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This article aims to realize an isolated dc–dc converter with high power density, high power efficiency, and low noise performance. Although a dual-active-half-bridge (DAHB) converter can achieve high efficiency, it requires input and output low-pass filters to suppress the operational ripple current and switching noise. Owing to the volume of the filters, a DAHB converter cannot be implemented with high power density. This article presents a design theory for a novel isolated bidirectional dc–dc converter with built-in filters. The proposed converter is derived from a DAHB converter and can eliminate the input and output filters via split windings and tank capacitors; the principle of elimination is based on $LC$ low-pass filter function and zero-ripple-current operation. As the number of transistors, capacitors, and magnetic cores of the proposed converter are equal to those of the DAHB converter, the application of the proposed converter allows volume reduction by eliminating the filter components at the input and output ports. Theoretical equations are derived to design a power flow control function and a filter function simultaneously. Finally, prototypes of a DAHB converter and the proposed converter are constructed for comparison. The results demonstrate that the input port noise of the proposed prototype is lower than that of the DAHB prototype by 10 dB (peak) over 1 MHz, and the proposed approach can achieve a significant improvement in efficiency.

Background and aim There exists no evidence on the relationship between endoscopic and histologic findings. Furthermore, even after multiple biopsy specimens were obtained, histologic examination usually fails to show the characteristic features of immune checkpoint inhibitor-associated colitis. In this study, we explored the endoscopic and histologic findings of immune checkpoint inhibitor-associated colitis. Methods Patients diagnosed with immune checkpoint inhibitor-associated colitis at our hospital between March 2018 and December 2018 were retrospectively assessed. The degree of mucosal inflammation was evaluated using endoscopic inflammation grade (inactive, mild, moderate, or severe disease) and further observed using magnifying endoscopy with crystal violet staining. Pit structures were classified into three types: regularly arranged pits with circular or elliptical shape (R type), irregularly arranged pits with inhomogeneous size and morphology (IR type), and pits with reduced density or pits that partially disappeared (AD type). Results Eleven patients (median age, 71 years; range, 44-83 years) were diagnosed with immune checkpoint inhibitor-associated colitis. All characteristic histologic findings, including crypt distortion, crypt abscesses, and apoptotic bodies, were observed at sites with moderate-to-severe endoscopic inflammation but not at sites with inactive-to-mild endoscopic inflammation. Characteristic histologic features were observed in 0%, 50%, and 100% of R-type, IR-type, and AD-type mucosa, respectively. Conclusions We revealed the possible utility of endoscopic images for selecting suitable target sites for biopsy and showed that endoscopic findings could reduce the time lag associated with tissue diagnosis and sampling errors due to biopsy.

Background and Aim Endoscopic resection for early gastric cancer (EGC) is widely performed. However, there is still a paucity of strong evidence regarding long‐term outcomes after endoscopic submucosal dissection (ESD) for the expanded indication criteria of the Japanese guidelines (ver. 2010). Methods Endoscopic submucosal dissection was performed in patients with EGC that met the expanded indication criteria: (i) cT1a, differentiated‐type EGC of 2 to 5 cm, ulcer negative or (ii) cT1a, differentiated‐type EGC of ≤3 cm, ulcer positive. Patients whose pathological examination fulfilled the curative resection criteria were then enrolled in this cohort study: negative vertical margin, negative lymphovascular invasion, and (i) pT1a, differentiated‐type, and ulcer negative; (ii) pT1a, differentiated‐type, ≤3 cm, and ulcer positive; or (iii) pT1b1 (2 cm in diameter and ulcer‐negative lesions, and 94 (44%) had ≤3 cm and ulcer‐positive lesions. The vital status at 5 years after ESD was confirmed in all (100%) patients. No local or metastatic recurrence was detected; however, 26 metachronous gastric cancers developed, and 1 patient died of metachronous gastric cancer. The 5‐year disease‐specific and overall survival rates were 99.5% (95% confidence interval [CI], 97.2%–100%) and 93.9% (95% CI, 89.8%–96.4%), respectively. Conclusion ESD for EGC that fulfills the expanded criteria is feasible and shows favorable long‐term outcomes.

Background and study aims Epinephrine-added submucosal injection solution is used to facilitate hemostasis of non-variceal upper gastrointestinal bleeding and to prevent delayed bleeding of large pedunculated colorectal lesions. However, its benefit in gastric endoscopic submucosal dissection (ESD) for early gastric cancer (EGC) is unclear. The effectiveness of epinephrine-added injection solution for outcomes of gastric ESD was examined using propensity score matching analysis. Patients and methods A total of 1,599 patients with solitary EGC (83 with non-epinephrine-added solution and 1,516 with epinephrine-added solution) between 2011 and 2018 were enrolled. Propensity scores were calculated to balance the distribution of baseline characteristics: age, sex, tumor location, specimen size, presence of ulcer scar, tumor depth, histological tumor type, and operators’ experience, and 1:3 matching was performed. En bloc resection rate, mean procedure time, delayed bleeding rate, and perforation rate were compared between the non-epinephrine (n = 79) and epinephrine (n = 237) groups. Results Mean procedure time was significantly shorter in the epinephrine group than in the non-epinephrine group (60 vs. 78 min, P Conclusion The results suggest that epinephrine-added injection solution is useful for reduction of gastric ESD procedure time, warranting validation in a randomized controlled trial.

Oxytocin is a central neuromodulator required for facilitating mate preferences for familiar individuals in a monogamous rodent (prairie vole), irrespective of sex. While the role of oxytocin in mate choice is only understood in a few monogamous species, its function in nonmonogamous species, comprising the vast majority of vertebrate species, remains unclear. To address this issue, we evaluated the involvement of an oxytocin homolog (isotocin, referred herein as oxt) in mate choice in medaka fish ( Oryzias latipes ). Female medaka prefer to choose familiar mates, whereas male medaka court indiscriminately, irrespective of familiarity. We generated mutants of the oxt ligand ( oxt ) and receptor genes ( oxtr1 and oxtr2 ) and revealed that the oxt-oxtr1 signaling pathway was essential for eliciting female mate preference for familiar males. This pathway was also required for unrestricted and indiscriminate mating strategy in males. That is, either oxt or oxtr1 mutation in males decreased the number of courtship displays toward novel females, but not toward familiar females. Further, males with these mutations exhibited enhanced mate-guarding behaviors toward familiar females, but not toward novel females. In addition, RNA-sequencing (seq) analysis revealed that the transcription of genes involved in gamma-amino butyric acid metabolism as well as those encoding ion-transport ATPase are up-regulated in both oxt and oxtr1 mutants only in female medaka, potentially explaining the sex difference of the mutant phenotype. Our findings provide genetic evidence that oxt-oxtr1 signaling plays a role in the mate choice for familiar individuals in a sex-specific manner in medaka fish.

Ordinary optimization methods for inductive power transfer (IPT) coils rely heavily on FEM simulations due to the large air gap between the primary and secondary coils. This problem is further compounded for dynamic inductive power transfer (DIPT) systems since DIPT requires more calculation points than IPT to know the average output power across the primary coil. This paper proposes a new design optimization method for DIPT systems utilizing a combination of FEM simulations and a neural network. A neural network trained by FEM results can generate a significantly larger number of design points than conventional methods in the same simulation time. To demonstrate the effectiveness of the proposed method, designs using the proposed and conventional methods are compared. The results achieve 20% smaller core volume and 26% higher average output power for the proposed method over conventional one with the same simulation time and design criteria. Furthermore, to verify the accuracy of the proposed method, the final design generated by the proposed method is compared with FEM results.

Background and Aim Stratifying gastric cancer (GC) risk and endoscopy findings in high‐risk individuals may provide effective surveillance for GC. We developed a computerized image‐ analysis system for endoscopic images to stratify the risk of GC. Methods The system was trained using images taken during endoscopic examinations with non‐magnified white‐light imaging. Patients were classified as high‐risk (patients with GC), moderate‐risk (patients with current or past Helicobacter pylori infection or gastric atrophy), or low‐risk (patients with no history of H. pylori infection or gastric atrophy). After selection, 20,960, 17,404, and 68,920 images were collected as training images for the high‐, moderate‐, and low‐risk groups, respectively. Results Performance of the artificial intelligence (AI) system was evaluated by the prevalence of GC in each group using an independent validation dataset of patients who underwent endoscopic examination and H. pylori serum antibody testing. In total, 12,824 images from 454 patients were included in the analysis. The time required for diagnosing all the images was 345 seconds. The AI system diagnosed 46, 250, and 158 patients as low‐, moderate‐, and high risk, respectively. The prevalence of GC in the low‐, moderate‐, and high‐risk groups was 2.2, 8.8, and 16.4%, respectively (P = 0.0017). Three experienced endoscopists also successfully stratified the risk; however, interobserver agreement was not satisfactory (kappa value of 0.27, indicating fair agreement). Conclusion The current AI system detected significant differences in the prevalence of GC among the low‐, moderate‐, and high‐risk groups, suggesting its potential for stratifying GC risk., The artificial intelligence system used in this study detected significant differences in the prevalence of gastric cancer (GC) among the low‐, moderate‐, and high‐risk groups, suggesting its potential for stratifying GC risk.

BACKGROUND AND AIM Underwater endoscopic mucosal resection (UEMR) is effective for superficial non-ampullary duodenal epithelial neoplasms (SNADEN). However, the incidence of residual lesion after UEMR, especially for large lesions (≥20 mm), and their prognosis remain unclear. We aimed to assess the incidence of residual lesions and further outcomes after UEMR for SNADEN. METHODS We carried out a retrospective study at a tertiary cancer institute. Candidates for the study were systematically retrieved from an endoscopic and pathological database from January 2013 to April 2018. RESULTS A total of 162 SNADEN resected with UEMR were analyzed. Median (range) procedure time was 5 (1-70) min. En bloc resection rates for large lesions (≥20 mm) and small lesions (

Lymphovascular invasion (LVI) is a strong predictive factor for lymph node metastasis (LNM) in early gastric cancer (GC). This study investigated the risk for LNM in pT1b GC without LVI based on Epstein-Barr virus (EBV) status in addition to conventional clinicopathological parameters.In total, 847 consecutive patients of pT1b GC without LVI who underwent surgery at three high-volume centers between 2005 and 2014 were retrospectively analyzed. Clinicopathological parameters and EBV status were evaluated, and univariate and multivariate analyses were performed to estimate LNM risk. With regard to the presence of those three parameters, risk stratification for LNM was performed and compared with a previously proposed risk classification that included low-risk (LNM 3.0%), intermediate-risk (LNM ≥ 3.0 and 19.6%), and high-risk (LNM ≥ 19.6%) groups.EBV-positive GC (EBVGC) accounted for 11.3% (96 of 847) of cases; LNM was lower in EBVGC than in non-EBVGC (1 of 96, 1.0% vs. 71/751, 9.5%). In the multivariate analysis, non-EBVGC [odds ratio (OR) 10.8, 95% confidence interval (CI) 1.48-78.9], age 65 years (OR 2.13, 95% CI 1.30-3.48), and tumor diameter 3 cm (OR 2.26, 95% CI 1.36-3.74) were independent risk factors for LNM. Patients with EBVGC were at low risk for LNM whereas those with all of three independent risk factors were at high risk (36 of 168, 21.4%, 95% CI 15.5-28.4).LNM risk stratification that includes EBV status is useful for clinical decision-making in pT1b GC cases without LVI.

Background and aim Simultaneous and metachronous head and neck cancers are likely to develop in patients with current or previous esophageal cancer. The Valsalva maneuver facilitates the visualization of the hypopharyngeal area during endoscopic observation, but it requires transnasal endoscopy. We developed a novel Valsalva maneuver using transoral endoscopy with a lip cover-type mouthpiece. Methods Between March 2018 and July 2018, 107 patients with current or previous esophageal cancer who were scheduled to undergo upper gastrointestinal endoscopy were included in our pilot study. We performed the Valsalva maneuver using our newly developed mouthpiece and transoral endoscopy in the patients and evaluated the hypopharyngeal region, including the postcricoid area and the posterior wall of the hypopharynx. The outcome measure was procedural success rate, which was graded as "complete," "incomplete," and "none." Results Observation of the hypopharyngeal area was "complete" in 81 patients (76%) using the Valsalva maneuver. However, in 25 patients and in 1 patient, observation was "incomplete" and "none," respectively. Seven lesions were newly detected in seven patients during the study period. Conclusions The Valsalva maneuver using transoral endoscopy with a lip cover-type mouthpiece is feasible for the visualization of the postcricoid area and the posterior wall of the hypopharynx. Particularly, this technique would contribute to early detection of head and neck cancers.

Conventional optimization methods for inductive power transfer (IPT) rely on the finite element method (FEM) simulations to extract parameters such as inductances, coupling coefficients, and stray magnetic fields. These simulations are often time-consuming and as a result, a full optimization cannot be achieved. This paper proposes a new design optimization method for IPT systems utilizing a combination of FEM simulations and a feedforward neural network. The proposed method can output a significantly larger number of design points than conventional methods in the same calculation time. Hence, users can select an optimized design point from the plots with higher resolution. This paper presents the proposed design optimization method and compares its benefits and trade-offs to the conventional method. Additionally, a prototype designed by the proposed method is constructed and experimental results are shown to verify the predicted values of inductances, coupling coefficients, and stray magnetic fields for the optimized solution against FEM simulation and the measured results.

Background and aims Endoscopic resection of nonampullary duodenal adenoma is often challenging, and its technique has not yet been standardized. To overcome the practical difficulty of conventional endoscopic mucosal resection, underwater endoscopic mucosal resection (UEMR) was recently developed; therefore, we investigated the effectiveness and safety of UEMR for nonampullary duodenal adenoma. Methods A multicenter, prospective cohort study was conducted at 21 institutions in Japan. We enrolled patients with no more than 2 nonampullary duodenal adenomas ≤20 mm in size, who were scheduled to undergo UEMR. After UEMR, follow-up endoscopies were scheduled at 2 and 12 months after the procedure, and biopsy specimens were taken from the post-UEMR scars. The primary endpoint was the proportion of patients with histologically proven nonrecurrence at follow-up endoscopy and biopsy. Results A total of 155 patients with 166 lesions underwent UEMR. One patient with a non-neoplastic lesion in the resected specimen and 10 patients with 10 lesions who were lost to follow-up were excluded. Finally, 144 patients with 155 lesions who received all follow-up endoscopies were analyzed for the primary endpoint. The proportion of patients with proven nonrecurrence was 97.2% (n = 140 of 144; 95% confidence interval, 92.8%–99.1%) which exceeded the predefined threshold value (92%). Two cases of delayed bleeding (1.2%) occurred and they were successfully managed by clips. All recurrences were successfully treated by additional endoscopic treatment. Conclusions This multicenter, prospective cohort study demonstrated effectiveness and safety of UEMR for nonampullary duodenal adenomas ≤20 mm in size. (University Hospital Medical Network Clinical Trials Registry, Number: UMIN000030414 ).

Background The current virtual chromoendoscopy equipment cannot completely detect superficial squamous cell carcinoma (SCC) in the esophagus, despite its development in the recent years. Thus, in this study, we aimed to elucidate the appropriate air volume during endoscopic observation to improve the visibility of esophageal SCC. Methods This retrospective study included a total of 101 flat type esophageal SCCs identified between April 2017 and January 2019 at the Department of Gastrointestinal Oncology, Osaka International Cancer Institute. Video images of narrow band imaging (NBI) under both less-air and standard-air conditions were recorded digitally. Videos were evaluated by five endoscopists. Relative visibility between less-air and standard-air conditions of the brownish area, brownish color change of the epithelium, and dilated intrapapillary capillary loop (IPCL) were graded as 5 (definitely better under less-air condition) to 1 (definitely worse under less-air condition), with 3 indicating average visibility (equivalent to standard-air observation). Results The mean (standard deviation) visibility score of the brownish area, brownish color change of the epithelium, and dilated IPCLs under less-air condition were 3.94 (0.58), 3.73 (0.57), and 4.13 (0.60), respectively, which were significantly better than that under standard-air condition (p Conclusions The present results suggested that NBI with less air might improve the visibility of flat type esophageal SCC compared with NBI with standard air. Less-air NBI observation may facilitate the detection of flat type esophageal SCC. Trial registration The present study is a non-intervention trial.

Objectives A superficial nonampullary duodenal epithelial tumor (SNADET) is defined as a mucosal or submucosal sporadic tumor of the duodenum that does not arise from the papilla of Vater. SNADETs rarely metastasize to the lymph nodes, and most can be treated endoscopically. However, SNADETs are sometimes missed during esophagogastroduodenoscopic examination. In this study, we constructed a convolutional neural network (CNN) and evaluated its ability to detect SNADETs. Methods A deep CNN was pretrained and fine-tuned using a training data set of the endoscopic images of SNADETs (duodenal adenomas [N = 65] and high-grade dysplasias [HGDs] [N = 31] [total 531 images]). The CNN evaluated a separate set of images from 26 adenomas, 8 HGDs, and 681 normal tissue (total 1,080 images). The gold standard for both the training data set and test data set was a "true diagnosis" made by board-certified endoscopists and pathologists. A detected tumor was marked with a rectangular frame on the endoscopic image. If it overlapped at least a part of the "true tumor" diagnosed by board-certified endoscopists, the CNN was considered to have "detected" the SNADET. Results The trained CNN detected 94.7% (378 of 399) of SNADETs on an image basis (94% [280 of 298] of adenomas and 100% [101 of 101] of HGDs) and 100% on a tumor basis. The time needed for screening the 399 images containing SNADETs and all 1,080 images (including normal images) was 12 and 31 seconds, respectively. Discussion We used a novel algorithm to construct a CNN for detecting SNADETs in a short time.

BACKGROUND AND AIM Multiple Lugol-voiding lesions (LVLs) on Lugol chromoendoscopy can predict the development of metachronous multiple cancers in the esophagus and the head and neck regions. However, Lugol chromoendoscopy sometimes causes adverse events such as chest pain and discomfort. We therefore investigated the endoscopic findings on narrow band imaging (NBI) or blue laser imaging (BLI) that correspond to the presence of multiple LVLs in patients with esophageal squamous cell carcinoma. METHODS First, we investigated the NBI/BLI findings corresponding to individual small LVLs (one-to-one correspondence). Second, we investigated the association between the grade of multiple LVLs and the five endoscopic findings, including multiple foci of dilated vessels (MDV), multiple small brownish areas without microvascular irregularity, and a nonuniform color tone. RESULTS One-to-one correspondence of endoscopic findings was analyzed in 106 small LVLs. The main findings matched with small LVLs were a focus of dilated vessels (44 lesions), a small brownish area (17 lesions), and a small brownish area with a focus of dilated vessels (19 lesions). The relationship between multiple LVLs and each finding assessed by NBI/BLI was assessed in 155 patients. Multivariate logistic regression indicated that the presence of MDV was the only finding independently associated with multiple LVLs (P

Second cancers in patients with esophageal cancer (EC) are common and have a poor prognosis. We evaluated the incidence of second cancers at different sites by patients’ ages when their index ECs were diagnosed. This study included patients who underwent endoscopic resection for superficial EC at our hospital between September 1994 and September 2011. Patients’ data, including sex, age at diagnosis, sequence of cancer incidence, cancer histology, and cancer site, were extracted from the cancer registry. Of 544 patients, 255 developed second cancers. Simultaneous head and neck cancers (HNCs) and other organ cancers (OCs) were, respectively, present in 15% (80/544) and 9.6% (52/544) of patients; and 30% (162/544) developed metachronous second cancers over a median follow-up period of 79.5 months (range 2–120), including 44 metachronous HNCs and 70 OCs. The cumulative incidence of metachronous HNCs was significantly higher in younger patients (

BACKGROUND AND AIM The true incidence of incomplete muscularis mucosa resection with cold snare polypectomy (CSP) is unknown. We examined the incidence of incomplete muscularis mucosa resection both with and without cold snare defect protrusion (CSDP). METHODS We prospectively enrolled patients undergoing polypectomy for 4 to 9mm nonpedunculated polyps. We evaluated the presence of CSDP immediately following CSP and biopsied the CSDP or the center of the mucosal defect without CSDP. The presence of the muscularis mucosa and any residual polyp in the biopsies was evaluated histologically. The primary outcome was the incidence of incomplete mucosal layer resection defined as the presence of muscularis mucosa or residual polyp in the biopsies. RESULTS From August 2017 to October 2018, 188 patients were screened, and 357 polyps were included. CSDP was detected in 122/355 (34%) evaluated mucosal defects. Excluding five lesions requiring hemostasis immediately following CSP, 352 mucosal defects were biopsied. After excluding 102 biopsies containing normal mucosa, we evaluated 250 biopsies. The overall incidence of incomplete mucosal layer resection was 63% (159/250), 76% (68/90) with CSDP and 57% (91/159) without CSDP (P

A novel filter built-in converter with split windings is presented. Because of its extreme simplicity, flexibility, and efficiency, it has the potential to replace some of the conventional electric power conversion methods used today. The background, design, and operation of the proposed filter built-in converter are discussed in this paper. The proposed converter is derived from a dual active half bridge (DAHB) converter, and it can achieve zero-ripple-current operation and LC low-pass filter function by the split windings and tank capacitors. Due to the zero-ripple-current operation and the LC low-pass filter function, the proposed converter can eliminate or decrease the input and output filters, and with a phase-shift control strategy, all the switches are operated under zero-voltage switching (ZVS) condition. In order to design a power flow control function and a filter function simultaneously, theoretical equations for these functions are derived. Finally, the DAHB and the proposed converter prototypes are constructed for comparison. The results show that the noise in the input port of the proposed prototype is smaller than that of the DAHB prototype by 16 dB (peak), and the proposed approach can achieve a significant improvement in efficiency.

Background and Study Aims: We have reported the usefulness of traction-assisted colorectal endoscopic submucosal dissection (TAC-ESD) to overcome the technical difficulty of colorectal ESD. However, the direction of traction is toward the anal side only. We retrospectively evaluate the safety and efficacy of “pulley” TAC-ESD. Patients and Methods: We retrospectively analyzed patients diagnosed with colorectal polyps and treated by “pulley” TAC-ESD at Osaka International Cancer Institute from December 2017 to June 2018. Results: During the study period, 79 patients with 81 lesions were treated by ESD, and 54 of these patients were treated by traction-assisted ESD. Among them, 7 underwent “pulley” traction-assisted ESD (6 men, 1 woman; age, 48–69 years), resulting in en bloc resection with no complications. This afforded good visibility of the submucosal layer in 6 patients, but it was not effective in the remaining patient with the muscle-retracting sign. Conclusion: The “pulley” method affords good visibility of the submucosal layer by changing the traction direction in cases that are difficult to manage by conventional traction-assisted ESD.

Background and study aims While knowledge of the natural history of early gastric cancer (EGC) may be useful in relevant clinical situations, few relevant reports are available. Therefore, we investigated the progression of EGC. We gathered data regarding 114 cases of EGC from 2005 to 2015 from a hospital cancer registry and analyzed 21 lesions that fulfilled five inclusion criteria. Deep progression was defined as submucosal invasion by a mucosal tumor and proper muscle invasion by a submucosal tumor. Lateral progression was defined as ≥ 20 % increase in size. During median follow-up of 23 months, one of 18 mucosal tumors showed deep progression and six showed lateral progression. Of three submucosal tumors, two showed deep progression and three showed lateral progression. Our study suggests that a certain proportion of mucosal cancers can lie dormant for several years. Further large-scale studies in a multicenter setting should overcome the limitations of this study.

Background Gastrointestinal stromal tumors (GISTs) are potentially malignant and are indicated for resection. The standard treatment for resectable GISTs is surgery, although endoscopic resection has been reported outside Japan. This study retrospectively analyzed the results of endoscopic resection of GISTs in Japan. Method We identified patients with GISTs treated only by endoscopic resection in our institute between January 2016 and December 2018, and analyzed their clinical and pathological characteristics. Results During the study period, 8 GISTs were resected only by endoscopy: 7 were located in the upper third of the stomach and 1 in the middle. All were intraluminal growth type. Median (range) tumor diameter was 20 (10-35) mm. All tumors were resected en bloc with a median (range) operation time of 67.5 (50-166) min. Complete perforation occurred in 5 cases, but the serosa remained in 2 and the outer layer of the muscularis propria remained in 1. The defect was endoscopically closed with clip-and-endoloop purse-string suturing (n=3), simple endoclipping (n=2), or over-the-scope clipping (n=2), and 1 did not require closure because the outer longitudinal muscle was preserved. Oral feeding was commenced on postoperative day (POD) 3 (median; range 2-4), and the patient was discharged on POD 6 (median; range 4-11). No serious adverse event developed after the procedures. Conclusion Endoscopic resection for selected cases of small intraluminal GISTs is feasible, making it a viable alternative treatment option to laparoscopic surgery.

Acrylic resin is employed in optical products such as lenses and light guiding panels because it is highly transparent. Optical components made using acrylic resin require hand polishing by skilled workers to give a mirror finish to the surface of components in order to obtain the required optical properties. However, polishing takes a lot of time and two problems that exist are that skilled workers are aging and that young skilled workers are few in number. In this research, a method of ultrasonic milling of acrylic resin which would give a mirror-surface finish to acrylic resin products without the need for hand polishing by skilled workers was proposed.

Simultaneous and metachronous head and neck cancers are likely to develop in patients with current or previous esophageal cancer. The Valsalva maneuver facilitates the visualization of the hypopharyngeal area during endoscopic observation, but it requires transnasal endoscopy. We developed a novel Valsalva maneuver using transoral endoscopy with a lip cover-type mouthpiece.Between March 2018 and July 2018, 107 patients with current or previous esophageal cancer who were scheduled to undergo upper gastrointestinal endoscopy were included in our pilot study. We performed the Valsalva maneuver using our newly developed mouthpiece and transoral endoscopy in the patients and evaluated the hypopharyngeal region, including the postcricoid area and the posterior wall of the hypopharynx. The outcome measure was procedural success rate, which was graded as "complete," "incomplete," and "none."Observation of the hypopharyngeal area was "complete" in 81 patients (76%) using the Valsalva maneuver. However, in 25 patients and in 1 patient, observation was "incomplete" and "none," respectively. Seven lesions were newly detected in seven patients during the study period.The Valsalva maneuver using transoral endoscopy with a lip cover-type mouthpiece is feasible for the visualization of the postcricoid area and the posterior wall of the hypopharynx. Particularly, this technique would contribute to early detection of head and neck cancers.

Multiple Lugol-voiding lesions (LVLs) on Lugol chromoendoscopy can predict the development of metachronous multiple cancers in the esophagus and the head and neck regions. However, Lugol chromoendoscopy sometimes causes adverse events such as chest pain and discomfort. We therefore investigated the endoscopic findings on narrow band imaging (NBI) or blue laser imaging (BLI) that correspond to the presence of multiple LVLs in patients with esophageal squamous cell carcinoma.First, we investigated the NBI/BLI findings corresponding to individual small LVLs (one-to-one correspondence). Second, we investigated the association between the grade of multiple LVLs and the five endoscopic findings, including multiple foci of dilated vessels (MDV), multiple small brownish areas without microvascular irregularity, and a nonuniform color tone.One-to-one correspondence of endoscopic findings was analyzed in 106 small LVLs. The main findings matched with small LVLs were a focus of dilated vessels (44 lesions), a small brownish area (17 lesions), and a small brownish area with a focus of dilated vessels (19 lesions). The relationship between multiple LVLs and each finding assessed by NBI/BLI was assessed in 155 patients. Multivariate logistic regression indicated that the presence of MDV was the only finding independently associated with multiple LVLs (P 0.01).The presence of MDV in the noncancerous background esophageal mucosa was significantly associated with multiple LVLs. This pilot study demonstrates that MDV has the potential to be a new risk factor for the development of metachronous multiple esophageal squamous cell carcinoma.

Background: Although the use of endoscopic submucosal dissection (ESD) as a minimally invasive treatment for large superficial colorectal neoplasms is increasing, colorectal ESD remains technically challenging. As perforation in the colorectum is generally considered to be associated with a higher risk of complications, the aim of this study was to investigate the characteristics of perforation caused by colorectal ESD. Methods: This retrospective study included 635 lesions treated with colorectal ESD, between February 2011 and December 2015, in a tertiary cancer center. We evaluated and compared the clinical course and short-term outcomes of the intraprocedural perforation group with those of the delayed perforation and no perforation groups. Results: Perforation occurred in 45 (7.1%) of the 635 cases. Thirty-six cases were intraprocedural perforation (5.7%), all of which were successfully closed with endoclips during the procedure. Nine cases of delayed perforation occurred (1.4%). No emergency surgery was performed in the intraprocedural perforation group; however, 5 of 9 cases underwent emergency surgery in the delayed perforation group (56%, p < 0.0001). There were statistically significant differences between the intraprocedural and delayed perforation groups with regard to the hospitalization period, fasting period, abdominal pain scale, peak white blood cell (WBC) count, and peak C-reactive protein (CRP), and between the intraprocedural and no perforation groups with regard to the location of the lesion, hospitalization period, fasting period, abdominal pain scale, peak WBC, peak CRP, and en bloc resection rate. Conclusions: While intraprocedural perforation due to colorectal ESD can be managed conservatively, delayed perforation can lead to serious adverse events.

Objectives: Since the development of techniques for endoscopic submucosal dissection (ESD), the indication range of endoscopic resection (ER) has been extended in early gastric cancer (EGC) treatment. For undifferentiated-type EGC, tumors with an intramucosal depth of invasion, no ulceration and a diameter of 20 mm or less were included in the expanded indications for ER in the Japanese Gastric Cancer Treatment Guidelines 2010. Nonetheless, because of difficulty in detecting lesions that meet the criteria for ER, the number of endoscopically resected cases of undifferentiated-type EGC is less than that of differentiated-type EGC. Methods: We retrospectively investigated the outcomes of ESD in 38 patients with 40 lesions of EGC in which the dominant pathological type was confirmed to be undifferentiated (signet ring cell carcinoma, poorly differentiated adenocarcinoma, mucinous adenocarcinoma) on histological examination of resected specimens. Results: Margin involvement and submucosal infiltration were common noncurative factors. Precise evaluation of the area and depth of lesions is a problem to be solved. Among a total of five patients with involved or uncertain horizontal margins, one of two patients who underwent additional surgery had residual cancer, and one of three patients who were observed had recurrence. Conclusions: Undifferentiated-type EGC with a positive horizontal margin may relapse after ESD. It is therefore essential to precisely evaluate the area of the lesion and to perform resection with an adequate safety margin to decrease the risk of recurrence.

This paper presents a magnetically integrated isolated bidirectional three-port DC-DC converter (TPC) that includes an integrated dual active bridge converter (DAB) and non-isolated bidirectional DC-DC converter (NBC), each of which can be independently controlled. The proposed TPC simultaneously uses large, small, and magnetizing inductances, of which the small and magnetizing inductances are used for the DAB function, while the large inductance is used for the TPC function. The proposed magnetic component can function as any of the three inductances in the TPC. We constructed a 750 W, 175 kHz prototype of the proposed TPC along with an example of a conventional TPC and measured their respective efficiencies. The results show the efficiencies of the integrated TPC were all above 90% across the entire range of output power and were nearly equal to those of the conventional device. However, compared to the conventional type, the magnetic components in the proposed converter were 10% smaller, and the overall size of the converter was 33% smaller.

A multi-port DC/DC converter having DC48V and DC12V ports is proposed for next generation HV sub system. The converter integrates an isolated DC/DC converter and a non-isolated DC/DC converter in one circuit. A low voltage side full-bridge and an inductor are shared by two topologies, and the number of switches and magnetic components can be saved. In the present study, a duty modulation method is proposed to reduce losses in light load condition. Moreover, to achieve compatibility of high efficiency and high power density, the switching frequency is increased and 600 V cascode type GaN FET is used for high voltage side switches. A 175 kHz, 1.0 kW prototype is constructed, and power density of 55 W/in 3 is achieved. The loss reduction in light load condition using the proposed duty modulation is verified. The measured efficiency is over 90% for a wide output range, and the maximum value achieves 93.9% for DC12V, and 95.3% for DC48V, respectively.

A highly accurate filter simulation requires a high precision SPICE model for the common mode choke. Conventional SPICE models for chokes consist of parallel RLC circuits and show a substantial difference between the measured and simulated impedance characteristics due to the lack of frequency-dependent complex permeability considerations. Here, we propose a novel SPICE model for a common mode choke that includes the frequency-dependent complex permeability. This model uses a transfer function in the s-domain to describe frequency-dependent elements. Moreover, two model parameter estimation methods are proposed; a measurement based method and a datasheet based method. High accuracy is achieved with the measurement based model by extracting the model parameter using the measured impedance characteristics of the actual coil. In the datasheet based method, the model parameter is estimated from the datasheet and the shape of the coil without the actual coil. Finally, we show that not only the impedance characteristics of a choke can be expressed, but also the insertion loss of a T-type filter can be predicted much more accurately than presently possible using a conventional model. This SPICE model is the first to express the frequency-dependent inductance and resistance of the choke with high accuracy; therefore, it is expected to be useful for filter design.

An experimental study of several types of ground heat exchangers (GHEs) installed in a steel pile foundation, including double-tube, U-tube, and multi-tube GHEs, was carried out at Saga University. Water flows through the heat exchangers and exchanges heat to or from the ground. The performance of GHEs was investigated under actual operation in the cooling mode with flow rates of 2, 4, and 8 l/min. Temperatures of the ground and GHE tube wall were measured to find the temperature distributions according to the depth of the ground and depth of the GHE tube wall. The temperatures of the inlet and outlet of circulated water were also measured to calculate the heat exchange rate. The double-tube had the highest heat exchange rate, followed by the multi-tube and U-tube GHEs. For example, the average heat exchange rate of GHEs over 24 h of continuous operation with a flow rate of 4 l/min was 49.6 W/m for the double-tube, 34.8 W/m for the multi-tube, and 30.4 W/m for the U-tube. An increasing flow rate increased the heat exchange rate of the GHEs. The heat exchange rates increased significantly for flow rate increases from 2 to 4 l/min, but only slightly changed from 4 to 8 l/min.

A three-port DC/DC converter (TPC) having DC48V and DC12V ports, and an isolated DC port is designed and analyzed. The newly designed TPC integrates a non-isolated bi-directional DC-DC (NBC) converter and an isolated dual-active-bridge (DAB) converter using a coupling inductor technique, and DC power can be delivered multi-directionally among three DC ports. In the present study, a loss estimation method for the TPC is developed in order to analyze losses in all load conditions. A 750 W, 125 kHz prototype using a Si MOSFET is constructed in order to confirm the accuracy of the newly developed estimation method. The measured efficiency is over 90% for a wide range of load conditions, and the calculated efficiency curves correspond well with the measured efficiencies. In addition, the improvement in efficiency provided by using a GaN FET is also discussed. The efficiency is expected to increase 2% by replacing the Si MOSFET with a GaN FET. Finally, a prototype using a GaN FET is constructed in order to verify the above estimation.