Partial Discharge Detection by TEV Sensors and Signal Propagation Analysis in Transformer Model

This paper deals with a detailed study on partial discharge (PD) generated in transformers using transient earth voltage (TEV) detection method. Experiment and numerical analysis are carried out using an iron box model which simulates a tank of an actual transformer. In the test model, propagation properties of TEV signal caused by PD occurring inside and outside of the transformer model are examined. Results reveal that the electromagnetic waves generated by PD in the model can leak from the opening window, having special frequency determined by the size of the opening window. It is also found that TEV sensor placed on the surface of the tank detects a TEV signal originating from the leaked electromagnetic wave. On the other hand, TEV signal by electromagnetic waves generated by an external PD source is found to have a wider frequency band than that by leaked electromagnetic wave. In addition, electromagnetic field and surface current analysis are performed using finite difference time domain (FDTD) method and simulated results are compared with experimental ones. As a result, it is shown that leaked electromagnetic wave excites a surface current on the outer tank wall of the transformer model. It is also found that there exists difference in the time required for TEV signal to arrive at the inside and outside sensors. The results indicate that PD emitting electromagnetic waves leaked from the dielectric discontinuities can be detected by the TEV method. Furthermore, these results suggest a combination of the detected waveform and its frequency band could lead to highly reliable diagnosis of the apparatus by TEV detection method.The 19th International Symposium on High Voltage Engineering (ISH 2015), August, 23 – 28, 2015, Pilsen, Czech Republi

Depth profiling analysis of solar wind helium collected in diamond-like carbon film from Genesis

The distribution of solar-wind ions in Genesis mission collectors, as determined by depth profiling analysis, constrains the physics of ion-solid interactions involving the solar wind. Thus, they provide an experimental basis for revealing ancient solar activities represented by solar-wind implants in natural samples. We measured the first depth profile of ^4He in a Genesis collector; the shallow implantation (peaking at <20 nm) required us to use sputtered neutral mass spectrometry with post-photoionization by a strong field. The solar wind He fluence calculated using depth profiling is ~8.5 × 10^(14) cm^(–2). The shape of the solar wind 4He depth profile is consistent with TRIM simulations using the observed ^4He velocity distribution during the Genesis mission. It is therefore likely that all solar-wind elements heavier than H are completely intact in this Genesis collector and, consequently, the solar particle energy distributions for each element can be calculated from their depth profiles. Ancient solar activities and space weathering of solar system objects could be quantitatively reproduced by solar particle implantation profiles

Higher incidence of aseptic loosening caused by a lower canal filling ratio with a modified modular stem in total hip arthroplasty

Purpose: Although a cementless modular prosthesis has shown reliable results, cases of unstable fixation and revision due to aseptic loosening were observed in our institute. The purpose of this study was to clarify the causes of unstable fixation of the prosthesis.Methods: A total of 144 patients (154 hips) who underwent total hip arthroplasty using the modular prosthesis were retrospectively investigated. For the cohort study, 97 patients (104 hips) were included. The femoral component survival rate and sleeve fixation were assessed at a minimum follow-up of 5 years. Patients were divided into 2 groups, including stable and unstable fixation groups,by sleeve fixation. Clinical and radiographic outcomes were compared. Results: The Kaplan-Meier survival rate at 9 years was 93% with revision for any reason as the endpoint in study cohort. The reasons for revision were recurrent dislocation (1 hip) and aseptic loosening of the stem (5 hips). A total of 88 hips (84.6%) showed stable fixation, and 16 hips (15.4%) showed unstable fixation at final follow-up. There was no significant difference in clinical outcomes between the 2 groups at final follow-up. The canal flare index was significantly higher, and the canal filling ratio was significantly lower in the unstable fixation group. Conclusion: Although the modified modular prosthesis was useful for treating anatomically difficult patients, we need to pay attention to both proximal/distal mismatch of the intramedullary canal and the canal filling ratio to achieve stable fixation and good long-term results

Hepatitis C virus NS4 protein impairs the Th1 polarization of immature dendritic cells

Dendritic cells (DCs) in chronic hepatitis C patients display impaired function, although the details remain unclear. To investigate the hepatitis C virus (HCV) protein that has the most impact on DC function, we compared five recombinant proteins and seven HCV protein genes in modulating DC phenotype and function. Immature DCs (iDCs) were established from healthy donor peripheral blood monocytes with granulocyte–macrophage colony stimulating factor (GM-CSF) and IL-4. Lipopolysaccharide was used to establish mature DCs (mDCs). Cells were then pulsed with HCV recombinant proteins or transfected with HCV plasmids and subsequently assayed for cell surface marker expression by flow cytometry. For cytokine and proliferative T-cell response analysis, DCs were cultured with autologous CD4 T cells and tuberculin purified protein derivative (PPD). Mean fluorescent intensity of CD86 was reduced in HCV protein-pulsed iDCs. Proliferative T-cell responses and Th1 cytokine concentrations were reduced with HCV nonstructural proteins (NS), particularly with HCV NS4. HCV nonstructural proteins, particularly NS4, change the iDC phenotype and reduce antigen-specific T-cell stimulatory function with Th1 cytokine reductions

A case of surgical resection for well-differentiated squamous cell carcinoma arising in a ciliated hepatic foregut cyst

Ciliated hepatic foregut cysts (CHFC) are extremely rare, and most are benign cysts of the liver arising from remnants of the embryonic foregut. CHFC is usually found incidentally and as mostly asymptomatic cysts. We report squamous cell carcinoma (SCC) arising in a CHFC in a 50-year-old Japanese woman. She consulted our hospital for upper abdominal pain.A computed tomography and an ultrasound showed a cystic region including calcification and a solid mass in segment 4 of the liver. Left hepatectomy, B6 bile duct resection, and biliary-jejunal anastomosis were performed. Microscopic examination revealed that part of the cyst was lined by a characteristic ciliated pseudostratified columnar epithelium surrounding a connective tissue, a slightly thick fibrotic smooth muscle stromal layer, and an outer fibrous capsule. The cyst wall contained a low-papillary mural nodule showing atypical squamous hyperplasia with high-grade dysplasia. Stromal invasion was identified at the base of the nodule, leading to the diagnosis of well-differentiated SCC arising from a CHFC. We recommend careful clinical follow-up for patients with relatively large CHFCs as potentially malignant lesions and excision if they show any clinical manifestation