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Preoperative low skeletal muscle mass and obesity have been identified as poor prognostic factors after gastrectomy for cancer, but the predictive value of combined quantitation of skeletal muscle mass and obesity remains unclear. This study examined the impact of combined body compositions on outcomes after gastrectomy for cancer.518 patients who had undergone gastric resection for cancer between 2004 and 2017 were analyzed retrospectively. Skeletal muscle mass (skeletal muscle mass index (SMI)) and visceral obesity (visceral fat area) were measured in preoperative computed tomographic images to categorize patients as outlined below. Impacts of these body compositions on outcomes after gastrectomy were investigated.Body composition was classified as high SMI without obesity in 231 patients (45%), high SMI with obesity in 202 (39%), low SMI without obesity in 55 (11%), and low SMI with obesity in 30 (6%). Postoperative complications developed in 128 patients (25%). Multivariate analysis identified low SMI with obesity as an independent risk factor for postoperative complications (odds ratio, 3.27; P = 0.010). Moreover, patients with low SMI without obesity had lower 5-year overall survival rates than patients with high SMI without obesity (64.4% vs. 88.0%; P 0.001) and worse 5-year relapse-free survival rates (61.3% vs. 81.3%; P = 0.002). Multivariate analysis identified low SMI without obesity as a significant risk factor for overall survival (hazard ratio, 3.033; P 0.001) and relapse-free survival (hazard ratio, 2.144; P = 0.008) after gastrectomy.Preoperative low SMI with obesity was an independent risk factor for postoperative complications, while low SMI without obesity was an independent risk factor for overall and relapse-free survival following gastrectomy for cancer.

The insulation material of high voltage motors and generators is a polymer composite which is composed of mica, which is inorganic silica (SiO 2 ), and organic polymer materials. In this section, concept of the electrical insulation design of the machines is introduced and the importance of partial discharge endurance is explained. Then, historical basic research on nano‐composite materials is reviewed in terms of partial discharge characteristics. Finally, recent progress in the development of nano‐composite application to high voltage generators is described. As another topic of polymer composite in generators and motors, stress grading system for coil end termination is briefly mentioned.

This study investigates the time to breakdown of epoxy/TiO 2 nanocomposites with a void defect. In the tests, partial discharge (PD) is continuously monitored to clarify the degradation of the nanocomposites. In evaluating the dependence of the maximum agglomerate size and the volume fractions of the TiO 2 particles, it is found that the agglomerate size, rather than the volume fractions, dominates the electrical insulation lifetime of the nanocomposites. Furthermore, the lifetime increases drastically when the agglomerate size exceeds a critical value. The continuous PD signal monitoring reveals that the lifetime extension of the nanocomposites is achieved due to delaying the electrical tree propagation in the nanocomposite, rather than extensions of the times required for the transition from the void discharges to the tree initiation.

This study investigates the relationship between void size and insulation lifetime due to partial discharges (PDs) in internal voids. Experimental results clearly show that the larger the void size, the shorter the insulation lifetime, which decreases the lifetime n-value index of the voltage-time characteristics. The results also show a clear relationship between the insulation lifetime of a solid insulator having void defects and the PD energy generated in the void, which is related to the cumulative PD energy density per cycle. Therefore, we propose estimating the insulation lifetime of an insulator with voids by calculating the cumulative PD energy density per cycle.

In this paper, the time-averaged power densities as well as the resulting temperature rise, on an end-turn stress grading (SG) system under PWM waveforms as functions of the carrier and the fundamental frequencies are systematically investigated by finite element method-based computations. A novel analytical approximation method to estimate the power densities and the temperature rises without time-consuming numerical computations are proposed. As a result, the maximum power density and the temperature rise increase nearly linearly with increasing fundamental and the carrier frequencies. It is suggested that power dissipations in the SG layer by the fundamental frequency component of a PWM waveform and those by the carrier frequency component can be clearly separated. Moreover, the estimated power densities and temperature rises based on the analytical approximations show reasonable agreement with the numerically computed ones, which indicates the validity of the proposed estimation method.

In this study, TiO 2 /epoxy nanocomposites are evaluated for impulse and AC breakdown strength when agglomerations of TiO 2 nanofillers are removed by centrifugation. It is found that the nanocomposites with micrometric agglomerates exhibit lower breakdown strengths than that of unfilled epoxy resin. However, with the removal of agglomerates larger than 0.5 µm for 0.4 vol% filler concentration, the breakdown strengths are higher than that of unfilled epoxy resin. Micrometric agglomerates of TiO 2 nanoparticles behave as defects, thus lowering the breakdown strength of the nanocomposites. When such agglomerates are removed prior to curing, an improvement of the breakdown strengths is observed with very low filler concentration.

Silicon carbide particle-loaded semi-conductive materials with electric field-dependent conductivity have been used for end-turn stress grading (SG) systems of high voltage rotating electrical machines for decades. Particularly, high voltage class turbogenerators use double-layer SG systems, at which two SG materials with different conductivities are applied, to reduce power dissipations within the SG materials. To prevent the excessive local heating of the SG material and resulting flashover, the field-dependent conductivities of the two SG materials, as well as length of the SG layer in the longitudinal direction along a coil, were optimized, by a nonlinear transient electrical field and thermal coupled analysis. The field-dependent conductivities of the SG materials were adjusted to the suitable ones by changing the average diameter of silicon carbide particles. Then, the appropriate length of the SG layer was selected to minimize the temperature rise in the system. As a result, the newly optimized double-layer SG system showed a 20% lower temperature rise, and more than 15% higher flashover voltage than the conventional ones. Therefore, the effectiveness of the optimized double-layer SG system is successfully confirmed.

This paper proposes a novel method for measuring the potential distribution along the stress grading system of a model stator bar whose voltage is over several tens kV. The technique uses a Pockels field vector sensor by introducing an inverse calculation process from the measured field profile to the potential profile on the measured stator bar. With this system, a potential distribution along a model bar under 50 kVp, 50 Hz voltage is successfully measured. In principle, it is possible to estimate the potential either by measuring the horizontal or vertical component of the field. The utilization of the vertical component is preferable in measuring a model bar due to robustness against optical alignment errors. Through the potential distribution measurement of the model bar, although the maximum value of the electric field increases slightly with the applied voltage, it is confirmed that the electric field grading function was working due to the non-linear resistive material.

Degradation of the electrical insulation within power transformers by partial discharge (PD) may lead to catastrophic failure of the apparatus, hence PD should be detected at an early stage. Ultra-high frequency (UHF) measurement method, i.e. detecting electromagnetic (EM) waves in the UHF range radiated from PD, has recently received attention for its various advantages, such as the robustness against external noises and its capability of localisation of the PD position. However, the EM waves suffer attenuation while propagating within transformers, in some cases, which results in undesirable low detection sensitivity. To evaluate the propagation and attenuation characteristics of the EM waves quantitatively, the simulation technique of the EM wave propagation is of importance. In this study, at first, the EM waveforms as well as attenuation properties of their amplitudes and cumulative energies while propagating through transformer windings in an oil-filled tank were experimentally investigated. Next, the detailed conditions for simulating the EM wave propagation based on time-domain finite integration technique were described. Then, the simulated results were compared with the experimentally obtained ones. These simulation and measurement results showed good agreement with each other, therefore the authors have successfully validated the newly developed simulation of the EM wave propagation.

Electric tree is a phenomenon of local dielectric breakdown with partial discharge (PD). It is also the final stage of insulation deterioration. The electrical treeing has been discussed by using conventional PD parameters such as the generation phase, charge amount and so on. Since the obtained PD waveforms were processed by an analog filter designed according to the frequency characteristics of the measurement instrument such as an oscilloscope, its waveform is a convolution of the original PD waveform and the transfer function of the measurement system. However, the feature values such as a rise time, fall time and frequency spectrum in the original PD waveform should show the behavior of electrons and ions in the discharge space. In this paper, the original PD waveforms generated in micro-silica/epoxy composite with the electrical tree were acquired, and the feature values of the original PD waveform were analyzed. In addition, the behavior of the electric charges in the discharge space was assessed from the change of the feature values.

Mica epoxy insulation as used for generator stator windings is required to be improved as regards withstand electrical stress and heat dissipation. Replacement of epoxy resins by epoxy nanocomposites is a useful method to fulfil a purpose of such improvement. This paper is aimed to evaluate PD-initiated breakdown (BD) performances as one of the most crucial characteristics using simulated model specimens. Two constituent materials, i.e. mica tapes and resin layers were set as about 40 and 10 µm in thickness, respectively. EDX analysis shows that the model specimens include silica nanofillers properly dispersed in narrow nanocomposite regions and are suitable for PD initiated BD experiments. It was found that PD initiated BD lifetime was 2.8 times in nanocomposites than in neat epoxy under a rather high electric stress condition.

Polymer nanocomposites have attracted attention for various superior insulation performances. However, the effect of nanocomposites on the insulation lifetime with an enclosed void defect is unclear. Also, the insulation lifetime extension mechanism has rarely been reported. This paper experimentally investigates the lifetime extension mechanism of epoxy/TiO 2 nanocomposites with the void defect. Centrifugation and dilution procedures are used to control the dispersion state of TiO 2 nanofillers. Time evolutions of partial discharge (PD) current are also recorded to investigate the insulation degradation procedure. Consequently, it is clarified that the lifetime becomes longer with increasing the maximum agglomerate size of the TiO 2 nanofillers. Results of the PD current monitoring suggest that the lifetime extension of the nanocomposite is achieved due to delaying the electrical tree propagation in the sample.

Entamoeba histolytica is distributed throughout the world. Invasive amebiasis affects millions of people globally, and the associated complications cause 40,000-100,000 deaths per year. In countries where fecal-oral transmission is unusual, amebic colitis is not common, and the infection may be seen in travelers to and emigrants from endemic areas. Without adequate treatment, amebic colitis may develop into fulminant and become rapidly fatal. With the current increase in global mobility, amebic colitis should be suspected even in patients not in the endemic areas. CT plays an important role in the diagnosis of amebic colitis by demonstrating the presence of colitis with the typical involvement of the cecum and rectum. Pathological features of atypical involvement are also demonstrated. Since preoperative diagnosis can reduce the mortality associated with necrotizing colitis, radiologists need to recognize the typical as well as atypical CT findings of amebic colitis. Considering this requirement, this paper aims to describe the histopathologic features of amebic colitis and to illustrate the spectrum of corresponding CT findings.

It is known that sarcopenia affects the overall short- and long-term outcomes of patients with gastric cancer (GC); however, the effect of muscle quality on infectious complications after gastrectomy for GC remains unclear. We investigated the associations between the preoperative quantity and quality of skeletal muscle on infectious complications following gastrectomy for GC. The subjects of this retrospective study were 353 GC patients who underwent radical gastrectomy between 2009 and 2018. We examined the relationships between their clinical factors, including skeletal muscle mass index and intramuscular adipose tissue content (IMAC), and infectious complications after gastrectomy. Infectious complications developed in 59 patients (16.7%). The independent risk factors for infectious complications identified by multivariate analysis were male gender (P

Epoxy nanocomposites (NCs) are known to have advantages when used in the electrical insulation of power equipment. Agglomerates of nanoparticles, which inevitably form during the fabrication process, can affect the insulating properties of the resultant nanocomposites. Our previous research has clarified that the impulse breakdown strength of the solid part, rather than the surface, of epoxy–TiO 2 NCs with agglomerates removed was higher than that of unfilled epoxy resin. Here, we investigated the dependence of the TiO 2 filler volume fraction on the AC breakdown strength of NCs whose agglomerate size was controlled. The volume fraction and the maximum agglomerate size were controlled using a simple dilution procedure and a centrifugation technique. The AC breakdown strength of the NCs was found to increase with decreasing volume fraction of TiO 2 nanoparticles when the maximum agglomerate size was controlled at the same level. The variation of the AC breakdown strength of the NCs decreased with decreasing maximum agglomerate size, suggesting that the existence of agglomerates larger than a critical size could affect the breakdown.

Agglomerates of nanoparticles which inevitably occur in the fabrication process of epoxy nanocomposite can affect the insulation properties of epoxy nanocomposite. This paper presents an attempt to clarify the effect of agglomerate size on two important insulation properties of epoxy/TiO 2 nanocomposite (NC). One is intrinsic AC breakdown strength and the other is long-term partial discharge lifetime. We used a centrifugation technique to control the maximum size of the agglomerates in the range from 5 μm down to 0.05 μm in each sample. As the results, AC intrinsic breakdown strength was increased with decreasing the maximum agglomerate size and became even higher than the neat epoxy resin when the maximum size is less than around 0.05um. On the other hand, partial discharge lifetime decreased with decreasing the maximum agglomerate size. It should be noted that the PD lifetime distinctively decreased when the agglomerate size is less than around 0.2 um indicating the existence of a critical agglomerate size which contribute to the suppression of partial discharge development resulting in the extension of the partial discharge lifetime.

SiC-based nonlinear conductive stress grading tape (SGT) has been used at an end-turn stress grading system of a form-wound rotating machine. Although previous researches reported that high-frequency repetitive pulses cause electric field enhancement and local heating at the SG system, few paper deals with the detailed electrical and thermal behaviors under pulse width modulation (PWM) waveforms, which contain not only the repetitive high-frequency, i.e., the carrier frequency, component but also the fundamental frequency component. In this study, the surface potential, the electric field, the time-averaged power densities as well as the resulting temperature rise under the 3-level PWM waveforms were investigated by the transient electric field and thermal coupled FEM simulation. Furthermore, the behavior of the accumulated charges within the SGT was analyzed, based on the simulation results. Consequently, it has been revealed that the charge behavior and the power densities by the carrier-frequency component and those by the fundamental frequency component could be separated individually.

Electric field grading system (SG system) is introduced to prevent partial discharge at the stator coil end of a rotating machine. The SG system consists of corona armor tape (CAT) and stress grading tape/paint (SGT/SGP). The CAT is a carbon-loaded highly-conductive tape and is wound over the main insulation. A SGT/SGP is a silicon carbide powder-loaded tape/paint with field-dependent conductivity and is wound over partially the end of CAT. In general, the conductivity of SGT/SGP also has temperature dependence, but has little field-dependence under higher temperature condition. The coil temperature under operating condition exceeds 100°C and this means the electric field on the coil end may increase due to the less non-linearity of SGT/SGP. When the temperature is high, the density of air decreases and surface discharge may occur easily even under the same field distribution. To examine this issue, light emission of partial discharge (PD) on a model bar system under 1-kHz AC voltage was observed by a photomultiplier tube and a digital camera equipped with an image intensifier. The temperature on SG system was set to 30, 70, and 100°C. Unexpectedly, light emission from PD became weaker and the light emission area became smaller as the temperature increased. Some reasonable explanations for this are as follows: the change in the occurrence phase of PD: and the amount of water contained in the vicinity of SG system surface. Although further investigation is required, but the unexpected increase in the PD pulses has not been observed so far within the measured range.

In this study, transient analysis of Stress Grading(SG) system under PWM waveform is conducted to reveal the effects of fundamental frequency on potential distribution and power density. Risetime, level and jump voltage of PWM waveform used in an analysis is 1μs, 3 and 5 kV, respectively. Fundamental and carrier frequencies are changed in the range from 50–500 Hz and 0.5-6 kHz, respectively. For comparison, analyses under sinusoidal and square voltages which correspond to fundamental and carrier frequencies are conducted. Analytical results show that maximum surface field on SG system under PWM waveform is 1.1 times higher than that under square voltage regardless of fundamental and carrier frequencies. Power density under PWM waveform increases than that under square voltage. The value of power density under PWM waveform is estimated by the sum of power density under sinusoidal voltage which corresponds to fundamental frequency and square voltage which corresponds to carrier frequency. The error of this estimated value is in the range from 8–15 %. This shows that estimated value is accurate enough to estimate temperature rise under PWM waveform.

Carcinoma-associated fibroblasts (CAFs) influence tumor initiation, progression, and metastasis within the tumor-associated stroma. This suggests that CAFs would be a potential target for tumor therapy. Here we found that Hydrogen peroxide-inducible clone-5 (Hic-5), also named transforming growth factor beta-1-induced transcript 1 protein (Tgfb1i1), was strongly induced in CAFs found in human colorectal cancer. To investigate the role of Hic-5 in CAFs, we isolated CAFs and the control counterpart normal fibroblasts (NFs) from human colorectal cancer and non-cancerous regions, respectively. Hic-5 was highly expressed in isolated human CAFs and strongly induced in NFs in culture by the supernatant from cultured colorectal cancer cells as well as cytokines such as TGF-β, IL-1β and stromal cell-derived factor 1 (SDF-1/CXCL12). Furthermore, tumor growth was inhibited in a co-culture assay with Hic-5 knockdown fibroblasts compared with control fibroblasts. To clarify the function and significance of Hic-5 in colorectal cancer in vivo, we utilized a mouse model of azoxymethane (AOM)-induced colorectal cancer using Hic-5-deficient mice. Lack of Hic-5 in CAFs completely prevented AOM-induced colorectal cancer development in the colon tissues of mice. Mechanistic investigation revealed that Hic-5 promoted the expression of lysyl oxidase and collagen I in human control counterpart fibroblasts. Taken together, these results demonstrate that Hic-5 in CAFs is responsible for orchestrating or generating a tumor-promoting stroma.

We prepared six kinds of epoxy resin nanocomposites with silica and an epoxy resin with no silica. The nanocomposites contain silica with different diameters (10, 50, and 100 nm) while their silica contents are 1, 5, 10, and 20 vol%. At 25 and 100 °C, the thermal conductivity has a nearly proportional dependence on the silica content and exhibits an almost reciprocal proportionality to the diameter of the silica. The latter result indicates that the interaction at filler-resin interfaces plays a significant role in heat transfer. However, this view contradicts an easy-to-understand thought that the filler-resin interfaces should work as a barrier for heat transfer. This in turn indicates that the interaction at filler-resin interfaces controls the bulk properties of the resin when the filler is in a nm size. Although the dielectric constant increases with the addition of the silica filler, its increment from the resin with no silica is the smallest in the resin with the 10-nm silica. Therefore, the addition of the 10-nm silica is adequate for electrical insulation purposes.

Polymer nanocomposite material, i.e., polymer insulating material with nano-sized inorganic additives, has recently received much attention for their superior dielectric performance as insulating media of high voltage power apparatus. The long-term insulation lifetime is one of the important factors, which determines the insulation reliability of the apparatus. In this research, the insulation lifetimes of epoxy/TiO2 nanocomposite and neat epoxy resin were experimentally investigated. The long-term experiments were carried out with a test electrode system with an artificial enclosed-void, which simulated air cavities contained within the insulation of the actual-scale apparatus. The time evolutions of partial discharge (PD) intensities were also recorded during the long-term experiment. Consequently, the epoxy/TiO2 nanocomposite showed more than 16 times longer lifetime compared to the neat epoxy resin. Finally, the superiority of the epoxy/TiO2 nanocomposite was discussed based on the PD energies.