Influence of microscopic defects in type-II superconducting thin films on the magnetic flux penetration

The magnetic flux penetration into thin type-II superconducting films with circular defects is investigated. The artificial circular defects (diameter = 40 μm) in an YBa2Cu3O72d thin film (thickness = 300 μm) were prepared by pulse-laser irradiation. The flux penetration into the zero-field-cooled superconducting film was visualized by means of the magneto-optic method. A stepwise increase of the external magnetic field allowed a detailed investigation of the influence of local defects on the flux penetration. For a magnetic field parallel to a long sample (longitudinal geometry) with a long cylindrical defect a single parabolic discontinuity line appears. Also in the case of a thin superconducting film exposed to a transverse magnetic field (transverse geometry), a single parabolic discontinuity line has been supposed in the vicinity of a local defect. On the contrary, our investigations show that the flux and current distribution around a single defect in a superconducting thin film can be determined not by a single, but by two discontinuity parabolas. In thin superconducting films in transverse geometry screening currents in the Meissner region (j front

Nondestructive magneto-optical characterization of natural and artificial fefects on 3" HTSC Wafers at liquid nitrogen temperature

Double-sided 3" HTSC Wafers were characterized by the magneto-optic technique. The presented apparatus allows a nondestructive and fast detection of local and extended inhomogeneities in the critical current density with high lateral resolution in the micrometer range. Additional gold-layers on the HTSC wafers, as they are sometmes used for the device production, do not influence the characterization result. The high sensitivity of the presented apparatus allows even the detection of local defects at higher temperature (77 K) where contrasts in the critical current are weaker and the magneto-optical characterization of HTSC thin Alms is milch more difficult than at lower temperatures. So the apparatus can be used even under conditions where cooling with liquid helium or closed-cycle refrigerators is not available. The sensitivity was tested on natural and artificial defects, the latter being prepared by means of a focused laser beam

Zerstörungsfreie magnetooptische Charakterisierung von natürlichen und künstlichen Defekten an 3-Zoll-HTSL-Wafern bei 77K

Doppelsei tige 3-Zoll-HTSL-Wafer wurden magnetooptisch charakterisiert. Der vorgestellte Aufbau erlaubt einen schnellen und zerstorungsfreien Nachweis von lokalen und ausgedehnten Inhornogenitiiten in der kritischen Stromdichte rnit hoher Ortsauflosung im Mikrometerbereich. Zusatzliche Goldschichten auf den HTSL-Wafem, wie sie manchmal in der Bauteilherstellung eingesetzt werden, beeinflussen nicht das Ergebnis der Messungen. Die hohe rnagnetische Empfindlichkeit erlaubt sogar den Nachweis lokaler Defekte bei 77 K, wo der Kontrast in den kntischen Stromen schwiicher ist und die Charakterisierung von HTSLFilmen vie1 schwieriger ist als bei tieferen Temperaturen. Der Aufbau kann daher selbst unter Bedjngungen eingesetzt werden, bei denen Kiihlung rnittels Flussig-Helium oder Kleinkuhler nicht zur Verfugung steht. Die Empfindljchkeit wurde an natiirlichen und lainstlichen Defekten iiberpriift, wobei letztere durch fokussierte Laserstrahlung hergestellt wurden

Structures in superconducting YBa2Cu3O7-delta thin films investigated by magneto-optic technique

Using a reflection magneto-optic technique we have investigated natural inhomogeneities and artificial struetures in YBCO thin films exposed to an external magnetic field. The artificial structures were mechanically scratched by scanning a diamond tip with different loading over the film, surface. Alternatively planar structures with reduced oxygen content could be patterned by heating the YBCO film, with a focused laser beam in nitrogen atmosphere. Depending on the laser annealing parameters different screening properties concerning the applied magnetic field could be achieved. As a magneto-optically active layer we used EuS films evaporated on glass as well as bismuth- and gallium-doped lutetium-iron-garnet films grown onto (111) oriented gadolinium-gallium-garnet substrates by liquid phase epitaxy. In contrast to measurements with EuS films that show only weak faraday rotation for temperatures higher than 20 K the magneto-optic studies have been expanded to about 60 K by using the garnet films

Western outcomes of circumferential endoscopic submucosal dissection for early esophageal squamous cell carcinoma

Background and Aims: Circumferential endoscopic submucosal dissection (cESD) in the esophagus has been reported to be feasible in small Eastern case series. We assessed the outcomes of cESD in the treatment of early esophageal squamous cell carcinoma (ESCC) in Western countries. Methods: We conducted an international study at 25 referral centers in Europe and Australia using prospective databases. We included all patients with ESCC treated with cESD before November 2022. Our main outcomes were curative resection according to European guidelines and adverse events. Results: A total of 171 cESDs were performed on 165 patients. En bloc and R0 resections rates were 98.2% (95% confidence interval [CI], 95.0-99.4) and 69.6% (95% CI, 62.3-76.0), respectively. Curative resection was achieved in 49.1% (95% CI, 41.7-56.6) of the lesions. The most common reason for noncurative resection was deep submucosal invasion (21.6%). The risk of stricture requiring 6 or more dilations or additional techniques (incisional therapy/stent) was high (71%), despite the use of prophylactic measures in 93% of the procedures. The rates of intraprocedural perforation, delayed bleeding, and adverse cardiorespiratory events were 4.1%, 0.6%, and 4.7%, respectively. Two patients died (1.2%) of a cESD-related adverse event. Overall and disease-free survival rates at 2 years were 91% and 79%. Conclusions: In Western referral centers, cESD for ESCC is curative in approximately half of the lesions. It can be considered a feasible treatment in selected patients. Our results suggest the need to improve patient selection and to develop more effective therapies to prevent esophageal strictures.</p

Western outcomes of circumferential endoscopic submucosal dissection for early esophageal squamous cell carcinoma

Background and Aims: Circumferential endoscopic submucosal dissection (cESD) in the esophagus has been reported to be feasible in small Eastern case series. We assessed the outcomes of cESD in the treatment of early esophageal squamous cell carcinoma (ESCC) in Western countries. Methods: We conducted an international study at 25 referral centers in Europe and Australia using prospective databases. We included all patients with ESCC treated with cESD before November 2022. Our main outcomes were curative resection according to European guidelines and adverse events. Results: A total of 171 cESDs were performed on 165 patients. En bloc and R0 resections rates were 98.2% (95% confidence interval [CI], 95.0-99.4) and 69.6% (95% CI, 62.3-76.0), respectively. Curative resection was achieved in 49.1% (95% CI, 41.7-56.6) of the lesions. The most common reason for noncurative resection was deep submucosal invasion (21.6%). The risk of stricture requiring 6 or more dilations or additional techniques (incisional therapy/stent) was high (71%), despite the use of prophylactic measures in 93% of the procedures. The rates of intraprocedural perforation, delayed bleeding, and adverse cardiorespiratory events were 4.1%, 0.6%, and 4.7%, respectively. Two patients died (1.2%) of a cESD-related adverse event. Overall and disease-free survival rates at 2 years were 91% and 79%. Conclusions: In Western referral centers, cESD for ESCC is curative in approximately half of the lesions. It can be considered a feasible treatment in selected patients. Our results suggest the need to improve patient selection and to develop more effective therapies to prevent esophageal strictures.</p

Western outcomes of circumferential endoscopic submucosal dissection for early esophageal squamous cell carcinoma

Background and aims: Circumferential endoscopic submucosal dissection (cESD) in the esophagus has been reported to be feasible in small Eastern case series. We assessed the outcomes of cESD in the treatment of early esophageal squamous cell carcinoma (ESCC) in Western countries. Methods: We conducted an international study at 25 referral centers in Europe and Australia using prospective databases. We included all patients with ESCC treated with cESD before November 2022. Our main outcomes were curative resection according to European guidelines and adverse events. Results: A total of 171 cESDs were performed on 165 patients. En bloc and R0 resections rates were 98.2% (95% CI 95.0%-99.4%) and 69.6% (95% CI 62.3%-76.0%), respectively. Curative resection was achieved in 49.1% (95% CI 41.7%-56.6%) of the lesions. The most common reason for non-curative resection was deep submucosal invasion (21.6%). The risk of stricture requiring six or more dilations or additional techniques (incisional therapy/stent) was high (71%), despite the use of prophylactic measures in 93% of the procedures. The rates of intraprocedural perforation, delayed bleeding and adverse cardiorespiratory events were 4.1%, 0.6% and 4.7%, respectively. Two patients died (1.2%) from a cESD-related adverse event. Overall and disease-free survival rates at 2 years were 91% and 79%. Conclusions: In Western referral centers, cESD for ESCC is curative in approximately half of the lesions. It can be considered a feasible treatment in selected patients. Our results suggest the need to improve patient selection and to develop more effective therapies to prevent esophageal strictures