Numerical simulation of flux jump behavior in REBaCuO ring bulks with an inhomogeneous J c profile during pulsed-field magnetization

Funder: Japan Agency for Medical Research and Development; doi: https://doi.org/10.13039/100009619Abstract: We have investigated the electromagnetic and thermal properties of a REBaCuO ring bulk with an inhomogeneous critical current density, Jc, profile during pulsed field magnetization (PFM) using a numerical simulation and compared those to a bulk with a homogeneous Jc profile. A notch was introduced in the bulk periphery, which was assumed as a crack existing in the actual bulk material. A sudden flux penetration (flux jump) took place through the notch area and as a result, a large temperature rise also took place around this notch. Consequently, the final trapped field profile was simulated to be a ‘C-shaped profile’, which qualitatively reproduced our previous experimental results. The size and position dependences of the notch on the flux penetration behaviour were also simulated, in which a larger and outer notch promotes the flux jump phenomenon easily. On the other hand, in the homogeneous model, under the same conditions, no flux jump phenomenon was observed. These results suggest that the imperfection in the bulk can be a possible starting point of the flux jump. The electromagnetic and thermal hoop stresses were also simulated in the ring bulk during PFM, in which the electromagnetic stress and the thermal stress were both observed to be lower than the fracture strength of the bulk material. This provides good evidence that the experimentally observed ‘C-shaped profile’ results from the flux jump rather than the fracture of the bulk

False vocal cord perforation with abscess treated by negative pressure wound therapy

Perforation of the larynx is very rare but may result in severe airway complications that include pneumothorax, pneumonia, mediastinitis, and retropharyngeal abscess. If conservative treatment fails, aggressive treatments including reconstructive surgery with pedicle flap are considered. Negative pressure wound therapy has been used for large skin defects, necrotizing fasciitis, pharyngocutaneous fistula, stoma dehiscence, osteoradionecrosis of the mandible, chyle fistula, flap failure, and lymphangioma in the field of head and neck surgery. We report a case of false vocal cord perforation with abscess successfully treated by negative pressure wound therapy after abscess treatment. The result suggests that negative pressure wound therapy can be an alternative or adjunctive approach for larynx perforation when the perforation is difficult to close after conservative therapy

A rare case of choroidal hemorrhage complicated with hypertension due to chronic renal failure

Background : Choroidal hemorrhage is usually seen as expulsive hemorrhage related to surgical invasion and is rarely observed in the absence of surgery or trauma. In this report, we describe a case of choroidal hemorrhage caused by hypertension related to chronic renal failure. Case : A 32-year-old man presented with sudden visual loss, eye pain and swelling in his left eye. He had a history of renal failure and hypertension. Eye examination demonstrated choroidal hemorrhage associated with ocular hypertension in his left eye and marked hypertensive retinopathy in his right eye. Observations : He was treated with hemodialysis and antihypertensive drugs. Upon repeat eye examinations, a gradual reabsorption of the choroidal hemorrhage was observed, although vitreous hemorrhage appeared in the left eye. The vitreous hemorrhage was treated with vitrectomy with the patient regaining good visual acuity post-surgery. Conclusions : This rare case suggests that patients with severe background disease need to be carefully observed

A Case Report of Tooth Wear Associated with a Patient's Inappropriate Efforts to Reduce Oral Malodor Caused by Endodontic Lesion

Here, we report a case of severe tooth wear associated with a patient's inappropriate efforts to reduce oral malodor. A 72-year-old male patient visited our breath clinic complaining of strong breath odor. Former dentists had performed periodontal treatments including scaling and root planing, but his oral malodor did not decrease. His own subsequent breath odor-reducing efforts included daily use of lemons and vinegar to reduce or mask the odor, eating and chewing hard foods to clean his teeth, and extensive tooth brushing with a hard-bristled toothbrush. Oral malodor was detected in our breath clinic by several tests, including an organoleptic test, portable sulphide monitor, and gas chromatography. Although patient's oral hygiene and periodontal condition were not poor on presentation, his teeth showed heavy wear and hypersensitiving with an unfitted restoration on tooth 16. Radiographic examination of the tooth did not reveal endodontic lesion, but when the metal crown was removed, severe pus discharge and strong malodor were observed. When this was treated, his breath odor was improved. After dental treatment and oral hygiene instruction, no further tooth wear was observed; he was not concerned about breath odor thereafter

Risk Factors for Anterior Skull Base Injury in Endoscopic Sinus Surgery

Objectives This retrospective study aimed to investigate the relationships between the Keros classification, the Gera classification, the vertical height of the posterior ethmoid roof (ER), and anterior ethmoidal artery (AEA) types in Japanese patients. Methods We investigated the computed tomography (CT) slices of paranasal sinuses (120 sides) of 60 patients; measured the cribriform plate (CP) depth, lateral lamella CP angle (LLCPA), and vertical height of the lateral ER from the hard palate (LERHP) at the coronal plane of the posterior ethmoidal artery (PEA); and reviewed the AEA types, whether floating or non-floating. Results CP depth was positively correlated with LLCPA (r=0.63; p Conclusion In females, low height of the posterior ethmoid sinus roof, where cerebrospinal fluid (CSF) leaks occurred while penetrating the basal lamella, often existed; the heights positively correlated with the Keros classification in Japanese patients. The Keros and Gera classifications, AEA type, and posterior ER height do not individually constitute a complete risk assessment but may correlate, preventing major complications, such as CSF leak and orbital hemorrhage

Methotrexate-associated lymphoproliferative disorder with multiple pulmonary nodules and bilateral cervical lymphadenopathy

As has been well recognized, methotrexate (MTX) leads to a state of immunosuppression and can provide a basis for the development of lymphoproliferative disorders (LPDs). MTX-associated LPDs can affect nodal sites as well as extranodal sites, though the manifestation of an LPD in the form of multiple pulmonary nodules is rare. Here, we report two cases of MTX-associated LPD with multiple bilateral pulmonary nodules, which was a finding suggestive of lung cancer, and bilateral cervical lymphadenopathy. After withdrawal of MTX, the multiple bilateral pulmonary nodules and bilateral cervical lymphadenopathy disappeared without chemotherapy in both cases. From these results, patients with pulmonary nodules and cervical lymphadenopathy should be examined for head and neck malignant tumors. Also, physicians should carefully check the administration of MTX. In patients with an MTX-associated LPD, we need to make an early diagnosis and consider discontinuing the administration of MTX as soon as possible