journals (Sweden)

José Alberto Gonçalves da Silva

1994-09-01

Full Text Available A impressão basilar é malformação frequentemente observada no Nordeste do Brasil. No período de 1971 a 1992 foram operados, em nosso Serviço, 260 pacientes com malformações occipitocervicais, sendo 29 (11,1% casos de impressão basilar pura, 18 (6,9% com malformação de Arnold-Chiari e 213 (81,9% com impressão basilar associada à malformação de Arnold-Chiari. São relatados os achados cirúrgicos do plano ósseo, da dura-máter, do tecido nervoso e dos vasos da fossa posterior.

Manufacturing P-N junctions in germanium bodies

International Nuclear Information System (INIS)

Hall, R.N.

1980-01-01

A method of producing p-n junctions in Ge so as to facilitate their use as radiation detectors involves forming a body of high purity p-type germanium, diffusing lithium deep into the body, in the absence of electrolytic processes, to form a junction between n-type and p-type germanium greater than 1 mm depth. (UK)

Sagittal reconstruction computed tomography in metrizamide cisternography. Useful diagnostic procedure for malformations in craniovertebral junction and posterior fossa

Energy Technology Data Exchange (ETDEWEB)

Mochizuki, H.; Okita, N.; Fujii, T.; Yoshioka, M.; Saito, H. (Tohoku Univ., Sendai (Japan). School of Medicine)

1982-08-01

We studied the sagittal reconstruction technique in computed tomography with metrizamide. Ten ml of metrizamide, 170 mg iodine/ml in concentration, were injected by lumbar puncture. After diffusion of the injected metrizamide, axial computed tomograms were taken by thin slice width (5 mm) with overlapped technique. Then electrical sagittal reconstruction was carried out by optioned software. Injection of metrizamide, non-ionic water soluble contrast media, made clear contrasts among bone, brain parenchyma and cerebrospinal fluid with computed tomography. Sagittal reconstruction technique could reveal more precise details and accurate anatomical relations than ordinary axial computed tomography. This technique was applied on 3 cases (Arnold-Chiari malformation, large cisterna magna and partial agenesis cerebellar vermis), which demonstrated a useful diagnostic procedure for abnormalities of craniovertebral junction and posterior fossa. The adverse reactions of metrizamide were negligible in our series.

The Dissolution of Double Holliday Junctions

DEFF Research Database (Denmark)

Bizard, Anna H; Hickson, Ian D

2014-01-01

as "double Holliday junction dissolution." This reaction requires the cooperative action of a so-called "dissolvasome" comprising a Holliday junction branch migration enzyme (Sgs1/BLM RecQ helicase) and a type IA topoisomerase (Top3/TopoIIIα) in complex with its OB (oligonucleotide/oligosaccharide binding......Double Holliday junctions (dHJS) are important intermediates of homologous recombination. The separate junctions can each be cleaved by DNA structure-selective endonucleases known as Holliday junction resolvases. Alternatively, double Holliday junctions can be processed by a reaction known......) fold containing accessory factor (Rmi1). This review details our current knowledge of the dissolution process and the players involved in catalyzing this mechanistically complex means of completing homologous recombination reactions....

Dynamics of Josephson junction arrays

International Nuclear Information System (INIS)

Hadley, P.

1989-01-01

The dynamics of Josephson junction arrays is a topic that lies at the intersection of the fields of nonlinear dynamics and Josephson junction technology. The series arrays considered here consist of several rapidly oscillating Josephson junctions where each junction is coupled equally to every other junction. The purpose of this study is to understand phaselocking and other cooperative dynamics of this system. Previously, little was known about high dimensional nonlinear systems of this sort. Numerical simulations are used to study the dynamics of these arrays. Three distinct types of periodic solutions to the array equations were observed as well as period doubled and chaotic solutions. One of the periodic solutions is the symmetric, in-phase solution where all of the junctions oscillate identically. The other two periodic solutions are symmetry-broken solutions where all of the junction do not oscillate identically. The symmetry-broken solutions are highly degenerate. As many as (N - 1) stable solutions can coexist for an array of N junctions. Understanding the stability of these several solutions and the transitions among them is vital to the design of useful devices

Association of visceral adiposity with oesophageal and junctional adenocarcinomas.

LENUS (Irish Health Repository)

Beddy, P

2012-02-01

BACKGROUND: Obesity is associated with an increased incidence of oesophageal and oesophagogastric junction adenocarcinoma, in particular Siewert types I and II. This study compared abdominal fat composition in patients with oesophageal\\/junctional adenocarcinoma with that in patients with oesophageal squamous cell carcinoma and gastric adenocarcinoma, and in controls. METHOD: In total, 194 patients (110 with oesophageal\\/junctional adenocarcinoma, 38 with gastric adenocarcinoma and 46 with oesophageal squamous cell carcinoma) and 90 matched control subjects were recruited. The abdominal fat area was assessed using computed tomography (CT), and the total fat area (TFA), visceral fat area (VFA) and subcutaneous fat area (SFA) were calculated. RESULTS: Patients with oesophageal\\/junctional adenocarcinoma had significantly higher TFA and VFA values compared with controls (both P < 0.001), patients with gastric adenocarcinoma (P = 0.013 and P = 0.006 respectively) and patients with oesophageal squamous cell carcinoma (both P < 0.001). For junctional tumours, the highest TFA and VFA values were seen in patients with Siewert type I tumours (respectively P = 0.041 and P = 0.033 versus type III; P = 0.332 and P = 0.152 versus type II). CONCLUSION: Patients with oesophageal\\/junctional adenocarcinoma, in particular oesophageal and Siewert type I junctional tumours, have greater CT-defined visceral adiposity than patients with gastric adenocarcinoma or oesophageal squamous cell carcinoma, or controls.

Tratamento da síndrome de Budd-Chiari por meio da colocação de tips e de "stent" venoso supra-hepático Transjugular intrahepatic portosystemic shunt (TIPS and suprahepatic venous stenting in the management of Budd-Chiari syndrome

Directory of Open Access Journals (Sweden)

Jurandi A. Bettio

2002-11-01

Full Text Available OBJETIVOS: Descrever o uso do "shunt" intra-hepático portossistêmico (TIPS e do "stent" venoso supra-hepático no manejo da síndrome de Budd-Chiari, enfocando suas indicações, aspectos técnicos e benefícios do procedimento. MATERIAIS E MÉTODOS: De janeiro de 1999 a março de 2002, nove casos de síndrome de Budd-Chiari foram encaminhados ao Serviço de Hemodinâmica do Hospital São Lucas, Porto Alegre, RS. A obstrução venosa supra-hepática foi constatada em todos os casos por meio de ultra-sonografia com Doppler em cores. A criação de TIPS foi realizada entre o sistema venoso supra-hepático ou a veia cava inferior e a veia porta, posicionando-se a endoprótese entre as duas abordagens. Doppler em cores pós-procedimento foi efetuado em todos os pacientes em períodos seriados. RESULTADOS: Três casos foram tratados inicialmente com inserção de "stent" venoso por apresentarem estenose preponderante em veias supra-hepáticas. Em dois desses casos ocorreu trombose do "stent", sendo necessária colocação de TIPS. Os demais seis casos foram tratados primariamente com TIPS. Dos oito "shunts" criados, trombose da endoprótese foi constatada em três casos, resolvidas com limpeza dos trombos e dilatação com balão em um caso e inserção de novas próteses nos demais. Embolização com molas de colaterais venosas ectasiadas foi efetuada em um paciente. CONCLUSÕES: A colocação de TIPS constitui-se numa estratégia terapêutica segura e efetiva na síndrome de Budd-Chiari, promovendo uma significativa melhora clínica e hemodinâmica dos pacientes, evitando procedimentos mais invasivos e podendo, em casos sem cirrose estabelecida, servir de tratamento definitivo da hipertensão portal.OBJECTIVE: To evaluate the use of transjugular intrahepatic portosystemic shunt (TIPS and suprahepatic venous stenting in the management of Budd-Chiari syndrome, emphasizing the indications, technical aspects and the advantages of the procedure

Result of surgical therapy in esophagogastric junction adenocarcinoma

International Nuclear Information System (INIS)

Shirinzadeh, A.; Fakhrjoo, E.

2007-01-01

To assess the outcome of surgical therapy and choice of surgical strategy for patients with adenocarcinoma of the gastroesophageal junction. Between February 1989 and January 2005 during 16 years, 335 patients (65 female, 270 male, mean age 56 years) with esophagogastric junction adenocarcinoma underwent surgical operation. The choice of surgical approach was based on the anatomical location of the tumor mass. Outcome of surgery, histopathologic characteristics, demographic data and long term survival rates were compared among three types of tumor defined as follows. Type I: Adenocarcinoma of the distal esophagus which infiltrates the esophagogastric junction from above. Type II: True carcinoma of the cardia arising immediately at the esophagogastric junction. Type III: Subcardial gastric carcinoma that infiltrates the esophagogastric junction and distal esophagus from below. Of the 335 patients undergoing resection, 110 (33%) had type I, 96 (28%) had type II, and 129 (39%) had type III. The preponderance of the male sex and the prevalence of metaplasia in distal esophagus decreased from type I to type III tumors (P<0.01). The prevalence of undifferentiated tumors increased from type I to type III tumors (P<0.01). Esophagectomy with resection of the proximal stomach for type I and extended total gastrectomy with transhiatal resection of the distal esophagus for type II and III were the primary procedures. The mean number of removed lymph node was higher in type III and II compared to type I tumors. The overall postoperative 30-day mortality was 8.4%. The death rate in transthoracic esophagectomy was higher than with extended total gastrectomy. The classification of adenocarcinoma of the esophagogastric junction into type I, II and III tumors helps in the selection of surgical approach. Type I tumors are approached as distal esophageal cancer. Type III tumors are a special form of gastric cancer and treated as a gastric cancer. The relation of type II tumors to

Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

DEFF Research Database (Denmark)

Jørgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne

2003-01-01

The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting...... in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal...... of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx...

Rare association between cystic fibrosis, Chiari I malformation, and hydrocephalus in a baby: a case report and review of the literature

Directory of Open Access Journals (Sweden)

Jea Andrew

2011-08-01

Full Text Available Abstract Introduction Cystic fibrosis, an epithelial cell transport disorder caused by mutations of the cystic fibrosis transmembrane conductance regulator gene, is not generally associated with malformations of the central nervous system. We review eight previously published reports detailing an infrequent association between cystic fibrosis and Chiari I malformation. Case presentation To the best of our knowledge, our report describes only the ninth case of a baby presenting with a new diagnosis of cystic fibrosis and Chiari I malformation, in this case in a 10-month-old, full-term Caucasian baby boy from the United States of America. Neurosurgical consultation was obtained for associated developmental delay, macrocephaly, bulging anterior fontanel, and papilledema. An MRI scan demonstrated an extensive Chiari I malformation with effacement of the fourth ventricle, obliteration of the outlets of the fourth ventricle and triventricular hydrocephalus without aqueductal stenosis. Our patient was taken to the operating room for ventriculoperitoneal shunt placement. Conclusions It is possible that the cystic fibrosis transmembrane conductance regulator gene may play a previously unrecognized role in central nervous system development; alternatively, this central nervous system abnormality may have been acquired due to constant valsalva from recurrent coughing or wheezing or metabolic and electrolyte imbalances that occur characteristically in cystic fibrosis.

Morphological variation of the kidney secondary to junctional parenchyma on ultrasound

International Nuclear Information System (INIS)

Lee, Ji Yoon; Park, Byeong Ho; Nam, Kyeong Jin; Choi, Jong Cheol; Koo, Bong Sig; Kim, Jou Yeoun; Ahn, Seung Eon; Lee, Yung Il

1996-01-01

To evaluate the prevalance of morphological variation of the kidney secondary to junctional parenchyma, as well as to analyze the ultrasonographic features of junctional parenchyma. Two hundred and eighty two kidneys of 141 patient without clinical or radiologic evidence of renal disease were prospectively analysed using ultrasound. In all patients, ultrasonograms were obtained in sagittal, coronal and transaxial planes. The kidney was considered to have morphological variation if the ultrasonogram demonstrated junctional parenchymal defect of line ; those showing such variation were classified as one of three types : continuous, discontinuous, or junctional parenchymal line or defect without junctional parenchyma. The prevalance and ultrasonographic features of the kidneys were evaluated. Morphological variation was noted in 71 cases(25%). the continuous type accounted for 54% of these, the discontinuous type for 38%, and junctional parenchymal defect or line without junctional parenchyma for 8%. In all cases, junctional parenchyma was located approximately at the junction of the upper and middle third of the kidney, and had the same echogenecity as the renal cortex. An understanding of the morphological variation of the kidney resulting from junctional renal parenchyma would be helpful in differentiating pseudotumor from true renal neoplasm

Junction detection and pathway selection

Science.gov (United States)

Peck, Alex N.; Lim, Willie Y.; Breul, Harry T.

1992-02-01

The ability to detect junctions and make choices among the possible pathways is important for autonomous navigation. In our script-based navigation approach where a journey is specified as a script of high-level instructions, actions are frequently referenced to junctions, e.g., `turn left at the intersection.' In order for the robot to carry out these kind of instructions, it must be able (1) to detect an intersection (i.e., an intersection of pathways), (2) know that there are several possible pathways it can take, and (3) pick the pathway consistent with the high level instruction. In this paper we describe our implementation of the ability to detect junctions in an indoor environment, such as corners, T-junctions and intersections, using sonar. Our approach uses a combination of partial scan of the local environment and recognition of sonar signatures of certain features of the junctions. In the case where the environment is known, we use additional sensor information (such as compass bearings) to help recognize the specific junction. In general, once a junction is detected and its type known, the number of possible pathways can be deduced and the correct pathway selected. Then the appropriate behavior for negotiating the junction is activated.

Several alternative approaches to the manufacturing of HTS Josephson junctions

OpenAIRE

Villegier , J.; Boucher , H.; Ghis , A.; Levis , M.; Méchin , Laurence; Moriceau , H.; Pourtier , F.; Vabre , M.; Nicoletti , S.; Correra , L.

1994-01-01

In this work we describe comparatively the fabrication and the characterization of various types of HTS Josephson junctions manufactured using different processes : grain boundary junctions have been studied both by the way of junctions on bicrystal substrates and of bi-epitaxial junctions. Ramp-edge types have been elaborated and characterized using mainly N-YBaCuO thin film as a barrier while the trilayer approach has been investigated through a-axis structures. YBaCuO or GdBaCuO supercondu...

The efficacy of intraoperative ultrasonography-assisted microinvasive cisterna magna reconstruction for Chiari malformation typeⅠwith syringomyelia

Directory of Open Access Journals (Sweden)

LI Peng-chao

2012-08-01

Full Text Available Objective To report the method and effect of intraoperative ultrasonography-assisted microinvasive cisterna magna reconstruction for Chiari malformation type Ⅰ with syringomyelia. Methods Ninty-three patients suffered from Chiari malformation typeⅠwith syringomyelia were treated by microinvasive cisterna magna reconstruction. The skin incision was 1.50-3.00 cm. The bone removal of foramen magnum was 1.50 cm × 2.00 cm with C1 reserved. Dura and arachnoid were incised and sutured linearly. All of the patients underwent cerebellar tonsillar resection and exploration of median aperture of fourth ventricle. Intraoperative ultrasonography was performed both before and after cerebellar tonsillar resection to judge the effect of cisterna magna reconstruction. According to Tator method, the curative effect was divided into 3 groups, improved, stable and worsen. MRI were reviewed at the same time, and the result was divided into syrinx disappeared, reduced, no change and expanded. Results The operation was successful in all patients. Postoperative complications included cerebellum hemorrhage (n = 1, cerebral infarction (n = 1, hydrocephalus (n = 1, subcutaneous dropsy (n = 2 and were recovered after specific treatment. All patients were followed up for 6 months to 12 months after operation. Thirty-six cases were improved, 55 cases were stable, and 2 cases got worse. The MRI showed that the syringomyelia shrinked or disappeared in 90 cases, no change in 3 cases and no expansion. Eighty cases were followed up for 30 months to 36 months after operation, 12 stable cases improved, 1 stable case got worse, while the others remained unchanged. The MRI showed no change was compared with previous follow-up imaging. Conclusion Microinvasive cisterna magna reconstruction is a surgical procedure with mininal injury, quick recovery, stable effect, fewer complications, and high security. Intraoperative ultrasonography provides reliable data and is easy to perform.

Klippel-Feil syndrome in association with Chiari zero malformation in the setting of acute traumatic spinal cord injury

Directory of Open Access Journals (Sweden)

Cameron M. McDougall, MD FRCS(C

2017-09-01

Conclusion: This is the first report of a Chiari zero malformation associated with KFS. This patient was managed with an initial conservative approach and delayed posterior fossa decompression. There was steady improvement in his neurological function. This appears to represent a viable treatment approach.

A unifying hypothesis for hydrocephalus, Chiari malformation, syringomyelia, anencephaly and spina bifida

Directory of Open Access Journals (Sweden)

Williams Helen

2008-04-01

Full Text Available Abstract This work is a modified version of the Casey Holter Memorial prize essay presented to the Society for Research into Hydrocephalus and Spina Bifida, June 29th 2007, Heidelberg, Germany. It describes the origin and consequences of the Chiari malformation, and proposes that hydrocephalus is caused by inadequate central nervous system (CNS venous drainage. A new hypothesis regarding the pathogenesis, anencephaly and spina bifida is described. Any volume increase in the central nervous system can increase venous pressure. This occurs because veins are compressible and a CNS volume increase may result in reduced venous blood flow. This has the potential to cause progressive increase in cerebrospinal fluid (CSF volume. Venous insufficiency may be caused by any disease that reduces space for venous volume. The flow of CSF has a beneficial effect on venous drainage. In health it moderates central nervous system pressure by moving between the head and spine. Conversely, obstruction to CSF flow causes localised pressure increases, which have an adverse effect on venous drainage. The Chiari malformation is associated with hindbrain herniation, which may be caused by low spinal pressure relative to cranial pressure. In these instances, there are hindbrain-related symptoms caused by cerebellar and brainstem compression. When spinal injury occurs as a result of a Chiari malformation, the primary pathology is posterior fossa hypoplasia, resulting in raised spinal pressure. The small posterior fossa prevents the flow of CSF from the spine to the head as blood enters the central nervous system during movement. Consequently, intermittent increases in spinal pressure caused by movement, result in injury to the spinal cord. It is proposed that posterior fossa hypoplasia, which has origins in fetal life, causes syringomyelia after birth and leads to damage to the spinal cord in spina bifida. It is proposed that hydrocephalus may occur as a result of

Superconductor-normal metal-superconductor process development for the fabrication of small Josephson junctions in ramp type configuration

International Nuclear Information System (INIS)

Poepel, R.; Hagedorn, D.; Weimann, T.; Buchholz, F.-I.; Niemeyer, J.

2000-01-01

At PTB, a fabrication process has been developed in SNS Nb/PdAu/Nb technology for the verification of small Josephson junctions (JJs) in the deep sub-micron range to enable the implementation of JJs as active elements in highly integrated superconducting circuits. Two steps of this technological development are described with regard to appropriately designed circuit layouts of JJ series arrays (JJAs), the first one in a conventional window type junction (WTJ) configuration and the second one in a ramp type junction (RTJ) configuration. Test circuits of JJAs containing up to 10 000 JJs have been fabricated and experimentally tested. In WTJ configuration, the circuits proved to be sensitive to external perturbing effects affecting the stability of circuit operation. In contrast to that, in RTJ configuration, the circuits realized showed correct function and a high grade of reliability of operation. To produce RTJ circuits, the technology parameters have been set to realize JJs with contact areas of A=0.25μmx1.3μm. At a thickness of the PdAu normal metal layer of d = 40 nm, the values achieved for the critical current density and for the product of critical current and normal state resistance are about j c = 200 k Acm -2 and about I c R N = 21 μV. (author)

Probing electrical transport in individual carbon nanotubes and junctions

International Nuclear Information System (INIS)

Kim, Tae-Hwan; Wendelken, John F; Li Anping; Du Gaohui; Li Wenzhi

2008-01-01

The electrical transport properties of individual carbon nanotubes (CNTs) and multi-terminal junctions of CNTs are investigated with a quadraprobe scanning tunneling microscope. The CNTs used in this study are made of stacked herringbone-type conical graphite sheets with a cone angle of ∼20 deg. to the tube axis, and the CNT junctions have no catalytic particles in the junction areas. The CNTs have a significantly higher resistivity than conventional CNTs with concentric walls. The straight CNTs display linear current-voltage (I-V) characteristics, indicating diffusive transport rather than ballistic transport. The structural deformation in CNTs with bends substantially increases the resistivity in comparison with that for the straight segments on the same CNTs, and the I-V curve departs slightly from linearity in curved segments. The junction area of the CNT junctions behaves like an ohmic-type scattering center with linear I-V characteristics. In addition, a gating effect has not been observed, in contrast to the case for conventional multi-walled CNT junctions. These unusual transport properties can be attributed to the enhanced inter-layer interaction in the herringbone-type CNTs.

NbN tunnel junctions

International Nuclear Information System (INIS)

Villegier, J.C.; Vieux-Rochaz, L.; Goniche, M.; Renard, P.; Vabre, M.

1984-09-01

All-niobium nitride Josephon junctions have been prepared successfully using a new processing called SNOP: Selective Niobium (nitride) Overlap Process. Such a process involves the ''trilayer'' deposition on the whole wafer before selective patterning of the electrodes by optically controlled dry reactive ion etching. Only two photomask levels are need to define an ''overlap'' or a ''cross-type'' junction with a good accuracy. The properties of the niobium nitride films deposited by DC-magnetron sputtering and the surface oxide growth are analysed. The most critical point to obtain high quality and high gap value junctions resides in the early stage of the NbN counterelectrode growth. Some possibilities to overcome such a handicap exist even if the fabrication needs substrate temperatures below 250 0 C

P-n junction diodes with polarization induced p-type graded InxGa1-xN layer

Science.gov (United States)

Enatsu, Yuuki; Gupta, Chirag; Keller, Stacia; Nakamura, Shuji; Mishra, Umesh K.

2017-10-01

In this study, p-n junction diodes with polarization induced p-type layer are demonstrated on Ga polar (0001) bulk GaN substrates. A quasi-p-type region is obtained by linearly grading the indium composition in un-doped InxGa1-xN layers from 0% to 5%, taking advantage of the piezoelectric and spontaneous polarization fields which exist in group III-nitride heterostructures grown in the typical (0001) or c-direction. The un-doped graded InxGa1-xN layers needed to be capped with a thin Mg-doped InxGa1-xN layer to make good ohmic contacts and to reduce the on-resistance of the p-n diodes. The Pol-p-n junction diodes exhibited similar characteristics compared to reference samples with traditional p-GaN:Mg layers. A rise in breakdown voltage from 30 to 110 V was observed when the thickness of the graded InGaN layer was increased from 100 to 600 nm at the same grade composition.

Chiari malformation Type I surgery in pediatric patients. Part 1: validation of an ICD-9-CM code search algorithm.

Science.gov (United States)

Ladner, Travis R; Greenberg, Jacob K; Guerrero, Nicole; Olsen, Margaret A; Shannon, Chevis N; Yarbrough, Chester K; Piccirillo, Jay F; Anderson, Richard C E; Feldstein, Neil A; Wellons, John C; Smyth, Matthew D; Park, Tae Sung; Limbrick, David D

2016-05-01

OBJECTIVE Administrative billing data may facilitate large-scale assessments of treatment outcomes for pediatric Chiari malformation Type I (CM-I). Validated International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code algorithms for identifying CM-I surgery are critical prerequisites for such studies but are currently only available for adults. The objective of this study was to validate two ICD-9-CM code algorithms using hospital billing data to identify pediatric patients undergoing CM-I decompression surgery. METHODS The authors retrospectively analyzed the validity of two ICD-9-CM code algorithms for identifying pediatric CM-I decompression surgery performed at 3 academic medical centers between 2001 and 2013. Algorithm 1 included any discharge diagnosis code of 348.4 (CM-I), as well as a procedure code of 01.24 (cranial decompression) or 03.09 (spinal decompression or laminectomy). Algorithm 2 restricted this group to the subset of patients with a primary discharge diagnosis of 348.4. The positive predictive value (PPV) and sensitivity of each algorithm were calculated. RESULTS Among 625 first-time admissions identified by Algorithm 1, the overall PPV for CM-I decompression was 92%. Among the 581 admissions identified by Algorithm 2, the PPV was 97%. The PPV for Algorithm 1 was lower in one center (84%) compared with the other centers (93%-94%), whereas the PPV of Algorithm 2 remained high (96%-98%) across all subgroups. The sensitivity of Algorithms 1 (91%) and 2 (89%) was very good and remained so across subgroups (82%-97%). CONCLUSIONS An ICD-9-CM algorithm requiring a primary diagnosis of CM-I has excellent PPV and very good sensitivity for identifying CM-I decompression surgery in pediatric patients. These results establish a basis for utilizing administrative billing data to assess pediatric CM-I treatment outcomes.

The fallopian tube-peritoneal junction: a potential site of carcinogenesis.

Science.gov (United States)

Seidman, Jeffrey D; Yemelyanova, Anna; Zaino, Richard J; Kurman, Robert J

2011-01-01

Junctions between different types of epithelia are hot spots for carcinogenesis, but the junction of the peritoneal mesothelium with the fallopian tubal epithelium, the tubal-peritoneal junction, has not been characterized earlier. A total of 613 junctional foci in 228 fallopian tube specimens from 182 patients who underwent surgery for a variety of indications, including 27 risk-reducing salpingo-oophorectomy specimens, were studied. Edema, congestion, and dilated lymphatic channels were commonly present. Transitional metaplasia was found at the junction in 20% of patients and mesothelial hyperplasia in 17%. Inflammation at the junction was seen predominantly in patients with salpingitis, torsion, or tubal pregnancy. Ovarian-type stroma was found at the junction in 5% of patients, and was found elsewhere in the tubal lamina propria in an additional 27% of patients. Findings in risk-reducing salpingo-oophorectomy specimens in women with BRCA mutations, a personal history of breast cancer, and/or a family history of breast/ovarian cancer were similar to those in controls. Transitional metaplasia specifically localizes to this junction, and is the probable source of Walthard cell nests. The recently highlighted significance of fimbrial tubal epithelium in the origin of serous ovarian carcinomas and a study suggesting that mucinous and Brenner tumors may arise from transitional-type epithelium in this location suggest that the tubal-peritoneal junction may play a role in the development of these tumors. This is the first comprehensive description of a hitherto unrecognized transitional zone in the adnexa.

Nonlocal Cooper pair splitting in a pSn-junction

NARCIS (Netherlands)

Veldhorst, M.; Brinkman, Alexander

2010-01-01

Perfect Cooper pair splitting is proposed, based on crossed Andreev reflection (CAR) in a p-type semiconductor-superconductor-n-type semiconductor (pSn) junction. The ideal splitting is caused by the energy filtering that is enforced by the band structure of the electrodes. The pSn junction is

Diagnosis and surgical treatment of a Chiari I-like malformation in an African lion (Panthera leo).

Science.gov (United States)

McCain, Stephanie; Souza, Marcy; Ramsay, Ed; Schumacher, Juergen; Hecht, Silke; Thomas, William

2008-09-01

A 13-mo-old intact male African lion (Panthera leo) presented with a 3-mo history of lethargy, ventral flexion of the neck, abnormal vocalization, and ataxia. Hemogram and serum biochemistries were within normal limits except for the presence of hypokalemia (2.7 mEq/L) and hypochloridemia (108 mEq/L). When no improvement was noted with oral potassium gluconate supplementation, a computed tomography scan of the brain and skull was performed, and no abnormalities were noted. However, magnetic resonance imaging detected occipital bone thickening, crowding of the caudal cranial fossa with cerebellar compression and herniation, and cervical syringohydromyelia, which was consistent with a Chiari I-like malformation. Foramen magnum decompression was performed to relieve the compression of the cerebellum. The animal recovered well with subsequent resolution of clinical signs. Hypovitaminosis A has been proposed previously as the underlying etiology for this malformation in lions with similar clinical presentations. This lion's serum and liver vitamin A concentrations were low (100 ng/ml and 25.31 microg/g, respectively) compared to concentrations reported for domestic carnivores and support hypovitaminosis A as the underlying cause of this animal's Chiari I-like malformation.

Doping enhanced barrier lowering in graphene-silicon junctions

Science.gov (United States)

Zhang, Xintong; Zhang, Lining; Chan, Mansun

2016-06-01

Rectifying properties of graphene-semiconductor junctions depend on the Schottky barrier height. We report an enhanced barrier lowering in graphene-Si junction and its essential doping dependence in this paper. The electric field due to ionized charge in n-type Si induces the same type doping in graphene and contributes another Schottky barrier lowering factor on top of the image-force-induced lowering (IFIL). We confirm this graphene-doping-induced lowering (GDIL) based on well reproductions of the measured reverse current of our fabricated graphene-Si junctions by the thermionic emission theory. Excellent matching between the theoretical predictions and the junction data of the doping-concentration dependent barrier lowering serves as another evidence of the GDIL. While both GDIL and IFIL are enhanced with the Si doping, GDIL exceeds IFIL with a threshold doping depending on the as-prepared graphene itself.

Restoration of the efferent phase of the sneeze reflex after regression of an Arnold-Chiari malformation with compression of the medulla oblongata.

Science.gov (United States)

Songu, Murat; Can, Nazan; Gelal, Fazil

2013-01-01

The precise location of the sneeze center in the human brain has not been definitively identified. The aim of this report is to contribute to the effort to detect its location. We report the case of a 13-year-old boy who presented to our outpatient clinic for evaluation of an inability to sneeze. In an attempt to trigger the afferent (nasal) phase of the sneeze reflex, we first applied a cotton swab and later a silver nitrate stick to the patient's nasal mucosa. Once that was accomplished, we observed that the patient could not complete the efferent (expiratory) phase of the sneeze reflex, and thus he did not sneeze. Cranial magnetic resonance imaging (MRI) revealed that his cerebellar tonsils extended approximately 10 mm inferiorly through the foramen magnum, which represented a type I Arnold-Chiari malformation. The tonsils were noted to have compressed the posterolateral portion of the medulla oblongata. At follow-up 21 months later, we noted that the patient was able to sneeze spontaneously as well as with nasal stimulation. Repeat MRI revealed that the Arnold-Chiari malformation had undergone a spontaneous partial regression, which resulted in relief of the compression of the medulla oblongata. We believe that the patient's earlier inability to sneeze might have been attributable to the compression of the medulla oblongata by the cerebellar tonsils and that the site of the compression might represent the location of his sneeze center.

Association of HTLV-I with Arnold Chiari syndrome and syringomyelia

Directory of Open Access Journals (Sweden)

Graça Maria de Castro Viana

Full Text Available HTLV-I is associated with a broad spectrum of manifestations, including tropical spastic paraparesis and adult T-cell leukemia/lymphoma. Arnold Chiari syndrome is a condition characterized by herniation of the cerebellar tonsils through the foramen magnum. This condition should be suspected in all patients with headache and impaired motor coordination. Syringomyelia is a developmental anomaly that leads to the formation of an intramedullary cavity. Its clinical presentation is classically characterized by syringomyelic dissociation of sensation, with suspended distribution in the proximal portion of the trunk and upper limbs and preservation in other regions. We report here a case of association of the three diseases, which is rare in clinical practice, illustrating the difficulty in the diagnosis and therapeutic management of these conditions.

A points-based algorithm for prognosticating clinical outcome of Chiari malformation Type I with syringomyelia: results from a predictive model analysis of 82 surgically managed adult patients.

Science.gov (United States)

Thakar, Sumit; Sivaraju, Laxminadh; Jacob, Kuruthukulangara S; Arun, Aditya Atal; Aryan, Saritha; Mohan, Dilip; Sai Kiran, Narayanam Anantha; Hegde, Alangar S

2018-01-01

OBJECTIVE Although various predictors of postoperative outcome have been previously identified in patients with Chiari malformation Type I (CMI) with syringomyelia, there is no known algorithm for predicting a multifactorial outcome measure in this widely studied disorder. Using one of the largest preoperative variable arrays used so far in CMI research, the authors attempted to generate a formula for predicting postoperative outcome. METHODS Data from the clinical records of 82 symptomatic adult patients with CMI and altered hindbrain CSF flow who were managed with foramen magnum decompression, C-1 laminectomy, and duraplasty over an 8-year period were collected and analyzed. Various preoperative clinical and radiological variables in the 57 patients who formed the study cohort were assessed in a bivariate analysis to determine their ability to predict clinical outcome (as measured on the Chicago Chiari Outcome Scale [CCOS]) and the resolution of syrinx at the last follow-up. The variables that were significant in the bivariate analysis were further analyzed in a multiple linear regression analysis. Different regression models were tested, and the model with the best prediction of CCOS was identified and internally validated in a subcohort of 25 patients. RESULTS There was no correlation between CCOS score and syrinx resolution (p = 0.24) at a mean ± SD follow-up of 40.29 ± 10.36 months. Multiple linear regression analysis revealed that the presence of gait instability, obex position, and the M-line-fourth ventricle vertex (FVV) distance correlated with CCOS score, while the presence of motor deficits was associated with poor syrinx resolution (p ≤ 0.05). The algorithm generated from the regression model demonstrated good diagnostic accuracy (area under curve 0.81), with a score of more than 128 points demonstrating 100% specificity for clinical improvement (CCOS score of 11 or greater). The model had excellent reliability (κ = 0.85) and was validated with

Budd-Chiari Syndrome: Two Cases with Different Courses

Directory of Open Access Journals (Sweden)

Shinjiro Inomata

2008-08-01

Full Text Available We report two cases of Budd-Chiari syndrome. Case 1: A 57-year-old man presented with leg edema and esophageal varices. Cavography showed obstruction of the inferior vena cava with antiphospholipid syndrome. Further, the patient showed positive serology for hepatitis C virus and consumed large quantities of alcohol. Percutaneous transluminal angioplasty was performed on this patient and anticoagulants administered; leg edema and esophageal varices were ameliorated although liver biopsy showed cirrhosis without evident congestion. More than 9 months since the diagnosis, restenosis of the inferior vena cava has not occurred. Case 2: A 73-year-old woman presented abdominal pain but no edema or varices. Cavography showed membranous obstruction of the inferior vena cava which required no therapy. Manifestation of portal hypertension was not present and liver function was maintained although liver biopsy showed obvious congestion. These cases showed untypical features against histopathology, and careful observation will be required for emergence of hepatocellular carcinoma.

Phonon spectroscopy with superconducting tunnel junctions

International Nuclear Information System (INIS)

Grimshaw, J.M.

1984-02-01

Superconducting tunnel junctions can be used as generators and detectors of monochromatic phonons of frequency larger than 80 GHz, as was first devised by Eisenmenger and Dayem (1967) and Kinder (1972a, 1973). In this report, we intend to give a general outline of this type of spectroscopy and to present the results obtained so far. The basic physics underlying phonon generation and detection are described in chapter I, a wider approach being given in the references therein. In chapter II, the different types of junctions are considered with respect to their use. Chapter III deals with the evaporation technique for the superconducting junctions. The last part of this report is devoted to the results that we have obtained on γ-irradiated LiF, pure Si and Phosphorous implanted Si. In these chapters, the limitations of the spectrometer are brought out and suggestions for further work are given [fr

Chlorpromazine reduces the intercellular communication via gap junctions in mammalian cells

International Nuclear Information System (INIS)

Orellana, Juan A.; Palacios-Prado, Nicolas; Saez, Juan C.

2006-01-01

In the work presented herein, we evaluated the effect of chlorpromazine (CPZ) on gap junctions expressed by two mammalian cell types; Gn-11 cells (cell line derived from mouse LHRH neurons) and rat cortical astrocytes maintained in culture. We also attempted to elucidate possible mechanisms of action of CPZ effects on gap junctions. CPZ, in concentrations comparable with doses used to treat human diseases, was found to reduce the intercellular communication via gap junctions as evaluated with measurements of dye coupling (Lucifer yellow). In both cell types, maximal inhibition of functional gap junctions was reached within about 1 h of treatment with CPZ, an recovery was almost complete at about 5 h after CPZ wash out. In both cell types, CPZ treatment increased the phosphorylation state of connexin43 (Cx43), a gap junction protein subunit. Moreover, CPZ reduced the reactivity of Cx43 (immunofluorescence) at cell interfaces and concomitantly increased its reactivity in intracellular vesicles, suggesting an increased retrieval from and/or reduced insertion into the plasma membrane. CPZ also caused cellular retraction reducing cell-cell contacts in a reversible manner. The reduction in contact area might destabilize existing gap junctions and abrogate formation of new ones. Moreover, the CPZ-induced reduction in gap junctional communication may depend on the connexins (Cxs) forming the junctions. If Cx43 were the only connexin expressed, MAPK-dependent phosphorylation of this connexin would induce closure of gap junction channels

Ginzburg–Landau theory of mesoscopic multi-band Josephson junctions

Energy Technology Data Exchange (ETDEWEB)

Romeo, F.; De Luca, R., E-mail: rdeluca@unisa.it

2017-05-15

Highlights: • We generalize, in the realm of the Ginzburg–Landau theory, the de Gennes matching-matrix method for the interface order parameters to describe the superconducting properties of multi-band mesoscopic Josephson junctions. • The results are in agreement with a microscopic treatment of nanobridge junctions. • Thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions. - Abstract: A Ginzburg–Landau theory for multi-band mesoscopic Josephson junctions has been developed. The theory, obtained by generalizing the de Gennes matching-matrix method for the interface order parameters, allows the study of the phase dynamics of various types of mesoscopic Josephson junctions. As a relevant application, we studied mesoscopic double-band junctions also in the presence of a superconducting nanobridge interstitial layer. The results are in agreement with a microscopic treatment of the same system. Furthermore, thermal stability of the nanobridge junction is discussed in connection with recent experiments on iron-based grain-boundary junctions.

Posterior fossa decompression with duraplasty in Chiari surgery: A technical note

Directory of Open Access Journals (Sweden)

Marcelo Ferreira Sabba

Full Text Available Summary Chiari malformation (CM is the most common and prevalent symptomatic congenital craniocervical malformation. Radiological diagnosis is established when the cerebellar tonsils are located 5 mm or more below the level of the foramen magnum on magnetic resonance imaging (MRI. Surgical treatment is indicated whenever there is symptomatic tonsillar herniation or syringomyelia/hydrocephalus. The main surgical treatment for CM without craniocervical instability (such as atlantoaxial luxation is posterior fossa decompression, with or without duraplasty. The authors describe in details and in a stepwise fashion the surgical approach of patients with CM as performed at the State University of Campinas, emphasizing technical nuances for minimizing the risks of the procedure and potentially improving patient outcome.

Sports participation with Chiari I malformation.

Science.gov (United States)

Strahle, Jennifer; Geh, Ndi; Selzer, Béla J; Bower, Regina; Himedan, Mai; Strahle, MaryKathryn; Wetjen, Nicholas M; Muraszko, Karin M; Garton, Hugh J L; Maher, Cormac O

2016-04-01

OBJECT There is currently no consensus on the safety of sports participation for patients with Chiari I malformation (CM-I). The authors' goal was to define the risk of sports participation for children with the imaging finding of CM-I. METHODS A prospective survey was administered to 503 CM-I patients at 2 sites over a 46-month period. Data were gathered on imaging characteristics, treatment, sports participation, and any sport-related injuries. Additionally, 81 patients completed at least 1 subsequent survey following their initial entry into the registry and were included in a prospective group, with a mean prospective follow-up period of 11 months. RESULTS Of the 503 CM-I patients, 328 participated in sports for a cumulative duration of 4641 seasons; 205 of these patients participated in contact sports. There were no serious or catastrophic neurological injuries. One patient had temporary extremity paresthesias that resolved within hours, and this was not definitely considered to be related to the CM-I. In the prospective cohort, there were no permanent neurological injuries. CONCLUSIONS No permanent or catastrophic neurological injuries were observed in CM-I patients participating in athletic activities. The authors believe that the risk of such injuries is low and that, in most cases, sports participation by children with CM-I is safe.

A numerical model of p-n junctions bordering on surfaces

Energy Technology Data Exchange (ETDEWEB)

Altermatt, P.P.; Aberle, A.G.; Jianhua Zhao; Aihua Wang; Heiser, G. [University of New South Wales, Sydney (Australia). Centre for Photovolatic Engineering

2002-10-01

Many solar cell structures contain regions where the emitter p-n junction borders on the surface. If the surface is not well passivated, a large amount of recombination occurs in such regions. This type of recombination is influenced by the electrostatics of both the p-n junction and the surface, and hence it is different from the commonly described recombination phenomena occurring in the p-n junction within the bulk. We developed a two-dimensional model for the recombination mechanisms occurring in emitter p-n junctions bordering on surfaces. The model is validated by reproducing the experimental I-V curves of specially designed silicon solar cells. It is shown under which circumstances a poor surface passivation, near where the p-n junction borders on the surface, reduces the fill factor and the open-circuit voltage. The model can be applied to many other types of solar cells. (author)

BPS dynamics of the triple (p,q) string junction

International Nuclear Information System (INIS)

Rey, S.-J.; Yee, J.-T.

1998-01-01

We study the dynamics of the triple junction of (p,q) strings in type IIB string theory. We probe the tension and mass density of (p,q) strings by studying harmonic fluctuations of the triple junction. We show that they agree perfectly with the BPS formula provided a suitable geometric interpretation of the junction is given. We provide a precise statement of the BPS limit and force-balance property. At weak coupling and sufficiently dense limit, we argue that a (p,q) string embedded in the string network is a 'wiggly string', whose low-energy dynamics can be described via a renormalization group evolved, smooth effective non-relativistic string. We also suggest the possibility that, upon type IIB strings being promoted to the M-theory membrane, there can exist 'evanescent' bound-states at the triple junction in the continuum. (orig.)

Spin-dependent quasiparticle tunneling in junction superconductor-isolator-ferromagnetic

International Nuclear Information System (INIS)

Shlapak, Yu.V.; Shaternik, V.E.; Rudenko, E.M.

2001-01-01

The influence of Andreev reflection of quasiparticles in transparent tunnel junctions of superconductor-isolator-ferromagnetic on electric-current transport is studied within the framework of the Blonder-Tinkham-Klapwijk (BTK) model. It's obtained that current and signal-to-noise ratio can be increased for the memory cell by using in it the double-barrier tunnel junction ferromagnetic-isolator-superconductor-isolator-ferromagnetic instead off the usual tunnel junction ferromagnetic-isolator-ferromagnetic. The evolution of non-linear (tunnel-type) current-voltage characteristics with increasing of the junction transparency is described. (orig.)

Spatial inhomogeneous barrier heights at graphene/semiconductor Schottky junctions

Science.gov (United States)

Tomer, Dushyant

Graphene, a semimetal with linear energy dispersion, forms Schottky junction when interfaced with a semiconductor. This dissertation presents temperature dependent current-voltage and scanning tunneling microscopy/spectroscopy (STM/S) measurements performed on graphene Schottky junctions formed with both three and two dimensional semiconductors. To fabricate Schottky junctions, we transfer chemical vapor deposited monolayer graphene onto Si- and C-face SiC, Si, GaAs and MoS2 semiconducting substrates using polymer assisted chemical method. We observe three main type of intrinsic spatial inhomogeneities, graphene ripples, ridges and semiconductor steps in STM imaging that can exist at graphene/semiconductor junctions. Tunneling spectroscopy measurements reveal fluctuations in graphene Dirac point position, which is directly related to the Schottky barrier height. We find a direct correlation of Dirac point variation with the topographic undulations of graphene ripples at the graphene/SiC junction. However, no such correlation is established at graphene/Si and Graphene/GaAs junctions and Dirac point variations are attributed to surface states and trapped charges at the interface. In addition to graphene ripples and ridges, we also observe atomic scale moire patterns at graphene/MoS2 junction due to van der Waals interaction at the interface. Periodic topographic modulations due to moire pattern do not lead to local variation in graphene Dirac point, indicating that moire pattern does not contribute to fluctuations in electronic properties of the heterojunction. We perform temperature dependent current-voltage measurements to investigate the impact of topographic inhomogeneities on electrical properties of the Schottky junctions. We observe temperature dependence in junction parameters, such as Schottky barrier height and ideality factor, for all types of Schottky junctions in forward bias measurements. Standard thermionic emission theory which assumes a perfect

Observation of supercurrent in graphene-based Josephson junction

Energy Technology Data Exchange (ETDEWEB)

Wang, Libin; Li, Sen; Kang, Ning [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Xu, Chuan; Ren, Wencai [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

2015-07-01

Josephson junctions with a normal metal region sandwiched between two superconductors (S) are known as superconductor- normal-superconductor (SNS) structures. It has attracted significant attention especially when changing the normal metal with graphene, which allow for high tunability with the gate voltage and to study the proximity effect of the massless Dirac fermions. Here we report our work on graphene-based Josephson junction with a new two dimensional superconductor crystal, which grown directly on graphene, as superconducting electrodes. At low temperature, we observer proximity effect induced supercurrent flowing through the junction. The temperature and the magnetic field dependences of the critical current characteristics of the junction are also studied. The critical current exhibits a Fraunhofer-type diffraction pattern against magnetic field. Our experiments provided a new route of fabrication of graphene-based Josephson junction.

Solution-grown organic single-crystalline p-n junctions with ambipolar charge transport.

Science.gov (United States)

Fan, Congcheng; Zoombelt, Arjan P; Jiang, Hao; Fu, Weifei; Wu, Jiake; Yuan, Wentao; Wang, Yong; Li, Hanying; Chen, Hongzheng; Bao, Zhenan

2013-10-25

Organic single-crystalline p-n junctions are grown from mixed solutions. First, C60 crystals (n-type) form and, subsequently, C8-BTBT crystals (p-type) nucleate heterogeneously on the C60 crystals. Both crystals continue to grow simultaneously into single-crystalline p-n junctions that exhibit ambipolar charge transport characteristics. This work provides a platform to study organic single-crystalline p-n junctions. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

‘Gap Junctions and Cancer: Communicating for 50 Years’

Science.gov (United States)

Aasen, Trond; Mesnil, Marc; Naus, Christian C.; Lampe, Paul D.; Laird, Dale W.

2017-01-01

Fifty years ago, tumour cells were found to lack electrical coupling, leading to the hypothesis that loss of direct intercellular communication is commonly associated with cancer onset and progression. Subsequent studies linked this phenomenon to gap junctions composed of connexin proteins. While many studies support the notion that connexins are tumour suppressors, recent evidence suggests that, in some tumour types, they may facilitate specific stages of tumour progression through both junctional and non-junctional signalling pathways. This Timeline article highlights the milestones connecting gap junctions to cancer, and underscores important unanswered questions, controversies and therapeutic opportunities in the field. PMID:27782134

Twelve years of chiari-like malformation and syringomyelia scanning in Cavalier King Charles Spaniels in the Netherlands : Towards a more precise phenotype

NARCIS (Netherlands)

Wijnrocx, Katrien; Van Bruggen, Leonie W L; Eggelmeijer, Wieteke; Noorman, Erik; Jacques, Arnold; Buys, Nadine; Janssens, Steven; Mandigers, Paul J J

2017-01-01

Chiari-like malformation (CM), syringomyelia (SM) and middle ear effusion (also called PSOM) are three conditions that frequently occur in Cavalier King Charles Spaniels (CKCS). Both CM and SM are currently screened in the Netherlands prior to breeding and are graded according to the British

Anchored PKA as a gatekeeper for gap junctions.

Science.gov (United States)

Pidoux, Guillaume; Taskén, Kjetil

2015-01-01

Anchored protein kinase A (PKA) bound to A Kinase Anchoring Protein (AKAP) mediates effects of localized increases in cAMP in defined subcellular microdomains and retains the specificity in cAMP-PKA signaling to distinct extracellular stimuli. Gap junctions are pores between adjacent cells constituted by connexin proteins that provide means of communication and transfer of small molecules. While the PKA signaling is known to promote human trophoblast cell fusion, the gap junction communication through connexin 43 (Cx43) is a prerequisite for this process. We recently demonstrated that trophoblast fusion is regulated by ezrin, a known AKAP, which binds to Cx43 and delivers PKA in the vicinity gap junctions. We found that disruption of the ezrin-Cx43 interaction abolished PKA-dependent phosphorylation of Cx43 as well as gap junction communication and subsequently cell fusion. We propose that the PKA-ezrin-Cx43 macromolecular complex regulating gap junction communication constitutes a general mechanism to control opening of Cx43 gap junctions by phosphorylation in response to cAMP signaling in various cell types.

Unilateral phrenic nerve stimulation for neurogenic hypoventilation in Arnold Chiari malformation

Directory of Open Access Journals (Sweden)

Nitin Garg

2013-01-01

Full Text Available Long- term ventilator dependence in patients with neurogenic hypoventilation is associated with significant morbidity and restricts mobility. Diaphragmatic pacing by phrenic nerve stimulation (PNS is a viable alternative. This is a case report of patient with Arnold-Chiari malformation with extensive syrinx who had neurogenic hypoventilation during sleep even after foramen magnum decompression and resolution of the syrinx. Unilateral PNS was done using spinal cord stimulator. With intermittent stimulation for 8 h while asleep, patient could be weaned off the ventilator completely. At 2 years follow- up, patient is ambulant and has returned to his routine activities. PNS is a good treatment tool in patients with neurogenic hypoventilation. Spinal cord stimulator can be used with optimal results. This is first such reported case of using spinal cord stimulator for PNS from India.

The budd-Chiari syndrome in a child: a case report and review of the literature.

Science.gov (United States)

Misra, Vatsala; Verma, Kachnar; Singh, Dharmendra Kumar; Misra, Sri Prakash

2012-12-01

The Budd-Chiari Syndrome is associated with hepatic venous outflow obstruction. This syndrome is rare in infants and children. As this syndrome is uncommon, especially in the paediatric age group, misdiagnoses and delays in the diagnosis are frequent. A high index of clinical suspicion along with a radiological aid and a histopathological correlation can lead to an early diagnosis and an appropriate management in such cases.This case report highlights the occurrence of this rare condition in the paediatric age group as well as it redefines the salient features of this syndrome.

Syringomyelia with Chiari I Malformation Presenting as Hip Charcot Arthropathy: A Case Report and Literature Review

Directory of Open Access Journals (Sweden)

Roya Memarpour

2015-01-01

Full Text Available Neuroarthropathy (neuropathic osteoarthropathy, also known as Charcot joint, is a condition characterized by a progressive articular surface destruction in the setting of impaired nociceptive and proprioceptive innervation of the involved joint. It is seen most commonly in the foot and ankle secondary to peripheral neuropathy associated with diabetes mellitus. Cases of hip (Charcot neuroarthropathy are rare and almost exclusively reported in patients with neurosyphilis (tabes dorsalis. We report a case of a 36-year-old man who presented to the emergency department complaining of right hip pain. On physical examination, pain and thermal sensory deficits were noted in the upper torso with a cape-like distribution, as well as signs of an upper motor neuron lesion in the left upper and lower extremities. A magnetic resonance imaging study (MRI of the right hip showed evidence of early articular surface destruction and periarticular edema consistent with hip Charcot arthropathy. An MRI of the spine revealed an Arnold-Chiari type I malformation with extensive syringohydromyelia of the cervical and thoracic spine.

The critical current of point symmetric Josephson tunnel junctions

International Nuclear Information System (INIS)

Monaco, Roberto

2016-01-01

Highlights: • We disclose some geometrical properties of the critical current field dependence that apply to a large class of Josephson junctions characterized by a point symmetric shape. • The developed theory is valid for any orientation of the applied magnetic field, therefore it allows the determine the consequences of field misalignment in the experimental setups. • We also address that the threshold curves of Josephson tunnel junctions with complex shapes can be expressed as a linear combination of the threshold curves of junctions with simpler point symmetric shapes. - Abstract: The physics of Josephson tunnel junctions drastically depends on their geometrical configurations. The shape of the junction determines the specific form of the magnetic-field dependence of its Josephson current. Here we address the magnetic diffraction patterns of specially shaped planar Josephson tunnel junctions in the presence of an in-plane magnetic field of arbitrary orientations. We focus on a wide ensemble of junctions whose shape is invariant under point reflection. We analyze the implications of this type of isometry and derive the threshold curves of junctions whose shape is the union or the relative complement of two point symmetric plane figures.

MgO magnetic tunnel junctions of enduring F-type upon annealing

International Nuclear Information System (INIS)

Schleicher, F; Halisdemir, U; Urbain, E; Gallart, M; Boukari, S; Beaurepaire, E; Gilliot, P; Bowen, M; Lacour, D; Montaigne, F; Hehn, M

2015-01-01

The authors performed magnetotransport experiments to determine whether annealing alters the oxygen vacancy-mediated tunnelling potential landscape of the central portion of a MgO ultrathin film within sputtered CoFeB/MgO/CoFeB magnetic tunnel junctions. Using the Î rel method reveals a temperature-dependent tunnelling barrier height for a non-annealed barrier that arises from single oxygen vacancies (F centres) and is qualitatively identical to that found for its partly and fully annealed counterparts. Thus these MTJs with F centres remain of F-type upon annealing. This explicitly confirms that the large tunnel-magnetoresistance (TMR) increase upon annealing results mainly from structural modifications of MgO and CoFeB and not from vacancy pairing within the barrier. Photoluminescence spectra performed on both annealed and non-annealed thin MgO films grown on CoFeB electrodes support this conclusion. This work should promote renewed scrutiny over the precise impact of annealing on tunnelling magnetotransport across MgO. (paper)

Microwave oscillator based on an intrinsic BSCCO-type Josephson junction

DEFF Research Database (Denmark)

Pedersen, Niels Falsig; Madsen, Søren Peder

2005-01-01

. The resulting model is a set of coupled nonlinear partial differential equations. By direct numerical simulations we have demonstrated that the qualitative behavior of the combined intrinsic Josephson junction and cavity system can be understood on the basis of general concepts of nonlinear oscillators...

Triple junction polymer solar cells for photoelectrochemical water splitting

NARCIS (Netherlands)

Esiner, S.; Eersel, van H.; Wienk, M.M.; Janssen, R.A.J.

2013-01-01

A triple junction polymer solar cell in a novel 1 + 2 type configuration provides photoelectrochemical water splitting in its maximum power point at V ˜ 1.70 V with an estimated solar to hydrogen energy conversion efficiency of 3.1%. The triple junction cell consists of a wide bandgap front cell and

Justification of Structural and Technological Solutions on Junction Perfecting on Permyakova and Shirotnaya Streets Intersection in Tyumen

Science.gov (United States)

Sannikov, S. P.; Timohovetz, V. D.; Kuzuek, A. Y.

2017-11-01

This article presents the justification of structurally-technological decisions on a junction perfecting on the intersection of Permyakova and Shirotnaya Streets in Tyumen. The authors made a comparative analysis of typical road junctions. Based on the comparison, the engineering decisions were made for an individual type of transport junctions. Several options of individual design were proposed and analyzed and three most suitable types for the road junctions were offered. On the basis of a multilateral studying and evaluation of the developed transport the article further proposed a transport junction with change-side traffic. The use of this type of intersection will increase the road junction capacity, reduce the number of accidents due to conflicting flows reduction which, in its turn, will increase the speed of cars.

Theoretical study of the Hoogsteen-Watson-Crick junctions in DNA.

Science.gov (United States)

Cubero, Elena; Luque, F Javier; Orozco, Modesto

2006-02-01

A series of d (AT)(n) oligonucleotides containing mixtures of normal B-type Watson-Crick and antiparallel Hoogsteen helices have been studied using molecular dynamics simulation techniques to analyze the structural and thermodynamic impact of the junction between Watson-Crick and antiparallel Hoogsteen structures. Analysis of molecular dynamics simulations strongly suggests that for all oligonucleotides studied the antiparallel Hoogsteen appears as a reasonable conformation, only slightly less stable than the canonical B-type Watson-Crick one. The junctions between the Watson-Crick and Hoogsteen structures introduces a priori a sharp discontinuity in the helix, because the properties of each type of conformation are very well preserved in the corresponding fragments. However, and quite counterintuitively, junctions do not largely distort the duplex in structural, dynamics or energetic terms. Our results strongly support the possibility that small fragments of antiparallel Hoogsteen duplex might be embedded into large fragments of B-type Watson-Crick helices, making possible protein-DNA interactions that are specific of the antiparallel Hoogsteen conformation.

Theoretical Study of the Hoogsteen–Watson-Crick Junctions in DNA

Science.gov (United States)

Cubero, Elena; Luque, F. Javier; Orozco, Modesto

2006-01-01

A series of d (AT)n oligonucleotides containing mixtures of normal B-type Watson-Crick and antiparallel Hoogsteen helices have been studied using molecular dynamics simulation techniques to analyze the structural and thermodynamic impact of the junction between Watson-Crick and antiparallel Hoogsteen structures. Analysis of molecular dynamics simulations strongly suggests that for all oligonucleotides studied the antiparallel Hoogsteen appears as a reasonable conformation, only slightly less stable than the canonical B-type Watson-Crick one. The junctions between the Watson-Crick and Hoogsteen structures introduces a priori a sharp discontinuity in the helix, because the properties of each type of conformation are very well preserved in the corresponding fragments. However, and quite counterintuitively, junctions do not largely distort the duplex in structural, dynamics or energetic terms. Our results strongly support the possibility that small fragments of antiparallel Hoogsteen duplex might be embedded into large fragments of B-type Watson-Crick helices, making possible protein-DNA interactions that are specific of the antiparallel Hoogsteen conformation. PMID:16287814

Preparation of p-type GaN-doped SnO2 thin films by e-beam evaporation and their applications in p-n junction

Science.gov (United States)

Lv, Shuliang; Zhou, Yawei; Xu, Wenwu; Mao, Wenfeng; Wang, Lingtao; Liu, Yong; He, Chunqing

2018-01-01

Various transparent GaN-doped SnO2 thin films were deposited on glass substrates by e-beam evaporation using GaN:SnO2 targets of different GaN weight ratios. It is interesting to find that carrier polarity of the thin films was converted from n-type to p-type with increasing GaN ratio higher than 15 wt.%. The n-p transition in GaN-doped SnO2 thin films was explained for the formation of GaSn and NO with increasing GaN doping level in the films, which was identified by Hall measurement and XPS analysis. A transparent thin film p-n junction was successfully fabricated by depositing p-type GaN:SnO2 thin film on SnO2 thin film, and a low leakage current (6.2 × 10-5 A at -4 V) and a low turn-on voltage of 1.69 V were obtained for the p-n junction.

Liver transplantation in a patient with primary antiphospholipid syndrome and Budd-Chiari syndrome

Science.gov (United States)

Reshetnyak, Tatiana M; Seredavkina, Natalia V; Satybaldyeva, Maria A; Nasonov, Evgeniy L; Reshetnyak, Vasiliy I

2015-01-01

The antiphospholipid syndrome (APS) is an acquired thrombophilic disorder in which autoantibodies are produced to a variety of phospholipids determinants of cell membranes or phospholipid binding proteins. There are few reports about association between antiphospholipid antibodies and development of Budd-Chiari syndrome (BCS). We report the case of BCS development in young Russian male with primary APS. The patient underwent orthotopic liver transplantation on August 26, 2012. At present time his state is good, the blood flow in the liver restored and its function is not impaired. We report about the first time the successful use of dabigatran etexilate for prolonged anticoagulation therapy in APS patient with BCS. In addition patient is managed with immunosuppressive drugs. PMID:26380049

Introducing chinese treatment experience of Budd-Chiari syndrome to world wide

International Nuclear Information System (INIS)

Li Linsun

2008-01-01

During the latest 20 years, the crucial progress has been made in the field of treatment for Budd-Chiari syndrome (BCS)in China with therapeutic methods transferring from surgical to interventional and achieving successful rate of 96%. Our unique contribution to the BCS interventional therapy should have made ourselves proud for being as a superior world position on account of large number of cases, abundant therapeutic contents and consummate skills. What a pity is that our achievement was not appreciated by international colleagues because of only a few papers published in SCI journals. So that, Chinese scholars ought to have doing more necessarily through diligently learning English, doing long term follow-up and performing more basic researches and actively joining international academic exchanges, let our good experiences of treatment for BCS be introduced to the world-wide. (authors)

Method for manufacturing nuclear radiation detector with deep diffused junction

International Nuclear Information System (INIS)

Hall, R.N.

1977-01-01

Germanium radiation detectors are manufactured by diffusing lithium into high purity p-type germanium. The diffusion is most readily accomplished from a lithium-lead-bismuth alloy at approximately 430 0 C and is monitored by a quartz half cell containing a standard composition of this alloy. Detectors having n-type cores may be constructed by converting high purity p-type germanium to n-type by a lithium diffusion and subsequently diffusing some of the lithium back out through the surface to create a deep p-n junction. Production of coaxial germanium detectors comprising deep p-n junctions by the lithium diffusion process is described

Long-Term Follow-Up After Successful Transjugular Intrahepatic Portosystemic Shunt Placement in a Pediatric Patient with Budd-Chiari Syndrome

International Nuclear Information System (INIS)

Carnevale, Francisco Cesar; Szejnfeld, Denis; Moreira, Airton Mota; Gibelli, Nelson; Gregorio, Miguel Angel De; Tannuri, Uenis; Cerri, Giovanni Guido

2008-01-01

Orthotopic liver transplantation is the standard of care in patients with Budd-Chiari syndrome (BCS), and transjugular intrahepatic portosystemic shunt (TIPS) has become an important adjunct procedure while the patient is waiting for a liver. No long-term follow up of TIPS in BCS patients has been published in children. We report successful 10-year follow-up of a child with BCS and iatrogenic TIPS dysfunction caused by oral contraceptive use.

Functional Budd-Chiari Syndrome Associated With Severe Polycystic Liver Disease

Directory of Open Access Journals (Sweden)

Precil Diego Miranda de Menezes Neves

2017-06-01

Full Text Available A 50-year-old woman with end-stage renal disease secondary to autosomal dominant polycystic kidney disease was referred to a quaternary care center due to significantly increased abdominal girth. Her physical examination revealed tense ascites and abdominal collateral veins. A 10-L paracentesis improved abdominal discomfort and disclosed a transudate, suggestive of portal hypertension. A computed tomographic scan revealed massive hepatomegaly caused by multiple cysts of variable sizes, distributed throughout all hepatic segments. Contrast-enhanced imaging uncovered extrinsic compression of hepatic and portal veins, resulting in functional Budd-Chiari syndrome and portal hypertension. Although image-guided drainage followed by sclerosis of dominant cysts could potentially lead to alleviation of the extrinsic compression, the associated significant risk of cyst hemorrhage and infection precluded this procedure. In this scenario, the decision was to submit the patient to a liver-kidney transplantation. After 1 year of this procedure, the patient maintains normal liver and kidney function and refers significant improvement in quality of life.

Percutaneous Transjugular Direct Porto-caval Shunt in Patients with Budd-Chiari Syndrome

International Nuclear Information System (INIS)

Quateen, A.; Pech, M.; Berg, T.; Bergk, A.; Podrabsky, P.; Felix, R.; Ricke, J.

2006-01-01

The purpose of the study was to evaluate the feasibility and effectiveness of direct porto-caval shunts in patients with Budd-Chiari syndrome (BCS) in whom there is no access to the hepatic veins during transjugular intrahepatic portosystemic shunt (TIPSS). We included six consecutive patients with fulminant/acute Budd-Chiari syndrome (mean age: 35 years) in whom a conventional TIPSS was not possible due to inaccessible hepatic veins. We performed a direct porto-caval shunt via a transhepatic approach. Patients were followed up by means of clinical examination, laboratory investigations, and Doppler ultrasound. TIPSS implantation from the inferior vena cava (IVC) was successful in all six patients (100%). The median transhepatic shunt length was 9 cm (8-10 cm). No procedure-related complications were observed in our patients. Early shunt occlusion occurred in three out of six patients (50%). In all three of these patients, the stent used to stabilize the shunt ended 1-2 cm before reaching the IVC. All occlusions were successfully recanalized. One of these patients developed recurrent early shunt as well as mesenteric and splenic vein occlusions. She died 7 days after TIPSS placement due to an unmanageable coagulation disorder. The remaining five patients were followed up by planned clinical examination and laboratory investigations (mean follow-up time was 15 months; patient 1 was followed up for 13 months, patient 2 for 14 months, patient 3 for 15 months, and patients 4 and 5 for 16 months) and all displayed a complete and durable resolution of liver failure and ascites without reintervention. In patients with acute liver failure originating from BCS and inaccessible hepatic veins, a direct transhepatic porto-caval shunt can be performed safely and effectively under ultrasound guidance. Future studies in larger patient groups should investigate if the patency of transcaval TIPSS with long transhepatic shunt segments is similar compared to conventional TIPSS via

Work function and temperature dependence of electron tunneling through an N-type perylene diimide molecular junction with isocyanide surface linkers.

Science.gov (United States)

Smith, Christopher E; Xie, Zuoti; Bâldea, Ioan; Frisbie, C Daniel

2018-01-18

Conducting probe atomic force microscopy (CP-AFM) was employed to examine electron tunneling in self-assembled monolayer (SAM) junctions. A 2.3 nm long perylene tetracarboxylic acid diimide (PDI) acceptor molecule equipped with isocyanide linker groups was synthesized, adsorbed onto Ag, Au and Pt substrates, and the current-voltage (I-V) properties were measured by CP-AFM. The dependence of the low-bias resistance (R) on contact work function indicates that transport is LUMO-assisted ('n-type behavior'). A single-level tunneling model combined with transition voltage spectroscopy (TVS) was employed to analyze the experimental I-V curves and to extract the effective LUMO position ε l = E LUMO - E F and the effective electronic coupling (Γ) between the PDI redox core and the contacts. This analysis revealed a strong Fermi level (E F ) pinning effect in all the junctions, likely due to interface dipoles that significantly increased with increasing contact work function, as revealed by scanning Kelvin probe microscopy (SKPM). Furthermore, the temperature (T) dependence of R was found to be substantial. For Pt/Pt junctions, R varied more than two orders of magnitude in the range 248 K tunneling mechanism and allow independent determination of ε l , giving values compatible with estimates of ε l based on analysis of the full I-V data. Theoretical analysis revealed a general criterion to unambiguously rule out a two-step transport mechanism: namely, if measured resistance data exhibit a pronounced Arrhenius-type temperature dependence, a two-step electron transfer scenario should be excluded in cases where the activation energy depends on contact metallurgy. Overall, our results indicate (1) the generality of the Fermi level pinning phenomenon in molecular junctions, (2) the utility of employing the single level tunneling model for determining essential electronic structure parameters (ε l and Γ), and (3) the importance of changing the nature of the contacts to

Gap Junctions

Science.gov (United States)

Nielsen, Morten Schak; Axelsen, Lene Nygaard; Sorgen, Paul L.; Verma, Vandana; Delmar, Mario; Holstein-Rathlou, Niels-Henrik

2013-01-01

Gap junctions are essential to the function of multicellular animals, which require a high degree of coordination between cells. In vertebrates, gap junctions comprise connexins and currently 21 connexins are known in humans. The functions of gap junctions are highly diverse and include exchange of metabolites and electrical signals between cells, as well as functions, which are apparently unrelated to intercellular communication. Given the diversity of gap junction physiology, regulation of gap junction activity is complex. The structure of the various connexins is known to some extent; and structural rearrangements and intramolecular interactions are important for regulation of channel function. Intercellular coupling is further regulated by the number and activity of channels present in gap junctional plaques. The number of connexins in cell-cell channels is regulated by controlling transcription, translation, trafficking, and degradation; and all of these processes are under strict control. Once in the membrane, channel activity is determined by the conductive properties of the connexin involved, which can be regulated by voltage and chemical gating, as well as a large number of posttranslational modifications. The aim of the present article is to review our current knowledge on the structure, regulation, function, and pharmacology of gap junctions. This will be supported by examples of how different connexins and their regulation act in concert to achieve appropriate physiological control, and how disturbances of connexin function can lead to disease. © 2012 American Physiological Society. Compr Physiol 2:1981-2035, 2012. PMID:23723031

Coaxial nuclear radiation detector with deep junction and radial field gradient

International Nuclear Information System (INIS)

Hall, R.N.

1979-01-01

Germanium radiation detectors are manufactured by diffusion lithium into high purity p-type germanium. The diffusion is most readily accomplished from a lithium-lead-bismuth alloy at approximately 430 0 and is monitored by a quartz half cell containing a standard composition of this alloy. Detectors having n-type cores may be constructed by converting high purity p-type germanium to n-type by a lithium diffusion and subsequently diffusing some of the lithium back out through the surface to create a deep p-n junction. Coaxial germanium detectors comprising deep p-n junctions are produced by the lithium diffusion process

Josephson junction analog and quasiparticle-pair current

DEFF Research Database (Denmark)

Bak, Christen Kjeldahl; Pedersen, Niels Falsig

1973-01-01

A close analogy exists between a Josephson junction and a phase-locked loop. A new type of electrical analog based on this principle is presented. It is shown that the inclusion in this analog of a low-pass filter gives rise to a current of the same form as the Josephson quasiparticle-pair current....... A simple picture of the quasiparticle-pair current, which gives the right dependences, is obtained by assuming a junction cutoff frequency to be at the energy gap. ©1973 American Institute of Physics...

Interventional treatment for the occlusive hepatic veins in Budd-Chiari syndrome

International Nuclear Information System (INIS)

Zhang Xitong; Xu Ke; Feng Bo; Su Hongying; Li Hong; Zu Maoheng; Cui Jingguo; Yang Xueliang; Zhao Jinxu; Chen Kai

2003-01-01

Objective: To evaluate the interventional methods for occlusive hepatic veins in Budd-Chiari syndrome and its mid and long-term effects. Methods: Forty-two patients (male 17 cases and female 25 cases) aged from 18 to 57 years old (mean 34.5 years) were studied. The liver functions were Child A in 23 cases, Child B in 6 cases, and Child C in 13 cases, respectively. A total of 92 hepatic veins were occluded. Among them, 29 left hepatic veins, 24 middle hepatic veins, 36 right hepatic veins, and 3 accessory hepatic veins were occluded. Thirty-four patients were accompanied with the stenotic or occlusive inferior vena cave (IVC) . The interventional methods included: (1) recanalization of occlusive hepatic veins (by transjugular, transfemoral, and percutaneous transhepatic route, or the combination of above three methods); (2) percutaneous transluminal angioplasty; (3) self-expanding stent implantation. The occlusive IVC in 32 patients also accepted PTA and/or stent implantation. Results: The successful recanalization was carried out in forty hepatic veins in 40 patients. PTA of occlusive veins was followed by stent implantation in 8 patients. The pressure of hepatic veins dropped from 34.5 cm H 2 O (25.0-48.0 cm H 2 O) to 22.0 cm H 2 O (12.0-35.0 cm H 2 O) after intervention (T=11.50, P < 0.01). The symptoms and pathological signs improved obviously in 32 cases and improved partly in 8 cases. During the follow-up period from 1 month to 54 months (mean 27.5 months), one cases died of liver function failure at one month after intervention. The re-intervention of occlusive veins in two cases were performed and the better results were acquired again. Five cases didn't accept re-intervention. Neither recurrence of symptoms nor re-occlusion of hepatic veins was found in the other 32 patients. Conclusion: (1) Multiple and synthetical interventional methods for the occlusive hepatic veins in Budd-Chiari syndrome can be utilized. (2) The intervention of hepatic vein is mini

Versatile multi-layer Josephson junction process for vortex molecules

Energy Technology Data Exchange (ETDEWEB)

Meckbach, Johannes Maximilian; Buehler, Simon; Merker, Michael; Il' in, Konstantin; Siegel, Michael [Institut fuer Mikro- und Nanoelektronische Systeme, KIT (Germany); Buckenmaier, Kai; Gaber, Tobias; Kienzle, Uta; Neumaier, Benjamin; Goldobin, Edward; Kleiner, Reinhold; Koelle, Dieter [Physikalisches Institut - Experimentalphysik II, Universitaet Tuebingen (Germany)

2012-07-01

In long Josephson junctions magnetic flux may penetrate the barrier resulting in a so-called Josephson-Vortex carrying one flux quantum Φ{sub 0}. In recent years a new type of Josephson-Vortex became available, which carries any arbitrary fraction Φ = -Φ{sub 0}κ/2π of magnetic flux. These fractional vortices (p-vortices) spontaneously appear at discontinuities of the Josephson phase along the junction, which in turn are created using a pair of current injectors. We present a new Nb/Al-AlO{sub x}/Nb process for the fabrication of Josephson junctions of very high quality. Placing two injector pairs along the strongly underdamped long junctions allows the investigation of fractional vortex molecules. The topological charge of each vortex and their interaction can be altered even during experiment by changing the individual injector currents. Vortex molecule states have been measured using asymmetric DC-SQUIDs coupled to the vortices by overlying pick-up loops. To uphold the p-vortices we use persistent currents, which can be altered using heat switches. Fractional vortex molecules are promising candidates for a new type of qubits.

On the stability of large-area Al-p-Si junction

International Nuclear Information System (INIS)

Tsyganov, Yu.S.

2006-01-01

Design of silicon radiation detector made of 12 kΩ · cm p-silicon with both amine- and amine-free hardeners epoxy resin junction edge passivation is presented. Before producing large-area detectors for measurements of efficiency of evaporation residues collection at the focal plane of the Dubna Gas-Filled Recoil Separator (DGFRS), a set of small-area test detectors was produced. Stability of the Al-(p)Si junction has been studied for a long time. Estimate of a realistic lifetime for the mentioned type of Al-Si rectifying junction is done

Charge transport across metal/molecular (alkyl) monolayer-Si junctions is dominated by the LUMO level

NARCIS (Netherlands)

Yaffe, O.; Qi, Y.; Scheres, L.M.W.; Puniredd, S.R.; Segev, L.; Ely, T.; Haick, H.; Zuilhof, H.; Vilan, A.; Kronik, L.; Kahn, A.; Cahen, D.

2012-01-01

We compare the charge transport characteristics of heavy-doped p(++)- and n(++)-Si-alkyl chain/Hg junctions. Based on negative differential resistance in an analogous semiconductor-inorganic insulator/metal junction we suggest that for both p(++)- and n(++)-type junctions, the energy difference

Four-junction superconducting circuit

Science.gov (United States)

Qiu, Yueyin; Xiong, Wei; He, Xiao-Ling; Li, Tie-Fu; You, J. Q.

2016-01-01

We develop a theory for the quantum circuit consisting of a superconducting loop interrupted by four Josephson junctions and pierced by a magnetic flux (either static or time-dependent). In addition to the similarity with the typical three-junction flux qubit in the double-well regime, we demonstrate the difference of the four-junction circuit from its three-junction analogue, including its advantages over the latter. Moreover, the four-junction circuit in the single-well regime is also investigated. Our theory provides a tool to explore the physical properties of this four-junction superconducting circuit. PMID:27356619

Tunnel magnetoresistance in double spin filter junctions

International Nuclear Information System (INIS)

Saffarzadeh, Alireza

2003-01-01

We consider a new type of magnetic tunnel junction, which consists of two ferromagnetic tunnel barriers acting as spin filters (SFs), separated by a nonmagnetic metal (NM) layer. Using the transfer matrix method and the free-electron approximation, the dependence of the tunnel magnetoresistance (TMR) on the thickness of the central NM layer, bias voltage and temperature in the double SF junction are studied theoretically. It is shown that the TMR and electron-spin polarization in this structure can reach very large values under suitable conditions. The highest value of the TMR can reach 99%. By an appropriate choice of the thickness of the central NM layer, the degree of spin polarization in this structure will be higher than that of the single SF junctions. These results may be useful in designing future spin-polarized tunnelling devices

Breaking gold nano-junctions simulation and analysis

DEFF Research Database (Denmark)

Lauritzen, Kasper Primdal

, to predict the structure of a gold junction just as it breaks. This method is based on artificial neural networks and can be used on experimental data, even when it is trained purely on simulated data. The method is extended to other types of experimental traces, where it is trained without the use......Simulating the movements of individual atoms allows us to look at and investigate the physical processes that happen in an experiment. In this thesis I use simulations to support and improve experimental studies of breaking gold nano-junctions. By using molecular dynamics to study gold nanowires, I...... can investigate their breaking forces under varying conditions, like stretching rate or temperature. This resolves a confusion in the literature, where the breaking forces of two different breaking structures happen to coincide. The correlations between the rupture and reformation of a gold junction...

Search for a proximity effect induced gap in gold/high Tc junctions

International Nuclear Information System (INIS)

Dessau, D.S.; Wells, B.O.; Shen, Z.; Spicer, W.E.; Arko, A.J.; List, R.S.; Olson, C.G.; Eom, C.B.; Mitzi, D.B.; Kapitulnik, A.; Geballe, T.H.

1991-01-01

We have used high-resolution photoemission spectroscopy to search for a proximity effect induced superconducting gap in gold overlayers on c-axis single crystals of Bi 2 Sr 2 CaCu 2 O 8 and a-axis thin films of YBa 2 Cu 3 O 7 . These two junction types give us a representative sampling of very well characterized near-ideal interfaces (gold/c-axis Bi 2 Sr 2 CaCu 2 O 8 ) and junctions in which the geometry more strongly favors the existence of the proximity effect but the interfacial quality may not be as ideal (gold/a-axis YBa 2 Cu 3 O 7 ). In neither of these junction types did we observe any evidence for a proximity effect induced gap, and we place an upper limit of approximately 5 meV on its existence in the junctions that we have studied

Craniometric Analysis of the Hindbrain and Craniocervical Junction of Chihuahua, Affenpinscher and Cavalier King Charles Spaniel Dogs With and Without Syringomyelia Secondary to Chiari-Like Malformation.

Science.gov (United States)

Knowler, Susan P; Kiviranta, Anna-Mariam; McFadyen, Angus K; Jokinen, Tarja S; La Ragione, Roberto M; Rusbridge, Clare

2017-01-01

To characterize and compare the phenotypic variables of the hindbrain and craniocervical junction associated with syringomyelia (SM) in the Chihuahua, Affenpinscher and Cavalier King Charles Spaniel (CKCS). Analysis of 273 T1-weighted mid-sagittal DICOM sequences of the hindbrain and craniocervical junction from 99 Chihuahuas, 42 Affenpinschers and 132 CKCSs. The study compared 22 morphometric features (11 lines, eight angles and three ratios) of dogs with and without SM using refined techniques based on previous studies of the Griffon Bruxellois (GB) using Discriminant Function Analysis and ANOVA with post-hoc corrections. The analysis identified 14/22 significant traits for SM in the three dog breeds, five of which were identical to those reported for the GB and suggest inclusion of a common aetiology. One ratio, caudal fossa height to the length of the skull base extended to an imaginary point of alignment between the atlas and supraoccipital bones, was common to all three breeds (p values 0.029 to Chihuahua had a smaller angle between the dens, atlas and basioccipital bone (p value < 0.001); Affenpinschers had a smaller distance from atlas to dens (p value 0.009); CKCS had a shorter distance between the spheno-occipital synchondrosis and atlas (p value 0.007). The selected morphometries successfully characterised conformational changes in the brain and craniocervical junction that might form the basis of a diagnostic tool for all breeds. The severity of SM involved a spectrum of abnormalities, incurred by changes in both angulation and size that could alter neural parenchyma compliance and/or impede cerebrospinal fluid channels.

Photocurrent generation in lateral graphene p-n junction created by electron-beam irradiation

KAUST Repository

Yu, Xuechao; Shen, Youde; Liu, Tao; Wu, Tao; Jie Wang, Qi

2015-01-01

Graphene has been considered as an attractive material for optoelectronic applications such as photodetectors owing to its extraordinary properties, e.g. broadband absorption and ultrahigh mobility. However, challenges still remain in fundamental and practical aspects of the conventional graphene photodetectors which normally rely on the photoconductive mode of operation which has the drawback of e.g. high dark current. Here, we demonstrated the photovoltaic mode operation in graphene p-n junctions fabricated by a simple but effective electron irradiation method that induces n-type doping in intrinsic p-type graphene. The physical mechanism of the junction formation is owing to the substrate gating effect caused by electron irradiation. Photoresponse was obtained for this type of photodetector because the photoexcited electron-hole pairs can be separated in the graphene p-n junction by the built-in potential. The fabricated graphene p-n junction photodetectors exhibit a high detectivity up to ~3 × 1010 Jones (cm Hz1/2 W−1) at room temperature, which is on a par with that of the traditional III–V photodetectors. The demonstrated novel and simple scheme for obtaining graphene p-n junctions can be used for other optoelectronic devices such as solar cells and be applied to other two dimensional materials based devices.

Photocurrent generation in lateral graphene p-n junction created by electron-beam irradiation

KAUST Repository

Yu, Xuechao

2015-07-08

Graphene has been considered as an attractive material for optoelectronic applications such as photodetectors owing to its extraordinary properties, e.g. broadband absorption and ultrahigh mobility. However, challenges still remain in fundamental and practical aspects of the conventional graphene photodetectors which normally rely on the photoconductive mode of operation which has the drawback of e.g. high dark current. Here, we demonstrated the photovoltaic mode operation in graphene p-n junctions fabricated by a simple but effective electron irradiation method that induces n-type doping in intrinsic p-type graphene. The physical mechanism of the junction formation is owing to the substrate gating effect caused by electron irradiation. Photoresponse was obtained for this type of photodetector because the photoexcited electron-hole pairs can be separated in the graphene p-n junction by the built-in potential. The fabricated graphene p-n junction photodetectors exhibit a high detectivity up to ~3 × 1010 Jones (cm Hz1/2 W−1) at room temperature, which is on a par with that of the traditional III–V photodetectors. The demonstrated novel and simple scheme for obtaining graphene p-n junctions can be used for other optoelectronic devices such as solar cells and be applied to other two dimensional materials based devices.

Tonsillar pulsatility before and after surgical decompression for children with Chiari malformation type 1: an application for true fast imaging with steady state precession

International Nuclear Information System (INIS)

Radmanesh, Alireza; Greenberg, Jacob K.; Smyth, Matthew D.; Limbrick, David D.; Chatterjee, Arindam; Sharma, Aseem

2015-01-01

We hypothesize that surgical decompression for Chiari malformation type 1 (CM-1) is associated with statistically significant decrease in tonsillar pulsatility and that the degree of pulsatility can be reliably assessed regardless of the experience level of the reader. An Institutional Review Board (IRB)-approved Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study was performed on 22 children with CM-1 (8 males; mean age 11.4 years) who had cardiac-gated true-FISP sequence and phase-contrast cerebrospinal fluid (CSF) flow imaging as parts of routine magnetic resonance (MR) imaging before and after surgical decompression. The surgical technique (decompression with or without duraplasty) was recorded for each patient. Three independent radiologists with different experience levels assessed tonsillar pulsatility qualitatively and quantitatively and assessed peritonsillar CSF flow qualitatively. Results were analyzed. To evaluate reliability, Fleiss kappa for multiple raters on categorical variables and intra-class correlation for agreement in pulsatility ratings were calculated. After surgical decompression, the degree of tonsillar pulsatility appreciably decreased, confirmed by t test, both qualitatively (p values <0.001, <0.001, and 0.045 for three readers) and quantitatively (amount of decrease/p value for three readers 0.7 mm/<0.001, 0.7 mm/<0.001, and 0.5 mm/0.022). There was a better agreement among the readers in quantitative assessment of tonsillar pulsatility (kappa 0.753-0.834), compared to qualitative assessment of pulsatility (kappa 0.472-0.496) and qualitative assessment of flow (kappa 0.056 to 0.203). Posterior fossa decompression with duraplasty led to a larger decrease in tonsillar pulsatility, compared to posterior fossa decompression alone. Tonsillar pulsatility in CM-1 is significantly reduced after surgical decompression. Quantitative assessment of tonsillar pulsatility was more reliable across readers than

Tonsillar pulsatility before and after surgical decompression for children with Chiari malformation type 1: an application for true fast imaging with steady state precession

Energy Technology Data Exchange (ETDEWEB)

Radmanesh, Alireza [University of California, San Francisco, Department of Radiology and Biomedical Imaging, San Francisco, CA (United States); Washington University School of Medicine, Mallinckrodt Institute of Radiology, St Louis, MO (United States); Greenberg, Jacob K.; Smyth, Matthew D.; Limbrick, David D. [Washington University School of Medicine, Department of Neurosurgery, St Louis, MO (United States); Chatterjee, Arindam; Sharma, Aseem [Washington University School of Medicine, Mallinckrodt Institute of Radiology, St Louis, MO (United States)

2015-04-01

We hypothesize that surgical decompression for Chiari malformation type 1 (CM-1) is associated with statistically significant decrease in tonsillar pulsatility and that the degree of pulsatility can be reliably assessed regardless of the experience level of the reader. An Institutional Review Board (IRB)-approved Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study was performed on 22 children with CM-1 (8 males; mean age 11.4 years) who had cardiac-gated true-FISP sequence and phase-contrast cerebrospinal fluid (CSF) flow imaging as parts of routine magnetic resonance (MR) imaging before and after surgical decompression. The surgical technique (decompression with or without duraplasty) was recorded for each patient. Three independent radiologists with different experience levels assessed tonsillar pulsatility qualitatively and quantitatively and assessed peritonsillar CSF flow qualitatively. Results were analyzed. To evaluate reliability, Fleiss kappa for multiple raters on categorical variables and intra-class correlation for agreement in pulsatility ratings were calculated. After surgical decompression, the degree of tonsillar pulsatility appreciably decreased, confirmed by t test, both qualitatively (p values <0.001, <0.001, and 0.045 for three readers) and quantitatively (amount of decrease/p value for three readers 0.7 mm/<0.001, 0.7 mm/<0.001, and 0.5 mm/0.022). There was a better agreement among the readers in quantitative assessment of tonsillar pulsatility (kappa 0.753-0.834), compared to qualitative assessment of pulsatility (kappa 0.472-0.496) and qualitative assessment of flow (kappa 0.056 to 0.203). Posterior fossa decompression with duraplasty led to a larger decrease in tonsillar pulsatility, compared to posterior fossa decompression alone. Tonsillar pulsatility in CM-1 is significantly reduced after surgical decompression. Quantitative assessment of tonsillar pulsatility was more reliable across readers than

Ballistic Graphene Josephson Junctions from the Short to the Long Junction Regimes.

Science.gov (United States)

Borzenets, I V; Amet, F; Ke, C T; Draelos, A W; Wei, M T; Seredinski, A; Watanabe, K; Taniguchi, T; Bomze, Y; Yamamoto, M; Tarucha, S; Finkelstein, G

2016-12-02

We investigate the critical current I_{C} of ballistic Josephson junctions made of encapsulated graphene-boron-nitride heterostructures. We observe a crossover from the short to the long junction regimes as the length of the device increases. In long ballistic junctions, I_{C} is found to scale as ∝exp(-k_{B}T/δE). The extracted energies δE are independent of the carrier density and proportional to the level spacing of the ballistic cavity. As T→0 the critical current of a long (or short) junction saturates at a level determined by the product of δE (or Δ) and the number of the junction's transversal modes.

Repulsive fluxons in a stack of Josephson junctions perturbed by a cavity

DEFF Research Database (Denmark)

Madsen, Søren; Pedersen, Niels Falsig; Christiansen, Peter Leth

2008-01-01

The BSCCO type intrinsic Josephson junction has been modeled as a stack of inductively coupled long Josephson junctions, which were described by a system of coupled sine-Gordon equations. In a system of 10 long Josephson junctions coupled to a linear cavity, we numerically investigate how...... of the inductive coupling strength, we investigate the cavity current, fluxon phase difference, and current–voltage characteristic. The stack-cavity system with in-phase fluxon motion may be utilized as a THz oscillator....

Benefit of neoadjuvant chemotherapy for Siewert type II esophagogastric junction adenocarcinoma.

Science.gov (United States)

Hosoda, Kei; Yamashita, Keishi; Katada, Natsuya; Moriya, Hiromitsu; Mieno, Hiroaki; Sakuramoto, Shinichi; Kikuchi, Shiro; Watanabe, Masahiko

2015-01-01

Our objective was to clarify if preoperative chemotherapy was associated with improved survival in Japanese patients with Siewert type II adenocarcinoma of the esophagogastric junction. We retrospectively reviewed the medical records of 86 patients with Siewert type II adenocarcinoma who underwent R0 resection at the Kitasato University between 1997 and 2013. Cox regression analysis using a backward stepwise selection method was performed to identify independent prognostic factors for relapse-free survival (RFS). The median age was 67 years. The male:female ratio was 74:12. Right thoracic, left thoracic and transhiatal approaches were performed in 10, 10 and 66 patients, respectively, and perioperative transfusion in 16 patients. Preoperative chemotherapy was administered to 19 patients; out of these, 13 received chemotherapy using the DCS regimen (docetaxel 40 mg/m(2), day 1; cisplatin 60 mg/m(2), day 1; S-1 80-120 mg/body, days 1-14; every 28 days). A median of three cycles of preoperative DCS chemotherapy were used. Histological responses of 1b, 2, 3 and unknown grades were obtained in three, three, four and three patients, respectively. The 5-year RFS rate was 55%, and the median follow-up period was 36 months. Cox regression analysis regarding RFS identified (y)pN1-3 [hazard ratio (HR)=4.44; 95% confidence interval (CI)=1.98-11.27], performance of perioperative transfusion (HR=4.71; 95% CI=1.69-11.88) and no preoperative chemotherapy (HR=3.75; 95% CI=1.22-14.26) as significant and independent indicators of poor prognosis. Preoperative chemotherapy using DCS is potentially beneficial for Japanese patients with Siewert type II adenocarcinoma. Further prospective clinical studies are required to confirm our findings. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

pn junctions based on a single transparent perovskite semiconductor BaSnO3

Science.gov (United States)

Kim, Hoon Min; Kim, Useong; Park, Chulkwon; Kwon, Hyukwoo; Lee, Woongjae; Kim, Tai Hoon; Kim, Kee Hoon; Char, Kookrin; Mdpl, Department Of Physics; Astronomy Team; Censcmr, Department Of Physics; Astronomy Team

2014-03-01

Successful p doping of transparent oxide semiconductor will further increase its potential, especially in the area of optoelectronic applications. We will report our efforts to dope the BaSnO3 (BSO) with K by pulsed laser deposition. Although the K doped BSO exhibits rather high resistivity at room temperature, its conductivity increases dramatically at higher temperatures. Furthermore, the conductivity decreases when a small amount of oxygen was removed from the film, consistent with the behavior of p type doped oxides. We have fabricated pn junctions by using K doped BSO as a p type and La doped BSO as an n type material. I_V characteristics of these devices show the typical rectifying behavior of pn junctions. We will present the analysis of the junction properties from the temperature dependent measurement of their electrical properties, which shows that the I_V characteristics are consistent with the material parameters such as the carrier concentration, the mobility, and the bandgap. Our demonstration of pn junctions based on a single transparent perovskite semiconductor further enhances the potential of BSO system with high mobility and stability.

Junction and circuit fabrication

International Nuclear Information System (INIS)

Jackel, L.D.

1980-01-01

Great strides have been made in Josephson junction fabrication in the four years since the first IC SQUID meeting. Advances in lithography have allowed the production of devices with planar dimensions as small as a few hundred angstroms. Improved technology has provided ultra-high sensitivity SQUIDS, high-efficiency low-noise mixers, and complex integrated circuits. This review highlights some of the new fabrication procedures. The review consists of three parts. Part 1 is a short summary of the requirements on junctions for various applications. Part 2 reviews intergrated circuit fabrication, including tunnel junction logic circuits made at IBM and Bell Labs, and microbridge radiation sources made at SUNY at Stony Brook. Part 3 describes new junction fabrication techniques, the major emphasis of this review. This part includes a discussion of small oxide-barrier tunnel junctions, semiconductor barrier junctions, and microbridge junctions. Part 3 concludes by considering very fine lithography and limitations to miniaturization. (orig.)

Deep level transient spectroscopic analysis of p/n junction implanted with boron in n-type silicon substrate

Science.gov (United States)

Wakimoto, Hiroki; Nakazawa, Haruo; Matsumoto, Takashi; Nabetani, Yoichi

2018-04-01

For P-i-N diodes implanted and activated with boron ions into a highly-resistive n-type Si substrate, it is found that there is a large difference in the leakage current between relatively low temperature furnace annealing (FA) and high temperature laser annealing (LA) for activation of the p-layer. Since electron trap levels in the n-type Si substrate is supposed to be affected, we report on Deep Level Transient Spectroscopy (DLTS) measurement results investigating what kinds of trap levels are formed. As a result, three kinds of electron trap levels are confirmed in the region of 1-4 μm from the p-n junction. Each DLTS peak intensity of the LA sample is smaller than that of the FA sample. In particular, with respect to the trap level which is the closest to the silicon band gap center most affecting the reverse leakage current, it was not detected in LA. It is considered that the electron trap levels are decreased due to the thermal energy of LA. On the other hand, four kinds of trap levels are confirmed in the region of 38-44 μm from the p-n junction and the DLTS peak intensities of FA and LA are almost the same, considering that the thermal energy of LA has not reached this area. The large difference between the reverse leakage current of FA and LA is considered to be affected by the deep trap level estimated to be the interstitial boron.

Manifestation of π-contacts in magnetic field dependence of I-V characteristics for proximity-type 2D Josephson junction array

International Nuclear Information System (INIS)

Rivera, V.A.G.; Sergeenkov, S.; Marega, E.; Araujo-Moreira, F.M.

2009-01-01

Results on the temperature and magnetic field dependence of current-voltage characteristics (CVC) are presented for SNS-type 2D ordered array of Nb-Cu 0.95 Al 0.05 -Nb junctions. The critical current I C (T,H) and the power exponent a(T,H)=1+Φ 0 I C (T,H)/2k B T of the nonlinear CVC law V=R[I-I C (T,H)] a(T,H) are found to have a maximum at non-zero value of applied magnetic field H p =225 Oe, which is attributed to manifestation of π-type Josephson contacts in our sample.

Junction structures based on the high-Tc superconductor YBa2Cu3O7-δ

International Nuclear Information System (INIS)

Gijs, M.A.M.

1993-01-01

An overview is given of the investigations of the Josephson effect in junction structures based on the high-T c superconductor YBa 2 Cu 3 O 7-δ , which were carried out at the Philips Research Laboratories in Eindhoven in the 1988-1990 period. The reported results are presented in their international scientific context, without attempting a complete review of the subject. However, the various junction types studied give a good idea of the scientific pursuits of high-T c junction researchers in this period. The following junctions are considered: in the category of 'weak link'-type junctions we have investigated YBa 2 Cu 3 O 7-δ -Ag-Nb point contact junctions, YBa 2 Cu 3 O 7-δ Dayem bridges and YBa 2 Cu 3 O 7-δ -Ag(-Al)-Pb proximity junctions. In these structures we combine a high-T c with a low-T c superconductor. We also fabricated planar 'all high-T c ' YBa 2 Cu 3 O 7-δ -Ag-YBa 2 Cu 3 O 7-δ junctions using a submicron structuring process. Next we have made tunnel junctions to study density of states effects of the high-T c superconductor : YBa 2 Cu 3 O 7-δ -Pb junctions using the degraded YBa 2 Cu 3 O 7-δ -Pb interface as a tunnel barrier, and YBa 2 Cu 3 O 7-δ -Ag-Al/Al 2 O 3 /Pb tunnel junctions based on the superconducting proximity effect. Our junction structures are electrically characterized and mostly studied in microwave and magnetic fields. Results are compared with current theoretical models. (orig.)

ANAESTHETIC MANAGEMENT IN A PATIENT WITH ARNOLD-CHI ARI MALFORMATION TYPE I AND SYRINGOMYELIA

OpenAIRE

Kartika; Pratap; Vijayalaxmi; Kalyan Chakravarthy; Nagaraju

2013-01-01

ABSTRACT: Syringomyelia is an unusual neurological condition characterised by the the presence of cystic cavity in the spinal cord resultin g in neurological manifestations. Here, we report a safe anesthetic management of patient with Arnold-Ch iari malformation type I and syringomyelia posted for foramen magnum decompression . INTRODUCTION: Arnold-Chiari malformation (ACM) is a developmental malformation characterised by downward displacement of cere...

CLASSIFICATION AND QUANTITATIVE ANALYSIS OF GEOGRAPHIC ATROPHY JUNCTIONAL ZONE USING SPECTRAL DOMAIN OPTICAL COHERENCE TOMOGRAPHY.

Science.gov (United States)

Qu, Jinfeng; Velaga, Swetha Bindu; Hariri, Amir H; Nittala, Muneeswar Gupta; Sadda, Srinivas

2017-08-22

The junctional zone at the border of areas of geographic atrophy (GA) in eyes with nonneovascular age-related macular degeneration is an important target region for future therapeutic strategies. The goal of this study was to perform a detailed classification and quantitative characterization of the junctional zone using spectral domain optical coherence tomography. Spectral domain optical coherence tomography volume cube scans (Spectralis OCT, 1024 × 37, Automatic Real Time > 9) were obtained from 15 eyes of 11 patients with GA because of nonneovascular age-related macular degeneration. Volume optical coherence tomography data were imported into previously described validated grading software (3D-OCTOR), and manual segmentation of the retinal pigment epithelium (RPE) and photoreceptor layers was performed on all B-scans (total of 555). Retinal pigment epithelium and photoreceptor defect maps were produced for each case. The borders of the photoreceptor defect area and RPE defect area were delineated individually on separate annotation layers. The two outlines were then superimposed to compare the areas of overlap and nonoverlap. The perimeter of the RPE defect area was calculated by the software in pixels. The superimposed outline of the photoreceptor defect area and the RPE defect area was scrutinized to classify the overlap configuration of the junctional zone into one of three categories: Type 0, exact correspondence between the edge of the RPE defect and photoreceptor defect; Type 1, loss of photoreceptors outside and beyond the edge of the RPE defect; Type 2, preservation of photoreceptors beyond the edge of the RPE defect. The relative proportion of the various border configurations was expressed as a percentage of the perimeter of the RPE defect. Each configuration was then classified into four subgroups according to irregularity of the RPE band and the presence of debris. Fifteen eyes of 11 patients (mean age: 79.3 ± 4.3 years; range: 79-94 years) were

Síndrome de Budd-Chiari. Avances en el conocimiento de su fisiopatología y nuevas estrategias terapeuticas

OpenAIRE

Hernández Guerra de Aguilar, Manuel

2006-01-01

El síndrome de Budd-Chiari (SBC) es una enfermedad poco frecuente que no obstante afecta a población joven con una alta morbimortalidad. A pesar del gran esfuerzo investigador realizado, quedan aún por hacer avances en el conocimiento fisiopatológico y en el ámbito terapéutico, ambos estrechamente vinculados, que mejoren el pronóstico de estos enfermos. Sin embargo, la baja incidencia de esta enfermedad ha dificultado la realización de estudios prospectivos y la obtención de resultados de in...

Flicker (1/f) noise in tunnel junction DC SQUIDS

International Nuclear Information System (INIS)

Koch, R.H.; Clarke, J.; Goubau, W.M.; Martinis, J.M.; Pegrum, C.M.; Van Harlingen, D.J.

1983-01-01

We have measured the spectral density of the 1/f voltage noise in current-biased resistively shunted Josephson tunnel junctions and dc SQUIDs. A theory in which fluctuations in the temperature give rise to fluctuations in the critical current and hence in the voltage predicts the magnitude of the noise quite accurately for junctions with areas of about 2 x 10 4 μm 2 , but significantly overestimates the noise for junctions with areas of about 6 μm 2 . DC SQUIDs fabricated from these two types of junctions exhibit substantially more 1/f voltage noise than would be predicted from a model in which the noise arises from critical current fluctuations in the junctions. This result was confirmed by an experiment involving two different bias current and flux modulation schemes, which demonstrated that the predominant 1/f voltage noise arises not from critical current fluctuations, but from some unknown source that can be regarded as an apparent 1/f flux noise. Measurements on five different configurations of dc SQUIDs fabricated with thin-film tunnel junctions and with widely varying areas, inductances, and junction capacitances show that the spectral density of the 1/f equivalent flux noise is roughtly constant, within a factor of three of (10 -10 /f)phi 2 0 Hz -1 . It is emphasized that 1/f flux noise may not be the predominant source of 1/f noise in SQUIDS fabricated with other technologies

Spectroscopy of Deep Traps in Cu2S-CdS Junction Structures

Directory of Open Access Journals (Sweden)

Eugenijus Gaubas

2012-12-01

Full Text Available Cu2S-CdS junctions of the polycrystalline material layers have been examined by combining the capacitance deep level transient spectroscopy technique together with white LED light additional illumination (C-DLTS-WL and the photo-ionization spectroscopy (PIS implemented by the photocurrent probing. Three types of junction structures, separated by using the barrier capacitance characteristics of the junctions and correlated with XRD distinguished precipitates of the polycrystalline layers, exhibit different deep trap spectra within CdS substrates.

Factor V Leiden mutation, prothrombin gene mutation, and deficiencies in coagulation inhibitors associated with Budd-Chiari syndrome and portal vein thrombosis: results of a case-control study

NARCIS (Netherlands)

Janssen, H. L.; Meinardi, J. R.; Vleggaar, F. P.; van Uum, S. H.; Haagsma, E. B.; van der Meer, F. J.; van Hattum, J.; Chamuleau, R. A.; Adang, R. P.; Vandenbroucke, J. P.; van Hoek, B.; Rosendaal, F. R.

2000-01-01

In a collaborative multicenter case-control study, we investigated the effect of factor V Leiden mutation, prothrombin gene mutation, and inherited deficiencies of protein C, protein S, and antithrombin on the risk of Budd-Chiari syndrome (BCS) and portal vein thrombosis (PVT). We compared 43 BCS

Factor V Leiden mutation, prothrombin gene mutation, and deficiencies in coagulation inhibitors associated with Budd-Chiari syndrome and portal vein thrombosis : results of a case-control study

NARCIS (Netherlands)

Janssen, HLA; Meinardi, [No Value; Vleggaar, FP; van Uum, SHM; Haagsma, EB; van der Meer, FJM; van Hattum, J; Chamuleau, RAFM; Adang, RP; Vandenbroucke, JP; van Hoek, B; Rosendaal, FR

2000-01-01

In a collaborative multicenter case-control study, we investigated the effect of factor V Leiden mutation, prothrombin gene mutation, and inherited deficiencies of protein C, protein S, and antithrombin on the risk of Budd-Chiari syndrome (BCS) and portal vein thrombosis (PVT), We compared 43 BCS

On the role of string-junction in hadron reactions

International Nuclear Information System (INIS)

Imachi, Masahiro; Otsuki, Shoichiro; Toyoda, Fumihiko.

1977-01-01

By taking a model that hadrons are confined composite systems of the urbaryon q linked by the string, possible roles of a three-string junction J in hadron reactions are examined. The junction brings about new patterns to the conventional urbaryon rearrangement diagram. The leading behaviour of anti BB annihilation cross section is naturally explained by the exchange of one junction pair (J anti J). The Regge intercept is related to the number of the exchanged q and J, satisfying the sum rule α sub(P) (0) + α sub(B) (0) = 2α sub(M) (0). The rearrangement diagram of q and J divides exotic exchange amplitude into two classes, one with rather slow s dependence and the other with rapid one, in agreement with experiment. In addition to the pole-pole type duality, a new type of duality (pole-cut) is expected for some components of anti BB amplitude. Both of q and J carrying four momentum lead to a successful counting rule at large momentum transfers. (auth.)

Josephson junctions with ferromagnetic alloy interlayer

Energy Technology Data Exchange (ETDEWEB)

Himmel, Nico

2015-07-23

a variation of j{sub c} and I{sub c}R{sub n} by the s-layer thickness up to the value of nonmagnetic SIS junctions is notable. Additionally information on the emergence of superconductivity with the s-layer thickness was acquired. The introduction of this thesis (Chapter 1) is intended to motivate the experimental efforts and put them into the research context. An account on the evolving field of quantum information processing shall highlight the relevance of performance enhancements of superconducting devices. The chapter also introduces the theories of electron tunneling and effects at Josephson barriers, which are essential to analyse the experimental data. Moreover a description of magnetism along with mechanisms and experiments related to π Josephson junctions are presented. In the following (Chapter 2) an overview about machines and processes for the fabrication and characterisation of thin film devices is given. The preparation of samples was performed at facilities of the Technical Faculty of the University of Kiel. Also information about the experimental setup are given. A focus is put on the deposition of layers with thickness gradients across the wafer and combinatorial sputtering to achieve independent variations of two layer parameters. Finally (Chapter 3) experimental data for different types of Josephson junctions are shown. Related theories, relevant publications and a discussion are introduced along with the data.

Josephson junctions with ferromagnetic alloy interlayer

International Nuclear Information System (INIS)

Himmel, Nico

2015-01-01

j c and I c R n by the s-layer thickness up to the value of nonmagnetic SIS junctions is notable. Additionally information on the emergence of superconductivity with the s-layer thickness was acquired. The introduction of this thesis (Chapter 1) is intended to motivate the experimental efforts and put them into the research context. An account on the evolving field of quantum information processing shall highlight the relevance of performance enhancements of superconducting devices. The chapter also introduces the theories of electron tunneling and effects at Josephson barriers, which are essential to analyse the experimental data. Moreover a description of magnetism along with mechanisms and experiments related to π Josephson junctions are presented. In the following (Chapter 2) an overview about machines and processes for the fabrication and characterisation of thin film devices is given. The preparation of samples was performed at facilities of the Technical Faculty of the University of Kiel. Also information about the experimental setup are given. A focus is put on the deposition of layers with thickness gradients across the wafer and combinatorial sputtering to achieve independent variations of two layer parameters. Finally (Chapter 3) experimental data for different types of Josephson junctions are shown. Related theories, relevant publications and a discussion are introduced along with the data.

Budd-Chiari syndrome and secondary nodular regenerative hyperplasia of the liver. Case report with special reference to diagnostic imaging

International Nuclear Information System (INIS)

Mutze, A.; Rueckert, R.; Rudolph, B.; Paris, S.; Podrabski, P.

1993-01-01

Nodular regenerative hyperplasia is a benign epithelial proliferation of the liver with unknown etiology. We observed a female patient with Budd-Chiari syndrome and secondary nodular regenerative hyperplasia of the liver over a period of five years. Patient history, diagnostic imaging (sonography, CT, MR imaging, angiography), and clinical course are demonstrated along with results of macroscopic and microscopic studies of explanted liver prior to liver transplantation. The patient presented with various predisposing factors in combination that favour the development of nodular regenerative hyperplasia. (orig.) [de

Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

International Nuclear Information System (INIS)

Cleland, A.N.

1991-04-01

Experiments investigating the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very small capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters; the tunneling rate in the moderately damped (Q ∼ 1) junction is seen to be reduced by a factor of 300 from that predicted for an undamped junction. The phase is seen to be a good quantum-mechanical variable. The experiments on small capacitance tunnel junctions extend the measurements on the larger-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wavefunction has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias. I present the first clear observation of the Coulomb blockade in single junctions. The electrical environment of the tunnel junction, however, strongly affects the behavior of the junction: higher resistance leads are observed to greatly sharpen the Coulomb blockade over that seen with lower resistance leads. I present theoretical descriptions of how the environment influences the junctions; comparisons with the experimental results are in reasonable agreement

Gap junctional coupling in the vertebrate retina: variations on one theme?

Science.gov (United States)

Völgyi, Béla; Kovács-Oller, Tamás; Atlasz, Tamás; Wilhelm, Márta; Gábriel, Róbert

2013-05-01

Gap junctions connect cells in the bodies of all multicellular organisms, forming either homologous or heterologous (i.e. established between identical or different cell types, respectively) cell-to-cell contacts by utilizing identical (homotypic) or different (heterotypic) connexin protein subunits. Gap junctions in the nervous system serve electrical signaling between neurons, thus they are also called electrical synapses. Such electrical synapses are particularly abundant in the vertebrate retina where they are specialized to form links between neurons as well as glial cells. In this article, we summarize recent findings on retinal cell-to-cell coupling in different vertebrates and identify general features in the light of the evergrowing body of data. In particular, we describe and discuss tracer coupling patterns, connexin proteins, junctional conductances and modulatory processes. This multispecies comparison serves to point out that most features are remarkably conserved across the vertebrate classes, including (i) the cell types connected via electrical synapses; (ii) the connexin makeup and the conductance of each cell-to-cell contact; (iii) the probable function of each gap junction in retinal circuitry; (iv) the fact that gap junctions underlie both electrical and/or tracer coupling between glial cells. These pan-vertebrate features thus demonstrate that retinal gap junctions have changed little during the over 500 million years of vertebrate evolution. Therefore, the fundamental architecture of electrically coupled retinal circuits seems as old as the retina itself, indicating that gap junctions deeply incorporated in retinal wiring from the very beginning of the eye formation of vertebrates. In addition to hard wiring provided by fast synaptic transmitter-releasing neurons and soft wiring contributed by peptidergic, aminergic and purinergic systems, electrical coupling may serve as the 'skeleton' of lateral processing, enabling important functions such

Impact of semiconducting electrodes on the electroresistance of ferroelectric tunnel junctions

Science.gov (United States)

Asa, M.; Bertacco, R.

2018-02-01

Ferroelectric tunnel junctions are promising candidates for the realization of energy-efficient digital memories and analog memcomputing devices. In this work, we investigate the impact of a semiconducting layer in series to the junction on the sign of electroresistance. To this scope, we compare tunnel junctions fabricated out of Pt/BaTiO3/La1/3Sr2/3MnO3 (LSMO) and Pt/BaTiO3/Nb:SrTiO3 (Nb:STO) heterostructures, displaying an opposite sign of the electroresistance. By capacitance-voltage profiling, we observe a behavior typical of Metal-Oxide-Semiconductor tunnel devices in both cases but compatible with the opposite sign of charge carriers in the semiconducting layer. While Nb:STO displays the expected n-type semiconducting character, metallic LSMO develops an interfacial p-type semiconducting layer. The different types of carriers at the semiconducting interfaces and the modulation of the depleted region by the ferroelectric charge have a deep impact on electroresistance, possibly accounting for the different sign observed in the two systems.

Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions.

Science.gov (United States)

Tomer, D; Rajput, S; Hudy, L J; Li, C H; Li, L

2015-05-29

Graphene (Gr) interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer Gr onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current-voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature for both junctions. Such behavior is attributed to barrier inhomogeneities that arise from interfacial disorders as revealed by scanning tunneling microscopy/spectroscopy. Assuming a Gaussian distribution of the barrier heights, mean values of 1.14 ± 0.14 eV and 0.76 ± 0.10 eV are found for Gr/Si and Gr/GaAs junctions, respectively. These findings resolve the origin of barrier height inhomogeneities in these Schottky junctions.

Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions

International Nuclear Information System (INIS)

Tomer, D; Rajput, S; Hudy, L J; Li, L; Li, C H

2015-01-01

Graphene (Gr) interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer Gr onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current–voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decrease in the ideality factor are observed with increasing temperature for both junctions. Such behavior is attributed to barrier inhomogeneities that arise from interfacial disorders as revealed by scanning tunneling microscopy/spectroscopy. Assuming a Gaussian distribution of the barrier heights, mean values of 1.14 ± 0.14 eV and 0.76 ± 0.10 eV are found for Gr/Si and Gr/GaAs junctions, respectively. These findings resolve the origin of barrier height inhomogeneities in these Schottky junctions. (paper)

Craniometric Analysis of the Hindbrain and Craniocervical Junction of Chihuahua, Affenpinscher and Cavalier King Charles Spaniel Dogs With and Without Syringomyelia Secondary to Chiari-Like Malformation.

Directory of Open Access Journals (Sweden)

Susan P Knowler

Full Text Available To characterize and compare the phenotypic variables of the hindbrain and craniocervical junction associated with syringomyelia (SM in the Chihuahua, Affenpinscher and Cavalier King Charles Spaniel (CKCS.Analysis of 273 T1-weighted mid-sagittal DICOM sequences of the hindbrain and craniocervical junction from 99 Chihuahuas, 42 Affenpinschers and 132 CKCSs. The study compared 22 morphometric features (11 lines, eight angles and three ratios of dogs with and without SM using refined techniques based on previous studies of the Griffon Bruxellois (GB using Discriminant Function Analysis and ANOVA with post-hoc corrections.The analysis identified 14/22 significant traits for SM in the three dog breeds, five of which were identical to those reported for the GB and suggest inclusion of a common aetiology. One ratio, caudal fossa height to the length of the skull base extended to an imaginary point of alignment between the atlas and supraoccipital bones, was common to all three breeds (p values 0.029 to <0.001. Associated with SM were a reduced occipital crest and two acute changes in angulation i 'sphenoid flexure' at the spheno-occipital synchondrosis ii 'cervical flexure' at the foramen magnum allied with medulla oblongata elevation. Comparing dogs with and without SM, each breed had a unique trait: Chihuahua had a smaller angle between the dens, atlas and basioccipital bone (p value < 0.001; Affenpinschers had a smaller distance from atlas to dens (p value 0.009; CKCS had a shorter distance between the spheno-occipital synchondrosis and atlas (p value 0.007.The selected morphometries successfully characterised conformational changes in the brain and craniocervical junction that might form the basis of a diagnostic tool for all breeds. The severity of SM involved a spectrum of abnormalities, incurred by changes in both angulation and size that could alter neural parenchyma compliance and/or impede cerebrospinal fluid channels.

Josephson junction arrays

International Nuclear Information System (INIS)

Bindslev Hansen, J.; Lindelof, P.E.

1985-01-01

In this review we intend to cover recent work involving arrays of Josephson junctions. The work on such arrays falls naturally into three main areas of interest: 1. Technical applications of Josephson junction arrays for high-frequency devices. 2. Experimental studies of 2-D model systems (Kosterlitz-Thouless phase transition, commensurate-incommensurate transition in frustrated (flux) lattices). 3. Investigations of phenomena associated with non-equilibrium superconductivity in and around Josephson junctions (with high current density). (orig./BUD)

Contemporary occurrence of hydrocephalus and Chiari I malformation in sagittal craniosynostosis. Case report and review of the literature.

Science.gov (United States)

Sgulò, Francesco Giovanni; Spennato, Pietro; Aliberti, Ferdinando; Di Martino, Giuliana; Cascone, Daniele; Cinalli, Giuseppe

2017-01-01

Chiari malformation type I (CM-I) and hydrocephalus are often associated with complex craniosynostosis. On the contrary, their simultaneous occurrence in monosutural synostosis is extremely rare. The pathophysiological hypothesis is that they may alter posterior fossa growth and lead to cerebellar tonsil herniation also without skull base primary involvement. Hydrocephalus is multifactorial and may be secondary to fourth ventricle outlet obstruction. The management of these cases is quite complex and not well defined. Cranial vault remodeling should be the only treatment when CM-I is asymptomatic and not related to syringomyelia. Suboccipital decompression should be reserved only in complicated CM-I, usually as a second surgical step following the correction of the supratentorial deformity. In our opinion, the associated hydrocephalus should be treated first in order to normalize intracranial hypertension before opening the cranial sutures. We report the case of a 26-month-old child that presented with sagittal craniosynostosis, hydrocephalus, and CM-I. He was managed by performing endoscopic third ventriculostomy (ETV) first and cranial vault remodeling thereafter. Clinico-radiological outcome was very satisfying. Concerning literature is reviewed; physiopathology and surgical management are discussed.

The nanostructure of myoendothelial junctions contributes to signal rectification between endothelial and vascular smooth muscle cells

DEFF Research Database (Denmark)

Brasen, Jens Christian; Jacobsen, Jens Christian Brings; von Holstein-Rathlou, Niels-Henrik

2012-01-01

Micro-anatomical structures in tissues have potential physiological effects. In arteries and arterioles smooth muscle cells and endothelial cells are separated by the internal elastic lamina, but the two cell layers often make contact through micro protrusions called myoendothelial junctions. Cross...... types and the myoendothelial junction. The model is implemented as a 2D axi-symmetrical model and solved using the finite element method. We have simulated diffusion of Ca(2+) and IP(3) between the two cell types and we show that the micro-anatomical structure of the myoendothelial junction in itself...

Fluxon dynamics in long Josephson junctions in the presence of a temperature gradient or spatial nonuniformity

DEFF Research Database (Denmark)

Krasnov, V.M.; Oboznov, V.A.; Pedersen, Niels Falsig

1997-01-01

Fluxon dynamics in nonuniform Josephson junctions was studied both experimentally and theoretically. Two types of nonuniform junctions were considered: the first type had a nonuniform spatial distribution of critical and bias currents and the second had a temperature gradient applied along...... the junction. An analytical expression for the I-V curve in the presence of a temperature gradient or spatial nonuniformity was derived. It was shown that there is no static thermomagnetic Nernst effect due to Josephson fluxon motion despite the existence of a force pushing fluxons in the direction of smaller...

Negative Differential Resistance in Atomic Carbon Chain-Graphene Junctions

International Nuclear Information System (INIS)

An Liping; Liu Chunmei; Liu Nianhua

2012-01-01

We investigate the electronic transport properties of atomic carbon chain-graphene junctions by using the density-functional theory combining with the non-equilibrium Green's functions. The results show that the transport properties are sensitively dependent on the contact geometry of carbon chain. From the calculated I-V curve we find negative differential resistance (NDR) in the two types of junctions. The NDR can be considered as a result of molecular orbitals moving related to the bias window. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Electronic thermometry in tunable tunnel junction

Science.gov (United States)

Maksymovych, Petro

2016-03-15

A tunable tunnel junction thermometry circuit includes a variable width tunnel junction between a test object and a probe. The junction width is varied and a change in thermovoltage across the junction with respect to the change in distance across the junction is determined. Also, a change in biased current with respect to a change in distance across the junction is determined. A temperature gradient across the junction is determined based on a mathematical relationship between the temperature gradient, the change in thermovoltage with respect to distance and the change in biased current with respect to distance. Thermovoltage may be measured by nullifying a thermoelectric tunneling current with an applied voltage supply level. A piezoelectric actuator may modulate the probe, and thus the junction width, to vary thermovoltage and biased current across the junction. Lock-in amplifiers measure the derivatives of the thermovoltage and biased current modulated by varying junction width.

Expansion of Chiari I-associated syringomyelia after posterior-fossa decompression.

Science.gov (United States)

Gil, Z; Rao, S; Constantini, S

2000-09-01

Chiari I malformation (CMI) is an abnormality that involves caudal herniation of the cerebellar tonsils into the foramen magnum. CMI has been shown to be closely associated with the development of syringomyelia (SM). Several theories have emerged to explain the apparent correlation between the existence of CMI with subsequent development of SM. However, the exact mechanism of the evolution of SM is still subject to controversy. We report here the case of a 12-year-old girl admitted to hospital with headache, vomiting, ataxia, and moderate pyramidal signs. Radiological evaluation revealed the presence of CMI, accompanied by a small SM. The patient underwent posterior fossa decompression and improved significantly. She was re-admitted 6 months later with clinical evidence of progressive spinal cord dysfunction. MR revealed gross expansion of the syrinx. This case raises questions regarding the pathophysiology of CMI and its association with SM. The case indicates the need for neurological and radiological follow-up for patients undergoing posterior fossa decompression due to CMI, even for those without an initial syrinx. This is the first report known to us of expansion of a syrinx following decompression of an associated CMI.

Espasmo hemifacial e impressão basilar associados a malformação de arnold-chiari relato de caso

Directory of Open Access Journals (Sweden)

Manoel Baldoino Leal Filho

1992-09-01

Full Text Available Os autores relatam o caso de uma paciente com espasmo hemifacial e impressão basilar associados a malformação de Arnold-Chiari. Com a descompressão cirúrgica da fossa posterior, empregada no tratamento da impressão basilar, houve melhora do quadro clínico e o espasmo hemifacial se reduziu quanto à frequência, duração e intensidade. É enfatizada a necessidade do tratamento etiológico do espasmo hemifacial, antes de se recorrer à toxina botulínica.

Comparision of results between two different techniques of cranio-cervical decompression in patients with Chiari I malformation.

Science.gov (United States)

Kunert, Przemysław; Janowski, Mirosław; Zakrzewska, Agnieszka; Marchel, Andrzej

2009-01-01

A variety of approaches are employed for treatment of Chiari I malformation. They differ in extent of cranio-c ervical decompression. A technique based on arachnoid preservation and duroplasty was introduced in our department in 2001. The aim of the study is to compare between the previous and the present technique. Retrospective analysis of 38 patients with Chiari I malformation treated between 1998 and 2004 was performed. The previous technique including arach- noid incision, coagulation of cerebellar tonsils, and fourth ventricle exploration without duroplasty was used to treat 21 patients (group 1). A further 17 patients were treated with the present technique consisting of arachnoid preservation and duroplasty (group 2). Complication rates as well as early and late results of treatment were evaluated. Karnofsky (KPS), Rankin (RS) and Bidziński (BS) scales were used for evaluation of results. Post-operative complications were detected in 9 patients in group 1 (43%). They included liquorrhoea (5 cases), meningitis (1 case), and symptoms progression (3 cases). There were no surgical complications in group 2 (p = 0.002). Neurological improvement in the early period (until discharge from hospital) occurred in 10 (48%) patients in group 1 and in 13 (76%) in group 2 (p = NS). Further improvement or lack of symptoms progression was found in 58% in group 1 and 82% in group 2 (p = NS). Assessment in KPS, RS and BS showed slightly better results of group 2 but the difference was statistically insignificant. Results of both techniques are comparable. The risk of post-operative complications after extra-arachnoid cranio-cervical decompression with duroplasty is, however, significantly lower.

Posterior cranial fossa dimensions in the Chiari I malformation: relation to pathogenesis and clinical presentation

International Nuclear Information System (INIS)

Stovner, L.J.; Bergan, U.; Nilsen, G.; Sjaastad, O.

1993-01-01

Skull dimensions were measured on lateral skull radiographs in 33 adult patients with MRI-verified Chiari I malformations and in 40 controls. The posterior cranial fossa was significantly smaller and shallower in patients than in controls. In the patients, there was a positive correlation between posterior fossa size and the degree of the cerebellar ectopia, which might indicate that a posterior cranial fossa which was originally too small had been expanded by the herniation of hindbrain structures at an early stage. No special clinical presentation was associated with a very small posterior cranial fossa, which may indicate that a small posterior cranial per se has little or no clinical significance, although it may be the primary developmental anomaly. (orig./GD)

A Monolithic Interconnected module with a tunnel Junction for Enhanced Electrical and Optical Performance

Energy Technology Data Exchange (ETDEWEB)

Murray, Christopher Sean; Wilt, David Morgan

1999-06-30

An improved thermophotovoltaic (TPV) n/p/n device is provided. Monolithic Interconnected Modules (MIMs), semiconductor devices converting infrared radiation to electricity, have been developed with improved electrical and optical performance. The structure is an n-type emitter on a p-type base with an n-type lateral conduction layer. The incorporation of a tunnel junction and the reduction in the amount of p-type material used results in negligible parasitic absorption, decreased series resistance, increased voltage and increased active area. The novel use of a tunnel junction results in the potential for a TPV device with efficiency greater than 24%.

A case report of secondary Budd-Chiari syndrome due to chronic empyema diagnosed by NMR-CT

International Nuclear Information System (INIS)

Takagi, Sayumi; Hattori, Akira; Yamauchi, Masayosi; Kimura, Kazuo; Suzino, Hajime; Sibata, Koji; Watanabe, Reijiro; Kameda, Haruo

1985-01-01

A 34-year-old male patient complained of general fatigue, ascites, and edema of the lower extremities. A chest x-ray film showed atelectasis of the right lung and pleural effusion of the right side. Liver ultrasonography revealed stenosis of the middle and right hepatic veins. Venacavography revealed stenosis of the inferior vena cava and collateral circulation. Finally, abdominal NMR-CT clearly visualized lunate stenosis and antero-lateral deviation of the inferior vena cava. He was diagnosed as having secondary Budd-Chiari syndrome resulting from the deviation and stenosis of the inferior vena cava due to distortion of the surrounding tissues by the thickened pleura which was caused by chronic empyema. (Namekawa, K.)

Current transport and electronic states in a,b-axis-oriented YBa2Cu3O7/PrBa2Cu3O7/YBa2Cu3O7 sandwich-type junctions

International Nuclear Information System (INIS)

Yoshida, J.; Nagano, T.; Hashimoto, T.

1996-01-01

Precise measurement of the temperature and voltage dependence of junction conductance has been carried out for a,b-axis-oriented YBa 2 Cu 3 O 7 /PrBa 2 Cu 3 O 7 /YBa 2 Cu 3 O 7 sandwich-type junctions to investigate the possible origin of Josephson coupling in these junctions. Regardless of the presence or absence of the Josephson effect, most of the junctions exhibited a dip in conductance around zero voltage in their dI/dV profiles at low temperatures. This dI/dV anomaly was attributed to the existence of a minimum in the density of states due to electron-electron interaction in disordered metals in the vicinity of a tunneling barrier within the junctions. The complex temperature dependence of junction conductance was reproduced well by a theoretical model in which both tunneling conduction paths and variable range hopping paths were assumed to exist within the PrBa 2 Cu 3 O 7 barrier layer. No definite evidence of current transport through a small number of localized levels or a metallic conduction path in PrBa 2 Cu 3 O 7 has been confirmed, even for junctions with a 20-nm-thick barrier layer. copyright 1996 The American Physical Society

Electrical resistivity of monolayers and bilayers of alkanethiols in tunnel junction with gate electrode

International Nuclear Information System (INIS)

York, Roger L.; Nacionales, David; Slowinski, Krzysztof

2005-01-01

The tunneling resistances of monolayers and bilayers of n-alkanethiols in macroscopic Hg-Hg junctions with an electrochemical gate are reported. The resistances near zero bias calculated per 1 hydrocarbon chain vary from (5 ± 4) x 10 12 Ω for n-nonanethiol to (4 ± 2) x 10 16 Ω for n-octadecanethiol. These values indicate that monolayers of hydrocarbons in Hg-Hg junctions are substantially more resistive as compared to measurements employing microscopic tunnel junctions. The tunneling resistances of monolayer junctions are approximately 1 order of magnitude larger than those of bilayer junctions containing the same number of atoms indicating inefficient electronic coupling across the non-bonded -CH 3 |Hg interface. The symmetric current-voltage curves observed for the asymmetric junctions of Hg-S-(CH 2 ) n -CH 3 |Hg type suggest that these junctions do not behave as molecular diodes. Additional experimental evidence for the nature of the -CH 3 |Hg interface in the Hg-S-(CH 2 ) n -CH 3 |Hg junction is also presented

CARRIER TRANSPORT IN MESOSCOPIC SILICON-COUPLED SUPERCONDUCTING JUNCTIONS

NARCIS (Netherlands)

VANHUFFELEN, WM; KLAPWIJK, TM; HESLINGA, DR; DEBOER, MJ; VANDERPOST, N

1993-01-01

An overview is presented of experimental results on supercurrent flow and transport at finite voltages in a well-characterized, sandwich-type superconductor-semiconductor-superconductor junction. Carrier transport through the structure is found to be dominated by the interfaces. At low temperatures,

Clinical application of Inoue-balloon in percutaneous transluminal angioplasty for Budd-Chiari syndrome

International Nuclear Information System (INIS)

Mei Jian; Qu Jian; Zhu Yaoqing; Wang Lei; Liu Cheng

2007-01-01

Objective: To investigate the feasibility and effect of recanalization of inferior vena cava with percutaneous transluminal angioplasty(PTA)by Inoue-balloon. Methods: Eighty-nine patients with Budd-chiari syndrome (BCS )were treated with PTA by Inoue-balloon. Results: After PTA, the median (interquartile range)diameter of hepatic segment inferior vena cava increased from 0.00 (0.20-0.00) cm to 1.90 (2.00 1.47)cm; (P < 0.001), and the mean pressure of inferior vena cava reduced from (20.63 ± 7.22) mmHg to (12.13 ± 5.60) mmHg; (P < 0.001); with only less serious complications as rupture in two cases and without need of prior minor diameter balloon dilation in Inoue-balloon PTA. Conclusion: The advantages of Inoue- balloon PTA for BCS are more reliable and facile than those of polyethylene balloon, and may take the place in the foreseen future. (authors)

Tight junctions and human diseases.

Science.gov (United States)

Sawada, Norimasa; Murata, Masaki; Kikuchi, Keisuke; Osanai, Makoto; Tobioka, Hirotoshi; Kojima, Takashi; Chiba, Hideki

2003-09-01

Tight junctions are intercellular junctions adjacent to the apical end of the lateral membrane surface. They have two functions, the barrier (or gate) function and the fence function. The barrier function of tight junctions regulates the passage of ions, water, and various macromolecules, even of cancer cells, through paracellular spaces. The barrier function is thus relevant to edema, jaundice, diarrhea, and blood-borne metastasis. On the other hand, the fence function maintains cell polarity. In other words, tight junctions work as a fence to prevent intermixing of molecules in the apical membrane with those in the lateral membrane. This function is deeply involved in cancer cell biology, in terms of loss of cell polarity. Of the proteins comprising tight junctions, integral membrane proteins occludin, claudins, and JAMs have been recently discovered. Of these molecules, claudins are exclusively responsible for the formation of tight-junction strands and are connected with the actin cytoskeleton mediated by ZO-1. Thus, both functions of tight junctions are dependent on the integrity of the actin cytoskeleton as well as ATP. Mutations in the claudin14 and the claudin16 genes result in hereditary deafness and hereditary hypomagnesemia, respectively. Some pathogenic bacteria and viruses target and affect the tight-junction function, leading to diseases. In this review, the relationship between tight junctions and human diseases is summarized.

A single-gradient junction technique to replace multiple-junction shifts for craniospinal irradiation treatment

International Nuclear Information System (INIS)

Hadley, Austin; Ding, George X.

2014-01-01

Craniospinal irradiation (CSI) requires abutting fields at the cervical spine. Junction shifts are conventionally used to prevent setup error–induced overdosage/underdosage from occurring at the same location. This study compared the dosimetric differences at the cranial-spinal junction between a single-gradient junction technique and conventional multiple-junction shifts and evaluated the effect of setup errors on the dose distributions between both techniques for a treatment course and single fraction. Conventionally, 2 lateral brain fields and a posterior spine field(s) are used for CSI with weekly 1-cm junction shifts. We retrospectively replanned 4 CSI patients using a single-gradient junction between the lateral brain fields and the posterior spine field. The fields were extended to allow a minimum 3-cm field overlap. The dose gradient at the junction was achieved using dose painting and intensity-modulated radiation therapy planning. The effect of positioning setup errors on the dose distributions for both techniques was simulated by applying shifts of ± 3 and 5 mm. The resulting cervical spine doses across the field junction for both techniques were calculated and compared. Dose profiles were obtained for both a single fraction and entire treatment course to include the effects of the conventional weekly junction shifts. Compared with the conventional technique, the gradient-dose technique resulted in higher dose uniformity and conformity to the target volumes, lower organ at risk (OAR) mean and maximum doses, and diminished hot spots from systematic positioning errors over the course of treatment. Single-fraction hot and cold spots were improved for the gradient-dose technique. The single-gradient junction technique provides improved conformity, dose uniformity, diminished hot spots, lower OAR mean and maximum dose, and one plan for the entire treatment course, which reduces the potential human error associated with conventional 4-shifted plans

Charge transport in junctions between d-wave superconductors

International Nuclear Information System (INIS)

Barash, Y.S.; Galaktionov, A.V.; Zaikin, A.D.

1995-01-01

We develop a microscopic analysis of superconducting and dissipative currents in junctions between superconductors with d-wave symmetry of the order parameter. We study the proximity effect in such superconductors and show that for certain crystal orientations the superconducting order parameter can be essentially suppressed in the vicinity of a nontransparent specularly reflecting boundary. This effect strongly influences the value and the angular dependence of the dc Josephson current j S . At T∼T c it leads to a crossover between j S ∝T c -T and j S ∝(T c -T) 2 respectively for homogeneous and nonhomogeneous distribution of the order parameter in the vicinity of a tunnel junction. We show that at low temperatures the current-phase relation j S (cphi) for superconductor--normal-metal--superconductor junctions and short weak links between d-wave superconductors is essentially nonharmonic and contains a discontinuity at cphi=0. This leads to further interesting features of such systems which can be used for pairing symmetry tests in high-temperature superconductors (HTSC). We also investigated the low-temperature I-V curves of normal-metal--superconductor and superconductor-superconductor tunnel junctions and demonstrated that depending on the junction type and crystal orientation these curves show zero-bias anomalies I∝V 2 , I∝V 2 ln(1/V), and I∝V 3 caused by the gapless behavior of the order parameter in d-wave superconductors. Many of our results agree well with recent experimental findings for HTSC compounds

T-junctions and perceived slant of partially occluded surfaces.

Science.gov (United States)

Grove, Philip M; Ono, Hiroshi; Kaneko, Hirohiko

2003-01-01

Häkkinen and Nyman (1997 Perception 26 29-38) reported that perceived slant is reduced when occlusion is a possible interpretation for the visual system. We present data from three experiments that confirm and expand on their finding. Our stimuli consisted of four types of stereograms depicting white central rectangles flanked on either side by two grey rectangles. The central white rectangles varied in height, thus manipulating the polarity of the T-junction information between the central and flanking rectangles. Perceived slant was smallest or not apparent when T-junction information indicated the central rectangles were nearer than the flanking rectangles and greatest when T-junction information indicated a farther central rectangle. Slant estimates for a stimulus containing a subjective pacmen-induced central rectangle were biased towards a depth step when an occlusion interpretation was possible.

Macroscopic quantum tunneling in Josephson tunnel junctions and Coulomb blockade in single small tunnel junctions

International Nuclear Information System (INIS)

Cleland, A.N.

1991-01-01

Experiments investigated the process of macroscopic quantum tunneling in a moderately-damped, resistively shunted, Josephson junction are described, followed by a discussion of experiments performed on very-small-capacitance normal-metal tunnel junctions. The experiments on the resistively-shunted Josephson junction were designed to investigate a quantum process, that of the tunneling of the Josephson-phase variable under a potential barrier, in a system in which dissipation plays a major role in the dynamics of motion. All the parameters of the junction were measured using the classical phenomena of thermal activation and resonant activation. Theoretical predictions are compared with the experimental results, showing good agreement with no adjustable parameters. The experiments on small-capacitance tunnel junctions extend the measurements on the large-area Josephson junctions from the region in which the phase variable has a fairly well-defined value, i.e. its wave function has a narrow width, to the region where its value is almost completely unknown. The charge on the junction becomes well-defined and is predicted to quantize the current through the junction, giving rise to the Coulomb blockade at low bias

Increasing gap junctional coupling: a tool for dissecting the role of gap junctions

DEFF Research Database (Denmark)

Axelsen, Lene Nygaard; Haugan, Ketil; Stahlhut, Martin

2007-01-01

Much of our current knowledge about the physiological and pathophysiological role of gap junctions is based on experiments where coupling has been reduced by either chemical agents or genetic modification. This has brought evidence that gap junctions are important in many physiological processes....... In a number of cases, gap junctions have been implicated in the initiation and progress of disease, and experimental uncoupling has been used to investigate the exact role of coupling. The inverse approach, i.e., to increase coupling, has become possible in recent years and represents a new way of testing...... the role of gap junctions. The aim of this review is to summarize the current knowledge obtained with agents that selectively increase gap junctional intercellular coupling. Two approaches will be reviewed: increasing coupling by the use of antiarrhythmic peptide and its synthetic analogs...

Does the mesodermal derangement in Chiari Type I malformation extend to the cervical spine? Evidence from an analytical morphometric study on cervical paraspinal muscles.

Science.gov (United States)

Thakar, Sumit; Kurudi Siddappa, Avinash; Aryan, Saritha; Mohan, Dilip; Sai Kiran, Narayanam Anantha; Hegde, Alangar S

2017-10-01

OBJECTIVE The mesodermal derangement in Chiari Type I malformation (CMI) has been postulated to encompass the cervical spine. The objectives of this study were to assess the cross-sectional areas (CSAs) of cervical paraspinal muscles (PSMs) in patients with CMI without syringomyelia, compare them with those in non-CMI subjects, and evaluate their correlations with various factors. METHODS In this retrospective study, the CSAs of cervical PSMs in 25 patients were calculated on T2-weighted axial MR images and computed as ratios with respect to the corresponding vertebral body areas. These values and the cervical taper ratios were then compared with those of age- and sex-matched non-CMI subjects and analyzed with respect to demographic data and clinicoradiological factors. RESULTS Compared with the non-CMI group, the mean CSA values for the rectus capitis minor and all of the subaxial PSMs were lower in the study group, and those of the deep extensors were significantly lower (p = 0.004). The cervical taper ratio was found to be significantly higher in the study cohort (p = 0.0003). A longer duration of symptoms and a steeper cervical taper ratio were independently associated with lower CSA values for the deep extensors (p = 0.04 and p = 0.03, respectively). The presence of neck pain was associated with a lower CSA value for the deep flexors (p = 0.03). CONCLUSIONS Patients with CMI demonstrate alterations in their cervical paraspinal musculature even in the absence of coexistent syringomyelia. Their deep extensor muscles undergo significant atrophic changes that worsen with the duration of their symptoms. This could be related to a significantly steeper cervical taper ratio that their cervical cords are exposed to. Neck pain in these patients is related to atrophy of their deep flexor muscles. A steeper cervical taper ratio and alterations in the PSMs could be additional indicators for surgery in patients with CMI without syringomyelia.

Inhomogeneity in barrier height at graphene/Si (GaAs) Schottky junctions

OpenAIRE

Tomer, D.; Rajput, S.; Hudy, L. J.; Li, C. H.; Li, L.

2015-01-01

Graphene interfaced with a semiconductor forms a Schottky junction with rectifying properties, however, fluctuations in the Schottky barrier height are often observed. In this work, Schottky junctions are fabricated by transferring chemical vapor deposited monolayer graphene onto n-type Si and GaAs substrates. Temperature dependence of the barrier height and ideality factor are obtained by current-voltage measurements between 215 and 350 K. An increase in the zero bias barrier height and decr...

Negative Differential Resistance due to Nonlinearities in Single and Stacked Josephson Junctions

DEFF Research Database (Denmark)

Filatrella, Giovanni; Pierro, Vincenzo; Pedersen, Niels Falsig

2014-01-01

Josephson junction systems with a negative differential resistance (NDR) play an essential role for applications. As a well-known example, long Josephson junctions of the BSCCO type have been considered as a source of terahertz radiation in recent experiments. Numerical results for the dynamics...... shapes of NDR region are considered, and we found that it is essential to distinguish between current bias and voltage bias....

Hyperglycaemia and diabetes impair gap junctional communication among astrocytes.

Science.gov (United States)

Gandhi, Gautam K; Ball, Kelly K; Cruz, Nancy F; Dienel, Gerald A

2010-03-15

Sensory and cognitive impairments have been documented in diabetic humans and animals, but the pathophysiology of diabetes in the central nervous system is poorly understood. Because a high glucose level disrupts gap junctional communication in various cell types and astrocytes are extensively coupled by gap junctions to form large syncytia, the influence of experimental diabetes on gap junction channel-mediated dye transfer was assessed in astrocytes in tissue culture and in brain slices from diabetic rats. Astrocytes grown in 15-25 mmol/l glucose had a slow-onset, poorly reversible decrement in gap junctional communication compared with those grown in 5.5 mmol/l glucose. Astrocytes in brain slices from adult STZ (streptozotocin)-treated rats at 20-24 weeks after the onset of diabetes also exhibited reduced dye transfer. In cultured astrocytes grown in high glucose, increased oxidative stress preceded the decrement in dye transfer by several days, and gap junctional impairment was prevented, but not rescued, after its manifestation by compounds that can block or reduce oxidative stress. In sharp contrast with these findings, chaperone molecules known to facilitate protein folding could prevent and rescue gap junctional impairment, even in the presence of elevated glucose level and oxidative stress. Immunostaining of Cx (connexin) 43 and 30, but not Cx26, was altered by growth in high glucose. Disruption of astrocytic trafficking of metabolites and signalling molecules may alter interactions among astrocytes, neurons and endothelial cells and contribute to changes in brain function in diabetes. Involvement of the microvasculature may contribute to diabetic complications in the brain, the cardiovascular system and other organs.

Supramolecular tunneling junctions

NARCIS (Netherlands)

Wimbush, K.S.

2012-01-01

In this study a variety of supramolecular tunneling junctions were created. The basis of these junctions was a self-assembled monolayer of heptathioether functionalized ß-cyclodextrin (ßCD) formed on an ultra-flat Au surface, i.e., the bottom electrode. This gave a well-defined hexagonally packed

Single-Molecule Photocurrent at a Metal-Molecule-Semiconductor Junction.

Science.gov (United States)

Vezzoli, Andrea; Brooke, Richard J; Higgins, Simon J; Schwarzacher, Walther; Nichols, Richard J

2017-11-08

We demonstrate here a new concept for a metal-molecule-semiconductor nanodevice employing Au and GaAs contacts that acts as a photodiode. Current-voltage traces for such junctions are recorded using a STM, and the "blinking" or "I(t)" method is used to record electrical behavior at the single-molecule level in the dark and under illumination, with both low and highly doped GaAs samples and with two different types of molecular bridge: nonconjugated pentanedithiol and the more conjugated 1,4-phenylene(dimethanethiol). Junctions with highly doped GaAs show poor rectification in the dark and a low photocurrent, while junctions with low doped GaAs show particularly high rectification ratios in the dark (>10 3 for a 1.5 V bias potential) and a high photocurrent in reverse bias. In low doped GaAs, the greater thickness of the depletion layer not only reduces the reverse bias leakage current, but also increases the volume that contributes to the photocurrent, an effect amplified by the point contact geometry of the junction. Furthermore, since photogenerated holes tunnel to the metal electrode assisted by the HOMO of the molecular bridge, the choice of the latter has a strong influence on both the steady state and transient metal-molecule-semiconductor photodiode response. The control of junction current via photogenerated charge carriers adds new functionality to single-molecule nanodevices.

A generic concept to overcome bandgap limitations for designing highly efficient multi-junction photovoltaic cells.

Science.gov (United States)

Guo, Fei; Li, Ning; Fecher, Frank W; Gasparini, Nicola; Ramirez Quiroz, Cesar Omar; Bronnbauer, Carina; Hou, Yi; Radmilović, Vuk V; Radmilović, Velimir R; Spiecker, Erdmann; Forberich, Karen; Brabec, Christoph J

2015-07-16

The multi-junction concept is the most relevant approach to overcome the Shockley-Queisser limit for single-junction photovoltaic cells. The record efficiencies of several types of solar technologies are held by series-connected tandem configurations. However, the stringent current-matching criterion presents primarily a material challenge and permanently requires developing and processing novel semiconductors with desired bandgaps and thicknesses. Here we report a generic concept to alleviate this limitation. By integrating series- and parallel-interconnections into a triple-junction configuration, we find significantly relaxed material selection and current-matching constraints. To illustrate the versatile applicability of the proposed triple-junction concept, organic and organic-inorganic hybrid triple-junction solar cells are constructed by printing methods. High fill factors up to 68% without resistive losses are achieved for both organic and hybrid triple-junction devices. Series/parallel triple-junction cells with organic, as well as perovskite-based subcells may become a key technology to further advance the efficiency roadmap of the existing photovoltaic technologies.

Porous silicon formation by hole injection from a back side p+/n junction for electrical insulation applications

International Nuclear Information System (INIS)

Fèvre, A; Menard, S; Defforge, T; Gautier, G

2016-01-01

In this paper, we propose to study the formation of porous silicon (PS) in low doped (1 × 10 14 cm −3 ) n-type silicon through hole injection from a back side p + /n junction in the dark. This technique is investigated within the framework of electrical insulation. Three different types of junctions are investigated. The first one is an epitaxial n-type layer grown on p + doped silicon wafer. The two other junctions are carried out by boron diffusion leading to p + regions with junction depths of 20 and 115 μm. The resulting PS morphology is a double layer with a nucleation layer (NL) and macropores fully filled with mesoporous material. This result is unusual for low doped n-type silicon. Morphology variations are described depending on the junction formation process, the electrolyte composition, the anodization current density and duration. In order to validate the more interesting industrial potentialities of the p + /n injection technique, a comparison is achieved with back side illumination in terms of resulting morphology and experiments confirm comparable results. Electrical characterizations of the double layer, including NL and fully filled macropores, are then performed. To our knowledge, this is the first electrical investigation in low doped n type silicon with this morphology. Compared to the bulk silicon, the measured electrical resistivities are 6–7 orders of magnitude higher at 373 K. (paper)

Relationships between junction temperature, electroluminescence spectrum and ageing of light-emitting diodes

Science.gov (United States)

Vaskuri, Anna; Kärhä, Petri; Baumgartner, Hans; Kantamaa, Olli; Pulli, Tomi; Poikonen, Tuomas; Ikonen, Erkki

2018-04-01

We have developed spectral models describing the electroluminescence spectra of AlGaInP and InGaN light-emitting diodes (LEDs) consisting of the Maxwell-Boltzmann distribution and the effective joint density of states. One spectrum at a known temperature for one LED specimen is needed for calibrating the model parameters of each LED type. Then, the model can be used for determining the junction temperature optically from the spectral measurement, because the junction temperature is one of the free parameters. We validated the models using, in total, 53 spectra of three red AlGaInP LED specimens and 72 spectra of three blue InGaN LED specimens measured at various current levels and temperatures between 303 K and 398 K. For all the spectra of red LEDs, the standard deviation between the modelled and measured junction temperatures was only 2.4 K. InGaN LEDs have a more complex effective joint density of states. For the blue LEDs, the corresponding standard deviation was 11.2 K, but it decreased to 3.5 K when each LED specimen was calibrated separately. The method of determining junction temperature was further tested on white InGaN LEDs with luminophore coating and LED lamps. The average standard deviation was 8 K for white InGaN LED types. We have six years of ageing data available for a set of LED lamps and we estimated the junction temperatures of these lamps with respect to their ageing times. It was found that the LEDs operating at higher junction temperatures were frequently more damaged.

Manipulating Josephson junctions in thin-films by nearby vortices

International Nuclear Information System (INIS)

Kogan, V.G.; Mints, R.G.

2014-01-01

Highlights: • Vortex located in a bank of a planar Josephson junction changes its character. • Vortex located at some discreet positions in thin strip bank suppresses to zero the zero-field current. • The number of these positions is equal to the number of vortices trapped. • Critical current-field patterns are strongly affected by the vortex position. - Abstract: It is shown that a vortex trapped in one of the banks of a planar edge-type Josephson junction in a narrow thin-film superconducting strip can change drastically the dependence of the junction critical current on the applied field, I c (H). When the vortex is placed at certain discrete positions in the strip middle, the pattern I c (H) has zero at H=0 instead of the traditional maximum of ‘0-type’ junctions. The number of these positions is equal to the number of vortices trapped at the same location. When the junction–vortex separation exceeds ∼W, the strip width, I c (H) is no longer sensitive to the vortex presence. The same is true for any separation if the vortex approaches the strip edges

Concept and design of super junction devices

Science.gov (United States)

Zhang, Bo; Zhang, Wentong; Qiao, Ming; Zhan, Zhenya; Li, Zhaoji

2018-02-01

The super junction (SJ) has been recognized as the " milestone” of the power MOSFET, which is the most important innovation concept of the voltage-sustaining layer (VSL). The basic structure of the SJ is a typical junction-type VSL (J-VSL) with the periodic N and P regions. However, the conventional VSL is a typical resistance-type VSL (R-VSL) with only an N or P region. It is a qualitative change of the VSL from the R-VSL to the J-VSL, introducing the bulk depletion to increase the doping concentration and optimize the bulk electric field of the SJ. This paper firstly summarizes the development of the SJ, and then the optimization theory of the SJ is discussed for both the vertical and the lateral devices, including the non-full depletion mode, the minimum specific on-resistance optimization method and the equivalent substrate model. The SJ concept breaks the conventional " silicon limit” relationship of R on∝V B 2.5, showing a quasi-linear relationship of R on∝V B 1.03.

Dynamics of domain wall networks with junctions

International Nuclear Information System (INIS)

Avelino, P. P.; Oliveira, J. C. R. E.; Martins, C. J. A. P.; Menezes, J.; Menezes, R.

2008-01-01

We use a combination of analytic tools and an extensive set of the largest and most accurate three-dimensional field theory numerical simulations to study the dynamics of domain wall networks with junctions. We build upon our previous work and consider a class of models which, in the limit of large number N of coupled scalar fields, approaches the so-called ''ideal'' model (in terms of its potential to lead to network frustration). We consider values of N between N=2 and N=20, and a range of cosmological epochs, and we also compare this class of models with other toy models used in the past. In all cases we find compelling evidence for a gradual approach to scaling, strongly supporting our no-frustration conjecture. We also discuss the various possible types of junctions (including cases where there is a hierarchy of them) and their roles in the dynamics of the network. Finally, we provide a cosmological Zel'dovich-type bound on the energy scale of this kind of defect network: it must be lower than 10 keV.

Desmosomal Molecules In and Out of Adhering Junctions: Normal and Diseased States of Epidermal, Cardiac and Mesenchymally Derived Cells

Directory of Open Access Journals (Sweden)

Sebastian Pieperhoff

2010-01-01

Full Text Available Current cell biology textbooks mention only two kinds of cell-to-cell adhering junctions coated with the cytoplasmic plaques: the desmosomes (maculae adhaerentes, anchoring intermediate-sized filaments (IFs, and the actin microfilament-anchoring adherens junctions (AJs, including both punctate (puncta adhaerentia and elongate (fasciae adhaerentes structures. In addition, however, a series of other junction types has been identified and characterized which contain desmosomal molecules but do not fit the definition of desmosomes. Of these special cell-cell junctions containing desmosomal glycoproteins or proteins we review the composite junctions (areae compositae connecting the cardiomyocytes of mature mammalian hearts and their importance in relation to human arrhythmogenic cardiomyopathies. We also emphasize the various plakophilin-2-positive plaques in AJs (coniunctiones adhaerentes connecting proliferatively active mesenchymally-derived cells, including interstitial cells of the heart and several soft tissue tumor cell types. Moreover, desmoplakin has also been recognized as a constituent of the plaques of the complexus adhaerentes connecting certain lymphatic endothelial cells. Finally, we emphasize the occurrence of the desmosomal transmembrane glycoprotein, desmoglein Dsg2, out of the context of any junction as dispersed cell surface molecules in certain types of melanoma cells and melanocytes. This broadening of our knowledge on the diversity of AJ structures indicates that it may still be too premature to close the textbook chapters on cell-cell junctions.

Common features of a vortex structure in long exponentially shaped Josephson junctions and Josephson junctions with inhomogeneities

International Nuclear Information System (INIS)

Boyadjiev, T.L.; Semerdjieva, E.G.; Shukrinov, Yu.M.

2007-01-01

We study the vortex structure in three different models of the long Josephson junction: the exponentially shaped Josephson junction and the Josephson junctions with the resistor and the shunt inhomogeneities in the barrier layer. For these three models the critical curves 'critical current-magnetic field' are numerically constructed. We develop the idea of the equivalence of the exponentially shaped Josephson junction and the rectangular junction with the distributed inhomogeneity and demonstrate that at some parameters of the shunt and the resistor inhomogeneities in the ends of the junction the corresponding critical curves are very close to the exponentially shaped one

Scientific publications on portal vein thrombosis and Budd-Chiari syndrome: a global survey of the literature.

Science.gov (United States)

Qi, Xingshun; Jia, Jia; Ren, Weirong; Yang, Man; De Stefano, Valerio; Wang, Juan; Fan, Daiming

2014-03-01

Portal vein thrombosis (PVT) and Budd-Chiari syndrome (BCS) are two rare vascular disorders of the liver that can lead to life-threatening complications. We conducted a global survey to systematically analyze the scientific publications in the fields of PVT and BCS. All papers regarding PVT and BCS were identified via the PubMed, EMBASE, and Cochrane library databases. The publication year, country, type of paper, study design, and number of citations were summarized. Good quality papers were defined as those in which a high proportion of homogeneous patients with BCS and/or PVT was observed. We identified 6691 and 4325 papers regarding PVT and BCS, respectively. The number of papers gradually increased over time. Researchers from the USA published the greatest number of papers (PVT: n=1418; BCS: n=888). Clinical studies were the most common type of paper (PVT: n=5395; BCS n=3171), but fewer than half of these observed more than 10 patients (PVT: n=2667/5395; BCS: n=1092/3171). Furthermore, fewer than half of the clinical studies with more than 10 patients were of good quality (PVT: 976/2667; BCS: 466/1092). According to the study design, the good quality papers were classified as cohort studies (PVT: n=865; BCS: n=421), case-control studies (PVT: n=98; BCS: n=45), and randomized controlled trials (PVT: n=13; BCS: n=0). The 5 most frequently cited original articles and guidelines/consensuses were also listed. Despite an increase in the number of papers regarding PVT and BCS over time, most of the papers had a small sample size, suggesting the necessity of large cohort studies or randomized controlled trials.

Behavior of tight-junction, adherens-junction and cell polarity proteins during HNF-4α-induced epithelial polarization

International Nuclear Information System (INIS)

Satohisa, Seiro; Chiba, Hideki; Osanai, Makoto; Ohno, Shigeo; Kojima, Takashi; Saito, Tsuyoshi; Sawada, Norimasa

2005-01-01

We previously reported that expression of tight-junction molecules occludin, claudin-6 and claudin-7, as well as establishment of epithelial polarity, was triggered in mouse F9 cells expressing hepatocyte nuclear factor (HNF)-4α [H. Chiba, T. Gotoh, T. Kojima, S. Satohisa, K. Kikuchi, M. Osanai, N. Sawada. Hepatocyte nuclear factor (HNF)-4α triggers formation of functional tight junctions and establishment of polarized epithelial morphology in F9 embryonal carcinoma cells, Exp. Cell Res. 286 (2003) 288-297]. Using these cells, we examined in the present study behavior of tight-junction, adherens-junction and cell polarity proteins and elucidated the molecular mechanism behind HNF-4α-initiated junction formation and epithelial polarization. We herein show that not only ZO-1 and ZO-2, but also ZO-3, junctional adhesion molecule (JAM)-B, JAM-C and cell polarity proteins PAR-3, PAR-6 and atypical protein kinase C (aPKC) accumulate at primordial adherens junctions in undifferentiated F9 cells. In contrast, CRB3, Pals1 and PATJ appeared to exhibit distinct subcellular localization in immature cells. Induced expression of HNF-4α led to translocation of these tight-junction and cell polarity proteins to beltlike tight junctions, where occludin, claudin-6 and claudin-7 were assembled, in differentiated cells. Interestingly, PAR-6, aPKC, CRB3 and Pals1, but not PAR-3 or PATJ, were also concentrated on the apical membranes in differentiated cells. These findings indicate that HNF-4α provokes not only expression of tight-junction adhesion molecules, but also modulation of subcellular distribution of junction and cell polarity proteins, resulting in junction formation and epithelial polarization

Flexible 2D layered material junctions

Science.gov (United States)

Balabai, R.; Solomenko, A.

2018-03-01

Within the framework of the methods of the electron density functional and the ab initio pseudopotential, we have obtained the valence electron density spatial distribution, the densities of electron states, the widths of band gaps, the charges on combined regions, and the Coulomb potentials for graphene-based flexible 2D layered junctions, using author program complex. It is determined that the bending of the 2D layered junctions on the angle α leads to changes in the electronic properties of these junctions. In the graphene/graphane junction, there is clear charge redistribution with different signs in the regions of junctions. The presence in the heterojunctions of charge regions with different signs leads to the formation of potential barriers. The greatest potential jump is in the graphene/fluorographene junction. The greatest value of the band gap width is in the graphene/graphane junction.

Dielectric properties of biological tissues in which cells are connected by communicating junctions

International Nuclear Information System (INIS)

Asami, Koji

2007-01-01

The frequency dependence of the complex permittivity of biological tissues has been simulated using a simple model that is a cubic array of spherical cells in a parallel plate capacitor. The cells are connected by two types of communicating junctions: one is a membrane-lined channel for plasmodesmata in plant tissues, and the other is a conducting patch of adjoining plasma membranes for gap junctions in animal tissues. Both junctions provided similar effects on the dielectric properties of the tissue model. The model without junction showed a dielectric relaxation (called β-dispersion) that was expected from an interfacial polarization theory for a concentrated suspension of spherical cells. The dielectric relaxation was the same as that of the model in which neighbouring cells were connected by junctions perpendicular to the applied electric field. When neighbouring cells were connected by junctions parallel to the applied electric field or in all directions, a dielectric relaxation appeared at a lower frequency side in addition to the β-dispersion, corresponding to the so called α-dispersion. When junctions were randomly introduced at varied probabilities P j , the low-frequency (LF) relaxation curve became broader, especially at P j of 0.2-0.5, and its intensity was proportional to P j up to 0.7. The intensity and the characteristic frequency of the LF relaxation both decreased with decreasing junction conductance. The simulations indicate that communicating junctions are important for understanding the LF dielectric relaxation in tissues

Dielectric properties of biological tissues in which cells are connected by communicating junctions

Science.gov (United States)

Asami, Koji

2007-06-01

The frequency dependence of the complex permittivity of biological tissues has been simulated using a simple model that is a cubic array of spherical cells in a parallel plate capacitor. The cells are connected by two types of communicating junctions: one is a membrane-lined channel for plasmodesmata in plant tissues, and the other is a conducting patch of adjoining plasma membranes for gap junctions in animal tissues. Both junctions provided similar effects on the dielectric properties of the tissue model. The model without junction showed a dielectric relaxation (called β-dispersion) that was expected from an interfacial polarization theory for a concentrated suspension of spherical cells. The dielectric relaxation was the same as that of the model in which neighbouring cells were connected by junctions perpendicular to the applied electric field. When neighbouring cells were connected by junctions parallel to the applied electric field or in all directions, a dielectric relaxation appeared at a lower frequency side in addition to the β-dispersion, corresponding to the so called α-dispersion. When junctions were randomly introduced at varied probabilities Pj, the low-frequency (LF) relaxation curve became broader, especially at Pj of 0.2-0.5, and its intensity was proportional to Pj up to 0.7. The intensity and the characteristic frequency of the LF relaxation both decreased with decreasing junction conductance. The simulations indicate that communicating junctions are important for understanding the LF dielectric relaxation in tissues.

A search for the coherently radiating fluxon state in stacks of long intrinsic Josephson junctions

CERN Document Server

Lee, H J; Bae, M H; Wang, H; Yamashita, T

2002-01-01

We studied the motion of fluxons in a stack of intrinsic Josephson junctions (IJJs) of Bi sub 2 Sr sub 2 CaCu sub 2 O sub 8 sub + subdelta single crystals in a long junction limit. Driven by the tunnelling bias, current Josephson fluxons excite plasma oscillations and move in resonance with the plasma propagation modes. We examined two types of samples in this study; mesa structure (UD1) and a stack of junctions sandwiched between normal-metallic electrodes (DSC1). In a high magnetic field, the hysteresis in the I-V characteristics of both-types of samples vanished. The resulting single I-V curve exhibited a cusp structure at characteristic bias voltages which were believed to be boundaries of different moving fluxon configurations. We studied the sample-geometry dependence of the cusp characteristics by comparing the results from the two types of samples.

Transoral approach to the craniovertebral junction Acesso transoral para a junção craniocervical

Directory of Open Access Journals (Sweden)

José Alberto Landeiro

2007-12-01

Full Text Available The transoral approach provides a safe exposure to lesions in the midline and the ventral side of the craniovertebral junction. The advantages of the transoral approach are 1 the impinging bony pathology and granulation tissue are accessible only via the ventral route; 2 the head is placed in the extended position, thus decreasing the angulation of the brainstem during the surgery; and 3 surgery is done through the avascular median pharyngeal raphe and clivus. We analyzed the clinical effects of odontoidectomy after treating 38 patients with basilar invagination. The anterior transoral operation to treat irreducible ventral compression in patients with basilar invagination was performed in 38 patients. The patients’ ages ranged from 34 to 67 years. Fourteen patients had associated Chiari malformation and eight had previously undergone posterior decompressive surgery. The main indication for surgery was significant neurological deterioration. Symptoms and signs included neck pain, myelopathy, lower cranial nerve dysfunction, nystagmus and gait disturbance. Extended exposure was performed in 24 patients. The surgery was beneficial to the majority of patients. There was one death within 10 days of surgery, due to pulmonary embolism. Postoperative complications included two cases of pneumonia, three cases of oronasal fistula with regurgitation and one cerebrospinal fluid leak. In patients with marked ventral compression, the transoral approach provides direct access to the anterior face of the craniovertebral junction and effective means for odontoidectomy.O acesso transoral é uma via direta e segura às lesões situadas na linha média e na face anterior da junção craniocervical. As vantagens do acesso transoral são as seguintes:1 a compressão óssea e o tecido de granulação localizam-se anteriormente e são accessíveis pela via anterior; 2 a cabeça do paciente é colocada em extensão, diminuindo a angulação do tronco cerebral durante

Microstructure of Josephson junctions: Effect on supercurrent transport in YBCO grain boundary and barrier layer junctions

International Nuclear Information System (INIS)

Merkle, K.L.; Huang, Y.

1998-01-01

The electric transport of high-temperature superconductors, such as YBa 2 Cu 3 O 7-x (YBCO), can be strongly restricted by the presence of high-angle grain boundaries (GB). This weak-link behavior is governed by the macroscopic GB geometry and the microscopic grain boundary structure and composition at the atomic level. Whereas grain boundaries present a considerable impediment to high current applications of high T c materials, there is considerable commercial interest in exploiting the weak-link-nature of grain boundaries for the design of microelectronic devices, such as superconducting quantum interference devices (SQUIDs). The Josephson junctions which form the basis of this technology can also be formed by introducing artificial barriers into the superconductor. The authors have examined both types of Josephson junctions by EM techniques in an effort to understand the connection between microstructure/chemistry and electrical transport properties. This knowledge is a valuable resource for the design and production of improved devices

Testicular cell junction: a novel target for male contraception.

Science.gov (United States)

Lee, Nikki P Y; Wong, Elissa W P; Mruk, Dolores D; Cheng, C Yan

2009-01-01

Even though various contraceptive methods are widely available, the number of unwanted pregnancies is still on the rise in developing countries, pressurizing the already resource limited nations. One of the major underlying reasons is the lack of effective, low cost, and safe contraceptives for couples. During the past decade, some studies were performed using animal models to decipher if the Sertoli-germ cell junction in the testis is a target for male fertility regulation. Some of these study models were based on the use of hormones and/or chemicals to disrupt the hypothalamic-pituitary-testicular axis (e.g., androgen-based implants or pills) and others utilized a panel of chemical entities or synthetic peptides to perturb spermatogenesis either reversibly or non-reversibly. Among them, adjudin, a potential male contraceptive, is one of the compounds exerting its action on the unique adherens junctions, known as ectoplasmic specializations, in the testis. Since the testis is equipped with inter-connected cell junctions, an initial targeting of one junction type may affect the others and these accumulative effects could lead to spermatogenic arrest. This review attempts to cover an innovative theme on how male infertility can be achieved by inducing junction instability and defects in the testis, opening a new window of research for male contraceptive development. While it will still take much time and effort of intensive investigation before a product can reach the consumable market, these findings have provided hope for better family planning involving men.

Dielectric effect on electric fields in the vicinity of the metal–vacuum–dielectric junction

International Nuclear Information System (INIS)

Chung, M.S.; Mayer, A.; Miskovsky, N.M.; Weiss, B.L.; Cutler, P.H.

2013-01-01

The dielectric effect was theoretically investigated in order to describe the electric field in the vicinity of a junction of a metal, dielectric, and vacuum. The assumption of two-dimensional symmetry of the junction leads to a simple analytic form and to a systematic numerical calculation for the field. The electric field obtained for the triple junction was found to be enhanced or reduced according to a certain criterion determined by the contact angles and dielectric constant. Further numerical calculations of the dielectric effect show that an electric field can experience a larger enhancement or reduction for a quadruple junction than that achieved for the triple junction. It was also found that even though it changes slowly in comparison with the shape effect, the dielectric effect was noticeably large over the entire range of the shape change. - Highlights: ► This work explains how a very strong electric field can be produced due to the dielectric in the vicinity of metal–dielectric contact. ► This work deals with configurations which enhance electric fields using the dielectric effect. The configuration is a type of junction at which metal, vacuum and dielectric meet. ► This work suggests the criterion to determine whether field enhancement occurs or not in the triple junction of metal, vacuum and dielectric. ► This work suggests that a quadruple junction is more effective in enhancing the electric field than a triple junction. The quadruple junction is formed by an additional vacuum portion to the triple junction. ► This work suggests that a triple junction can be a breakthrough candidate for a cold electron source

Transport Properties of ZnSe- ITO Hetero Junction

Science.gov (United States)

Ichibakase, Tsuyoshi

In this report, ITO(Indium Tin Oxide) was used on the glass substrates as the transparent electrode, and ZnSe layer was prepared by the vacuum deposition on this ITO. Then, the electrical characteristics of this sample were investigated by mans of the electric current transport analysis. The sample that ZnSe was prepared as 3.4 μm in case of ITO-ZnSe sample, has high density level at the junction surface. The ITO-ZnSe junction has two type of diffusion current. However, the ITO-ZnSe sample that ZnSe layer was prepared as 0.1 μm can be assumed as the ohmic contact, and ITO-ZnSe(0.1μm) -CdTe sample shows the avalanche breakdown, and it is considered that the avalanche breakdown occurs in CdTe layer. It is difficult to occur the avalanche breakdown, if ZnSe-CdTe junction has high-density level and CdTe layer has high-density defect. Hence, the ZnSe-CdTe sample that CdTe layer was prepared on ITO-ZnSe(0.1μm) substrate has not high-density level at the junction surface, and the CdTe layer with little lattice imperfection can be prepared. It found that ITO-ZnSe(0.1μm) substrate is available for the II-VI compounds semiconductor device through above analysis result.

The status of intercellular junctions in established lens epithelial cell lines.

Science.gov (United States)

Dave, Alpana; Craig, Jamie E; Sharma, Shiwani

2012-01-01

Cataract is the major cause of vision-related disability worldwide. Mutations in the crystallin genes are the most common known cause of inherited congenital cataract. Mutations in the genes associated with intercellular contacts, such as Nance-Horan Syndrome (NHS) and Ephrin type A receptor-2 (EPHA2), are other recognized causes of congenital cataract. The EPHA2 gene has been also associated with age-related cataract, suggesting that intercellular junctions are important in not only lens development, but also in maintaining lens transparency. The purpose of this study was to analyze the expression and localization of the key cell junction and cytoskeletal proteins, and of NHS and EPHA2, in established lens epithelial cell lines to determine their suitability as model epithelial systems for the functional investigation of genes involved in intercellular contacts and implicated in cataract. The expression and subcellular localization of occludin and zona occludens protein-1 (ZO-1), which are associated with tight junctions; E-cadherin, which is associated with adherence junctions; and the cytoskeletal actin were analyzed in monolayers of a human lens epithelial cell line (SRA 01/04) and a mouse lens epithelial cell line (αTN4). In addition, the expression and subcellular localization of the NHS and EPHA2 proteins were analyzed in these cell lines. Protein or mRNA expression was respectively determined by western blotting or reverse transcription-polymerase chain reaction (RT-PCR), and localization was determined by immunofluorescence labeling. Human SRA 01/04 and mouse αTN4 lens epithelial cells expressed either the proteins of interest or their encoding mRNA. Occludin, ZO-1, and NHS proteins localized to the cellular periphery, whereas E-cadherin, actin, and EPHA2 localized in the cytoplasm in these cell lines. The human SRA 01/04 and mouse αTN4 lens epithelial cells express the key junctional proteins. The localization patterns of these proteins suggest that

A prospective controlled study of sleep respiratory events in patients with craniovertebral junction malformation.

Science.gov (United States)

Botelho, Ricardo Vieira; Bittencourt, Lia Rita Azeredo; Rotta, José Marcos; Tufik, Sergio

2003-12-01

Craniovertebral junction malformation (CVJM) or Chiari malformation in adults, with or without syringomyelia and basilar invagination, produces neuronal dysfunction of the brainstem, cerebellum, cranial nerves, and upper spinal cord. The respiratory center and some of its afferent and efferent components can be altered in these diseases. The authors studied patients with and without CVJM to determine whether this physical feature contributed to sleep disturbances. Respiratory manifestations during sleep were studied prospectively, by using whole-night polysomnography, in 32 symptomatic patients (CVJM group) and 16 healthy volunteers (control group). Patients with CVJM presented with more sleep disturbances (reports of snoring and apnea) than those in the control group. The apnea/hypopnea index values were higher in patients with CVJMs than in the control group (13 +/- 15 compared with 3 +/- 6; p = 0.007) and the rate of central sleep apneas was higher in the CVJM than in the control group (22 +/- 30 compared with 4 +/- 8%; p = 0.009). The apnea/hypopnea index was highest in the subgroup with basilar invagination than in the other subgroups. The central apneic episodes were more frequent in the patients with basilar invagination (35 +/- 40%; p = 0.001) and in those with syringomyelia (17.6 +/- 24.6%; p = 0.003) than in the control group (4 +/- 8%). Patients with symptomatic CVJM, especially those with basilar invagination, presented with more sleep respiratory compromise than did those in the control group. The incidence of sleep apnea/hypopnea syndrome is significantly higher in patients with CVJM.

A Simple Method for Decreasing the Liquid Junction Potential in a Flow-through-Type Differential pH Sensor Probe Consisting of pH-FETs by Exerting Spatiotemporal Control of the Liquid Junction

Science.gov (United States)

Yamada, Akira; Mohri, Satoshi; Nakamura, Michihiro; Naruse, Keiji

2015-01-01

The liquid junction potential (LJP), the phenomenon that occurs when two electrolyte solutions of different composition come into contact, prevents accurate measurements in potentiometry. The effect of the LJP is usually remarkable in measurements of diluted solutions with low buffering capacities or low ion concentrations. Our group has constructed a simple method to eliminate the LJP by exerting spatiotemporal control of a liquid junction (LJ) formed between two solutions, a sample solution and a baseline solution (BLS), in a flow-through-type differential pH sensor probe. The method was contrived based on microfluidics. The sensor probe is a differential measurement system composed of two ion-sensitive field-effect transistors (ISFETs) and one Ag/AgCl electrode. With our new method, the border region of the sample solution and BLS is vibrated in order to mix solutions and suppress the overshoot after the sample solution is suctioned into the sensor probe. Compared to the conventional method without vibration, our method shortened the settling time from over two min to 15 s and reduced the measurement error by 86% to within 0.060 pH. This new method will be useful for improving the response characteristics and decreasing the measurement error of many apparatuses that use LJs. PMID:25835300

Molecular electronic junction transport

DEFF Research Database (Denmark)

Solomon, Gemma C.; Herrmann, Carmen; Ratner, Mark

2012-01-01

Whenasinglemolecule,oracollectionofmolecules,isplacedbetween two electrodes and voltage is applied, one has a molecular transport junction. We discuss such junctions, their properties, their description, and some of their applications. The discussion is qualitative rather than quantitative, and f...

Gap junctions and motor behavior

DEFF Research Database (Denmark)

Kiehn, Ole; Tresch, Matthew C.

2002-01-01

The production of any motor behavior requires coordinated activity in motor neurons and premotor networks. In vertebrates, this coordination is often assumed to take place through chemical synapses. Here we review recent data suggesting that electrical gap-junction coupling plays an important role...... in coordinating and generating motor outputs in embryonic and early postnatal life. Considering the recent demonstration of a prevalent expression of gap-junction proteins and gap-junction structures in the adult mammalian spinal cord, we suggest that neuronal gap-junction coupling might also contribute...... to the production of motor behavior in adult mammals....

Keratitis-Ichthyosis-Deafness syndrome-associated Cx26 mutants produce nonfunctional gap junctions but hyperactive hemichannels when co-expressed with wild type Cx43

Science.gov (United States)

García, Isaac E.; Maripillán, Jaime; Jara, Oscar; Ceriani, Ricardo; Palacios-Muñoz, Angelina; Ramachandran, Jayalakshimi; Olivero, Pablo; Pérez-Acle, Tomás; González, Carlos; Sáez, Juan C.; Contreras, Jorge E.; Martínez, Agustín D.

2015-01-01

Mutations in Cx26 gene are found in most cases of human genetic deafness. Some mutations produce syndromic deafness associated with skin disorders, like Keratitis Ichthyosis Deafness syndrome (KID). Because in the human skin Cx26 is co-expressed with other connexins, like Cx43 and Cx30, and since KID syndrome is inherited as autosomal dominant condition, it is possible that KID mutations change the way Cx26 interacts with other co-expressed connexins. Indeed, some Cx26 syndromic mutations showed gap junction dominant negative effect when co-expressed with wild type connexins, including Cx26 and Cx43. The nature of these interactions and the consequences on hemichannels and gap junction channels functions remain unknown. In this study we demonstrate that syndromic mutations at the N-terminus segment of Cx26, change connexin oligomerization compatibility, allowing aberrant interactions with Cx43. Strikingly, heteromeric oligomer formed by Cx43/Cx26 (syndromic mutants) show exacerbated hemichannel activity, but nonfunctional gap junction channels; this also occurs for those Cx26 KID mutants that do not show functional homomeric hemichannels. Heterologous expression of these hyperactive heteromeric hemichannels increases cell membrane permeability, favoring ATP release and Ca2+ overload. The functional paradox produced by oligomerization of Cx43 and Cx26 KID mutants could underlie the severe syndromic phenotype in human skin. PMID:25625422

Ferromagnetic Josephson Junctions for Cryogenic Memory

Science.gov (United States)

Niedzielski, Bethany M.; Gingrich, Eric C.; Khasawneh, Mazin A.; Loloee, Reza; Pratt, William P., Jr.; Birge, Norman O.

2015-03-01

Josephson junctions containing ferromagnetic materials are of interest for both scientific and technological purposes. In principle, either the amplitude of the critical current or superconducting phase shift across the junction can be controlled by the relative magnetization directions of the ferromagnetic layers in the junction. Our approach concentrates on phase control utilizing two junctions in a SQUID geometry. We will report on efforts to control the phase of junctions carrying either spin-singlet or spin-triplet supercurrent for cryogenic memory applications. Supported by Northorp Grumman Corporation and by IARPA under SPAWAR Contract N66001-12-C-2017.

Superconductor-Insulator transition in a single Josephson junction

International Nuclear Information System (INIS)

Sonin, E.B.; PenttilA, J.S.; Parts, O.; Hakonen, P.J.; Paalanen, M.A.

1999-01-01

For ultra small Josephson junctions, when quantum effects become important, dissipative phase transition (DPT) has been predicted. The physical origin of this transition is the suppression of macroscopic quantum tunneling of the phase by tile interaction with dissipative quantum-mechanical environment. Macroscopic quantum tunneling destroys superconductivity of a junction, whereas suppression of tunneling restores superconductivity. Hence, this transition is often called a superconductor-insulator transition (SIT). SIT was predicted for various systems, but its detection in a single Josephson junction is of principal importance since it is the simplest system where this transition is expected, without any risk of being masked by other physical processes, as is possible in more complicated systems like regular or' random Josephson junction arrays. In this Letter we present results of our measurements on R = dV/dI vs. I curves, for a variety of single small isolated Josephson junctions, shunted and un shunted, with different values of capacitance C and normal state tunneling resistance RT. We have detected a crossover. between two types of RI-curves with an essentially different behavior at small currents. On the basis of this crossover, we are able to map out the whole phase diagram for a Josephson junction. The position of the observed phase boundary did not agree with that expected from the original theory. However, the theory revised to take into account a finite accuracy of our voltage measurements (viz., the minimum voltage which we are able to detect), explains well the observed phase diagram. Our important conclusion is that the concept of dissipative phase transition (DPT) and superconductor-insulator transition (SIT) are not completely identical as assumed before. Both are accompanied by the sign change of the thermo resistance, which is traditionally considered as a signature of SIT. Thus any DPT is SIT, but not vice versa. We argue that the real signature

Electronic noise of superconducting tunnel junction detectors

International Nuclear Information System (INIS)

Jochum, J.; Kraus, H.; Gutsche, M.; Kemmather, B.; Feilitzsch, F. v.; Moessbauer, R.L.

1994-01-01

The optimal signal to noise ratio for detectors based on superconducting tunnel junctions is calculated and compared for the cases of a detector consisting of one single tunnel junction, as well as of series and of parallel connections of such tunnel junctions. The influence of 1 / f noise and its dependence on the dynamical resistance of tunnel junctions is discussed quantitatively. A single tunnel junction yields the minimum equivalent noise charge. Such a tunnel junction exhibits the best signal to noise ratio if the signal charge is independent of detector size. In case, signal charge increases with detector size, a parallel or a series connection of tunnel junctions would provide the optimum signal to noise ratio. The equivalent noise charge and the respective signal to noise ratio are deduced as functions of tunnel junction parameters such as tunneling time, quasiparticle lifetime, etc. (orig.)

Modeling and Design of Graphene GaAs Junction Solar Cell

Directory of Open Access Journals (Sweden)

Yawei Kuang

2015-01-01

Full Text Available Graphene based GaAs junction solar cell is modeled and investigated by Silvaco TCAD tools. The photovoltaic behaviors have been investigated considering structure and process parameters such as substrate thickness, dependence between graphene work function and transmittance, and n-type doping concentration in GaAs. The results show that the most effective region for photo photogenerated carriers locates very close to the interface under light illumination. Comprehensive technological design for junction yields a significant improvement of power conversion efficiency from 0.772% to 2.218%. These results are in good agreement with the reported experimental work.

Transjugular intrahepatic portosystemic shunt for severe jaundice in patients with acute Budd-Chiari syndrome.

Science.gov (United States)

He, Fu-Liang; Wang, Lei; Zhao, Hong-Wei; Fan, Zhen-Hua; Zhao, Meng-Fei; Dai, Shan; Yue, Zhen-Dong; Liu, Fu-Quan

2015-02-28

To evaluate the feasibility of transjugular intrahepatic portosystemic shunt (TIPS) for severe jaundice secondary to acute Budd-Chiari syndrome (BCS). From February 2009 to March 2013, 37 patients with severe jaundice secondary to acute BCS were treated. Sixteen patients without hepatic venule, hepatic veins (HV) obstruction underwent percutaneous angioplasty of the inferior vena cava (IVC) and/or HVs. Twenty-one patients with HV occlusion underwent TIPS. Serum bilirubin, liver function, demographic data and operative data of the two groups of patients were analyzed. Twenty-one patients underwent TIPS and the technical success rate was 100%, with no technical complications. Sixteen patients underwent recanalization of the IVC and/or HVs and the technical success rate was 100%. The mean procedure time for TIPS was 84.0±12.11 min and angioplasty was 44.11±5.12 min (Pjaundice in either group. Severe jaundice is not a contraindication for TIPS in patients with acute BCS and TIPS is appropriate for severe jaundice due to BCS.

Atomic-scaled characterization of graphene PN junctions

Science.gov (United States)

Zhou, Xiaodong; Wang, Dennis; Dadgar, Ali; Agnihotri, Pratik; Lee, Ji Ung; Reuter, Mark C.; Ross, Frances M.; Pasupathy, Abhay N.

Graphene p-n junctions are essential devices for studying relativistic Klein tunneling and the Veselago lensing effect in graphene. We have successfully fabricated graphene p-n junctions using both lithographically pre-patterned substrates and the stacking of vertical heterostructures. We then use our 4-probe STM system to characterize the junctions. The ability to carry out scanning electron microscopy (SEM) in our STM instrument is essential for us to locate and measure the junction interface. We obtain both the topography and dI/dV spectra at the junction area, from which we track the shift of the graphene chemical potential with position across the junction interface. This allows us to directly measure the spatial width and roughness of the junction and its potential barrier height. We will compare the junction properties of devices fabricated by the aforementioned two methods and discuss their effects on the performance as a Veselago lens.

The prognostic relevance of parapyloric lymph node metastasis in Siewert type II/III adenocarcinoma of the esophagogastric junction.

Science.gov (United States)

Wang, Jia-Bin; Lin, Man-Qiang; Li, Ping; Xie, Jian-Wei; Lin, Jian-Xian; Lu, Jun; Chen, Qi-Yue; Cao, Long-Long; Lin, Mi; Zheng, Chao-Hui; Huang, Chang-Ming

2017-12-01

The purpose of this study was to evaluate the prognosis of patients with Siewert type II/III adenocarcinoma of the esophagogastric junction (AEG) with parapyloric lymph node (No. 5 and 6 lymph nodes, PLN) metastasis and to determine the need for PLN dissection for patients with type II/III AEG. A total of 1008 patients with type II/III AEG who underwent a transabdominal total gastrectomy were enrolled. The long-term surgical outcome of PLN-positive patients and the therapeutic value of PLN dissection were analyzed. There was no significant difference in the incidence of PLN metastasis between type II and III cancers (5.7% vs. 8.5%, P > 0.05). PLN metastasis was a significant prognostic factor for type II/III cancers (HR 1.63; P = 0.001). Among type II/III cancers, the 5-year survival of patients with PLN-positive cancers was much lower than that of patients with PLN-negative cancers (21.3% vs. 60.8%, P  0.05). In the analysis of the therapeutic value of lymph node dissection in each station for type II and III cancers after radical resection, lymph nodes with the lowest therapeutic value index after No. 12a were No. 5 and 6 lymph nodes. Patients with type II/III AEG with PLN metastasis have a poor prognosis, similar to patients with stage IV disease. PLN dissection offers marginal therapeutic value for patients with type II/III AEG. Copyright © 2017 Elsevier Ltd, BASO ~ The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.

Four-state non-volatile memory in a multiferroic spin filter tunnel junction

Science.gov (United States)

Ruan, Jieji; Li, Chen; Yuan, Zhoushen; Wang, Peng; Li, Aidong; Wu, Di

2016-12-01

We report a spin filter type multiferroic tunnel junction with a ferromagnetic/ferroelectric bilayer barrier. Memory functions of a spin filter magnetic tunnel junction and a ferroelectric tunnel junction are combined in this single device, producing four non-volatile resistive states that can be read out in a non-destructive manner. This concept is demonstrated in a LaNiO3/Pr0.8Ca0.2MnO3/BaTiO3/La0.7Sr0.3MnO3 all-oxide tunnel junction. The ferromagnetic insulator Pr0.8Ca0.2MnO3 serves as the spin filter and the ferromagnetic metal La0.7Sr0.3MnO3 is the spin analyzer. The ferroelectric polarization reversal in the BaTiO3 barrier switches the tunneling barrier height to produce a tunneling electroresistance. The ferroelectric switching also modulates the spin polarization and the spin filtering efficiency in Pr0.8Ca0.2MnO3.

Organization of cellular receptors into a nanoscale junction during HIV-1 adhesion.

Directory of Open Access Journals (Sweden)

Terrence M Dobrowsky

2010-07-01

Full Text Available The fusion of the human immunodeficiency virus type 1 (HIV-1 with its host cell is the target for new antiretroviral therapies. Viral particles interact with the flexible plasma membrane via viral surface protein gp120 which binds its primary cellular receptor CD4 and subsequently the coreceptor CCR5. However, whether and how these receptors become organized at the adhesive junction between cell and virion are unknown. Here, stochastic modeling predicts that, regarding binding to gp120, cellular receptors CD4 and CCR5 form an organized, ring-like, nanoscale structure beneath the virion, which locally deforms the plasma membrane. This organized adhesive junction between cell and virion, which we name the viral junction, is reminiscent of the well-characterized immunological synapse, albeit at much smaller length scales. The formation of an organized viral junction under multiple physiopathologically relevant conditions may represent a novel intermediate step in productive infection.

Electron transport in dipyridazine and dipyridimine molecular junctions: a first-principles investigation

Science.gov (United States)

Parashar, Sweta

2018-05-01

We present density functional theory-nonequilibrium Green’s function method for electron transport of dipyridazine and dipyridimine molecular junctions with gold, copper and nickel electrodes. Our investigation reveals that the junctions formed with gold and copper electrodes bridging dipyridazine molecule through thiol anchoring group enhance current as compared to the junctions in which the molecule and electrode were coupled directly. Further, nickel electrode displays weak decrease of current with increase of voltage at about 1.2 V. The result is fully rationalized by means of the distribution of molecular orbitals as well as shift in molecular energy levels and HOMO-LUMO gap with applied bias voltage. Our findings are compared with theoretical and experimental results available for other molecular junctions. Present results predict potential avenues for changing the transport behavior by not only changing the electrodes, but also the position of nitrogen atom and type of anchoring-atom that connect molecule and electrodes, thus extending applications of dipyridazine and dipyridimine molecule in future integrated circuits.

Progress in the development of metamorphic multi-junction III-V space solar cells

Energy Technology Data Exchange (ETDEWEB)

Sinharoy, S.; Patton, M.O.; Valko, T.M.; Weizer, V.G. [Essential Research Inc., Cleveland, OH (United States)

2002-07-01

Theoretical calculations have shown that highest-efficiency III-V multi-junction solar cells require alloy structures that cannot be grown on a lattice-matched substrate. Ever since the first demonstration of high efficiency metamorphic single-junction 1.1 and 1.2 eV InGaAs solar cells, interest has grown in the development of multi-junction cells of this type, using graded buffer layer technology. Essential Research Incorporated (ERI) is currently developing a dual-junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air-mass zero (AMO), one-sun efficiency of 27%, and 100-sun efficiency of 31.1%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort involves the development of a 2.1 eV A1GaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple-junction concentrator tandem cell (projected practical AMO efficiency 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual-junction cell performance. For the triple-junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper. (author)

Primary Budd-Chiari syndrome - a single center experience.

Science.gov (United States)

Raszeja-Wyszomirska, Joanna; Mieżyńska-Kurtycz, Joanna; Marlicz, Wojciech; Lawniczak, Małgorzata; Wójcicki, Maciej

2012-09-01

Budd-Chiari syndrome (BCS) is recognized as a clinical manifestation of various prothrombotic conditions which may be lethal within 3 years of the onset of symptoms if untreated. This study is a retrospective analysis of patients with BCS managed between 2004 and 2011. The diagnosis was confirmed with contrast CT-angiography and/or Doppler ultrasound. BCS was diagnosed in 20 patients (11 females and 9 males), median age 38 years (ranging from 18 to 56). Twelve patients were referred as acute BCS for the liver transplant (LTx) assessment. Thrombosis of the hepatic veins was caused by myeloproliferative disorders (n=8), end-stage liver disease (n=4), protein C deficiency (n=3), paroxysmal nocturnal hemoglobinuria (PNH) (n=1), antiphospholipid syndrome (n=1) and secondary poliglobulia (n=1). In two patients the origin of BCS could not be established despite appropriate screening. Median follow-up was 29 months. Low molecular heparin with subsequent conversion to vitamin K antagonists was routinely applied in all patients. Two patients underwent TIPS procedure with good long term outcome and 10 subjects received LTx; 1 patient was lost to follow-up and 1 died of chest infection 9 years since the diagnosis of BCS was made; 14 patients, including those who received LTx, were alive and well at least one year after BCS diagnosis. All survivors remain stable and are followed-up on a regular basis. Strict adherence to the diagnostic and therapeutic guidelines plays a crucial role in the management of BCS patients. Our results confirm the efficacy of anticoagulation as well as TIPS and/or OLT in treatment of this rare condition.

Charge and spin current oscillations in a tunnel junction induced by magnetic field pulses

Energy Technology Data Exchange (ETDEWEB)

Dartora, C.A., E-mail: cadartora@eletrica.ufpr.br [Electrical Engineering Department, Federal University of Parana (UFPR), C.P. 19011 Curitiba, 81.531-970 PR (Brazil); Nobrega, K.Z., E-mail: bzuza1@yahoo.com.br [Federal Institute of Education, Science and Technolgy of Maranhão (IFMA), Av. Marechal Castelo Branco, 789, São Luís, 65.076-091 MA (Brazil); Cabrera, G.G., E-mail: cabrera@ifi.unicamp.br [Instituto de Física ‘Gleb Wataghin’, Universidade Estadual de Campinas (UNICAMP), C.P. 6165, Campinas 13.083-970 SP (Brazil)

2016-08-15

Usually, charge and spin transport properties in tunnel junctions are studied in the DC bias regime and/or in the adiabatic regime of time-varying magnetic fields. In this letter, the temporal dynamics of charge and spin currents in a tunnel junction induced by pulsed magnetic fields is considered. At low bias voltages, energy and momentum of the conduction electrons are nearly conserved in the tunneling process, leading to the description of the junction as a spin-1/2 fermionic system coupled to time-varying magnetic fields. Under the influence of pulsed magnetic fields, charge and spin current can flow across the tunnel junction, displaying oscillatory behavior, even in the absence of DC bias voltage. A type of spin capacitance function, in close analogy to electric capacitance, is predicted.

Two-dimensional dopant profiling of gallium nitride p-n junctions by scanning capacitance microscopy

Science.gov (United States)

Lamhamdi, M.; Cayrel, F.; Frayssinet, E.; Bazin, A. E.; Yvon, A.; Collard, E.; Cordier, Y.; Alquier, D.

2016-04-01

Two-dimensional imaging of dopant profiles for n and p-type regions are relevant for the development of new power semiconductors, especially for gallium nitride (GaN) for which classical profiling techniques are not adapted. This is a challenging task since it needs a technique with simultaneously good sensitivity, high spatial resolution and high dopant gradient resolution. To face these challenges, scanning capacitance microscopy combined with Atomic Force Microscopy is a good candidate, presenting reproducible results, as demonstrated in literature. In this work, we attempt to distinguish reliably and qualitatively the various doping concentrations and type at p-n and unipolar junctions. For both p-n and unipolar junctions three kinds of samples were prepared and measured separately. The space-charge region of the p-n metallurgical junction, giving rise to different contrasts under SCM imaging, is clearly observed, enlightening the interest of the SCM technique.

Two-dimensional dopant profiling of gallium nitride p–n junctions by scanning capacitance microscopy

Energy Technology Data Exchange (ETDEWEB)

Lamhamdi, M. [GREMAN UMR 7347-Université de Tours, 10 Rue Thales de Milet, BP 7155, 37071 Tours (France); Ecole national des sciences appliquées khouribga, Université Hassan 1er, 26000 Settat (Morocco); Cayrel, F. [GREMAN UMR 7347-Université de Tours, 10 Rue Thales de Milet, BP 7155, 37071 Tours (France); Frayssinet, E. [CRHEA-CNRS, Rue Bernard Grégory, Sophia Antipolis, 06560 Valbonne (France); Bazin, A.E.; Yvon, A.; Collard, E. [STMicroelectronics, 16 Rue Pierre et Marie Curie, BP 7155, 37071 Tours (France); Cordier, Y. [CRHEA-CNRS, Rue Bernard Grégory, Sophia Antipolis, 06560 Valbonne (France); Alquier, D. [GREMAN UMR 7347-Université de Tours, 10 Rue Thales de Milet, BP 7155, 37071 Tours (France)

2016-04-01

Two-dimensional imaging of dopant profiles for n and p-type regions are relevant for the development of new power semiconductors, especially for gallium nitride (GaN) for which classical profiling techniques are not adapted. This is a challenging task since it needs a technique with simultaneously good sensitivity, high spatial resolution and high dopant gradient resolution. To face these challenges, scanning capacitance microscopy combined with Atomic Force Microscopy is a good candidate, presenting reproducible results, as demonstrated in literature. In this work, we attempt to distinguish reliably and qualitatively the various doping concentrations and type at p–n and unipolar junctions. For both p–n and unipolar junctions three kinds of samples were prepared and measured separately. The space-charge region of the p–n metallurgical junction, giving rise to different contrasts under SCM imaging, is clearly observed, enlightening the interest of the SCM technique.

Analysis of the treatment of 576 patients with congenital craniovertebral junction malformations.

Science.gov (United States)

Li, Lianfeng; Yu, Xinguang; Wang, Peng; Chen, Lifeng

2012-01-01

We aim to report our experience treating craniovertebral junction malformations (CVJM) and to investigate the management of this uncommon condition. Between 2000 and 2009, 629 patients with CVJM underwent surgery in our department. Fifty-three patients were lost to follow-up; therefore 576 patients completed follow-up, for an average period of 3 years and 2 months. All patients were diagnosed on the basis of clinical presentation and imaging features, and we found that anomalies of the occipitocervical junction manifested as four major types. Different microsurgical treatments were carried out in these patients according to disease type, and the effectiveness of individualised treatments was analysed. Categorizing patients with CVJM into these four types to simplify this somewhat unclear area could provide insight into the pathogenesis of the anomaly and a basis for rational surgical treatment. Copyright © 2011. Published by Elsevier Ltd.

Stability of large-area molecular junctions

NARCIS (Netherlands)

Akkerman, Hylke B.; Kronemeijer, Auke J.; Harkema, Jan; van Hal, Paul A.; Smits, Edsger C. P.; de Leeuw, Dago M.; Blom, Paul W. M.

The stability of molecular junctions is crucial for any application of molecular electronics. Degradation of molecular junctions when exposed to ambient conditions is regularly observed. In this report the stability of large-area molecular junctions under ambient conditions for more than two years

Superconducting flux qubits with π-junctions

International Nuclear Information System (INIS)

Shcherbakova, Anastasia

2014-01-01

In this thesis, we present a fabrication technology of Al/AlO x /Al Josephson junctions on Nb pads. The described technology gives the possibility of combining a variety of Nb-based superconducting circuits, like pi-junction phase-shifters with sub-micron Al/AlO x /Al junctions. Using this approach, we fabricated hybrid Nb/Al flux qubits with and without the SFS-junctions and studied dispersive magnetic field response of these qubits as well as their spectroscopy characteristics.

Transport properties of monolayer and bilayer graphene p-n junctions with charge puddles in the quantum Hall regime

International Nuclear Information System (INIS)

Cheng Shuguang

2010-01-01

Recent experiments have confirmed that the electron-hole inhomogeneity in graphene is a new type of charge disorder. Motivated by such confirmation, we theoretically study the transport properties of a monolayer graphene (MLG) based p-n junction and a bilayer graphene (BLG) p-n junction in the quantum Hall regime where electron-hole puddles are considered. By using the non-equilibrium Green function method, both the current and conductance are obtained. We find that, in the presence of the electron-hole inhomogeneity, the lowest quantized conductance plateau at e 2 /h emerges in the MLG p-n junction under very small charge puddle disorder strength. For a BLG p-n junction, however, the conductance in the p-n region is enhanced with charge puddles, and the lowest quantized conductance plateau emerges at 2e 2 /h. Besides, when an ideal quantized conductance plateau is formed for a MLG p-n junction, the universal conductance fluctuation is found to be 2e 2 /3h. Furthermore, we also investigate the influence of Anderson disorder on such p-n junctions and the comparison and discussion are given accordingly. To compare the two models with different types of disorder, we investigate the conductance distribution specially. Finally the influence of disorder strength on the conductance of a MLG p-n junction is investigated.

Malformación de Arnold-Chiari: la pérdida de la sonrisa

Directory of Open Access Journals (Sweden)

Antonio Martínez-Sabater

2014-12-01

Full Text Available La Malformación de Arnold-Chiari es una enfermedad rara caracterizada por la presencia de síntomas insidiosos que pueden suponer un retraso en el diagnóstico. Las características sintomatológicas como el dolor, la pérdida de fuerza progresiva, los mareos, etc., junto con los efectos secundarios de los fármacos indicados para el tratamiento sintomático (anticonvulsionantes, antidepresivos, analgésicos, etc. supone una pérdida de la calidad de vida de la persona. Aspectos de la calidad de vida que en un entorno biomédico suelen pasar desapercibidos, y juntamente, con la falta de repercusión exterior de la patología, supone la incomprensión de las personas del entorno. Con el fin de poder conocer las percepciones y experiencias de una persona afecta se ha utilizado la historia de vida, presentando la historia de Javi, que por su doble vertiente de persona afecta y personal sanitario, se convierte en informante clave.

Josephson junctions with ferromagnetic interlayer

International Nuclear Information System (INIS)

Wild, Georg Hermann

2012-01-01

We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO x /Pd 0.82 Ni 0.18 /Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to π-coupling is observed for a thickness d F =6 nm of the ferromagnetic Pd 0.82 Ni 0.18 interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd 0.82 Ni 0.18 has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

Josephson junctions with ferromagnetic interlayer

Energy Technology Data Exchange (ETDEWEB)

Wild, Georg Hermann

2012-03-04

We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

Inhibition of connexin43 gap junction channels by the endocrine disruptor ioxynil

International Nuclear Information System (INIS)

Leithe, Edward; Kjenseth, Ane; Bruun, Jarle; Sirnes, Solveig; Rivedal, Edgar

2010-01-01

Gap junctions are intercellular plasma membrane domains containing channels that mediate transport of ions, metabolites and small signaling molecules between adjacent cells. Gap junctions play important roles in a variety of cellular processes, including regulation of cell growth and differentiation, maintenance of tissue homeostasis and embryogenesis. The constituents of gap junction channels are a family of trans-membrane proteins called connexins, of which the best-studied is connexin43. Connexin43 functions as a tumor suppressor protein in various tissue types and is frequently dysregulated in human cancers. The pesticide ioxynil has previously been shown to act as an endocrine disrupting chemical and has multiple effects on the thyroid axis. Furthermore, both ioxynil and its derivative ioxynil octanoate have been reported to induce tumors in animal bioassays. However, the molecular mechanisms underlying the possible tumorigenic effects of these compounds are unknown. In the present study we show that ioxynil and ioxynil octanoate are strong inhibitors of connexin43 gap junction channels. Both compounds induced rapid loss of connexin43 gap junctions at the plasma membrane and increased connexin43 degradation. Ioxynil octanoate, but not ioxynil, was found to be a strong activator of ERK1/2. The compounds also had different effects on the phosphorylation status of connexin43. Taken together, the data show that ioxynil and ioxynil octanoate are potent inhibitors of intercellular communication via gap junctions.

Finite element analysis of inclined nozzle-plate junctions

International Nuclear Information System (INIS)

Dixit, K.B.; Seth, V.K.; Krishnan, A.; Ramamurthy, T.S.; Dattaguru, B.; Rao, A.K.

1979-01-01

Estimation of stress concentration at nozzle to plate or shell junctions is a significant problem in the stress analysis of nuclear reactors. The topic is a subject matter of extensive investigations and earlier considerable success has been reported on analysis for the cases when the nozzle is perpendicular to the plate or is radial to the shell. Analytical methods for the estimation of stress concentrations for the practical situations when the intersecting nozzle is inclined to the plate or is non-radial to the shell is rather scanty. Specific complications arise in dealing with the junction region when the nozzle with circular cross-section meets the non-circular cut-out on the plate or shell. In this paper a finite element analysis is developed for inclined nozzles and results are presented for nozzle-plate junctions. A method of analysis is developed with a view to achieving simultaneously accuracy of results and simplicity in the choice of elements and their connectivity. The circular nozzle is treated by axisymmetric conical shell elements. The nozzle portion in the region around the junction and the flat plate is dealt with by triangular flat shell elements. Special transition elements are developed for joining the flat shell elements with the axisymmetric elements under non-axisymmetric loading. A substructure method of analysis is adopted which achieves considerable economy in handling the structure and also conveniently combines the different types of elements in the structure. (orig.)

Malformação de Chiari do tipo II sintomática

Directory of Open Access Journals (Sweden)

SALOMÃO J. FRANCISCO

1998-01-01

Full Text Available Os autores analisam uma série de 17 crianças portadoras de mielodisplasias que desenvolveram sinais e sintomas da malformação de Chiari do tipo II. De acordo com a idade, dois grupos ficaram bem definidos: Grupo I, crianças no primeiro ano de vida, em que predominaram sinais e sintomas de comprometimento do tronco encefálico e nervos cranianos bulbares (n=13; Grupo II, composto por crianças com idade superior a um ano, em que as principais manifestações foram dor cervical e sinais cerebelares (n=4. O resultado do tratamento cirúrgico nos dois grupos foi distinto: enquanto a mortalidade no Grupo I atingiu 46,1%, nenhum paciente do Grupo II veio a falecer. O tratamento inicial consistiu na instalação ou revisão de derivação ventricular, sendo a descompressão crânio-vertebral reservada àqueles que não se beneficiaram com esses procedimentos. Os autores enfatizam a necessidade do imediato reconhecimento e tratamento do quadro, de modo a se obter resultados satisfatórios.

Electron optics with ballistic graphene junctions

Science.gov (United States)

Chen, Shaowen

Electrons transmitted across a ballistic semiconductor junction undergo refraction, analogous to light rays across an optical boundary. A pn junction theoretically provides the equivalent of a negative index medium, enabling novel electron optics such as negative refraction and perfect (Veselago) lensing. In graphene, the linear dispersion and zero-gap bandstructure admit highly transparent pn junctions by simple electrostatic gating, which cannot be achieved in conventional semiconductors. Robust demonstration of these effects, however, has not been forthcoming. Here we employ transverse magnetic focusing to probe propagation across an electrostatically defined graphene junction. We find perfect agreement with the predicted Snell's law for electrons, including observation of both positive and negative refraction. Resonant transmission across the pn junction provides a direct measurement of the angle dependent transmission coefficient, and we demonstrate good agreement with theory. Comparing experimental data with simulation reveals the crucial role played by the effective junction width, providing guidance for future device design. Efforts toward sharper pn junction and possibility of zero field Veselago lensing will also be discussed. This work is supported by the Semiconductor Research Corporations NRI Center for Institute for Nanoelectronics Discovery and Exploration (INDEX).

Peltier cooling in molecular junctions

Science.gov (United States)

Cui, Longji; Miao, Ruijiao; Wang, Kun; Thompson, Dakotah; Zotti, Linda Angela; Cuevas, Juan Carlos; Meyhofer, Edgar; Reddy, Pramod

2018-02-01

The study of thermoelectricity in molecular junctions is of fundamental interest for the development of various technologies including cooling (refrigeration) and heat-to-electricity conversion1-4. Recent experimental progress in probing the thermopower (Seebeck effect) of molecular junctions5-9 has enabled studies of the relationship between thermoelectricity and molecular structure10,11. However, observations of Peltier cooling in molecular junctions—a critical step for establishing molecular-based refrigeration—have remained inaccessible. Here, we report direct experimental observations of Peltier cooling in molecular junctions. By integrating conducting-probe atomic force microscopy12,13 with custom-fabricated picowatt-resolution calorimetric microdevices, we created an experimental platform that enables the unified characterization of electrical, thermoelectric and energy dissipation characteristics of molecular junctions. Using this platform, we studied gold junctions with prototypical molecules (Au-biphenyl-4,4'-dithiol-Au, Au-terphenyl-4,4''-dithiol-Au and Au-4,4'-bipyridine-Au) and revealed the relationship between heating or cooling and charge transmission characteristics. Our experimental conclusions are supported by self-energy-corrected density functional theory calculations. We expect these advances to stimulate studies of both thermal and thermoelectric transport in molecular junctions where the possibility of extraordinarily efficient energy conversion has been theoretically predicted2-4,14.

Specific protein-protein interactions of calsequestrin with junctional sarcoplasmic reticulum of skeletal muscle

International Nuclear Information System (INIS)

Damiani, E.; Margreth, A.

1990-01-01

Minor protein components of triads and of sarcoplasmic reticulum (SR) terminal cisternae (TC), i.e. 47 and 37 kDa peptides and 31-30 kDa and 26-25 kDa peptide doublets, were identified from their ability to bind 125 I calsequestrin (CS) in the presence of EGTA. The CS-binding peptides are specifically associated with the junctional membrane of TC, since they could not be detected in junctional transverse tubules and in longitudinal SR fragments. The 31-30 kDa peptide doublet, exclusively, did not bind CS in the presence of Ca 2+ . Thus, different types of protein-protein interactions appear to be involved in selective binding of CS to junctional TC

Visualization of the current density in Josephson junctions with 0- and π-facets

International Nuclear Information System (INIS)

Guerlich, Christian

2010-01-01

With Low-Temperature-Electron-Microscopy (LTSEM) it is possible to analyse the transport properties of solids at low temperatures. In particular it is possible to image the supercurrent density j s in Josephson junctions. This was demonstrated by comparing TTREM-images with calculated values for j s . In this thesis ramp-type Nd 2-x Ce x CuO 4-y /Nb-Josephson-junctions (NCCO/Nb) and Josephson junctions with a ferromagnetic interlayer Nb/Al-Al 2 O 3 /NiCu/Nb, so-called SIFS (superconductor-insulator-ferromagnet-superconductor) Josephson junctions were studied.It was demonstrated that LTSEM provides direct imaging of the sign change of the order parameter in superconductors with d x 2 -y 2 -symmetry. This was a controversial issue over the last decade. A step like variation in the thickness of the F-layer allows the fabrication of linear and annular Josephson junctions with different numbers of 0 and π facets. With the LTSEM 0-, π-, 0-π-, 0-π-0-, 0/2-π-0/2-, 20 x (0-π)- as well as square-shaped-, circular- and annular-Josephson-junctions were studied. It was demonstrated, that these junctions are of good quality and have critical current densities up to 42 A/cm 2 at T=4.2 K, which is a record value for SIFS junctions with a NiCu F-layer so far. By comparing the measurements with simulations a first indication of a semifluxon at the 0-π-boundary was found. (orig.)

Geodynamical simulation of the RRF triple junction

Science.gov (United States)

Wang, Z.; Wei, D.; Liu, M.; Shi, Y.; Wang, S.

2017-12-01

Triple junction is the point at which three plate boundaries meet. Three plates at the triple junction form a complex geological tectonics, which is a natural laboratory to study the interactions of plates. This work studies a special triple junction, the oceanic transform fault intersects the collinear ridges with different-spreading rates, which is free of influence of ridge-transform faults and nearby hotspots. First, we build 3-D numerical model of this triple junction used to calculate the stead-state velocity and temperature fields resulting from advective and conductive heat transfer. We discuss in detail the influence of the velocity and temperature fields of the triple junction from viscosity, spreading rate of the ridge. The two sides of the oceanic transform fault are different sensitivities to the two factors. And, the influence of the velocity mainly occurs within 200km of the triple junction. Then, we modify the model by adding a ridge-transform fault to above model and directly use the velocity structure of the Macquarie triple junction. The simulation results show that the temperature at both sides of the oceanic transform fault decreases gradually from the triple junction, but the temperature difference between the two sides is a constant about 200°. And, there is little effect of upwelling velocity away from the triple junction 100km. The model results are compared with observational data. The heat flux and thermal topography along the oceanic transform fault of this model are consistent with the observed data of the Macquarie triple junction. The earthquakes are strike slip distributed along the oceanic transform fault. Their depths are also consistent with the zone of maximum shear stress. This work can help us to understand the interactions of plates of triple junctions and help us with the foundation for the future study of triple junctions.

SAGITTAL DIAMETER OF FORAMEN MAGNUM IN NORMAL POPULATION: AN MRI STUDY

OpenAIRE

Lakshmi

2015-01-01

Lower position of cerebellar tonsils was frequently noticed in Western studies. In some of the studies, sagittal diameter of foramen magnum was found to be larger in cases of Chiari malformation. However, there are no Indian studies for comparison. Our study was proposed to determine the standard values for sagittal diameter of foramen magnum in various age groups and both sexes. This gives a guideline for further studies in pathological conditions like Craniovertebral Junctional ...

Complicações pós-operatórias em 139 casos de impressão basilar e/ou malformação de Arnold-Chiari

Directory of Open Access Journals (Sweden)

José Alberto Gonçalves da Silva

1981-09-01

Full Text Available No presente trabalho, foram analisadas as complicações pós-operatórias observadas em 139 casos de impressão basilar e/ou malformação de Arnold-Chiari. Os autores chamam a atenção para a menor ocorrência de complicações e de mortalidade verificadas nos pacientes que foram submetidos à plástica da dura-mater da fossa posterior.

Dynamics of the Josephson multi-junction system with junctions characterized by non-sinusoidal current - phase relationship

International Nuclear Information System (INIS)

Abal'osheva, I.; Lewandowski, S.J.

2004-01-01

It is shown that the inclusion of junctions characterized by non-sinusoidal current - phase relationship in the systems composed of multiple Josephson junctions - results in the appearance of additional system phase states. Numerical simulations and stability considerations confirm that those phase states can be realized in practice. Moreover, spontaneous formation of the grain boundary junctions in high-T c superconductors with non-trivial current-phase relations due to the d-wave symmetry of the order parameter is probable. Switching between the phase states of multiple grain boundary junction systems can lead to additional 1/f noise in high-T c superconductors. (author)

Theoretical and experimental investigations on synchronization in many-junction arrays of HTSC Josephson junctions. Final report

International Nuclear Information System (INIS)

Seidel, P.; Heinz, E.; Pfuch, A.; Machalett, F.; Krech, W.; Basler, M.

1996-06-01

Different many-junction arrays of Josephson junctions were studied theoretically to analyse the mechanisms of synchronization, the influence of internal and external parameters and the maximal allowed spread of parameters for the single junctions. Concepts to realize arrays using standard high-T c superconductor technology were created, e.g. the new arrangement of multijunction superconducting loops (MSL). First experimental results show the relevance of this concept. Intrinsic one-dimensional arrays in thin film technology were prepared as mesas out of Bi or Tl 2212 films. to characterize HTSC Josephson junctions methods based on the analysis of microwave-induced steps were developed. (orig.) [de

Single P-N junction tandem photovoltaic device

Science.gov (United States)

Walukiewicz, Wladyslaw [Kensington, CA; Ager, III, Joel W.; Yu, Kin Man [Lafayette, CA

2011-10-18

A single P-N junction solar cell is provided having two depletion regions for charge separation while allowing the electrons and holes to recombine such that the voltages associated with both depletion regions of the solar cell will add together. The single p-n junction solar cell includes an alloy of either InGaN or InAlN formed on one side of the P-N junction with Si formed on the other side in order to produce characteristics of a two junction (2J) tandem solar cell through only a single P-N junction. A single P-N junction solar cell having tandem solar cell characteristics will achieve power conversion efficiencies exceeding 30%.

Characterization of the Tetraspan Junctional Complex (4JC) superfamily.

Science.gov (United States)

Chou, Amy; Lee, Andre; Hendargo, Kevin J; Reddy, Vamsee S; Shlykov, Maksim A; Kuppusamykrishnan, Harikrishnan; Medrano-Soto, Arturo; Saier, Milton H

2017-03-01

Connexins or innexins form gap junctions, while claudins and occludins form tight junctions. In this study, statistical data, derived using novel software, indicate that these four junctional protein families and eleven other families of channel and channel auxiliary proteins are related by common descent and comprise the Tetraspan (4 TMS) Junctional Complex (4JC) Superfamily. These proteins all share similar 4 transmembrane α-helical (TMS) topologies. Evidence is presented that they arose via an intragenic duplication event, whereby a 2 TMS-encoding genetic element duplicated tandemly to give 4 TMS proteins. In cases where high resolution structural data were available, the conclusion of homology was supported by conducting structural comparisons. Phylogenetic trees reveal the probable relationships of these 15 families to each other. Long homologues containing fusions to other recognizable domains as well as internally duplicated or fused domains are reported. Large "fusion" proteins containing 4JC domains proved to fall predominantly into family-specific patterns as follows: (1) the 4JC domain was N-terminal; (2) the 4JC domain was C-terminal; (3) the 4JC domain was duplicated or occasionally triplicated and (4) mixed fusion types were present. Our observations provide insight into the evolutionary origins and subfunctions of these proteins as well as guides concerning their structural and functional relationships. Copyright © 2016 Elsevier B.V. All rights reserved.

Numerical simulations of flux flow in stacked Josephson junctions

DEFF Research Database (Denmark)

Madsen, Søren Peder; Pedersen, Niels Falsig

2005-01-01

We numerically investigate Josephson vortex flux flow states in stacked Josephson junctions, motivated by recent experiments trying to observe the vortices in a square vortex lattice when a magnetic field is applied to layered high-Tc superconductors of the Bi2Sr2CaCu2Ox type. By extensive...

Search for the in-phase Flux Flow mode in stacked Josephson junctions

DEFF Research Database (Denmark)

Pedersen, Niels Falsig; Madsen, Søren Peder

2006-01-01

Josephson vortex flux flow states in stacked Josephson junctions are investigated numerically. The aim of the work is to understand the mechanisms behind the formation of triangular (anti-phase) and square (in-phase) vortex lattices, and is motivated by recent experiments on layered BSCCO type high......-T-c superconductors in a magnetic field. In order to keep the problem as simple as possible we consider in detail only the case with two junctions in the stack. (c) 2006 Elsevier B.V. All rights reserved....

Phase Sensitive Measurements of Ferromagnetic Josephson Junctions for Cryogenic Memory Applications

Science.gov (United States)

Niedzielski, Bethany Maria

A Josephson junction is made up of two superconducting layers separated by a barrier. The original Josephson junctions, studied in the early 1960's, contained an insulating barrier. Soon thereafter, junctions with normal-metal barriers were also studied. Ferromagnetic materials were not even theoretically considered as a barrier layer until around 1980, due to the competing order between ferromagnetic and superconducting systems. However, many exciting physical phenomena arise in hybrid superconductor/ferromagnetic devices, including devices where the ground state phase difference between the two superconductors is shifted by pi. Since their experimental debut in 2001, so-called pi junctions have been demonstrated by many groups, including my own, in systems with a single ferromagnetic layer. In this type of system, the phase of the junction can be set to either 0 or pi depending on the thickness of the ferromagnetic layer. Of interest, however, is the ability to control the phase of a single junction between the 0 and pi states. This was theoretically shown to be possible in a system containing two ferromagnetic layers (spin-valve junctions). If the materials and their thicknesses are properly chosen to manipulate the electron pair correlation function, then the phase state of a spin-valve Josephson junction should be capable of switching between the 0 and ? phase states when the magnetization directions of the two ferromagnetic layers are oriented in the antiparallel and parallel configurations, respectively. Such a phase-controllable junction would have immediate applications in cryogenic memory, which is a necessary component to an ultra-low power superconducting computer. A fully superconducting computer is estimated to be orders of magnitude more energy-efficient than current semiconductor-based supercomputers. The goal of this work was to experimentally verify this prediction for a phase-controllable ferromagnetic Josephson junction. To address this

Ultrathin reduced graphene oxide films as transparent top-contacts for light switchable solid-state molecular junctions

DEFF Research Database (Denmark)

Li, Tao; Jevric, Martyn; Hauptmann, Jonas Rahlf

2013-01-01

A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules. The electr......A new type of solid-state molecular junction is introduced, which employs reduced graphene oxide as a transparent top contact that permits a self-assembled molecular monolayer to be photoswitched in situ, while simultaneously enabling charge-transport measurements across the molecules...

The anatomical locus of T-junction processing.

Science.gov (United States)

Schirillo, James A

2009-07-01

Inhomogeneous surrounds can produce either asymmetrical or symmetrical increment/decrement induction by orienting T-junctions to selectively group a test patch with surrounding regions [Melfi, T., & Schirillo, J. (2000). T-junctions in inhomogeneous surrounds. Vision Research, 40, 3735-3741]. The current experiments aimed to determine where T-junctions are processed by presenting each eye with a different image so that T-junctions exist only in the fused percept. Only minor differences were found between retinal and cortical versus cortical-only conditions, indicating that T-junctions are processed cortically.

Mixing in T-junctions

NARCIS (Netherlands)

Kok, Jacobus B.W.; van der Wal, S.

1996-01-01

The transport processes that are involved in the mixing of two gases in a T-junction mixer are investigated. The turbulent flow field is calculated for the T-junction with the k- turbulence model by FLOW3D. In the mathematical model the transport of species is described with a mixture fraction

Effect of low and staggered gap quantum wells inserted in GaAs tunnel junctions

Science.gov (United States)

Louarn, K.; Claveau, Y.; Marigo-Lombart, L.; Fontaine, C.; Arnoult, A.; Piquemal, F.; Bounouh, A.; Cavassilas, N.; Almuneau, G.

2018-04-01

In this article, we investigate the impact of the insertion of either a type I InGaAs or a type II InGaAs/GaAsSb quantum well on the performances of MBE-grown GaAs tunnel junctions (TJs). The devices are designed and simulated using a quantum transport model based on the non-equilibrium Green’s function formalism and a 6-band k.p Hamiltonian. We experimentally observe significant improvements of the peak tunneling current density on both heterostructures with a 460-fold increase for a moderately doped GaAs TJ when the InGaAs QW is inserted at the junction interface, and a 3-fold improvement on a highly doped GaAs TJ integrating a type II InGaAs/GaAsSb QW. Thus, the simple insertion of staggered band lineup heterostructures enables us to reach a tunneling current well above the kA cm‑2 range, equivalent to the best achieved results for Si-doped GaAs TJs, implying very interesting potential for TJ-based components, such as multi-junction solar cells, vertical cavity surface emitting lasers and tunnel-field effect transistors.

Photodetection in p–n junctions formed by electrolyte-gated transistors of two-dimensional crystals

KAUST Repository

Kozawa, Daichi

2016-11-16

Transition metal dichalcogenide monolayers have attracted much attention due to their strong light absorption and excellent electronic properties. These advantages make this type of two-dimensional crystal a promising one for optoelectronic device applications. In the case of photoelectric conversion devices such as photodetectors and photovoltaic cells, p–n junctions are one of the most important devices. Here, we demonstrate photodetection with WSe2 monolayer films. We prepare the electrolyte-gated ambipolar transistors and electrostatic p–n junctions are formed by the electrolyte-gating technique at 270 K. These p-n junctions are cooled down to fix the ion motion (and p-n junctions) and we observed the reasonable photocurrent spectra without the external bias, indicating the formation of p-n junctions. Very interestingly, two-terminal devices exhibit higher photoresponsivity than that of three-terminal ones, suggesting the formation of highly balanced anion and cation layers. The maximum photoresponsivity reaches 5 mA/W in resonance with the first excitonic peak. Our technique provides important evidence for optoelectronics in atomically thin crystals.

Photodetection in p–n junctions formed by electrolyte-gated transistors of two-dimensional crystals

KAUST Repository

Kozawa, Daichi; Pu, Jiang; Shimizu, Ryo; Kimura, Shota; Chiu, Ming-Hui; Matsuki, Keiichiro; Wada, Yoshifumi; Sakanoue, Tomo; Iwasa, Yoshihiro; Li, Lain-Jong; Takenobu, Taishi

2016-01-01

Transition metal dichalcogenide monolayers have attracted much attention due to their strong light absorption and excellent electronic properties. These advantages make this type of two-dimensional crystal a promising one for optoelectronic device applications. In the case of photoelectric conversion devices such as photodetectors and photovoltaic cells, p–n junctions are one of the most important devices. Here, we demonstrate photodetection with WSe2 monolayer films. We prepare the electrolyte-gated ambipolar transistors and electrostatic p–n junctions are formed by the electrolyte-gating technique at 270 K. These p-n junctions are cooled down to fix the ion motion (and p-n junctions) and we observed the reasonable photocurrent spectra without the external bias, indicating the formation of p-n junctions. Very interestingly, two-terminal devices exhibit higher photoresponsivity than that of three-terminal ones, suggesting the formation of highly balanced anion and cation layers. The maximum photoresponsivity reaches 5 mA/W in resonance with the first excitonic peak. Our technique provides important evidence for optoelectronics in atomically thin crystals.

Effect of junction configurations on microdroplet formation in a T-junction microchannel

Science.gov (United States)

Lih, F. L.; Miao, J. M.

2015-03-01

This study investigates the dynamic formation process of water microdroplets in a silicon oil flow in a T-junction microchannel. Segmented water microdroplets are formed at the junction when the water flow is perpendicularly injected into the silicon oil flow in a straight rectangular microchannel. This study further presents the effects of the water flow inlet geometry on hydrodynamic characteristics of water microdroplet formation. A numerical multiphase volume of fluid (VOF) scheme is coupled to solve the unsteady three-dimensional laminar Navier-Stokes equations to depict the droplet formation phenomena at the junction. Predicted results on the length and generated frequency of the microdroplets agree well with experimental results in a T-junction microchannel with straight and flat inlets (the base model) for both fluid flows. Empirical correlations are reported between the volumetric flow ratio and the dimensionless microdroplet length or dimensionless frequency of droplet generation at a fixed capillary number of 4.7 · 10-3. The results of this study indicate a reduction in the droplet length of approximately 21% if the straight inlet for the water flow is modified to a downstream sudden contraction inlet for the water flow.

Chaos synchronization in a Josephson junction system via active sliding mode control

International Nuclear Information System (INIS)

Zhao Yang; Wang Wei

2009-01-01

In this letter, two types of active siding control methods are proposed and applied to achieve chaotic synchronization in a Josephson junction system. Numerical simulations are used to verify the proposed control techniques.

Poster - Thur Eve - 57: Craniospinal irradiation with jagged-junction IMRT approach without beam edge matching for field junctions.

Science.gov (United States)

Cao, F; Ramaseshan, R; Corns, R; Harrop, S; Nuraney, N; Steiner, P; Aldridge, S; Liu, M; Carolan, H; Agranovich, A; Karva, A

2012-07-01

Craniospinal irradiation were traditionally treated the central nervous system using two or three adjacent field sets. A intensity-modulated radiotherapy (IMRT) plan (Jagged-Junction IMRT) which overcomes problems associated with field junctions and beam edge matching, improves planning and treatment setup efficiencies with homogenous target dose distribution was developed. Jagged-Junction IMRT was retrospectively planned on three patients with prescription of 36 Gy in 20 fractions and compared to conventional treatment plans. Planning target volume (PTV) included the whole brain and spinal canal to the S3 vertebral level. The plan employed three field sets, each with a unique isocentre. One field set with seven fields treated the cranium. Two field sets treated the spine, each set using three fields. Fields from adjacent sets were overlapped and the optimization process smoothly integrated the dose inside the overlapped junction. For the Jagged-Junction IMRT plans vs conventional technique, average homogeneity index equaled 0.08±0.01 vs 0.12±0.02, and conformity number equaled 0.79±0.01 vs 0.47±0.12. The 95% isodose surface covered (99.5±0.3)% of the PTV vs (98.1±2.0)%. Both Jagged-Junction IMRT plans and the conventional plans had good sparing of the organs at risk. Jagged-Junction IMRT planning provided good dose homogeneity and conformity to the target while maintaining a low dose to the organs at risk. Jagged-Junction IMRT optimization smoothly distributed dose in the junction between field sets. Since there was no beam matching, this treatment technique is less likely to produce hot or cold spots at the junction in contrast to conventional techniques. © 2012 American Association of Physicists in Medicine.

Normal-state conductance used to probe superconducting tunnel junctions for quantum computing

Energy Technology Data Exchange (ETDEWEB)

Chaparro, Carlos; Bavier, Richard; Kim, Yong-Seung; Kim, Eunyoung; Oh, Seongshik [Department of Physics and Astronomy, Rutgers, The State University of New Jersey, Piscataway, NJ 08854 (United States); Kline, Jeffrey S; Pappas, David P, E-mail: carlosch@physics.rutgers.ed, E-mail: ohsean@physics.rutgers.ed [National Institute of Standards and Technology, Boulder, CO 80305 (United States)

2010-04-15

Here we report normal-state conductance measurements of three different types of superconducting tunnel junctions that are being used or proposed for quantum computing applications: p-Al/a-AlO/p-Al, e-Re/e-AlO/p-Al, and e-V/e-MgO/p-V, where p stands for polycrystalline, e for epitaxial, and a for amorphous. All three junctions exhibited significant deviations from the parabolic behavior predicted by the WKB approximation models. In the p-Al/a-AlO/p-Al junction, we observed enhancement of tunneling conductances at voltages matching harmonics of Al-O stretching modes. On the other hand, such Al-O vibration modes were missing in the epitaxial e-Re/e-AlO/p-Al junction. This suggests that absence or existence of the Al-O stretching mode might be related to the crystallinity of the AlO tunnel barrier and the interface between the electrode and the barrier. In the e-V/e-MgO/p-V junction, which is one of the candidate systems for future superconducting qubits, we observed suppression of the density of states at zero bias. This implies that the interface is electronically disordered, presumably due to oxidation of the vanadium surface underneath the MgO barrier, even if the interface was structurally well ordered, suggesting that the e-V/e-MgO/p-V junction will not be suitable for qubit applications in its present form. This also demonstrates that the normal-state conductance measurement can be effectively used to screen out low quality samples in the search for better superconducting tunnel junctions.

Theoretical investigation of GaAsBi/GaAsN tunneling field-effect transistors with type-II staggered tunneling junction

Science.gov (United States)

Wang, Yibo; Liu, Yan; Han, Genquan; Wang, Hongjuan; Zhang, Chunfu; Zhang, Jincheng; Hao, Yue

2017-06-01

We investigate GaAsBi/GaAsN system for the design of type-II staggered hetero tunneling field-effect transistor (hetero-TFET). Strain-symmetrized GaAsBi/GaAsN with effective lattice match to GaAs exhibits a type-II band lineup, and the effective bandgap EG,eff at interface is significantly reduced with the incorporation of Bi and N elements. The band-to-band tunneling (BTBT) rate and drive current of GaAsBi/GaAsN hetero-TFETs are boosted due to the utilizing of the type-II staggered tunneling junction with the reduced EG,eff. Numerical simulation shows that the drive current and subthreshold swing (SS) characteristics of GaAsBi/GaAsN hetero-TFETs are remarkably improved by increasing Bi and N compositions. The dilute content GaAs0.85Bi0.15/GaAs0.92N0.08 staggered hetero-nTFET achieves 7.8 and 550 times higher ION compared to InAs and In0.53Ga0.47As homo-TFETs, respectively, at the supply voltage of 0.3 V. GaAsBi/GaAsN heterostructure is a potential candidate for high performance TFET.

Valley dependent transport in graphene L junction

Science.gov (United States)

Chan, K. S.

2018-05-01

We studied the valley dependent transport in graphene L junctions connecting an armchair lead and a zigzag lead. The junction can be used in valleytronic devices and circuits. Electrons injected from the armchair lead into the junction is not valley polarized, but they can become valley polarized in the zigzag lead. There are Fermi energies, where the current in the zigzag lead is highly valley polarized and the junction is an efficient generator of valley polarized current. The features of the valley polarized current depend sensitively on the widths of the two leads, as well as the number of dimers in the armchair lead, because this number has a sensitive effect on the band structure of the armchair lead. When an external potential is applied to the junction, the energy range with high valley polarization is enlarged enhancing its function as a generator of highly valley polarized current. The scaling behavior found in other graphene devices is also found in L junctions, which means that the results presented here can be extended to junctions with larger dimensions after appropriate scaling of the energy.

delta-biased Josephson tunnel junctions

DEFF Research Database (Denmark)

Monaco, R.; Mygind, Jesper; Koshelet, V.

2010-01-01

Abstract: The behavior of a long Josephson tunnel junction drastically depends on the distribution of the dc bias current. We investigate the case in which the bias current is fed in the central point of a one-dimensional junction. Such junction configuration has been recently used to detect...... the persistent currents circulating in a superconducting loop. Analytical and numerical results indicate that the presence of fractional vortices leads to remarkable differences from the conventional case of uniformly distributed dc bias current. The theoretical findings are supported by detailed measurements...

Temperature-sensitive junction transformations for mid-wavelength HgCdTe photovoltaic infrared detector arrays by laser beam induced current microscope

Energy Technology Data Exchange (ETDEWEB)

Qiu, Weicheng [College of Photoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China); National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Hu, Weida, E-mail: wdhu@mail.sitp.ac.cn; Lin, Tie; Yin, Fei; Zhang, Bo; Chen, Xiaoshuang; Lu, Wei [National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Sciences, Shanghai 200083 (China); Cheng, Xiang' ai, E-mail: xiang-ai-cheng@126.com; Wang, Rui [College of Photoelectric Science and Engineering, National University of Defense Technology, Changsha, Hunan 410073 (China)

2014-11-10

In this paper, we report on the disappearance of the photosensitive area extension effect and the unusual temperature dependence of junction transformation for mid-wavelength, n-on-p HgCdTe photovoltaic infrared detector arrays. The n-type region is formed by B{sup +} ion implantation on Hg-vacancy-doped p-type HgCdTe. Junction transformations under different temperatures are visually captured by a laser beam induced current microscope. A physical model of temperature dependence on junction transformation is proposed and demonstrated by using numerical simulations. It is shown that Hg-interstitial diffusion and temperature activated defects jointly lead to the p-n junction transformation dependence on temperature, and the weaker mixed conduction compared with long-wavelength HgCdTe photodiode contributes to the disappearance of the photosensitive area extension effect in mid-wavelength HgCdTe infrared detector arrays.

Junction depth measurement using carrier illumination

International Nuclear Information System (INIS)

Borden, Peter

2001-01-01

Carrier Illumination [trade mark] (CI) is a new method recently developed to meet the need for a non-destructive, high throughput junction depth measurement on patterned wafers. A laser beam creates a quasi-static excess carrier profile in the semiconductor underlying the activated junction. The excess carrier profile is fairly constant below the junction, and drops rapidly in the junction, creating a steep index of refraction gradient at the junction edge. Interference with light reflected from this index gradient provides a signal that is analyzed to determine the junction depth. The paper summarizes evaluation of performance in full NMOS and PMOS process flows, on both bare and patterned wafers. The aims have been to validate (1) performance in the presence of underlying layers typically found at the source/drain (S/D) process steps and (2) measurement on patterned wafers. Correlation of CI measurements to SIMS and transistor drive current are shown. The data were obtained from NMOS structures using As S/D and LDD implants. Correlations to SRP, SIMS and sheet resistance are shown for PMOS structures using B 11 LDD implants. Gage capability measurements are also presented

Planar intrinsic Josephson junctions with in-plane aligned YBCO films

CERN Document Server

Zhang, L; Kobayashi, T; Goto, T; Mukaida, M

2002-01-01

Planar type devices were fabricated by patterning in-plane aligned YBa sub 2 Cu sub 3 O sub 7 sub - subdelta (YBCO) films. The current-voltage characteristics along the c-axis at various temperatures and oxygen contents were measured. The current voltage curves showing supercurrent and hysteresis were obtained for the samples annealed at an oxygen pressure of 1.3 x 10 sup 4 Pa, while the supercurrent and hysteresis became smaller and even disappeared as the oxygen pressure decreased. The relationships between the critical currents and temperatures are similar to those of d-wave superconducting tunnel junctions. These results indicate the formation of stacks of intrinsic Josephson junctions, which are useful for developing high-frequency electron devices.

Planar intrinsic Josephson junctions with in-plane aligned YBCO films

International Nuclear Information System (INIS)

Zhang, L; Moriya, M; Kobayashi, T; Goto, T; Mukaida, M

2002-01-01

Planar type devices were fabricated by patterning in-plane aligned YBa 2 Cu 3 O 7-δ (YBCO) films. The current-voltage characteristics along the c-axis at various temperatures and oxygen contents were measured. The current voltage curves showing supercurrent and hysteresis were obtained for the samples annealed at an oxygen pressure of 1.3 x 10 4 Pa, while the supercurrent and hysteresis became smaller and even disappeared as the oxygen pressure decreased. The relationships between the critical currents and temperatures are similar to those of d-wave superconducting tunnel junctions. These results indicate the formation of stacks of intrinsic Josephson junctions, which are useful for developing high-frequency electron devices

Current–voltage characteristics of manganite–titanite perovskite junctions

Directory of Open Access Journals (Sweden)

Benedikt Ifland

2015-07-01

Full Text Available After a general introduction into the Shockley theory of current voltage (J–V characteristics of inorganic and organic semiconductor junctions of different bandwidth, we apply the Shockley theory-based, one diode model to a new type of perovskite junctions with polaronic charge carriers. In particular, we studied manganite–titanate p–n heterojunctions made of n-doped SrTi1−yNbyO3, y = 0.002 and p-doped Pr1−xCaxMnO3, x = 0.34 having a strongly correlated electron system. The diffusion length of the polaron carriers was analyzed by electron beam-induced current (EBIC in a thin cross plane lamella of the junction. In the J–V characteristics, the polaronic nature of the charge carriers is exhibited mainly by the temperature dependence of the microscopic parameters, such as the hopping mobility of the series resistance and a colossal electro-resistance (CER effect in the parallel resistance. We conclude that a modification of the Shockley equation incorporating voltage-dependent microscopic polaron parameters is required. Specifically, the voltage dependence of the reverse saturation current density is analyzed and interpreted as a voltage-dependent electron–polaron hole–polaron pair generation and separation at the interface.

Hysteresis development in superconducting Josephson junctions

International Nuclear Information System (INIS)

Refai, T.F.; Shehata, L.N.

1988-09-01

The resistively and capacitive shunted junction model is used to investigate hysteresis development in superconducting Josephson junctions. Two empirical formulas that relate the hysteresis width and the quasi-particle diffusion length in terms of the junctions electrical parameters, temperature and frequency are obtained. The obtained formulas provide a simple tool to investigate the full potentials of the hysteresis phenomena. (author). 9 refs, 3 figs

Experimental analysis and theoretical model for anomalously high ideality factors in ZnO/diamond p-n junction diode

International Nuclear Information System (INIS)

Wang Chengxin; Yang Guowei; Liu Hongwu; Han Yonghao; Luo Jifeng; Gao Chunxiao; Zou Guangtian

2004-01-01

High-quality heterojunctions between p-type diamond single-crystalline films and highly oriented n-type ZnO films were fabricated by depositing the p-type diamond single-crystal films on the I o -type diamond single crystal using a hot filament chemical vapor deposition, and later growing a highly oriented n-type ZnO film on the p-type diamond single-crystal film by magnetron sputtering. Interestingly, anomalously high ideality factors (n>>2.0) in the prepared ZnO/diamond p-n junction diode in the interim bias voltage range were measured. For this, detailed electronic characterizations of the fabricated p-n junction were conducted, and a theoretical model was proposed to clarify the much higher ideality factors of the special heterojunction diode

Two cases of Budd-Chiari syndrome complicated by hepatocellular carcinoma. Hemodynamic study with computed tomography and venacavography

Energy Technology Data Exchange (ETDEWEB)

Takayasu, Kenichi; Moriyama, Noriyuki; Suzuki, Masao [National Cancer Center, Tokyo (Japan). Hospital

1982-12-01

Two patients with Budd-Chiari syndrome complicated by hepatocellular carcinoma in whom CT and inferior venacavography were carried out are described. The imaging study with CT disclosed: 1) calcified inferior vena cava (IVC) at the level of the diaphragm and lack of enhancement of the IVC and hepatic veins after contrast enhancement, 2) markedly dilated inferior right hepatic vein, 3) marked compensatory enlargement of the caudate lobe, 4) icile-like thrombus extending caudally in the IVC and dilatation of that portion of the IVC, and 5) enlarged and dilated azygos, hemiazygos and anterior longitudinal venous trunk of the internal vertebral venous plexus, and with cavography, 1) the inferior right hepatic vein as a venous outlet to maintain the liver functions, and 2) occlusion of the right and left hepatic vein openings and a communicating vein between the left hepatic and caudate lobe vein.

Posterior fossa reconstruction using titanium plate for the treatment of cerebellar ptosis after decompression for Chiari malformation.

Science.gov (United States)

Udani, Vikram; Holly, Langston T; Chow, Daniel; Batzdorf, Ulrich

2014-01-01

We describe our use of a perforated titanium plate to perform a partial posterior fossa cranioplasty in the treatment of cerebellar ptosis and dural ectasia after posterior fossa decompression (PFD). Twelve patients who had undergone PFD underwent posterior fossa reconstruction using a titanium plate. Symptoms were related to either descent of the cerebellum into the decompression or to dural ectasia into the craniectomy defect. Twelve patients who had undergone large suboccipital craniectomies and who presented with persistent headaches and some with neurological symptoms related to syringomyelia, underwent reoperation with placement of a small titanium plate. Ten of 12 patients showed symptomatic improvement after reoperation. Placement of a titanium plate appears to be an effective method of treatment of cerebellar ptosis and dural ectasia after PFD for Chiari malformation. Copyright © 2014 Elsevier Inc. All rights reserved.

Structural studies of YBCO ramp Josephson junctions for rapid single flux quantum circuits

Energy Technology Data Exchange (ETDEWEB)

Gustafsson, M.; Olsson, E.; Huang, M.Q.; Komissinski, P.V.; Mozhaev, P.B.; Ivanov, Z.G.

1999-11-01

Ramp-type Josephson junctions with barrier layers of Ga doped PrBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} have been investigated using scanning and transmission electron microscopy. The microstructures have been correlated to the ramp geometry. The junctions exhibited low excess current. This is believed to be due to the uniform thickness of barrier layer deposited on the ion-milled edges. The uniformity of the barrier is presumed to be a result of the smooth ramp, which promoted uniform nucleation and epitaxial growth.

Energy scales in YBaCuO grain boundary biepitaxial Josephson junctions

Energy Technology Data Exchange (ETDEWEB)

Tafuri, F., E-mail: tafuri@na.infn.it [Dip. Ingegneria dell' Informazione, Seconda Universita di Napoli, 81031 Aversa (CE) (Italy); CNR-SPIN, UOS Napoli, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Dip. Scienze Fisiche, Universita di Napoli Federico II, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Stornaiuolo, D. [DPMC, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4 (Switzerland); CNR-SPIN, UOS Napoli, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Lucignano, P. [CNR-ISC, sede di Tor Vergata, Via del Fosso del Cavaliere 100, 00133 Roma (Italy); Dip. Scienze Fisiche, Universita di Napoli Federico II, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Galletti, L. [Dip. Scienze Fisiche, Universita di Napoli Federico II, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Longobardi, L. [Dip. Ingegneria dell' Informazione, Seconda Universita di Napoli, 81031 Aversa (CE) (Italy); Massarotti, D. [Dip. Scienze Fisiche, Universita di Napoli Federico II, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); CNR-SPIN, UOS Napoli, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Montemurro, D. [NEST and Scuola Normale Superiore, Piazza San Silvestro 12, I-56127 Pisa (Italy); Papari, G. [INPAC - Institute for Nanoscale Physics and Chemistry, Nanoscale Superconductivity and Magnetism Pulsed Fields Group, K.U. Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Dip. Scienze Fisiche, Universita di Napoli Federico II, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); Barone, A.; Tagliacozzo, A. [Dip. Scienze Fisiche, Universita di Napoli Federico II, Monte S. Angelo via Cinthia, 80126 Napoli (Italy); CNR-SPIN, UOS Napoli, Monte S. Angelo via Cinthia, 80126 Napoli (Italy)

2012-09-15

Self-assembled nanoscale channels may naturally arise in the growth process of grain boundaries (GBs) in high critical temperature superconductor (HTS) systems, and deeply influence the transport properties of the GB Josephson junctions (JJs). By isolating nano-channels in YBCO biepitaxial JJs and studying their properties, we sort out specific fingerprints of the mesoscopic nature of the contacts. The size of the channels combined to the characteristic properties of HTS favors a special regime of the proximity effect, where normal state coherence prevails on the superconducting coherence in the barrier region. Resistance oscillations from the current-voltage characteristic encode mesoscopic information on the junction and more specifically on the minigap induced in the barrier. Thouless energy emerges as a characteristic energy of these types of Josephson junctions. Possible implications on the understanding of coherent transport of quasiparticles in HTS and of the dissipation mechanisms are discussed, along with elements to take into account when designing HTS nanostructures.

Fluctuation in Interface and Electronic Structure of Single-Molecule Junctions Investigated by Current versus Bias Voltage Characteristics.

Science.gov (United States)

Isshiki, Yuji; Fujii, Shintaro; Nishino, Tomoaki; Kiguchi, Manabu

2018-03-14

Structural and electronic detail at the metal-molecule interface has a significant impact on the charge transport across the molecular junctions, but its precise understanding and control still remain elusive. On the single-molecule scale, the metal-molecule interface structures and relevant charge transport properties are subject to fluctuation, which contain the fundamental science of single-molecule transport and implication for manipulability of the transport properties in electronic devices. Here, we present a comprehensive approach to investigate the fluctuation in the metal-molecule interface in single-molecule junctions, based on current-voltage ( I- V) measurements in combination with first-principles simulation. Contrary to conventional molecular conductance studies, this I- V approach provides a correlated statistical description of both the degree of electronic coupling across the metal-molecule interface and the molecular orbital energy level. This statistical approach was employed to study fluctuation in single-molecule junctions of 1,4-butanediamine (DAB), pyrazine (PY), 4,4'-bipyridine (BPY), and fullerene (C 60 ). We demonstrate that molecular-dependent fluctuation of σ-, π-, and π-plane-type interfaces can be captured by analyzing the molecular orbital (MO) energy level under mechanical perturbation. While the MO level of DAB with the σ-type interface shows weak distance dependence and fluctuation, the MO level of PY, BPY, and C 60 features unique distance dependence and molecular-dependent fluctuation against the mechanical perturbation. The MO level of PY and BPY with the σ+π-type interface increases with the increase in the stretch distance. In contrast, the MO level of C 60 with the π-plane-type interface decreases with the increase in the stretching perturbation. This study provides an approach to resolve the structural and electronic fluctuation in the single-molecule junctions and insight into the molecular-dependent fluctuation in

Fabrication of Josephson Junction without shadow evaporation

Science.gov (United States)

Wu, Xian; Ku, Hsiangsheng; Long, Junling; Pappas, David

We developed a new method of fabricating Josephson Junction (Al/AlOX/Al) without shadow evaporation. Statistics from room temperature junction resistance and measurement of qubits are presented. Unlike the traditional ``Dolan Bridge'' technique, this method requires two individual lithographies and straight evaporations of Al. Argon RF plasma is used to remove native AlOX after the first evaporation, followed by oxidation and second Al evaporation. Junction resistance measured at room temperature shows linear dependence on Pox (oxidation pressure), √{tox} (oxidation time), and inverse proportional to junction area. We have seen 100% yield of qubits made with this method. This method is promising because it eliminates angle dependence during Junction fabrication, facilitates large scale qubits fabrication.

Quantum synchronization effects in intrinsic Josephson junctions

International Nuclear Information System (INIS)

Machida, M.; Kano, T.; Yamada, S.; Okumura, M.; Imamura, T.; Koyama, T.

2008-01-01

We investigate quantum dynamics of the superconducting phase in intrinsic Josephson junctions of layered high-T c superconductors motivated by a recent experimental observation for the switching rate enhancement in the low temperature quantum regime. We pay attention to only the capacitive coupling between neighboring junctions and perform large-scale simulations for the Schroedinger equation derived from the Hamiltonian considering the capacitive coupling alone. The simulation focuses on an issue whether the switching of a junction induces those of the other junctions or not. The results reveal that the superconducting phase dynamics show synchronous behavior with increasing the quantum character, e.g., decreasing the junction plane area and effectively the temperature. This is qualitatively consistent with the experimental result

Gap Junctions Contribute to the Regulation of Walking-Like Activity in the Adult Mudpuppy (Necturus Maculatus.

Directory of Open Access Journals (Sweden)

Igor Lavrov

Full Text Available Although gap junctions are widely expressed in the developing central nervous system, the role of electrical coupling of neurons and glial cells via gap junctions in the spinal cord in adults is largely unknown. We investigated whether gap junctions are expressed in the mature spinal cord of the mudpuppy and tested the effects of applying gap junction blocker on the walking-like activity induced by NMDA or glutamate in an in vitro mudpuppy preparation. We found that glial and neural cells in the mudpuppy spinal cord expressed different types of connexins that include connexin 32 (Cx32, connexin 36 (Cx36, connexin 37 (Cx37, and connexin 43 (Cx43. Application of a battery of gap junction blockers from three different structural classes (carbenexolone, flufenamic acid, and long chain alcohols substantially and consistently altered the locomotor-like activity in a dose-dependent manner. In contrast, these blockers did not significantly change the amplitude of the dorsal root reflex, indicating that gap junction blockers did not inhibit neuronal excitability nonselectively in the spinal cord. Taken together, these results suggest that gap junctions play a significant modulatory role in the spinal neural networks responsible for the generation of walking-like activity in the adult mudpuppy.

Entropy Flow Through Near-Critical Quantum Junctions

Science.gov (United States)

Friedan, Daniel

2017-05-01

This is the continuation of Friedan (J Stat Phys, 2017. doi: 10.1007/s10955-017-1752-8). Elementary formulas are derived for the flow of entropy through a circuit junction in a near-critical quantum circuit close to equilibrium, based on the structure of the energy-momentum tensor at the junction. The entropic admittance of a near-critical junction in a bulk-critical circuit is expressed in terms of commutators of the chiral entropy currents. The entropic admittance at low frequency, divided by the frequency, gives the change of the junction entropy with temperature—the entropic "capacitance". As an example, and as a check on the formalism, the entropic admittance is calculated explicitly for junctions in bulk-critical quantum Ising circuits (free fermions, massless in the bulk), in terms of the reflection matrix of the junction. The half-bit of information capacity per end of critical Ising wire is re-derived by integrating the entropic "capacitance" with respect to temperature, from T=0 to T=∞.

Ballistic Josephson junctions based on CVD graphene

Science.gov (United States)

Li, Tianyi; Gallop, John; Hao, Ling; Romans, Edward

2018-04-01

Josephson junctions with graphene as the weak link between superconductors have been intensely studied in recent years, with respect to both fundamental physics and potential applications. However, most of the previous work was based on mechanically exfoliated graphene, which is not compatible with wafer-scale production. To overcome this limitation, we have used graphene grown by chemical vapour deposition (CVD) as the weak link of Josephson junctions. We demonstrate that very short, wide CVD-graphene-based Josephson junctions with Nb electrodes can work without any undesirable hysteresis in their electrical characteristics from 1.5 K down to a base temperature of 320 mK, and their gate-tuneable critical current shows an ideal Fraunhofer-like interference pattern in a perpendicular magnetic field. Furthermore, for our shortest junctions (50 nm in length), we find that the normal state resistance oscillates with the gate voltage, consistent with the junctions being in the ballistic regime, a feature not previously observed in CVD-graphene-based Josephson junctions.

Overlap junctions for high coherence superconducting qubits

Science.gov (United States)

Wu, X.; Long, J. L.; Ku, H. S.; Lake, R. E.; Bal, M.; Pappas, D. P.

2017-07-01

Fabrication of sub-micron Josephson junctions is demonstrated using standard processing techniques for high-coherence, superconducting qubits. These junctions are made in two separate lithography steps with normal-angle evaporation. Most significantly, this work demonstrates that it is possible to achieve high coherence with junctions formed on aluminum surfaces cleaned in situ by Ar plasma before junction oxidation. This method eliminates the angle-dependent shadow masks typically used for small junctions. Therefore, this is conducive to the implementation of typical methods for improving margins and yield using conventional CMOS processing. The current method uses electron-beam lithography and an additive process to define the top and bottom electrodes. Extension of this work to optical lithography and subtractive processes is discussed.

Surface-Enhanced Raman Scattering in Molecular Junctions.

Science.gov (United States)

Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

2017-08-18

Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

Hetero-junctions of Boron Nitride and Carbon Nanotubes: Synthesis and Characterization

Energy Technology Data Exchange (ETDEWEB)

Yap, Yoke Khin

2013-03-14

Hetero-junctions of boron nitride nanotubes (BNNTs) and carbon nanotubes (CNTs) are expected to have appealing new properties that are not available from pure BNNTs and CNTs. Theoretical studies indicate that BNNT/CNT junctions could be multifunctional and applicable as memory, spintronic, electronic, and photonics devices with tunable band structures. This will lead to energy and material efficient multifunctional devices that will be beneficial to the society. However, experimental realization of BNNT/CNT junctions was hindered by the absent of a common growth technique for BNNTs and CNTs. In fact, the synthesis of BNNTs was very challenging and may involve high temperatures (up to 3000 degree Celsius by laser ablation) and explosive chemicals. During the award period, we have successfully developed a simple chemical vapor deposition (CVD) technique to grow BNNTs at 1100-1200 degree Celsius without using dangerous chemicals. A series of common catalyst have then been identified for the synthesis of BNNTs and CNTs. Both of these breakthroughs have led to our preliminary success in growing two types of BNNT/CNT junctions and two additional new nanostructures: 1) branching BNNT/CNT junctions and 2) co-axial BNNT/CNT junctions, 3) quantum dots functionalized BNNTs (QDs-BNNTs), 4) BNNT/graphene junctions. We have started to understand their structural, compositional, and electronic properties. Latest results indicate that the branching BNNT/CNT junctions and QDs-BNNTs are functional as room-temperature tunneling devices. We have submitted the application of a renewal grant to continue the study of these new energy efficient materials. Finally, this project has also strengthened our collaborations with multiple Department of Energy's Nanoscale Science Research Centers (NSRCs), including the Center for Nanophase Materials Sciences (CNMS) at Oak Ridge National Laboratory, and the Center for Integrated Nanotechnologies (CINTs) at Sandia National Laboratories and Los

The role of apical cell-cell junctions and associated cytoskeleton in mechanotransduction.

Science.gov (United States)

Sluysmans, Sophie; Vasileva, Ekaterina; Spadaro, Domenica; Shah, Jimit; Rouaud, Florian; Citi, Sandra

2017-04-01

Tissues of multicellular organisms are characterised by several types of specialised cell-cell junctions. In vertebrate epithelia and endothelia, tight and adherens junctions (AJ) play critical roles in barrier and adhesion functions, and are connected to the actin and microtubule cytoskeletons. The interaction between junctions and the cytoskeleton is crucial for tissue development and physiology, and is involved in the molecular mechanisms governing cell shape, motility, growth and signalling. The machineries which functionally connect tight and AJ to the cytoskeleton comprise proteins which either bind directly to cytoskeletal filaments, or function as adaptors for regulators of the assembly and function of the cytoskeleton. In the last two decades, specific cytoskeleton-associated junctional molecules have been implicated in mechanotransduction, revealing the existence of multimolecular complexes that can sense mechanical cues and translate them into adaptation to tensile forces and biochemical signals. Here, we summarise the current knowledge about the machineries that link tight and AJ to actin filaments and microtubules, and the molecular basis for mechanotransduction at epithelial and endothelial AJ. © 2017 Société Française des Microscopies and Société de Biologie Cellulaire de France. Published by John Wiley & Sons Ltd.

Primary Tunnel Junction Thermometry

International Nuclear Information System (INIS)

Pekola, Jukka P.; Holmqvist, Tommy; Meschke, Matthias

2008-01-01

We describe the concept and experimental demonstration of primary thermometry based on a four-probe measurement of a single tunnel junction embedded within four arrays of junctions. We show that in this configuration random sample specific and environment-related errors can be avoided. This method relates temperature directly to Boltzmann constant, which will form the basis of the definition of temperature and realization of official temperature scales in the future

The influence of junction conformation on RNA cleavage by the hairpin ribozyme in its natural junction form.

Science.gov (United States)

Thomson, J B; Lilley, D M

1999-01-01

In the natural form of the hairpin ribozyme the two loop-carrying duplexes that comprise the majority of essential bases for activity form two adjacent helical arms of a four-way RNA junction. In the present work we have manipulated the sequence around the junction in a way known to perturb the global folding properties. We find that replacement of the junction by a different sequence that has the same conformational properties as the natural sequence gives closely similar reaction rate and Arrhenius activation energy for the substrate cleavage reaction. By comparison, rotation of the natural sequence in order to alter the three-dimensional folding of the ribozyme leads to a tenfold reduction in the kinetics of cleavage. Replacement with the U1 four-way junction that is resistant to rotation into the antiparallel structure required to allow interaction between the loops also gives a tenfold reduction in cleavage rate. The results indicate that the conformation of the junction has a major influence on the catalytic activity of the ribozyme. The results are all consistent with a role for the junction in the provision of a framework by which the loops are presented for interaction in order to create the active form of the ribozyme. PMID:10024170

Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family

Directory of Open Access Journals (Sweden)

Balda Maria S

2009-12-01

Full Text Available Abstract Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.

Type VII collagen is enriched in the enamel organic matrix associated with the dentin-enamel junction of mature human teeth.

Science.gov (United States)

McGuire, Jacob D; Walker, Mary P; Mousa, Ahmad; Wang, Yong; Gorski, Jeff P

2014-06-01

The inner enamel region of erupted teeth is known to exhibit higher fracture toughness and crack growth resistance than bulk phase enamel. However, an explanation for this behavior has been hampered by the lack of compositional information for the residual enamel organic matrix. Since enamel-forming ameloblasts are known to express type VII collagen and type VII collagen null mice display abnormal amelogenesis, the aim of this study was to determine whether type VII collagen is a component of the enamel organic matrix at the dentin-enamel junction (DEJ) of mature human teeth. Immunofluorescent confocal microscopy of demineralized tooth sections localized type VII collagen to the organic matrix surrounding individual enamel rods near the DEJ. Morphologically, immunoreactive type VII collagen helical-bundles resembled the gnarled-pattern of enamel rods detected by Coomassie Blue staining. Western blotting of whole crown or enamel matrix extracts also identified characteristic Mr=280 and 230 kDa type VII dimeric forms, which resolved into 75 and 25 kDa bands upon reduction. As expected, the collagenous domain of type VII collagen was resistant to pepsin digestion, but was susceptible to purified bacterial collagenase. These results demonstrate the inner enamel organic matrix in mature teeth contains macromolecular type VII collagen. Based on its physical association with the DEJ and its well-appreciated capacity to complex with other collagens, we hypothesize that enamel embedded type VII collagen fibrils may contribute not only to the structural resilience of enamel, but may also play a role in bonding enamel to dentin. Copyright © 2014 Elsevier Inc. All rights reserved.

Fabrication and properties of sub-micrometric YBCO biepitaxial junctions

Energy Technology Data Exchange (ETDEWEB)

Stornaiuolo, D; Born, D; Barone, A [CNR-INFM Coherentia, Napoli (Italy); Cedergren, K; Bauch, T; Lombardi, F [MC2 Chalmers University of Technology, Goteborg (Sweden); Rotoli, G [CNISM and Universita dell' Aquila (Italy); Tafuri, F, E-mail: stornaiuolo@na.infh.i [Seconda Universita degli Studi di Napoli, Aversa (Italy)

2009-03-01

We report on the fabrication procedure and the transport properties of submicron grain boundary biepitaxial YBCO Josephson junctions. These first results are very encouraging and justify further expectations on improved performances for such types of devices. A reduced and more controlled faceting along the grain boundary interface, for instance, will better preserve intrinsic d-wave effects, and favour the study of fluxons dynamics.

Design of thin InGaAsN(Sb) n-i-p junctions for use in four-junction concentrating photovoltaic devices

Science.gov (United States)

Wilkins, Matthew M.; Gupta, James; Jaouad, Abdelatif; Bouzazi, Boussairi; Fafard, Simon; Boucherif, Abderraouf; Valdivia, Christopher E.; Arès, Richard; Aimez, Vincent; Schriemer, Henry P.; Hinzer, Karin

2017-04-01

Four-junction solar cells for space and terrestrial applications require a junction with a band gap of ˜1 eV for optimal performance. InGaAsN or InGaAsN(Sb) dilute nitride junctions have been demonstrated for this purpose, but in achieving the 14 mA/cm2 short-circuit current needed to match typical GaInP and GaAs junctions, the open-circuit voltage (VOC) and fill factor of these junctions are compromised. In multijunction devices incorporating materials with short diffusion lengths, we study the use of thin junctions to minimize sensitivity to varying material quality and ensure adequate transmission into lower junctions. An n-i-p device with 0.65-μm absorber thickness has sufficient short-circuit current, however, it relies less heavily on field-aided collection than a device with a 1-μm absorber. Our standard cell fabrication process, which includes a rapid thermal anneal of the contacts, yields a significant improvement in diffusion length and device performance. By optimizing a four-junction cell around a smaller 1-sun short-circuit current of 12.5 mA/cm2, we produced an InGaAsN(Sb) junction with open-circuit voltage of 0.44 V at 1000 suns (1 sun=100 mW/cm2), diode ideality factor of 1.4, and sufficient light transmission to allow >12.5 mA/cm2 in all four subcells.

Harmonic synchronization in resistively coupled Josephson junctions

International Nuclear Information System (INIS)

Blackburn, J.A.; Gronbech-Jensen, N.; Smith, H.J.T.

1994-01-01

The oscillations of two resistively coupled Josephson junctions biased only by a single dc current source are shown to lock harmonically in a 1:2 mode over a significant range of bias current, even when the junctions are identical. The dependence of this locking on both junction and coupling parameters is examined, and it is found that, for this particular two-junction configuration, 1:1 locking can never occur, and also that a minimum coupling coefficient is needed to support harmonic locking. Some issues related to subharmonic locking are also discussed

Use of p- and n-type vapor phase doping and sub-melt laser anneal for extension junctions in sub-32 nm CMOS technology

Energy Technology Data Exchange (ETDEWEB)

Nguyen, N.D., E-mail: Duy.Nguyen@imec.b [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Rosseel, E. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Takeuchi, S. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Department of Physics and Astronomy, KU Leuven, B-3001 Leuven (Belgium); Everaert, J.-L. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Yang, L. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Department of Chemistry and INPAC Institute, KU Leuven, B-3001 Leuven (Belgium); Goossens, J.; Moussa, A.; Clarysse, T.; Richard, O.; Bender, H. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Zaima, S. [Department of Crystalline Materials Science, Graduate School of Engineering, Nagoya University, Furo-cho, Nagoya, 464-8603 (Japan); Sakai, A. [Department of System Innovation, Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, Osaka 560-8531 (Japan); Loo, R. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Lin, J.C. [TSMC, R and D, 8, Li-Hsin 6th Rd., Hsinchu Science-Based Park, Hsinchu, Taiwan (China); TSMC assignee at IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Vandervorst, W. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Instituut voor Kern- en Stralingsfysika - IKS, KU Leuven, B-3001 Leuven (Belgium); Caymax, M. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium)

2010-01-01

We evaluated the combination of vapor phase doping and sub-melt laser anneal as a novel doping strategy for the fabrication of source and drain extension junctions in sub-32 nm CMOS technology, aiming at both planar and non-planar device applications. High quality ultra shallow junctions with abrupt profiles in Si substrates were demonstrated on 300 mm Si substrates. The excellent results obtained for the sheet resistance and the junction depth with boron allowed us to fulfill the requirements for the 32 nm as well as for the 22 nm technology nodes in the PMOS case by choosing appropriate laser anneal conditions. For instance, using 3 laser scans at 1300 {sup o}C, we measured an active dopant concentration of about 2.1 x 10{sup 20} cm{sup -} {sup 3} and a junction depth of 12 nm. With arsenic for NMOS, ultra shallow junctions were achieved as well. However, as also seen for other junction fabrication schemes, low dopant activation level and active dose (in the range of 1-4 x 10{sup 13} cm{sup -} {sup 2}) were observed although dopant concentration versus depth profiles indicate that the dopant atoms were properly driven into the substrate during the anneal step. The electrical deactivation of a large part of the in-diffused dopants was responsible for the high sheet resistance values.

Use of p- and n-type vapor phase doping and sub-melt laser anneal for extension junctions in sub-32 nm CMOS technology

International Nuclear Information System (INIS)

Nguyen, N.D.; Rosseel, E.; Takeuchi, S.; Everaert, J.-L.; Yang, L.; Goossens, J.; Moussa, A.; Clarysse, T.; Richard, O.; Bender, H.; Zaima, S.; Sakai, A.; Loo, R.; Lin, J.C.; Vandervorst, W.; Caymax, M.

2010-01-01

We evaluated the combination of vapor phase doping and sub-melt laser anneal as a novel doping strategy for the fabrication of source and drain extension junctions in sub-32 nm CMOS technology, aiming at both planar and non-planar device applications. High quality ultra shallow junctions with abrupt profiles in Si substrates were demonstrated on 300 mm Si substrates. The excellent results obtained for the sheet resistance and the junction depth with boron allowed us to fulfill the requirements for the 32 nm as well as for the 22 nm technology nodes in the PMOS case by choosing appropriate laser anneal conditions. For instance, using 3 laser scans at 1300 o C, we measured an active dopant concentration of about 2.1 x 10 20 cm - 3 and a junction depth of 12 nm. With arsenic for NMOS, ultra shallow junctions were achieved as well. However, as also seen for other junction fabrication schemes, low dopant activation level and active dose (in the range of 1-4 x 10 13 cm - 2 ) were observed although dopant concentration versus depth profiles indicate that the dopant atoms were properly driven into the substrate during the anneal step. The electrical deactivation of a large part of the in-diffused dopants was responsible for the high sheet resistance values.

Supramolecular Systems and Chemical Reactions in Single-Molecule Break Junctions.

Science.gov (United States)

Li, Xiaohui; Hu, Duan; Tan, Zhibing; Bai, Jie; Xiao, Zongyuan; Yang, Yang; Shi, Jia; Hong, Wenjing

2017-04-01

The major challenges of molecular electronics are the understanding and manipulation of the electron transport through the single-molecule junction. With the single-molecule break junction techniques, including scanning tunneling microscope break junction technique and mechanically controllable break junction technique, the charge transport through various single-molecule and supramolecular junctions has been studied during the dynamic fabrication and continuous characterization of molecular junctions. This review starts from the charge transport characterization of supramolecular junctions through a variety of noncovalent interactions, such as hydrogen bond, π-π interaction, and electrostatic force. We further review the recent progress in constructing highly conductive molecular junctions via chemical reactions, the response of molecular junctions to external stimuli, as well as the application of break junction techniques in controlling and monitoring chemical reactions in situ. We suggest that beyond the measurement of single molecular conductance, the single-molecule break junction techniques provide a promising access to study molecular assembly and chemical reactions at the single-molecule scale.

Development of p-type amorphous Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films and fabrication of pn hetero junction

Energy Technology Data Exchange (ETDEWEB)

Sanal, K.C., E-mail: sanalcusat@gmail.com [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kerala 682022 (India); Inter University Center for Nanomaterials and Devices (IUCND), Cochin University of Science and Technology, Kerala 682022 (India); Center for Advanced Materials, Cochin University of Science and Technology, Kerala 682022 (India); Jayaraj, M.K., E-mail: mkj@cusat.ac.in [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Kerala 682022 (India); Center for Advanced Materials, Cochin University of Science and Technology, Kerala 682022 (India)

2014-07-01

Highlights: • Growth of p-type semiconducting amorphous Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films by co-sputtering. • Atomic percentage of Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films from the XPS analysis. • Variation of bandgap with boron concentration in Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films. • Demonstration of p–n hetero junctions fabricated in the structure n-Si/p-Cu{sub 1−x}B{sub x}O{sub 2−δ}/Au. - Abstract: Transparent conducting amorphous p type Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films were grown by RF magnetron co-sputtering at room temperature, using copper and boron targets in oxygen atmosphere. The structural, electrical as well as optical properties were studied. Composition of the films was analyzed by XPS. Amorphous structure of as deposited films was confirmed by GXRD. Surface morphology of the films was analyzed by AFM studies. p-Type nature and concentration of carriers were investigated by Hall effect measurement. Band gap of the films was found to increase with the atomic content of boron in the film. A p–n hetero junction using p-type Cu{sub 1−x}B{sub x}O{sub 2−δ} and n-type silicon was fabricated in the structure n-Si/p-Cu{sub 1−x}B{sub x}O{sub 2−δ}/Au which showed rectifying behavior. As deposited amorphous Cu{sub 1−x}B{sub x}O{sub 2−δ} thin films with lower carrier concentration can be used as a channel layer for thin film transistors.

Optical and Electrical Properties of Al/(p)Bi2S3 Schottky Junction

International Nuclear Information System (INIS)

Kachari, T.; Wary, G.; Rahman, A.

2010-01-01

Thin film Al/(p)Bi 2 S 3 Schottky junctions were prepared by vacuum evaporation under pressure 10 -6 Torr. The p-type Bi 2 S 3 thin films with acceptor concentration (3.36-7.33)x10 16 /cm 3 were obtained by evaporating 'In' along with Bi 2 S 3 powder and then annealing the films at 453K for 5 hours. Different junction-parameters such as ideality factor, barrier height, effective Richardson's constant, short-circuit current, etc. were determined from I-V characteristics. The junctions exhibited rectifying I-V characteristics and also photovoltaic effect. Ideality factor was found to decrease with the increase of temperature. Proper doping, annealing, and hydrogenation are necessary to reduce the series resistance so as to achieve high carrier efficiency. More works are being carried out in this direction.

Horizontal Assembly of Single Nanowire Diode Fabricated by p-n Junction GaN NW Grown by MOCVD

Directory of Open Access Journals (Sweden)

Ji-Hyeon Park

2014-01-01

Full Text Available Uniaxially p-n junction gallium nitride nanowires have been synthesized via metal-organic chemical vapor deposition method. Nanowires prepared on Si(111 substrates were found to grow perpendicular to the substrate, and the transmission electron microscopy studies demonstrated that the nanowires had singlecrystalline structures with a growth axis. The parallel assembly of the p-n junction nanowire was prepared on a Si substrate with a thermally grown SiO2 layer. The transport studies of horizontal gallium nitride nanowire structures assembled from p- and n-type materials show that these junctions correspond to well-defined p-n junction diodes. The p-n junction devices based on GaN nanowires suspended over the electrodes were fabricated and their electrical properties were investigated. The horizontally assembled gallium nitride nanowire diodes suspended over the electrodes exhibited a substantial increase in conductance under UV light exposure. Apart from the selectivity to different light wavelengths, high responsivity and extremely short response time have also been obtained.

Josephson junctions of multiple superconducting wires

Science.gov (United States)

Deb, Oindrila; Sengupta, K.; Sen, Diptiman

2018-05-01

We study the spectrum of Andreev bound states and Josephson currents across a junction of N superconducting wires which may have s - or p -wave pairing symmetries and develop a scattering matrix based formalism which allows us to address transport across such junctions. For N ≥3 , it is well known that Berry curvature terms contribute to the Josephson currents; we chart out situations where such terms can have relatively large effects. For a system of three s -wave or three p -wave superconductors, we provide analytic expressions for the Andreev bound-state energies and study the Josephson currents in response to a constant voltage applied across one of the wires; we find that the integrated transconductance at zero temperature is quantized to integer multiples of 4 e2/h , where e is the electron charge and h =2 π ℏ is Planck's constant. For a sinusoidal current with frequency ω applied across one of the wires in the junction, we find that Shapiro plateaus appear in the time-averaged voltage across that wire for any rational fractional multiple (in contrast to only integer multiples in junctions of two wires) of 2 e /(ℏ ω ) . We also use our formalism to study junctions of two p -wave and one s -wave wires. We find that the corresponding Andreev bound-state energies depend on the spin of the Bogoliubov quasiparticles; this produces a net magnetic moment in such junctions. The time variation of these magnetic moments may be controlled by an external voltage applied across the junction. We discuss experiments which may test our theory.

A multiple p-n junction structure obtained from as-grown Czochralski silicon crystals by heat treatment - Application to solar cells

Science.gov (United States)

Chi, J. Y.; Gatos, H. C.; Mao, B. Y.

1980-01-01

Multiple p-n junctions have been prepared in as-grown Czochralski p-type silicon through overcompensation near the oxygen periodic concentration maxima by oxygen thermal donors generated during heat treatment at 450 C. Application of the multiple p-n-junction configuration to photovoltaic energy conversion has been investigated. A new solar-cell structure based on multiple p-n-junctions was developed. Theoretical analysis showed that a significant increase in collection efficiency over the conventional solar cells can be achieved.

Molecular Diffusion through Cyanobacterial Septal Junctions.

Science.gov (United States)

Nieves-Morión, Mercedes; Mullineaux, Conrad W; Flores, Enrique

2017-01-03

Heterocyst-forming cyanobacteria grow as filaments in which intercellular molecular exchange takes place. During the differentiation of N 2 -fixing heterocysts, regulators are transferred between cells. In the diazotrophic filament, vegetative cells that fix CO 2 through oxygenic photosynthesis provide the heterocysts with reduced carbon and heterocysts provide the vegetative cells with fixed nitrogen. Intercellular molecular transfer has been traced with fluorescent markers, including calcein, 5-carboxyfluorescein, and the sucrose analogue esculin, which are observed to move down their concentration gradient. In this work, we used fluorescence recovery after photobleaching (FRAP) assays in the model heterocyst-forming cyanobacterium Anabaena sp. strain PCC 7120 to measure the temperature dependence of intercellular transfer of fluorescent markers. We find that the transfer rate constants are directly proportional to the absolute temperature. This indicates that the "septal junctions" (formerly known as "microplasmodesmata") linking the cells in the filament allow molecular exchange by simple diffusion, without any activated intermediate state. This constitutes a novel mechanism for molecular transfer across the bacterial cytoplasmic membrane, in addition to previously characterized mechanisms for active transport and facilitated diffusion. Cyanobacterial septal junctions are functionally analogous to the gap junctions of metazoans. Although bacteria are frequently considered just as unicellular organisms, there are bacteria that behave as true multicellular organisms. The heterocyst-forming cyanobacteria grow as filaments in which cells communicate. Intercellular molecular exchange is thought to be mediated by septal junctions. Here, we show that intercellular transfer of fluorescent markers in the cyanobacterial filament has the physical properties of simple diffusion. Thus, cyanobacterial septal junctions are functionally analogous to metazoan gap junctions

Electrical responses by effects of molecular adsorption on channel and junctions of carbon nanotube field effect transistors

International Nuclear Information System (INIS)

Kang, Donghun; Park, Wanjun

2008-01-01

We report the adsorption effect on the electrical transport of nanotube field effect transistors. The source-drain current is monitored separately for the nanotube channel and the metal-nanotube junction under different pressures of ambient air with a blocking passivation. The metal-nanotube junction shows a significant change from p-type to ambipolar upon vacuum pumping, while the nanotube channel changes modestly. The metal-nanotube junction is found to be far more sensitive to the environment than the nanotube channel. We suggest that the adsorption states underneath the blocking layer do not desorb, and thus the positive carriers would not be diluted upon the vacuum pumping. This result is interpreted as the formation of an i-p-i and p-i-p junction with charge transfer by oxygen molecules. (fast track communication)

Josephson edge junctions on YBa2Cu3O7 thin films prepared with Br-ethanol etching

International Nuclear Information System (INIS)

Faley, M.I.; Poppe, U.; Daehne, U.; Goncharov, Yu.G.; Klein, N.; Urban, K.; Soltner, H.

1993-01-01

To produce damage-free edges is one of the main problems in the preparation of the Josephson edge-type junctions and interconnects in multilayer structures including high temperature superconductors. The commonly used ion beam etching has the disadvantages of the risk of contamination by redeposited material and structural damage to the surface of the edge. Vasquez et al and Gurvitch et al introduced a nonaqueous Br-ethanol etching for the preparation of clean surfaces of YBa 2 Cu 3 O 7 single crystals and thin films. We have developed a procedure of deep-UV-photolithography combined with nonaqueous Br-ethanol etching for the preparation of the Josephson edge-type junctions. Here we present the improvement of this method and report further results on the study of the electron transport properties of Josephson junctions with the edges of YBa 2 Cu 3 O 7 thin films produced by this technique. (orig.)

Josephson tunnel junctions in niobium films

International Nuclear Information System (INIS)

Wiik, Tapio.

1976-12-01

A method of fabricating stable Josephson tunnel junctions with reproducible characteristics is described. The junctions have a sandwich structure consisting of a vacuum evaporated niobium film, a niobium oxide layer produced by the glow discharge method and a lead film deposited by vacuum evaporation. Difficulties in producing thin-film Josephson junctions are discussed. Experimental results suggest that the lower critical field of the niobium film is the most essential parameter when evaluating the quality of these junctions. The dependence of the lower critical field on the film thickness and on the Ginzburg-Landau parameter of the film is studied analytically. Comparison with the properties of the evaporated films and with the previous calculations for bulk specimens shows that the presented model is applicable for most of the prepared samples. (author)

Effect of bundle junction face and misalignment on the pressure drops across a randomly loaded and aligned 12 bundles in CANDU fuel channel

Energy Technology Data Exchange (ETDEWEB)

Suk, H. C.; Sim, K. S.; Chang, C. H.; Lee, Y. O. [Korea Atomic Energy Reaearch Institute, Taejon (Korea, Republic of)

1996-06-01

The pressure drop of twelve fuel bundle string in the CANDU-6 fuel channel is equal to the sum of the eleven junction pressure losses, the bundle string entrance and exit pressure losses, the skin friction pressure loss, and other appendage pressure losses, where the junction loss is dependent on the bundle and faces and angular alignments of the junctions. The results of the single junction pressure drop tests in a short rig show that the most probable pressure drop of the eleven junction was analytically equal to the eleven times of average pressure drop of all the possible single junction pressure drops, and also that the largest and smallest junction pressure drops across the eleven junctions probably occurred only with BA and BB type junctions, respectively, where A and B denote the bundle end sides with an end-plates on which a company monogram is stamped and unstamped, respectively. 5 refs., 7 figs., 1 tab. (author).

Kink propagation and trapping in a two-dimensional curved Josephson junction

DEFF Research Database (Denmark)

Gorria, Carlos; Gaididei, Yuri Borisovich; Sørensen, Mads Peter

2004-01-01

for Josephson junctions of overlap type. A collective variable approach based on the kink position and the kink width depending on the transversal coordinate is developed. The latter allows to take into account both longitudinal and centrifugal forces which act on the nonlinear excitation moving in a region...

Differences and similarities of adenocarcinomas of the esophagus and esophagogastric junction

NARCIS (Netherlands)

Marsman, W. A.; Tytgat, G. N. J.; ten Kate, F. J. W.; van Lanschot, J. J. B.

2005-01-01

During the last few decades there has been an alarming rise in the incidence of tumors originating at the esophagogastric junction (EGJ) [1]. The reason for this is unknown. Tumors of the EGJ can be categorized in two types of cancer divided according to their anatomical origin: distal esophageal

Molecular series-tunneling junctions.

Science.gov (United States)

Liao, Kung-Ching; Hsu, Liang-Yan; Bowers, Carleen M; Rabitz, Herschel; Whitesides, George M

2015-05-13

Charge transport through junctions consisting of insulating molecular units is a quantum phenomenon that cannot be described adequately by classical circuit laws. This paper explores tunneling current densities in self-assembled monolayer (SAM)-based junctions with the structure Ag(TS)/O2C-R1-R2-H//Ga2O3/EGaIn, where Ag(TS) is template-stripped silver and EGaIn is the eutectic alloy of gallium and indium; R1 and R2 refer to two classes of insulating molecular units-(CH2)n and (C6H4)m-that are connected in series and have different tunneling decay constants in the Simmons equation. These junctions can be analyzed as a form of series-tunneling junctions based on the observation that permuting the order of R1 and R2 in the junction does not alter the overall rate of charge transport. By using the Ag/O2C interface, this system decouples the highest occupied molecular orbital (HOMO, which is localized on the carboxylate group) from strong interactions with the R1 and R2 units. The differences in rates of tunneling are thus determined by the electronic structure of the groups R1 and R2; these differences are not influenced by the order of R1 and R2 in the SAM. In an electrical potential model that rationalizes this observation, R1 and R2 contribute independently to the height of the barrier. This model explicitly assumes that contributions to rates of tunneling from the Ag(TS)/O2C and H//Ga2O3 interfaces are constant across the series examined. The current density of these series-tunneling junctions can be described by J(V) = J0(V) exp(-β1d1 - β2d2), where J(V) is the current density (A/cm(2)) at applied voltage V and βi and di are the parameters describing the attenuation of the tunneling current through a rectangular tunneling barrier, with width d and a height related to the attenuation factor β.

Direct assessment of p-n junctions in single GaN nanowires by Kelvin probe force microscopy

Science.gov (United States)

Minj, Albert; Cros, Ana; Auzelle, Thomas; Pernot, Julien; Daudin, Bruno

2016-09-01

Making use of Kelvin probe force microscopy, in dark and under ultraviolet illumination, we study the characteristics of p-n junctions formed along the axis of self-organized GaN nanowires (NWs). We map the contact potential difference of the single NW p-n junctions to locate the space charge region and directly measure the depletion width and the junction voltage. Simulations indicate a shrinkage of the built-in potential for NWs with small diameter due to surface band bending, in qualitative agreement with the measurements. The photovoltage of the NW/substrate contact is studied by analyzing the response of NW segments with p- and n-type doping under illumination. Our results show that the shifts of the Fermi levels, and not the changes in surface band bending, are the most important effects under above band-gap illumination. The quantitative electrical information obtained here is important for the use of NW p-n junctions as photovoltaic or rectifying devices at the nanoscale, and is especially relevant since the technique does not require the formation of ohmic contacts to the NW junction.

Counterdoped very shallow p+/n junctions obtained by B and Sb implantation and codiffusion in Si

Science.gov (United States)

Solmi, Sandro

1998-02-01

In this article we investigate the B and Sb codiffusion upon postimplantation annealing in order to fabricate very shallow p+/n junctions (⩽70 nm), suitable for a complementary metal-oxide-semiconductor technology with a channel length of 0.18 μm. The junctions are prepared by implanting Sb and subsequently BF2, at a higher dose, in an n-type Si substrate. The preamorphization with Sb avoids the B channeling and increases the n-type doping in the junction region, thus confining the depth of the p layer. Furthermore, both the transient enhanced diffusion, being the B implanted in a preamorphized layer, and the standard diffusion, due to the pairing between donors and acceptors, are strongly reduced. This procedure allows us to obtain very shallow junctions even after annealings with relatively high thermal budget, like 800 °C/8 h or 900 °C/1 h, or 950 °C/10 min or 1000 °C/60 s. We verified that dopant diffusion is strongly affected by a direct donor-acceptor interaction, and that good prediction of the experimental results can only be obtained using a simulation code which takes into account the formation of neutral, near immobile, Sb-B pairs.

Performance of single-junction and dual-junction InGaP/GaAs solar cells under low concentration ratios

International Nuclear Information System (INIS)

Khan, Aurangzeb; Yamaguchi, Masafumi; Takamoto, Tatsuya

2004-01-01

A study of the performance of single-junction InGaP/GaAs and dual-junction InGaP/GaAs tandem cells under low concentration ratios (up to 15 suns), before and after 1 MeV electron irradiation is presented. Analysis of the tunnel junction parameters under different concentrated light illuminations reveals that the peak current (J P ) and valley current (J V ) densities should be greater than the short-circuit current density (J sc ) for better performance. The tunnel junction behavior against light intensity improved after irradiation. This led to the suggestion that the peak current density (J P ) and valley current density (J V ) of the tunnel junction were enhanced after irradiation or the peak current was shifted to higher concentration. The recovery of the radiation damage under concentrated light illumination conditions suggests that the performance of the InGaP/GaAs tandem solar cell can be enhanced even under low concentration ratios

Current noise in tunnel junctions

Energy Technology Data Exchange (ETDEWEB)

Frey, Moritz; Grabert, Hermann [Physikalisches Institut, Universitaet Freiburg, Hermann-Herder-Strasse 3, 79104, Freiburg (Germany)

2017-06-15

We study current fluctuations in tunnel junctions driven by a voltage source. The voltage is applied to the tunneling element via an impedance providing an electromagnetic environment of the junction. We use circuit theory to relate the fluctuations of the current flowing in the leads of the junction with the voltage fluctuations generated by the environmental impedance and the fluctuations of the tunneling current. The spectrum of current fluctuations is found to consist of three parts: a term arising from the environmental Johnson-Nyquist noise, a term due to the shot noise of the tunneling current and a third term describing the cross-correlation between these two noise sources. Our phenomenological theory reproduces previous results based on the Hamiltonian model for the dynamical Coulomb blockade and provides a simple understanding of the current fluctuation spectrum in terms of circuit theory and properties of the average current. Specific results are given for a tunnel junction driven through a resonator. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Transjugular intrahepatic portosystemic shunt for the treatment of Budd-Chiari syndrome

International Nuclear Information System (INIS)

Han Guohong; He Chuangye; Yin Zhanxin; Meng Xiangjie; Wang Jianhong; Zhang Hongbo; Zhou Xinming; Wu Kaichun; Ding Jie; Fan Daiming

2008-01-01

Objective: To evaluate the efficacy of transjugular intrahepatic portosystemic shunt (TIPS) for Budd-Chiari syndrome (BCS). Methods: 14 patients with clinical findings of progressive liver function abnormality and severe complication of portal hypertension (upper gastrointestinal bleeding and refractory ascites)were diagnosed as BCS. Based on imaging manifestations, these patients were classified as follows: obstruction of inferior vena cava (1 case); obstruction of hepatic veins (5 cases); combined obstruction (obstruction of hepatic veins and inferior vena cava)(8 cases). During the procedure, different puncture points were selected for fulfilling the real condition; including 7 cases from hepatic vein to portal vein; 4 cases from inferior vena cava to hepatic vein, 4 cases from the right hepatic vein to portal vein. After the operation, the follow-up evaluation of blood flow in the shunt was performed. Results: All of these patients were successfully performed with TIPS, with average pressure of portal vein decreasing from (4.9 ± 1.4) KPa to(3.2 ± 1.5) KPa. After 5 to 64 mouths follow-up, the recurrent upper gastrointestinal bleeding occurred in two patients due to stent stenosis and were well controlled through balloon angioplasty. Conclusions: TIPS is an effective treatment for BCS with progressive liver dysfunction or severe portal hypertension with upper gastrointestinal bleeding and refractory ascites. In addition, it also contributes to the treatment of the recurrent or severe portal hypertension after the inferior vena cava or hepatic vein angioplasty. (authors)

Vibrationally coupled electron transport through single-molecule junctions

Energy Technology Data Exchange (ETDEWEB)

Haertle, Rainer

2012-04-26

vibrational effects have a profound influence on the transport characteristics of a single-molecule contact and play therefore a fundamental role in this transport problem. Our findings demonstrate that vibrationally coupled electron transport through a molecular junction involves two types of processes: (i) transport processes, where an electron tunnels through the molecular bridge from one lead to the other, and (ii) electron-hole pair creation processes, where an electron tunnels from one of the leads onto the molecular bridge and back to the same lead again. Transport processes directly contribute to the electrical current flowing through a molecular contact and involve both excitation and deexcitation processes of the vibrational modes of the junction. Electron-hole pair creation processes do not directly contribute to the electrical current and typically involve only deexcitation processes. Nevertheless, they constitute a cooling mechanism for the vibrational modes of a single-molecule junction that is as important as cooling by transport processes. As the level of vibrational excitation determines the efficiency of electron transport processes, they have an indirect influence on the electrical current flowing through the junction. As we show, however, this influence can be substantial, in particular, if the molecule is coupled asymmetrically to the leads. Accounting for all these processes and their complex interrelationship, we analyze a number of intriguing transport phenomena, including rectification, negative differential resistance, anomalous peak broadening, mode-selective vibrational excitation and vibrationally induced decoherence. Moreover, we show that higher levels of vibrational excitation are obtained for weaker electronic-vibrational coupling. Thus, based on physical grounds, we establish a relation between the weak electronic-vibrational coupling limit and the limit of large bias voltages, where the level of vibrational excitation in a molecular junction

Curved Josephson junction

International Nuclear Information System (INIS)

Dobrowolski, Tomasz

2012-01-01

The constant curvature one and quasi-one dimensional Josephson junction is considered. On the base of Maxwell equations, the sine–Gordon equation that describes an influence of curvature on the kink motion was obtained. It is showed that the method of geometrical reduction of the sine–Gordon model from three to lower dimensional manifold leads to an identical form of the sine–Gordon equation. - Highlights: ► The research on dynamics of the phase in a curved Josephson junction is performed. ► The geometrical reduction is applied to the sine–Gordon model. ► The results of geometrical reduction and the fundamental research are compared.

CT-findings in pain syndromes originated from thoraco-lumbar junction

International Nuclear Information System (INIS)

Dimitrov, I.; Karadjova, M.; Malchanova, V.

2007-01-01

The thoraco-lumbar junction syndrome imitates, as far as clinical symptoms are concerned, low back pain, caused by disc protrusion in the lower lumbar vertebral segments. It is manifested by referred pain in the area, innervated by posterior and anterior primary rami (dorsal and ventral rami), belonging to thoraco-lumbar junction vertebral segments (Th11-L2). Eighty one patients with clinically diagnosed thoraco-lumbar junction syndrome underwent CT-investigations, that aimed establishing pathological processes, leading to this clinical symptomatology. 148 vertebral levels were examined. In 67 patients we scanned two consecutive levels to find the type of change of the zygapophyseal joints. We found facet tropism (asymmetry) in 72 patients (88.8%) or in 117 levels (79.6%), degenerated faced joints in 63 patients (77.8%), pathology of the intervertebral disc - in 33 patients (43.1%) including 5 patients (6.2%) with disc prolapse. When investigating on two subsequent segments (Th11-Th12 and Th12-L1) sudden anatomical change in orientation of facets occurred in 55 patients (82%). Our findings support the hypothesis of the facet-joint origin of this ailment. (authors)

Nonlinear viscous vortex motion in two-dimensional Josephson-junction arrays

International Nuclear Information System (INIS)

Hagenaars, T.J.; Tiesinga, P.H.E.; van Himbergen, J.E.; Jose, J.V.

1994-01-01

When a vortex in a two-dimensional Josephson-junction array is driven by a constant external current it may move as a particle in a viscous medium. Here we study the nature of this viscous motion. We model the junctions in a square array as resistively and capacitively shunted Josephson junctions and carry out numerical calculations of the current-voltage characteristics. We find that the current-voltage characteristics in the damped regime are well described by a model with a nonlinear viscous force of the form F D =η(y)y=[A/(1+By]y, where y is the vortex velocity, η(y) is the velocity-dependent viscosity, and A and B are constants for a fixed value of the Stewart-McCumber parameter. This result is found to apply also for triangular lattices in the overdamped regime. Further qualitative understanding of the nature of the nonlinear friction on the vortex motion is obtained from a graphic analysis of the microscopic vortex dynamics in the array. The consequences of having this type of nonlinear friction law are discussed and compared to previous theoretical and experimental studies

Josephson tunnel junctions with ferromagnetic interlayer

International Nuclear Information System (INIS)

Weides, M.P.

2006-01-01

Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al 2 O 3 tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or π coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, π) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-π Josephson junction. At a certain temperature this 0-π junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum Φ 0 . Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T → 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

Josephson tunnel junctions with ferromagnetic interlayer

Energy Technology Data Exchange (ETDEWEB)

Weides, M.P.

2006-07-01

Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

AC Josephson effect in YBa2Cu3O7-δ bicrystal grain boundary junctions

International Nuclear Information System (INIS)

Fischer, G.M.; Andreev, A.V.; Divin, Y.Ya.; Freltoft, T.; Mygind, J.; Pedersen, N.F.; Shen Yueqiang; Vase, P.

1994-01-01

The ac Josephson effect in YBa 2 Cu 3 O 7-δ bicrystal grain boundary junctions was studied in the temperature range from 4K to 90K. Junctions with widths from 0.2 to 50 μm were made on SrTiO 3 bicrystal substrates by laser ablation and e-beam lithography. The linewidth of the Josephson oscillations is derived from the shape of the dc voltage response to low-intensity, f = 70 GHz radiation at voltages V ≅ (h/2e) f, assuming the RSJ model. The effect of the size on the Josephson behavior of this type of high-T c junctions was studied. Close to T c the linewidth of the Josephson oscillations was shown to be determined by thermal fluctuations. (orig.)

Mechanically Stacked Dual-Junction and Triple-Junction III-V/Si-IBC Cells with Efficiencies Exceeding 31.5% and 35.4%: Preprint

Energy Technology Data Exchange (ETDEWEB)

Schnabel, Manuel [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tamboli, Adele C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Warren, Emily L [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Schulte-Huxel, Henning [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Klein, Talysa [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Van Hest, Marinus F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Geisz, John F [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Stradins, Paul [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Steiner, Myles A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Rienaecker, Michael [Institute for Solar Energy Research Hamelin (ISFH); Merkle, Agnes [Institute for Solar Energy Research Hamelin (ISFH); Kajari-Schroeder, S. [Institute for Solar Energy Research Hamelin (ISFH); Niepelt, Raphael [Institute for Solar Energy Research Hamelin (ISFH); Schmidt, Jan [Institute for Solar Energy Research Hamelin (ISFH); Leibniz Universitat Hannover; Brendel, Rolf [Institute for Solar Energy Research Hamelin (ISFH); Leibniz Universitat Hannover; Peibst, Robby [Institute for Solar Energy Research Hamelin (ISFH); Leibniz Universitat Hannover

2017-10-02

Despite steady advancements in the efficiency of crystalline Silicon (c-Si) photovoltaics (PV) within the last decades, the theoretical efficiency limit of 29.4 percent depicts an insurmountable barrier for silicon-based single-junction solar cells. Combining the Si cell with a second absorber material on top in a dual junction tandem or triple junction solar cell is an attractive option to surpass this limit significantly. We demonstrate a mechanically stacked GaInP/Si dual-junction cell with an in-house measured efficiency of 31.5 percent and a GaInP/GaAs/Si triple-junction cell with a certified efficiency of 35.4 percent.

Electromagnetic waves in single- and multi-Josephson junctions

International Nuclear Information System (INIS)

Matsumoto, Hideki; Koyama, Tomio; Machida, Masahiko

2008-01-01

The terahertz wave emission from the intrinsic Josephson junctions is one of recent topics in high T c superconductors. We investigate, by numerical simulation, properties of the electromagnetic waves excited by a constant bias current in the single- and multi-Josephson junctions. Nonlinear equations of phase-differences are solved numerically by treating the effects of the outside electromagnetic fields as dynamical boundary conditions. It is shown that the emitted power of the electromagnetic wave can become large near certain retrapping points of the I-V characteristics. An instability of the inside phase oscillation is related to large amplitude of the oscillatory waves. In the single- (or homogeneous mutli-) Josephson junctions, electromagnetic oscillations can occur either in a form of standing waves (shorter junctions) or by formation of vortex-antivortex pairs (longer junctions). How these two effects affects the behavior of electromagnetic waves in the intrinsic Josephson junctions is discussed

The effect and mechanism of the bipolar junction transistor in different temperature

International Nuclear Information System (INIS)

Wang Dong; Lu Wu; Ren Diyuan; Li Aiwu; Kuang Zhibing

2007-01-01

The annealing-effect of bipolar junction transistor in different temperature is investigated. It is found that the anneal of the bipolar transistor is related to the annealing-temperature, and the annealing-effect of the different type transistor is dissimilar. The possible mechanism is discussed. (authors)

Tunable Nitride Josephson Junctions.

Energy Technology Data Exchange (ETDEWEB)

Missert, Nancy A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Henry, Michael David [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Lewis, Rupert M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Howell, Stephen W. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolfley, Steven L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Brunke, Lyle Brent [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Wolak, Matthaeus [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

2017-12-01

We have developed an ambient temperature, SiO₂/Si wafer - scale process for Josephson junctions based on Nb electrodes and Ta x N barriers with tunable electronic properties. The films are fabricated by magnetron sputtering. The electronic properties of the Ta_xN barriers are controlled by adjusting the nitrogen flow during sputtering. This technology offers a scalable alternative to the more traditional junctions based on AlO_x barriers for low - power, high - performance computing.

A role for recombination junctions in the segregation of mitochondrial DNA in yeast.

Science.gov (United States)

Lockshon, D; Zweifel, S G; Freeman-Cook, L L; Lorimer, H E; Brewer, B J; Fangman, W L

1995-06-16

In S. cerevisiae, mitochondrial DNA (mtDNA) molecules, in spite of their high copy number, segregate as if there were a small number of heritable units. The rapid segregation of mitochondrial genomes can be analyzed using mtDNA deletion variants. These small, amplified genomes segregate preferentially from mixed zygotes relative to wild-type mtDNA. This segregation advantage is abolished by mutations in a gene, MGT1, that encodes a recombination junction-resolving enzyme. We show here that resolvase deficiency causes a larger proportion of molecules to be linked together by recombination junctions, resulting in the aggregation of mtDNA into a small number of cytological structures. This change in mtDNA structure can account for the increased mitotic loss of mtDNA and the altered pattern of mtDNA segregation from zygotes. We propose that the level of unresolved recombination junctions influences the number of heritable units of mtDNA.

Bio-inspired nanostructures for implementing vertical pn-junctions

KAUST Repository

Saffih, Faycal

2011-08-04

An apparatus, system, and method having a 3D pn-junction structure are presented. One embodiment of an apparatus includes a substrate, a first doped structure, and a second doped structure. In one embodiment, the first doped structure has a first doping type. The first doped structure may be formed above the substrate and extend outwardly from an upper surface of the substrate. In one embodiment, the second doped structure has a second doping type. The second doped structure may be formed above the substrate and in contact with the first doped structure. Additionally, the second doped structure may extend outwardly from the upper surface of the substrate.

Bio-inspired nanostructures for implementing vertical pn-junctions

KAUST Repository

Saffih, Faycal

2011-01-01

An apparatus, system, and method having a 3D pn-junction structure are presented. One embodiment of an apparatus includes a substrate, a first doped structure, and a second doped structure. In one embodiment, the first doped structure has a first doping type. The first doped structure may be formed above the substrate and extend outwardly from an upper surface of the substrate. In one embodiment, the second doped structure has a second doping type. The second doped structure may be formed above the substrate and in contact with the first doped structure. Additionally, the second doped structure may extend outwardly from the upper surface of the substrate.

Scattering theory of superconductive tunneling in quantum junctions

International Nuclear Information System (INIS)

Shumeiko, V.S.; Bratus', E.N.

1997-01-01

A consistent theory of superconductive tunneling in single-mode junctions within a scattering formulation of Bogolyubov-de Gennes quantum mechanics is presented. The dc Josephson effect and dc quasiparticle transport in the voltage-biased junctions are considered. Elastic quasiparticle scattering by the junction determines the equilibrium Josephson current. The origin of Andreev bound states in tunnel junctions and their role in equilibrium Josephson transport are discussed. In contrast, quasiparticle tunneling in voltage-biased junctions is determined by inelastic scattering. A general expression for inelastic scattering amplitudes is derived and the quasiparticle current is calculated at all voltages with emphasis on a discussion of the properties of sub gap tunnel current and the nature of subharmonic gap structure

Josephson effect in SIFS junctions at arbitrary scattering

International Nuclear Information System (INIS)

Pugach, N. G.; Kupriyanov, M. Yu.; Goldobin, E.; Koelle, D.; Kleiner, R.

2011-01-01

Full text: The interplay between dirty and clean limits in Superconductor-Ferromagnet-Superconductor (SFS) Josephson junctions is a subject of intensive theoretical studies. SIFS junctions, containing an additional insulator (I) barrier are interesting as potential logic elements in superconducting circuits, since their critical current I c can be tuned over a wide range, still keeping a high I c R N product, where R N is the normal resistance of the junction. They are also a convenient model system for a comparative study of the 0-π transitions for arbitrary relations between characteristic lengths of the F-layer: the layer thickness d, the mean free path l, the magnetic length ξ H =v F /2H, and the nonmagnetic coherence length ξ 0 =v F /2πT, where v F is the Fermi velocity, H is the exchange magnetic energy, and T is the temperature. The spatial variations of the order parameter are described by the complex coherent length in the ferromagnet ξ F -1 = ξ 1 -1 + iξ 2 -1 . It is well known, that in the dirty limit (l 1,2 ) described by the Usadel equations both ξ 1 2 = ξ 2 2 = v F l/3H. In this work the spatial distribution of the anomalous Green's functions and the Josephson current in the SIFS junction are calculated. The linearized Eilenberger equations are solved together with the Zaitsev boundary conditions. This allows comparing the dirty and the clean limits, investigating a moderate disorder, and establishing the applicability limits of the Usadel equations for such structures. We demonstrate that for an arbitrary relation between l, ξ H , and d the spatial distribution of the anomalous Green's function can be approximated by a single exponent with reasonable accuracy, and we find its effective decay length and oscillation period for several values of ξ H , l and d. The role of different types of the FS interface is analyzed. The applicability range of the Usadel equation is established. The results of calculations have been applied to the

Chemically etched edges of YBa2Cu3O7 films for interconnects, crossovers and Josephson junctions

International Nuclear Information System (INIS)

Poppe, U.; Faley, M.I.; Urban, K.; Soltner, H.

1993-01-01

To produce damage-free edges is one of the main problems during the preparation of Josephson edge-type junctions and interconnects in multilayer structures including high temperature superconductors. The inherently short and anisotropic coherence length in high temperature superconductors makes it also difficult to fabricate Josephson junctions from these materials. One promising technique which helps to overcome such problems using a nonaqueous chemical etching with a Br-ethanol solution was first presented in a recent publication. Here we report results obtained with the use of this method: test of insulation properties of PrBa 2 Cu 3 O 7 , PrBa 2 Cu 2.85 Ga 0.15 O 7 , and SrTiO 3 used for crossovers and Josephson junctions. Some features of interconnects and Josephson junctions, prepared on the basis of the chemical technique are also discussed. (orig.)

Short chain molecular junctions: Charge transport versus dipole moment

International Nuclear Information System (INIS)

Ikram, I. Mohamed; Rabinal, M.K.

2015-01-01

Graphical abstract: - Highlights: • The role of dipole moment of organic molecules on molecular junctions has been studied. • Molecular junctions constituted using propargyl molecules of different dipole moments. • The electronic properties of the molecules were calculated using Gaussian software. • Junctions show varying rectification due to their varying dipole moment and orientation. - Abstract: The investigation of the influence of dipole moment of short chain organic molecules having three carbon atoms varying in end group on silicon surface was carried on. Here, we use three different molecules of propargyl series varying in dipole moment and its orientation to constitute molecular junctions. The charge transport mechanism in metal–molecules–semiconductor (MMS) junction obtained from current–voltage (I–V) characteristics shows the rectification behavior for two junctions whereas the other junction shows a weak rectification. The electronic properties of the molecules were calculated using Gaussian software package. The observed rectification behavior of these junctions is examined and found to be accounted to the orientation of dipole moment and electron cloud density distribution inside the molecules

Some chaotic features of intrinsically coupled Josephson junctions

International Nuclear Information System (INIS)

Kolahchi, M.R.; Shukrinov, Yu.M.; Hamdipour, M.; Botha, A.E.; Suzuki, M.

2013-01-01

Highlights: ► Intrinsically coupled Josephson junctions model a high-T c superconductor. ► Intrinsically coupled Josephson junctions can act as a chaotic nonlinear system. ► Chaos could be due to resonance overlap. ► Avoiding parameters that lead to chaos is important for the design of resonators. -- Abstract: We look for chaos in an intrinsically coupled system of Josephson junctions. This study has direct applications for the high-T c resonators which require coherence amongst the junctions

Highly sensitive wide bandwidth photodetector based on internal photoemission in CVD grown p-type MoS2/graphene Schottky junction.

Science.gov (United States)

Vabbina, PhaniKiran; Choudhary, Nitin; Chowdhury, Al-Amin; Sinha, Raju; Karabiyik, Mustafa; Das, Santanu; Choi, Wonbong; Pala, Nezih

2015-07-22

Two dimensional (2D) Molybdenum disulfide (MoS2) has evolved as a promising material for next generation optoelectronic devices owing to its unique electrical and optical properties, such as band gap modulation, high optical absorption, and increased luminescence quantum yield. The 2D MoS2 photodetectors reported in the literature have presented low responsivity compared to silicon based photodetectors. In this study, we assembled atomically thin p-type MoS2 with graphene to form a MoS2/graphene Schottky photodetector where photo generated holes travel from graphene to MoS2 over the Schottky barrier under illumination. We found that the p-type MoS2 forms a Schottky junction with graphene with a barrier height of 139 meV, which results in high photocurrent and wide spectral range of detection with wavelength selectivity. The fabricated photodetector showed excellent photosensitivity with a maximum photo responsivity of 1.26 AW(-1) and a noise equivalent power of 7.8 × 10(-12) W/√Hz at 1440 nm.

Field emission current from a junction field-effect transistor

International Nuclear Information System (INIS)

Monshipouri, Mahta; Abdi, Yaser

2015-01-01

Fabrication of a titanium dioxide/carbon nanotube (TiO 2 /CNT)-based transistor is reported. The transistor can be considered as a combination of a field emission transistor and a junction field-effect transistor. Using direct current plasma-enhanced chemical vapor deposition (DC-PECVD) technique, CNTs were grown on a p-typed (100)-oriented silicon substrate. The CNTs were then covered by TiO 2 nanoparticles 2–5 nm in size, using an atmospheric pressure CVD technique. In this device, TiO 2 /CNT junction is responsible for controlling the emission current. High on/off-current ratio and proper gate control are the most important advantages of device. A model based on Fowler–Nordheim equation is utilized for calculation of the emission current and the results are compared with experimental data. The effect of TiO 2 /CNT hetero-structure is also investigated, and well modeled

Gap junctions and connexin-interacting proteins

NARCIS (Netherlands)

Giepmans, Ben N G

2004-01-01

Gap junctions form channels between adjacent cells. The core proteins of these channels are the connexins. Regulation of gap junction communication (GJC) can be modulated by connexin-associating proteins, such as regulatory protein phosphatases and protein kinases, of which c-Src is the

A genome-wide association study identifies candidate loci associated to syringomyelia secondary to Chiari-like malformation in Cavalier King Charles Spaniels.

Science.gov (United States)

Ancot, Frédéric; Lemay, Philippe; Knowler, Susan P; Kennedy, Karen; Griffiths, Sandra; Cherubini, Giunio Bruto; Sykes, Jane; Mandigers, Paul J J; Rouleau, Guy A; Rusbridge, Clare; Kibar, Zoha

2018-03-22

Syringomyelia (SM) is a common condition affecting brachycephalic toy breed dogs and is characterized by the development of fluid-filled cavities within the spinal cord. It is often concurrent with a complex developmental malformation of the skull and craniocervical vertebrae called Chiari-like malformation (CM) characterized by a conformational change and overcrowding of the brain and cervical spinal cord particularly at the craniocervical junction. CM and SM have a polygenic mode of inheritance with variable penetrance. We identified six cranial T1-weighted sagittal MRI measurements that were associated to maximum transverse diameter of the syrinx cavity. Increased syrinx transverse diameter has been correlated previously with increased likelihood of behavioral signs of pain. We next conducted a whole genome association study of these traits in 65 Cavalier King Charles Spaniel (CKCS) dogs (33 controls, 32 with extreme phenotypes). Two loci on CFA22 and CFA26 were found to be significantly associated to two traits associated with a reduced volume and altered orientation of the caudal cranial fossa. Their reconstructed haplotypes defined two associated regions that harbor only two genes: PCDH17 on CFA22 and ZWINT on CFA26. PCDH17 codes for a cell adhesion molecule expressed specifically in the brain and spinal cord. ZWINT plays a role in chromosome segregation and its expression is increased with the onset of neuropathic pain. Targeted genomic sequencing of these regions identified respectively 37 and 339 SNPs with significantly associated P values. Genotyping of tagSNPs selected from these 2 candidate loci in an extended cohort of 461 CKCS (187 unaffected, 274 SM affected) identified 2 SNPs on CFA22 that were significantly associated to SM strengthening the candidacy of this locus in SM development. We identified 2 loci on CFA22 and CFA26 that contained only 2 genes, PCDH17 and ZWINT, significantly associated to two traits associated with syrinx transverse

Planar Josephson tunnel junctions in a transverse magnetic field

DEFF Research Database (Denmark)

Monacoa, R.; Aarøe, Morten; Mygind, Jesper

2007-01-01

demagnetization effects imposed by the tunnel barrier and electrodes geometry are important. Measurements of the junction critical current versus magnetic field in planar Nb-based high-quality junctions with different geometry, size, and critical current density show that it is advantageous to use a transverse......Traditionally, since the discovery of the Josephson effect in 1962, the magnetic diffraction pattern of planar Josephson tunnel junctions has been recorded with the field applied in the plane of the junction. Here we discuss the static junction properties in a transverse magnetic field where...

Engineering of Droplet Manipulation in Tertiary Junction Microfluidic Channels

Science.gov (United States)

2017-06-30

mechanics point-of-view, the larger motivation to carry out this research work derives from its application in biomedical engineering for sorting CTCs...AFRL-AFOSR-JP-TR-2017-0055 Engineering of Droplet Manipulation in Tertiary Junction Microfluidic Channels Shalini Gupta INDIAN INSTITUTE OF...2017 2. REPORT TYPE Final 3. DATES COVERED (From - To) 14 May 2015 to 13 Nov 2016 4. TITLE AND SUBTITLE Engineering of Droplet Manipulation in

Summary of theoretical and experimental investigation of grating type, silicon photovoltaic cells. [using p-n junctions on light receiving surface of base crystal

Science.gov (United States)

Chen, L. Y.; Loferski, J. J.

1975-01-01

Theoretical and experimental aspects are summarized for single crystal, silicon photovoltaic devices made by forming a grating pattern of p/n junctions on the light receiving surface of the base crystal. Based on the general semiconductor equations, a mathematical description is presented for the photovoltaic properties of such grating-like structures in a two dimensional form. The resulting second order elliptical equation is solved by computer modeling to give solutions for various, reasonable, initial values of bulk resistivity, excess carrier concentration, and surface recombination velocity. The validity of the computer model is established by comparison with p/n devices produced by alloying an aluminum grating pattern into the surface of n-type silicon wafers. Current voltage characteristics and spectral response curves are presented for cells of this type constructed on wafers of different resistivities and orientations.

RF Shot Noise Measurements in Au Atomic-scale Junctions

Science.gov (United States)

Chen, Ruoyu

Conduction electrons are responsible for many physical or chemical phenomena in condensed matter systems, and their behavior can be directly studied by electronic transport measurements. In conventional transport measurements, conductance or resistance is usually the focus. Such a measurement can be as simple as a quick two terminal DC check by a multi-meter, or a more sophisticated lock-in measurement of multiple higher harmonic signals synchronized to different frequencies. Conductance carries direct information about the quasi-particle density of states and the local electronic distributions, which are usually Fermi-Dirac distribution. Conductance is modified or dominated by scattering from defacts or interfaces, and could also reflect the spin-spin exchange interactions or inelastic couplings with phonons and photons. Naturally one can ask the question: is there anything else we can measure electronically, which carries extra information that a conductance measurement does not provide? One answer to this question is the electronic noise. While the conductance reflects the average charge conduction ability of a system, noise describes how the physical quantities fluctuate around their average values. Some of the fluctuations carry information about their physical origins. This thesis will focus on one particular type of the electronic noise shot noise, but other types of noise will also be introduced and discussed. We choose to measure the radio frequency component of shot noise, combining with a modulated lock-in detection technique, which provides a method to largely get rid of other unwanted low-frequency noise signals. Au atomic-scale junctions are the systems we studied here. Au is relatively well understood and will not generate too many complications, so it's ideal as the first platform for us to understand both shot noise itself and our RF technique. On the other hand, the atomic scale raises fundamental questions about electronic transport and local

Transitional basal cells at the squamous-columnar junction generate Barrett’s oesophagus

Science.gov (United States)

Jiang, Ming; Li, Haiyan; Zhang, Yongchun; Yang, Ying; Lu, Rong; Liu, Kuancan; Lin, Sijie; Lan, Xiaopeng; Wang, Haikun; Wu, Han; Zhu, Jian; Zhou, Zhongren; Xu, Jianming; Lee, Dong-Kee; Zhang, Lanjing; Lee, Yuan-Cho; Yuan, Jingsong; Abrams, Julian A.; Wang, Timothy G.; Sepulveda, Antonia R.; Wu, Qi; Chen, Huaiyong; Sun, Xin; She, Junjun; Chen, Xiaoxin; Que, Jianwen

2017-01-01

In several organ systems the transitional zone between different types of epithelia is a hotspot for pre-neoplastic metaplasia and malignancy1–3. However, the cell-of-origin for the metaplastic epithelium and subsequent malignancy, remains obscure1–3. In the case of Barrett’s oesophagus (BE), intestinal metaplasia occurs at the gastro-oesophageal junction, where stratified squamous epithelium transitions into simple columnar cells4. Based on different experimental models, several alternative cell types have been proposed as the source of the metaplasia, but in all cases the evidence is inconclusive and no model completely mimics BE with the presence of intestinal goblet cells5–8. Here, we describe a novel transitional columnar epithelium with distinct basal progenitor cells (p63+ KRT5+ KRT7+) in the squamous-columnar junction (SCJ) in the upper gastrointestinal tract of the mouse. We use multiple models and lineage tracing strategies to show that this unique SCJ basal cell population serves as a source of progenitors for the transitional epithelium. Moreover, upon ectopic expression of CDX2 these transitional basal progenitors differentiate into intestinal-like epithelium including goblet cells, thus reproducing Barrett’s metaplasia. A similar transitional columnar epithelium is present at the transitional zones of other mouse tissues, including the anorectal junction, and, importantly, at the gastro-oesophageal junction in the human gut. Acid reflux-induced oesophagitis and the multilayered epithelium (MLE) believed to be a precursor of BE are both characterized by the expansion of the transitional basal progenitor cells. Taken together our findings reveal the presence of a previously unidentified transitional zone in the epithelium of the upper gastrointestinal tract and provide evidence that the p63+ KRT7+ basal cells in this zone are the cell-of-origin for MLE and BE. PMID:29019984

Magnetic and transport properties of single and double perpendicular magnetic tunnel junctions

International Nuclear Information System (INIS)

Cuchet, Lea

2015-01-01

Due to their advantageous properties in terms of data retention, storage density and critical current density for Spin Transfer Torque (STT) switching, the magnetic tunnel junctions with perpendicular anisotropy have become predominant in the developments for MRAM applications. The aim of this thesis is to improve the anisotropy and transport properties of such structures and to realize even more complex stacks such as perpendicular double junctions. Studies on the magnetic properties and Tunnel Magnetoresistance (TMR) measurements showed that to optimize the performances of the junctions, all the thicknesses of the different layers constituting the stack have to be adapted. To guaranty both a large TMR as well a strong perpendicular anisotropy, compromises are most of the time needed. Studies as a function of magnetic thickness enabled to extract the saturation magnetization, the critical thickness and the magnetic dead layer thickness both in the bottom reference and the top storage layer in structures capped with Ta. This type of junction could be tested electrically after patterning the sample into nano-pillars. Knowing that perpendicular anisotropy mostly arises at the metal/oxide interface, the Ta capping layer was replaced by a MgO one, leading to a huge increase in the anisotropy of the free layer. A second top reference was then added on such a stack to create functional perpendicular double junctions. CoFeB/insertion/CoFeB synthetic antiferromagnetic storage layers could be developed and were proved to be stable enough to replace the standard Co/Pt-based reference layers. (author) [fr

Particle detection with superconducting tunnel junctions

International Nuclear Information System (INIS)

Jany, P.

1990-08-01

At the Institute of Experimental Nuclear Physics of the University of Karlsruhe (TH) and at the Institute for Nuclear Physics of the Kernforschungszentrum Karlsruhe we started to produce superconducting tunnel junctions and to investigate them for their suitability as particle detectors. The required facilities for the production of tunnel junctions and the experimental equipments to carry out experiments with them were erected. Experiments are presented in which radiations of different kinds of particles could successfully be measured with the tunnel junctions produced. At first we succeeded in detectioning light pulses of a laser. In experiments with alpha-particles of an energy of 4,6 MeV the alpha-particles were detected with an energy resolution of 1,1%, and it was shown in specific experiments that the phonons originating from the deposition of energy by an alpha-particle in the substrate can be detected with superconducting tunnel junctions at the surface. On that occasion it turned out that the signals could be separated with respect to their point of origin (tunnel junction, contact leads, substrate). Finally X-rays with an energy of 6 keV were detected with an energy resolution of 8% in a test arrangement that makes use of the so-called trapping effect to read out a larger absorber volume. (orig.) [de

Effect of solar-cell junction geometry on open-circuit voltage

Science.gov (United States)

Weizer, V. G.; Godlewski, M. P.

1985-01-01

Simple analytical models have been found that adequately describe the voltage behavior of both the stripe junction and dot junction grating cells as a function of junction area. While the voltage in the former case is found to be insensitive to junction area reduction, significant voltage increases are shown to be possible for the dot junction cell. With regard to cells in which the junction area has been increased in a quest for better performance, it was found that (1) texturation does not affect the average saturation current density J0, indicating that the texturation process is equivalent to a simple extension of junction area by a factor of square root of 3 and (2) the vertical junction cell geometry produces a sizable decrease in J0 that, unfortunately, is more than offset by the effects of attendant areal increases.

Bismuth-catalyzed and doped silicon nanowires for one-pump-down fabrication of radial junction solar cells.

Science.gov (United States)

Yu, Linwei; Fortuna, Franck; O'Donnell, Benedict; Jeon, Taewoo; Foldyna, Martin; Picardi, Gennaro; Roca i Cabarrocas, Pere

2012-08-08

Silicon nanowires (SiNWs) are becoming a popular choice to develop a new generation of radial junction solar cells. We here explore a bismuth- (Bi-) catalyzed growth and doping of SiNWs, via vapor-liquid-solid (VLS) mode, to fabricate amorphous Si radial n-i-p junction solar cells in a one-pump-down and low-temperature process in a single chamber plasma deposition system. We provide the first evidence that catalyst doping in the SiNW cores, caused by incorporating Bi catalyst atoms as n-type dopant, can be utilized to fabricate radial junction solar cells, with a record open circuit voltage of V(oc) = 0.76 V and an enhanced light trapping effect that boosts the short circuit current to J(sc) = 11.23 mA/cm(2). More importantly, this bi-catalyzed SiNW growth and doping strategy exempts the use of extremely toxic phosphine gas, leading to significant procedure simplification and cost reduction for building radial junction thin film solar cells.

Interface-Engineered Charge-Transport Properties in Benzenedithiol Molecular Electronic Junctions via Chemically p-Doped Graphene Electrodes.

Science.gov (United States)

Jang, Yeonsik; Kwon, Sung-Joo; Shin, Jaeho; Jeong, Hyunhak; Hwang, Wang-Taek; Kim, Junwoo; Koo, Jeongmin; Ko, Taeg Yeoung; Ryu, Sunmin; Wang, Gunuk; Lee, Tae-Woo; Lee, Takhee

2017-12-06

In this study, we fabricated and characterized vertical molecular junctions consisting of self-assembled monolayers of benzenedithiol (BDT) with a p-doped multilayer graphene electrode. The p-type doping of a graphene film was performed by treating pristine graphene (work function of ∼4.40 eV) with trifluoromethanesulfonic (TFMS) acid, producing a significantly increased work function (∼5.23 eV). The p-doped graphene-electrode molecular junctions statistically showed an order of magnitude higher current density and a lower charge injection barrier height than those of the pristine graphene-electrode molecular junctions, as a result of interface engineering. This enhancement is due to the increased work function of the TFMS-treated p-doped graphene electrode in the highest occupied molecular orbital-mediated tunneling molecular junctions. The validity of these results was proven by a theoretical analysis based on a coherent transport model that considers asymmetric couplings at the electrode-molecule interfaces.

Advance of Mechanically Controllable Break Junction for Molecular Electronics.

Science.gov (United States)

Wang, Lu; Wang, Ling; Zhang, Lei; Xiang, Dong

2017-06-01

Molecular electronics stands for the ultimate size of functional elements, keeping up with an unstoppable trend over the past few decades. As a vital component of molecular electronics, single molecular junctions have attracted significant attention from research groups all over the world. Due to its pronounced superiority, the mechanically controllable break junctions (MCBJ) technique has been widely applied to characterize the dynamic performance of single molecular junctions. This review presents a system analysis for single-molecule junctions and offers an overview of four test-beds for single-molecule junctions, thus offering more insight into the mechanisms of electron transport. We mainly focus on the development of state-of-the-art mechanically controlled break junctions. The three-terminal gated MCBJ approaches are introduced to manipulate the electron transport of molecules, and MCBJs are combined with characterization techniques. Additionally, applications of MCBJs and remarkable properties of single molecules are addressed. Finally, the challenges and perspective for the mechanically controllable break junctions technique are provided.

Microwave phase locking of Josephson-junction fluxon oscillators

DEFF Research Database (Denmark)

Salerno, M.; Samuelsen, Mogens Rugholm; Filatrella, G.

1990-01-01

Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two-dimensional fun......Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two...

Connexin 26-mediated gap junctional intercellular communication suppresses paracellular permeability of human intestinal epithelial cell monolayers

International Nuclear Information System (INIS)

Morita, Hidekazu; Katsuno, Tatsuro; Hoshimoto, Aihiro; Hirano, Noriaki; Saito, Yasushi; Suzuki, Yasuo

2004-01-01

In some cell types, gap junctional intercellular communication (GJIC) is associated with tight junctions. The present study was performed to determine the roles of GJIC in regulation of the barrier function of tight junctions. Caco-2 human colonic cells were used as a monolayer model, and barrier function was monitored by measuring mannitol permeability and transepithelial electrical resistance (TER). The monolayers were chemically disrupted by treatment with oleic acid and taurocholic acid. Western blotting analyses were performed to evaluate the protein levels of connexins, which are components of gap junctional intercellular channels. Cx26 expression was detected in preconfluent Caco-2 cells, and its level increased gradually after the monolayer reached confluency. These results prompted us to examine whether overexpression of Cx26 affects barrier function. Monolayers of Caco-2 cells stably expressing Cx26 showed significantly lower mannitol permeability and higher TER than mock transfectants when the monolayers were chemically disrupted. The levels of claudin-4, an important component of tight junctions, were significantly increased in the stable Cx26 transfectant. These results suggest that Cx26-mediated GJIC may play a crucial role in enhancing the barrier function of Caco-2 cell monolayers

Solar cell junction temperature measurement of PV module

KAUST Repository

Huang, B.J.

2011-02-01

The present study develops a simple non-destructive method to measure the solar cell junction temperature of PV module. The PV module was put in the environmental chamber with precise temperature control to keep the solar PV module as well as the cell junction in thermal equilibrium with the chamber. The open-circuit voltage of PV module Voc is then measured using a short pulse of solar irradiation provided by a solar simulator. Repeating the measurements at different environment temperature (40-80°C) and solar irradiation S (200-1000W/m2), the correlation between the open-circuit voltage Voc, the junction temperature Tj, and solar irradiation S is derived.The fundamental correlation of the PV module is utilized for on-site monitoring of solar cell junction temperature using the measured Voc and S at a short time instant with open circuit. The junction temperature Tj is then determined using the measured S and Voc through the fundamental correlation. The outdoor test results show that the junction temperature measured using the present method, Tjo, is more accurate. The maximum error using the average surface temperature Tave as the junction temperature is 4.8 °C underestimation; while the maximum error using the present method is 1.3 °C underestimation. © 2010 Elsevier Ltd.

Transition voltages of vacuum-spaced and molecular junctions with Ag and Pt electrodes

KAUST Repository

Wu, Kunlin

2014-07-07

The transition voltage of vacuum-spaced and molecular junctions constructed with Ag and Pt electrodes is investigated by non-equilibrium Green\\'s function formalism combined with density functional theory. Our calculations show that, similarly to the case of Au-vacuum-Au previously studied, the transition voltages of Ag and Pt metal-vacuum-metal junctions with atomic protrusions on the electrode surface are determined by the local density of states of the p-type atomic orbitals of the protrusion. Since the energy position of the Pt 6p atomic orbitals is higher than that of the 5p/6p of Ag and Au, the transition voltage of Pt-vacuum-Pt junctions is larger than that of both Ag-vacuum-Ag and Au-vacuum-Au junctions. When one moves to analyzing asymmetric molecular junctions constructed with biphenyl thiol as central molecule, then the transition voltage is found to depend on the specific bonding site for the sulfur atom in the thiol group. In particular agreement with experiments, where the largest transition voltage is found for Ag and the smallest for Pt, is obtained when one assumes S binding at the hollow-bridge site on the Ag/Au(111) surface and at the adatom site on the Pt(111) one. This demonstrates the critical role played by the linker-electrode binding geometry in determining the transition voltage of devices made of conjugated thiol molecules. © 2014 AIP Publishing LLC.

Soliton excitations in Josephson tunnel junctions

DEFF Research Database (Denmark)

Lomdahl, P. S.; Sørensen, O. H.; Christiansen, Peter Leth

1982-01-01

A detailed numerical study of a sine-Gordon model of the Josephson tunnel junction is compared with experimental measurements on junctions with different L / λJ ratios. The soliton picture is found to apply well on both relatively long (L / λJ=6) and intermediate (L / λJ=2) junctions. We find good...... agreement for the current-voltage characteristics, power output, and for the shape and height of the zero-field steps (ZFS). Two distinct modes of soliton oscillations are observed: (i) a bunched or congealed mode giving rise to the fundamental frequency f1 on all ZFS's and (ii) a "symmetric" mode which...... on the Nth ZFS yields the frequency Nf1 Coexistence of two adjacent frequencies is found on the third ZFS of the longer junction (L / λJ=6) in a narrow range of bias current as also found in the experiments. Small asymmetries in the experimental environment, a weak magnetic field, e.g., is introduced via...

Costimulation of N-methyl-d-aspartate and muscarinic neuronal receptors modulates gap junctional communication in striatal astrocytes

OpenAIRE

Rouach, N.; Tencé, M.; Glowinski, J.; Giaume, C.

2002-01-01

Cocultures of neurons and astrocytes from the rat striatum were used to determine whether the stimulation of neuronal receptors could affect the level of intercellular communication mediated by gap junctions in astrocytes. The costimulation of N-methyl-D-asparte (NMDA) and muscarinic receptors led to a prominent reduction of astrocyte gap junctional communication (GJC) in coculture. This treatment was not effective in astrocyte cultures, these cells being devoid of NMDA receptors. Both types ...

Field modulation of the critical current in magnetic Josephson junctions

International Nuclear Information System (INIS)

Blamire, M G; Smiet, C B; Banerjee, N; Robinson, J W A

2013-01-01

The dependence of the critical current of a simple Josephson junction on the applied magnetic field is well known and, for a rectangular junction, gives rise to the classic ‘Fraunhofer’ modulation with periodic zeros at the fields that introduce a flux quantum into the junction region. Much recent work has been performed on Josephson junctions that contain magnetic layers. The magnetization of such layers introduces additional flux into the junction and, for large junction areas or strong magnetic materials, can significantly distort the modulation of the critical current and strongly suppress the maximum critical current. The growing interest in junctions that induce odd-frequency triplet pairing in a ferromagnet, and the need to make quantitative comparisons with theory, mean that a full understanding of the role of magnetic barriers in controlling the critical current is necessary. This paper analyses the effect of magnetism and various magnetic configurations on Josephson critical currents; the overall treatment applies to junctions of general shape, but the specific cases of square and rectangular junctions are considered. (paper)

Shunted-Josephson-junction model. II. The nonautonomous case

DEFF Research Database (Denmark)

Belykh, V. N.; Pedersen, Niels Falsig; Sørensen, O. H.

1977-01-01

The shunted-Josephson-junction model with a monochromatic ac current drive is discussed employing the qualitative methods of the theory of nonlinear oscillations. As in the preceding paper dealing with the autonomous junction, the model includes a phase-dependent conductance and a shunt capacitance....... The mathematical discussion makes use of the phase-space representation of the solutions to the differential equation. The behavior of the trajectories in phase space is described for different characteristic regions in parameter space and the associated features of the junction IV curve to be expected are pointed...... out. The main objective is to provide a qualitative understanding of the junction behavior, to clarify which kinds of properties may be derived from the shunted-junction model, and to specify the relative arrangement of the important domains in the parameter-space decomposition....

Josephson junction arrays and superconducting wire networks

International Nuclear Information System (INIS)

Lobb, C.J.

1992-01-01

Techniques used to fabricate integrated circuits make it possible to construct superconducting networks containing as many as 10 6 wires or Josephson junctions. Such networks undergo phase transitions from resistive high-temperature states to ordered low-resistance low-temperature states. The nature of the phase transition depends strongly on controllable parameters such as the strength of the superconductivity in each wire or junction and the external magnetic field. This paper will review the physics of these phase transitions, starting with the simplest zero-magnetic field case. This leads to a Kosterlitz-Thouless transition when the junctions or wires are weak, and a simple mean-field fransition when the junctions or wires are strong. Rich behavior, resulting from frustration, occurs in the presence of a magnetic field. (orig.)

Impressão basilar e malformação de Arnold-Chiari: considerações técnico-cirúrgicas a propósito de 13 casos

Directory of Open Access Journals (Sweden)

José A. Gonçalves da Silva

1978-03-01

Full Text Available Os autores empregaram detalhes técnicos pessoais para descompressão da fossa posterior em casos de impressão basilar e/ou maliormação de Arnold-Chiari, consistente em intuoação endotraqueal sem retroflexão da cabeça do paciente, sendo o mesmo operado em posição sentada e com a cabeça ereta. Foi realizada plástica da paquimeninge da fossa posterior com dura-mater de cadáver conservada em glicerina.

Phenomenological approach to bistable behavior of Josephson junctions

International Nuclear Information System (INIS)

Nishi, K.; Nara, S.; Hamanaka, K.

1985-01-01

The interaction of unbiased Josephson junction with external electromagnetic field in the presence of externally applied uniform magnetic field is theoretically examined by means of phenomenological treatment. It is proposed that an irradiated junction with suitably chosen parameters shows a bistable behavior of voltage across the junction as a function of the radiation intensity

Multiplication in Silicon p-n Junctions

DEFF Research Database (Denmark)

Moll, John L.

1965-01-01

Multiplication values were measured in the collector junctions of silicon p-n-p and n-p-n transistors before and after bombardment by 1016 neutrons/cm2. Within experimental error there was no change either in junction fields, as deduced from capacitance measurements, or in multiplication values i...

Heat Transport in Graphene Ferromagnet-Insulator-Superconductor Junctions

Institute of Scientific and Technical Information of China (English)

LI Xiao-Wei

2011-01-01

We study heat transport in a graphene ferromagnet-insulator-superconducting junction. It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor (FIS) junction is an oscillatory function of the barrier strength x in the thin-barrier limit. The gate potential U0 decreases the amplitude of thermal conductance oscillation. Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh. The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.%@@ We study heat transport in a graphene ferromagnet-insulator-superconducting junction.It is found that the thermal conductance of the graphene ferromagnet-insulator-superconductor(FIS)junction is an oscillatory function of the barrier strength X in the thin-barrier limit.The gate potential Uo decreases the amplitude of thermal conductance oscillation.Both the amplitude and phase of the thermal conductance oscillation varies with the exchange energy Eh.The thermal conductance of a graphene FIS junction displays the usual exponential dependence on temperature, reflecting the s-wave symmetry of superconducting graphene.

Morphology of the cemento-enamel junction in premolar teeth.

Science.gov (United States)

Arambawatta, Kapila; Peiris, Roshan; Nanayakkara, Deepthi

2009-12-01

The present study attempted to describe the distribution of the mineralized tissues that compose the cemento-enamel junction, with respect to both the different types of permanent premolars of males and females and the various surfaces of individual teeth. The cervical region of ground sections of 67 premolars that had been extracted for orthodontic reasons were analyzed using transmitted light microscopy to identify which of the following tissue interrelationships was present at the cemento-enamel junction: cementum overlapping enamel; enamel overlapping cementum; edge-to-edge relationship between cementum and enamel; or the presence of gaps between the enamel and cementum with exposed dentin. An edge-to-edge interrelation between root cementum and enamel was predominant (55.1%). In approximately one-third of the sample, gaps between cementum and enamel with exposed dentin were observed. Cementum overlapping enamel was less prevalent than previously reported, and enamel overlapping cementum was seen in a very small proportion of the sample. In any one tooth, the distribution of mineralized tissues at the cemento-enamel junction was irregular and unpredictable. The frequency of gaps between enamel and cementum with exposure of dentin was higher than previously reported, which suggests that this region is fragile and strongly predisposed to pathological changes. Hence, this region should be protected and carefully managed during routine clinical procedures such as dental bleaching, orthodontic treatment, and placement of restorative materials.

Current amplifier and flux-buffer designs using an exponential flux shuttle with a Josephson junction synthetic inductor

International Nuclear Information System (INIS)

Gershenson, M.

1989-01-01

A current amplifier design based on the principle of fluxon propagation in a multi-junction Exponential Flux Shuttle has been investigated. In this design, the critical current of the junction is increased exponentially and the SQUID inductance is a JJ (Josephson Junction) equivalent inductance. Current gain can be achieved by generating fluxons at the low end and dissipating them at the high end where the load is located. Advantages over other types of linear devices are discussed. Two parallel Exponential Flux Shuttles can be used to duplicate flux from a high inductance input coil t a low inductance output. Device performance of the two circuits are evaluated by computer simulation, noise performance is discussed

Terahertz Responses of Intrinsic Josephson Junctions in High TC Superconductors

International Nuclear Information System (INIS)

Wang, H. B.; Wu, P. H.; Yamashita, T.

2001-01-01

High frequency responses of intrinsic Josephson junctions up to 2.5THz, including the observation of Shapiro steps under various conditions, are reported and discussed in this Letter. The sample was an array of intrinsic Josephson junctions singled out from inside a high T C superconducting Bi 2 Sr 2 CaCu 2 O 8+x single crystal, with a bow-tie antenna integrated to it. The number of junctions in the array was controllable, the junctions were homogeneous, the distribution of applied irradiation among the junctions was even, and the junctions could synchronously respond to high frequency irradiation

Development of superconducting tunnel junction radiation detectors

Energy Technology Data Exchange (ETDEWEB)

Katagiri, Masaki; Kishimoto, Maki; Ukibe, Masahiro; Nakamura, Tatsuya; Nakazawa, Masaharu [Japan Atomic Energy Research Inst., Tokyo (Japan); Kurakado, Masahiko; Ishibashi, Kenji; Maehata, Keisuke

1998-07-01

Study on development of high energy resolution X-ray detector using superconducting tunnel junction (STJ) for radiation detection was conducted for 5 years under cooperation of University of Tokyo group and Kyushu University group by Quantum measurement research group of Advanced fundamental research center of JAERI. As the energy resolution of STJ could be obtained better results than that of Si semiconductor detector told to be actually best at present, this study aimed to actualize an X-ray detector usable for the experimental field and to elucidate radiation detection mechanism due to STJ. The STJ element used for this study was the one developed by Kurakado group of Nippon Steel Corp. As a results, some technical problems were almost resolved, which made some trouble when using the STJ element to detection element of X-ray spectrometer. In order to make the X-ray detector better, it is essential to manufacture a STJ element and develop serial junction type STJ element on the base of optimization of the element structure and selection and single crystallization of new superconducting materials such as Ta and others, activating the research results. (G.K.)

Long Josephson Junction Stack Coupled to a Cavity

DEFF Research Database (Denmark)

Madsen, Søren Peder; Pedersen, Niels Falsig; Groenbech-Jensen, N.

2007-01-01

A stack of inductively coupled long Josephson junctions are modeled as a system of coupled sine-Gordon equations. One boundary of the stack is coupled electrically to a resonant cavity. With one fluxon in each Josephson junction, the inter-junction fluxon forces are repulsive. We look at a possible...... transition, induced by the cavity, to a bunched state....

Investigations on rectifying behavior of Y{sub 0.95}Ca{sub 0.05}MnO{sub 3}/Si junction

Energy Technology Data Exchange (ETDEWEB)

Dhruv, Davit [Department of Physics, Saurashtra University, Rajkot-36000 (India); V.V.P. Engineering College, Gujarat Technological University, Rajkot – 360 005 (India); Joshi, Zalak; Gadani, Keval; Boricha, Hetal; Pandya, D. D.; Solanki, P. S.; Shah, N. A., E-mail: snikesh@yahoo.com [Department of Physics, Saurashtra University, Rajkot-36000 (India); Joshi, A. D. [Goverment Engineering College, Rajkot – 360 005 (India)

2016-05-06

In this communication, we report the rectifying properties observed across the junction, consists of Ca{sup +2} doped hexagonal YMnO{sub 3} manganite film, grown on n-type (100) Si single crystalline substrate. The junction was grown using cost effective chemical solution deposition (CSD) technique by employing spin coating method. Surface morphology of Y{sub 0.9}5Ca{sub 0.05}MnO{sub 3}/Si (YCMO/Si) film was carried out by atomic force microscopy and magnetic response of film was studied by magnetic force microscopy. Current – voltage characteristics of the junction was carried out by using Keithley source meter in current perpendicular to plane (CPP) mode at different temperatures. Rectification in I – V behavior has been observed for the junction at all the temperatures studied. With increase in temperature, rectification ratio, in the range of 10{sup 4}, increases across the junction. Results have been discussed in the context of thermal effects.

Structural Origins of Conductance Fluctuations in Gold–Thiolate Molecular Transport Junctions

KAUST Repository

French, William R.

2013-03-21

We report detailed atomistic simulations combined with high-fidelity conductance calculations to probe the structural origins of conductance fluctuations in thermally evolving Au-benzene-1,4-dithiolate-Au junctions. We compare the behavior of structurally ideal junctions (where the electrodes are modeled as flat surfaces) to structurally realistic, experimentally representative junctions resulting from break-junction simulations. The enhanced mobility of metal atoms in structurally realistic junctions results in significant changes to the magnitude and origin of the conductance fluctuations. Fluctuations are larger by a factor of 2-3 in realistic junctions compared to ideal junctions. Moreover, in junctions with highly deformed electrodes, the conductance fluctuations arise primarily from changes in the Au geometry, in contrast to results for junctions with nondeformed electrodes, where the conductance fluctuations are dominated by changes in the molecule geometry. These results provide important guidance to experimentalists developing strategies to control molecular conductance, and also to theoreticians invoking simplified structural models of junctions to predict their behavior. © 2013 American Chemical Society.

Structural Origins of Conductance Fluctuations in Gold–Thiolate Molecular Transport Junctions

KAUST Repository

French, William R.; Iacovella, Christopher R.; Rungger, Ivan; Souza, Amaury Melo; Sanvito, Stefano; Cummings, Peter T.

2013-01-01

We report detailed atomistic simulations combined with high-fidelity conductance calculations to probe the structural origins of conductance fluctuations in thermally evolving Au-benzene-1,4-dithiolate-Au junctions. We compare the behavior of structurally ideal junctions (where the electrodes are modeled as flat surfaces) to structurally realistic, experimentally representative junctions resulting from break-junction simulations. The enhanced mobility of metal atoms in structurally realistic junctions results in significant changes to the magnitude and origin of the conductance fluctuations. Fluctuations are larger by a factor of 2-3 in realistic junctions compared to ideal junctions. Moreover, in junctions with highly deformed electrodes, the conductance fluctuations arise primarily from changes in the Au geometry, in contrast to results for junctions with nondeformed electrodes, where the conductance fluctuations are dominated by changes in the molecule geometry. These results provide important guidance to experimentalists developing strategies to control molecular conductance, and also to theoreticians invoking simplified structural models of junctions to predict their behavior. © 2013 American Chemical Society.

Silicon fiber with p-n junction

International Nuclear Information System (INIS)

Homa, D.; Cito, A.; Pickrell, G.; Hill, C.; Scott, B.

2014-01-01

In this study, we fabricated a p-n junction in a fiber with a phosphorous doped silicon core and fused silica cladding. The fibers were fabricated via a hybrid process of the core-suction and melt-draw techniques and maintained overall diameters ranging from 200 to 900 μm and core diameters of 20–800 μm. The p-n junction was formed by doping the fiber with boron and confirmed via the current-voltage characteristic. The demonstration of a p-n junction in a melt-drawn silicon core fiber paves the way for the seamless integration of optical and electronic devices in fibers.

Quantum-limited detection of millimeter waves using superconducting tunnel junctions

International Nuclear Information System (INIS)

Mears, C.A.

1991-09-01

The quasiparticle tunneling current in a superconductor-insulator- superconductor (SIS) tunnel junction is highly nonlinear. Such a nonlinearity can be used to mix two millimeter wave signals to produce a signal at a much lower intermediate frequency. We have constructed several millimeter and sub-millimeter wave SIS mixers in order to study high frequency response of the quasiparticle tunneling current and the physics of high frequency mixing. We have made the first measurement of the out-of-phase tunneling currents in an SIS tunnel junction. We have developed a method that allows us to determine the parameters of the high frequency embedding circuit by studying the details of the pumped I-V curve. We have constructed a 80--110 GHz waveguide-based mixer test apparatus that allows us to accurately measure the gain and added noise of the SIS mixer under test. Using extremely high quality tunnel junctions, we have measured an added mixer noise of 0.61 ± 0.36 quanta, which is within 25 percent of the quantum limit imposed by the Heisenberg uncertainty principle. This measured performance is in excellent agreement with that predicted by Tucker's theory of quantum mixing. We have also studied quasioptically coupled millimeter- and submillimeter-wave mixers using several types of integrated tuning elements. 83 refs

Field emission current from a junction field-effect transistor

Energy Technology Data Exchange (ETDEWEB)

Monshipouri, Mahta; Abdi, Yaser, E-mail: y.abdi@ut.ac.ir [University of Tehran, Nano-Physics Research Laboratory, Department of Physics (Iran, Islamic Republic of)

2015-04-15

Fabrication of a titanium dioxide/carbon nanotube (TiO{sub 2}/CNT)-based transistor is reported. The transistor can be considered as a combination of a field emission transistor and a junction field-effect transistor. Using direct current plasma-enhanced chemical vapor deposition (DC-PECVD) technique, CNTs were grown on a p-typed (100)-oriented silicon substrate. The CNTs were then covered by TiO{sub 2} nanoparticles 2–5 nm in size, using an atmospheric pressure CVD technique. In this device, TiO{sub 2}/CNT junction is responsible for controlling the emission current. High on/off-current ratio and proper gate control are the most important advantages of device. A model based on Fowler–Nordheim equation is utilized for calculation of the emission current and the results are compared with experimental data. The effect of TiO{sub 2}/CNT hetero-structure is also investigated, and well modeled.

Sputtered indium-tin oxide/cadmium telluride junctions and cadmium telluride surfaces

International Nuclear Information System (INIS)

Courreges, F.G.; Fahrenbruch, A.L.; Bube, R.H.

1980-01-01

The properties of indium-tin oxide (ITO)/CdTe junction solar cells prepared by rf sputtering of ITO on P-doped CdTe single-crystal substrates have been investigated through measurements of the electrical and photovoltaic properties of ITO/CdTe and In/CdTe junctions, and of electron beam induced currents (EBIC) in ITO/CdTe junctions. In addition, surface properties of CdTe related to the sputtering process were investigated as a function of sputter etching and thermal oxidation using the techniques of surface photovoltage and photoluminescence. ITO/CdTe cells prepared by this sputtering method consist of an n + -ITO/n-CdTe/p-CdTe buried homojunction with about a 1-μm-thick n-type CdTe layer formed by heating of the surface of the CdTe during sputtering. Solar efficiencies up to 8% have been observed with V/sub 0c/=0.82 V and J/sub s/c=14.5 mA/cm 2 . The chief degradation mechanism involves a decrease in V/sub 0c/ with a transformation of the buried homojunction structure to an actual ITO/CdTe heterojunction

Theoretical Study of the Hoogsteen–Watson-Crick Junctions in DNA

OpenAIRE

Cubero, Elena; Luque, F. Javier; Orozco, Modesto

2005-01-01

A series of d (AT)n oligonucleotides containing mixtures of normal B-type Watson-Crick and antiparallel Hoogsteen helices have been studied using molecular dynamics simulation techniques to analyze the structural and thermodynamic impact of the junction between Watson-Crick and antiparallel Hoogsteen structures. Analysis of molecular dynamics simulations strongly suggests that for all oligonucleotides studied the antiparallel Hoogsteen appears as a reasonable conformation, only slightly less ...

Quasiparticle current in superconductor-semiconductor-superconductor junctions

International Nuclear Information System (INIS)

Tartakovskij, A.V.; Fistul', M.V.

1988-01-01

It is shown that the quasiparticle current in a superconductor-semiconductor-superconductor junction may significantly increase as a result of resonant passage of the quasiparticle along particular trajectories from periodically situated localized centers. A prediction of the theory is that with increasing junction resistance there should be a change from an excessive current to a insufficient current on the current-voltage characteristics (at high voltages). The effect of transparency of the boundaries on resonance tunneling in such junctions is also investigated

Transport properties of molecular junctions

CERN Document Server

Zimbovskaya, Natalya A

2013-01-01

A comprehensive overview of the physical mechanisms that control electron transport and the characteristics of metal-molecule-metal (MMM) junctions is presented. As far as possible, methods and formalisms presented elsewhere to analyze electron transport through molecules are avoided. This title introduces basic concepts—a description of the electron transport through molecular junctions—and briefly describes relevant experimental methods. Theoretical methods commonly used to analyze the electron transport through molecules are presented. Various effects that manifest in the electron transport through MMMs, as well as the basics of density-functional theory and its applications to electronic structure calculations in molecules are presented. Nanoelectronic applications of molecular junctions and similar systems are discussed as well. Molecular electronics is a diverse and rapidly growing field. Transport Properties of Molecular Junctions presents an up-to-date survey of the field suitable for researchers ...

Multizamide myelography and computed tomography in malformations of the cranio-vertebral junction and of the spine

Energy Technology Data Exchange (ETDEWEB)

Gahbauer, H.; Rommel, T.; Banniza von Bazan, U.

1982-11-01

The Arnold-Chiari syndrome and the dysrhaphic disturbances are highly complex pathologic pictures. Often, the clinical findings and the variety of the basic pathologic disturbances are confusing. However, it is not always possible to detect all aspects of the disturbance in one conventional myelographic examination. In primary metrizamide computed tomography the applied KM dosages are considerably lower. This method facilitates the detailed imaging of osseous malformations, of associated spinal and paraspinal masses and their relation to the spinal cord.

International comparison. High-precision comparison of voltages generated by SINIS and SIS Josephson junction arrays at the 10 mV level

Energy Technology Data Exchange (ETDEWEB)

Karpov, O.V.; Koutovoi, V.D.; Sherstobitov, S.V. [Institute for Physical-Technical and Radiotechnical Measurements, VNIIFTRI, Gostandart of Russia, Mendeleevo, Moscow Region (Russian Federation); Niemeyer, J. [Physikalisch-Technische Bundesanstalt, PTB, Braunschweig (Germany)

2001-07-01

A high-precision comparison of dc voltages generated by a 10 GHz SINIS (superconductor/insulator/normal/insulator/superconductor) Josephson non-hysteretic junction array and a 70 GHz SIS (superconductor/insulator/superconductor) Josephson junction array is described. The paper also describes a method of minimizing the Type A measurement uncertainty. The measurements were carried out at the 10 mV level. The agreement between both output voltages was determined to 0.2 nV with a Type A uncertainty of 0.5 nV. (authors)

Systematic study of shallow junction formation on germanium substrates

DEFF Research Database (Denmark)

Hellings, Geert; Rosseel, Erik; Clarysse, Trudo

2011-01-01

Published results on Ge junctions are benchmarked systematically using RS–XJ plots. The electrical activation level required to meet the ITRS targets is calculated. Additionally, new results are presented on shallow furnace-annealed B junctions and shallow laser-annealed As junctions. Co-implanting...

InGaN pn-junctions grown by PA-MBE: Material characterization and fabrication of nanocolumn electroluminescent devices

Science.gov (United States)

Gherasoiu, I.; Yu, K. M.; Reichertz, L.; Walukiewicz, W.

2015-09-01

PN junctions are basic building blocks of many electronic devices and their performance depends on the structural properties of the component layers and on the type and the amount of the doping impurities incorporated. Magnesium is the common p-type dopant for nitride semiconductors while silicon and more recently germanium are the n-dopants of choice. In this paper, therefore we analyze the quantitative limits for Mg and Ge incorporation on GaN and InGaN with high In content. We also discuss the challenges posed by the growth and characterization of InGaN pn-junctions and we discuss the properties of large area, long wavelength nanocolumn LEDs grown on silicon (1 1 1) by PA-MBE.

Unjoined primary and secondary neural tubes: junctional neural tube defect, a new form of spinal dysraphism caused by disturbance of junctional neurulation.

Science.gov (United States)

Eibach, Sebastian; Moes, Greg; Hou, Yong Jin; Zovickian, John; Pang, Dachling

2017-10-01

Primary and secondary neurulation are the two known processes that form the central neuraxis of vertebrates. Human phenotypes of neural tube defects (NTDs) mostly fall into two corresponding categories consistent with the two types of developmental sequence: primary NTD features an open skin defect, an exposed, unclosed neural plate (hence an open neural tube defect, or ONTD), and an unformed or poorly formed secondary neural tube, and secondary NTD with no skin abnormality (hence a closed NTD) and a malformed conus caudal to a well-developed primary neural tube. We encountered three cases of a previously unrecorded form of spinal dysraphism in which the primary and secondary neural tubes are individually formed but are physically separated far apart and functionally disconnected from each other. One patient was operated on, in whom both the lumbosacral spinal cord from primary neurulation and the conus from secondary neurulation are each anatomically complete and endowed with functioning segmental motor roots tested by intraoperative triggered electromyography and direct spinal cord stimulation. The remarkable feature is that the two neural tubes are unjoined except by a functionally inert, probably non-neural band. The developmental error of this peculiar malformation probably occurs during the critical transition between the end of primary and the beginning of secondary neurulation, in a stage aptly called junctional neurulation. We describe the current knowledge concerning junctional neurulation and speculate on the embryogenesis of this new class of spinal dysraphism, which we call junctional neural tube defect.

Single-event burnout of power bipolar junction transistors

International Nuclear Information System (INIS)

Titus, J.L.; Johnson, G.H.; Schrimpf, R.D.; Galloway, K.F.

1991-01-01

Experimental evidence of single-event burnout of power bipolar junctions transistors (BJTs) is reported for the first time. Several commercial power BJTs were characterized in a simulated cosmic ray environment using mono-energetic ions at the tandem Van de Graaff accelerator facility at Brookhaven National Laboratory. Most of the device types exposed to this simulated environment exhibited burnout behavior. In this paper the experimental technique, data, and results are presented, while a qualitative model is used to help explain those results and trends observed in this experiment

Junction Potentials Bias Measurements of Ion Exchange Membrane Permselectivity.

Science.gov (United States)

Kingsbury, Ryan S; Flotron, Sophie; Zhu, Shan; Call, Douglas F; Coronell, Orlando

2018-04-17

Ion exchange membranes (IEMs) are versatile materials relevant to a variety of water and waste treatment, energy production, and industrial separation processes. The defining characteristic of IEMs is their ability to selectively allow positive or negative ions to permeate, which is referred to as permselectivity. Measured values of permselectivity that equal unity (corresponding to a perfectly selective membrane) or exceed unity (theoretically impossible) have been reported for cation exchange membranes (CEMs). Such nonphysical results call into question our ability to correctly measure this crucial membrane property. Because weighing errors, temperature, and measurement uncertainty have been shown to not explain these anomalous permselectivity results, we hypothesized that a possible explanation are junction potentials that occur at the tips of reference electrodes. In this work, we tested this hypothesis by comparing permselectivity values obtained from bare Ag/AgCl wire electrodes (which have no junction) to values obtained from single-junction reference electrodes containing two different electrolytes. We show that permselectivity values obtained using reference electrodes with junctions were greater than unity for CEMs. In contrast, electrodes without junctions always produced permselectivities lower than unity. Electrodes with junctions also resulted in artificially low permselectivity values for AEMs compared to electrodes without junctions. Thus, we conclude that junctions in reference electrodes introduce two biases into results in the IEM literature: (i) permselectivity values larger than unity for CEMs and (ii) lower permselectivity values for AEMs compared to those for CEMs. These biases can be avoided by using electrodes without a junction.