Probing Electronic Band Structures of Dielectric Polymers via Pre-Breakdown Conduction.

The electronic band structure, especially the defect states at the conduction band tail, dominates electron transport and electrical degradation of a dielectric material under an extremely high electric field. However, the electronic band structure in a dielectric is barely well studied due to experimental challenges in detecting the electrical conduction to an extremely high electric field, i.e., prebreakdown. In this work, the electronic band structure of polymer dielectric films is probed through an in situ prebreakdown conduction measurement method in conjunction with a space-charge-limited-current spectroscopic analysis. An exponential distribution of defect states at the conduction band tail with varying trap levels is observed in accordance with the specific morphological disorder in the polymer dielectric, and the experimental defect states show also a favorable agreement with the calculated density of states from the density functional theory. The methodology demonstrated in this work bridges the molecule-structure-determined electronic band structure and the macro electrical conduction behavior with a highly improved understanding of material properties that control the electrical breakdown, and paves a way for guiding the modification of existing material and the exploration of novel materials for high electric field applications.

Learning curve for the surgical time of laparoscopic cholecystectomy performed by surgical trainees using the three-port method: how many cases are needed for stabilization?

BACKGROUND: The assessment of laparoscopic cholecystectomy (LC) skills using operating times has not been well reported. We examined the total and partial operating times for LC procedures performed by surgical trainees to determine the required number of surgeries until the surgical time stabilizes. METHODS: We reviewed the video records of 514 consecutive LCs using the three-port method, performed by 16 surgical trainees. The total and partial surgical times were calculated and correlated to the surgeons' experience. RESULTS: The median total surgical time for a trainee's first LC was 112 (range 71-226) minutes. It reduced rapidly after the first 20 LCs and plateaued to its minimum after approximately 60 cases. A statistically significant time decrease was observed between the first 10 (median, range 112, 46-252 min) and the next 50-59 cases (64, 34-198 min), but not between the 50-59 and the subsequent 100-109 cases (71, 33-127 min). The total times taken by trainees who had performed > 50 operations were not significantly different from those taken by instructors during the study period. Surgery for 125 patients with acute cholecystitis took a significantly longer time (median 99 vs. 74 min with non-acute cholecystitis); however, the abovementioned time reduction findings showed similar results regardless of the patient's acute inflammation status. The partial operating times around the cervical/cystic duct and gallbladder bed reduced uniformly between the first 10 and the following 50-59 cases. Although time variations in total and cervical/cystic duct operating times were not correlated to the surgical experience, time fluctuation of gallbladder bed procedures reduced after 60 cases. CONCLUSION: The time required to perform an LC was inversely correlated with the experience of surgical trainees and halved after the first 60 cases. The surgical experience required for LC time stabilization is approximately 60 cases.

Laparoscopic transabdominal preperitoneal hernioplasty for bilateral obturator hernias and left inguinal hernia with emaciation caused by anorexia nervosa: A case report.

A 55-year-old woman receiving treatment for anorexia nervosa presented with abdominal pain and right thigh pain. Her body mass index was 12.9 kg/m2 . Computed tomography showed fluid storage in the distal side of the right obturator foramen and revealed a dilated small bowel without a starting point of obstruction. We diagnosed a naturally reduced incarcerated right obturator hernia and performed elective surgery with a laparoscopic approach for hernia repair the next day. Intraperitoneal observation revealed bilateral obturator hernias and a left direct-type inguinal hernia. Transabdominal preperitoneal hernioplasty was performed using two self-gripping polyester meshes for bilateral obturator hernia repair and a lightweight 3D-shaped mesh for left inguinal hernia repair. Women with emaciation caused by anorexia nervosa may be more likely to have complex hernias, including obturator hernia, and laparoscopic approaches may be useful for preoperatively diagnosed nonstrangulated obturator hernias.

Comparison of the oncological outcomes of stenting as a bridge to surgery and surgery alone in stages II to III obstructive colorectal cancer: a retrospective study.

PURPOSE: We evaluated the oncological outcomes of bridge to surgery (BTS) using stent compared with surgery alone for obstructive colorectal cancer. METHODS: Consecutive patients who underwent curative resection for stages II to III obstructive colorectal cancer at our institution from January 2009 to March 2020, were registered retrospectively and divided into 43 patients in the BTS group and 65 patients in the surgery alone group. We compared the surgical and oncological outcomes between the 2 groups. RESULTS: Stent-related perforation did not occur. One patient in whom the stent placement was unsuccessful underwent emergency surgery with poor decompression (clinical success rate, 97.7%). The pathological characteristics were not significantly different between the groups. The following surgical outcomes in the BTS group were superior to those in the surgery alone group; nonemergency surgery (P<0.001), surgical approach (P=0.006), and length of hospital stay (P=0.020). The median follow-up time was 44.9 months (range, 1.1-126.5 months). The 3-year relapse-free survival rates were 68.4% and 58.2% (P=0.411), and the overall survival rates were 78.3% and 88.2% (P=0.255) in the surgery alone and BTS groups, respectively. The 3-year locoregional recurrence rates were 10.2% and 8.0% (P=0.948), and distant metastatic recurrence rates were 13.3% and 30.4% (P=0.035) in the surgery alone and BTS groups, respectively. CONCLUSION: This study revealed that BTS with stent may be associated with a higher frequency of distant metastatic recurrence. Stent for stages II to III obstructive colorectal cancer potentially worsens oncological outcomes.

Comparison of surgical smoke between open surgery and laparoscopic surgery for colorectal disease in the COVID-19 era.

BACKGROUND: Surgical smoke during operation is a well-known health hazard for medical staff. This study aimed to investigate the dynamics of surgical smoke during open surgery or laparoscopic surgery for colorectal disease. METHODS: This study quantitated particulate matter (PM) counts as part of surgical smoke in 31 consecutive patients who underwent colectomy at the Niigata City General Hospital using a laser particle counter. Particles were graded by size as ≤ 2.5 µm PM (PM2.5) or > 2.5 µm PM (large PM). Operative procedures were categorized as either open surgery (n = 14) or laparoscopic surgery (n = 17). RESULTS: The median patient age was 72 (range 41-89) years and 58.1% were male. The total PM2.5, PM2.5 per hour, and maximum PM2.5 per minute counts during operation were significantly higher in open surgery than in laparoscopic surgery (P = 0.001, P < 0.001, and P = 0.029, respectively). Large PM counts (total, per hour, and maximum per minute) were also higher in the open surgery group than in the laparoscopic surgery group. The maximum PM2.5 concentration recorded was 38.6 µm/m3, which is considered "unhealthy for sensitive groups" according to the U.S. Environment Protection Agency air quality index standards, if it was a 24-h period mean value. CONCLUSION: Exposure to surgical smoke is lower during laparoscopic surgery than during open surgery for colorectal diseases.

Is radiological psoas muscle area measurement a predictor of postoperative complications after rectal resection for rectal cancer? A retrospective study.

PURPOSE: Previous studies have reported that sarcopenia increases the risk of postoperative complications following colorectal resection. This retrospective study assessed the postoperative complications of rectal resection associated with sarcopenia. METHODS: We retrospectively analyzed 262 patients who underwent curative low anterior resection for primary rectal cancer from January 2008 to May 2020 at our institution. The patients were divided into a sarcopenia group (normalized total psoas muscle area < 6.36 cm2/m2 in males and < 3.92 cm2/m2 in females; N = 49) and a non-sarcopenia group (N = 213). RESULTS: The overall rate of postoperative complications within 30 days of surgery was higher in the sarcopenia group than in the non-sarcopenia group (46.9 vs. 29.6%; P = 0.028). The rate of postoperative remote infections was higher in the sarcopenia group than in the non-sarcopenia group (12.2 vs. 2.8%; P = 0.012). Sarcopenia was found to be a predictor of remote infection by a multivariate analysis (odds ratio, 4.08; 95% confidence interval, 1.12-14.80; P = 0.033). CONCLUSION: Sarcopenia diagnosed using the psoas muscle index was found to be an independent predictive factor for postoperative remote infection after curative low anterior resection for rectal cancer.

[A Case of Suspected Lynch Syndrome Due to Radical Resection for Descending Colon Cancer and Renal Pelvic Cancer].

A 60-year-old woman was admitted on account of presenting with bloody stools. She had a history of endometrial cancer surgery. Family history revealed 3 colorectal cancer cases among the first or second relatives. Colonoscopy and contrast- enhanced computed tomography revealed descending colon cancer and left renal pelvic cancer. We performed partial resection of the descending/transverse colon with D3 lymph node dissection and total resection of the left kidney and ureter with curative intent. Postoperative pathological diagnosis revealed descending colon cancer(pT4bN0M1c, pStage Ⅳc)and left renal pelvic cancer (T1N0M0, Stage Ⅰ). In this case, Lynch syndrome was suspected based on the family history and medical history. The clinical findings were consistent with Amsterdam Criteria Ⅱ. The microsatellite instability(MSI)test result was MSI-H and the BRAF genetic test result showed a wild type. Immunohistochemical staining of descending colon cancer tissue showed loss of expression of MSH2 and MSH6 proteins. Genetic counseling was provided because Lynch syndrome was strongly suspected. Capecitabine plus oxaliplatin therapy was performed for 6 months for descending colon cancer. Nine months postoperatively, the patient remained recurrence-free for both colon cancer and renal pelvic cancer. We report a case of suspected Lynch syndrome triggered by double cancer of the descending colon and renal pelvis.

Ileo-right colonic reconstruction preserving all four colonic vessels after esophagectomy for cancer.

When colonic graft is used as an esophageal substitute after esophagectomy, one or two feeding vessels of the colon are cut to obtain sufficient length, the graft is passed via the subcutaneous route, and microvascular anastomosis is often used to avoid fatal complications. Sixteen consecutive ileo-right colonic reconstructions via the posterior mediastinal or retrosternal route with preservation of all four colonic vessels were performed in the past eight years. We presented the surgical technique and evaluation of this surgical method. In 15 out of 16 consecutive cases, the graft could be pulled up to the neck through the posterior mediastinal or retrosternal route while preserving all four colonic vessels. Reconstruction was not possible in one patient because of ileocolic vessel injury during colonic mobilization. Anastomotic leakage occurred in three patients, but all were minor and were treated conservatively. There were no patients with graft necrosis resulting from insufficient blood supply. Ileo-right colonic reconstruction with preservation of all four colonic vessels through the posterior mediastinal or retrosternal route is a safe and feasible procedure and is considered the first choice for colonic reconstruction as an esophageal substitute.

Influence of Suture Materials on Incisional Hernia Rate after Laparoscopic Colorectal Cancer Surgery: A Propensity Score Analysis.

OBJECTIVES: Incisional hernia is a common problem after colorectal surgery, and a laparoscopic approach does not reduce the incisional hernia rate. Previous reports have described the risk factors for incisional hernia; however, the impact of suture materials remains unclear. As such, this study compared the incisional hernia rate using different suture materials for abdominal wall closure after laparoscopic colorectal cancer surgery. METHODS: Patients undergoing laparoscopic colorectal cancer surgery between January 2014 and December 2016 were included in this study. We separated patients into the following two groups based on the suture materials used for abdominal wall closure: (1.) fast-absorbable group and (2.) non-absorbable group. The primary outcome was incisional hernia rate that was diagnosed using computed tomography. We compared outcomes between these two groups using propensity score matching. RESULTS: Before matching, 394 patients were included (168 in the fast-absorbable group and 226 in the non-absorbable group). After one-to-one matching, patients were stratified into the fast-absorbable group (n = 158) and the non-absorbable group (n = 158). The incisional hernia rate was higher in the fast-absorbable group than in the non-absorbable group (13.9% vs. 6.3%; P = 0.04). The median time to develop an incisional hernia was significantly shorter in the fast-absorbable group (6.7 months vs. 12.3 months; P < 0.01). The incidence of surgical site infection was not different between the two groups, but the incidence of suture sinus was lower in the fast-absorbable group (0% vs. 5.1%; P < 0.01). CONCLUSIONS: The use of fast-absorbable sutures may increase the risk of incisional hernia after laparoscopic colorectal cancer surgery.

Surgical approach for right-sided colonic diverticular bleeding: A single-center review of 43 consecutive cases.

INTRODUCTION: While Asian populations develop colonic diverticular disease predominantly in the right colon, Western populations mainly present with left-sided disease. The present study aimed to clarify the outcomes of surgical treatment for right-sided colonic diverticular bleeding. METHODS: Medical records of 43 patients who underwent surgery for right-sided colonic diverticular bleeding between 2010 and 2019 were reviewed. Those whose general condition became unstable underwent open surgery at our institution. Patients were then divided into two groups, the open surgery group (n = 17) and laparoscopic surgery group (n = 26), after which operative outcomes between both groups were compared. RESULTS: This study included 36 men and seven women with a median age of 76 (range: 37-91) years. Laparoscopic surgery had a significantly longer operative time (183.5 minutes vs 110 minutes; P < .001) and significantly lower intraoperative blood transfusion rate (19.2% vs 82.4%; P < .001) than open surgery. The laparoscopic surgery group had earlier resumption of postoperative meals than open surgery group (postoperative day 3 vs postoperative day 4; P = .010). No significant difference in postoperative complications was observed between both groups. With regard to long-term outcomes, none of the cases exhibited rebleeding from the right-sided colon. CONCLUSION: The present study revealed that laparoscopic surgery promoted lower intraoperative blood transfusion rates and earlier resumption of postoperative meals compared to open surgery for right-sided colonic diverticular bleeding. Hence, laparoscopic surgery can be feasible for right-sided colonic diverticular bleeding provided that the patient's general condition is stable.

Internal hernia beneath the obturator nerve after robot-assisted lateral lymph node dissection for rectal cancer: A case report and literature review.

A 63-year-old man who underwent robot-assisted laparoscopic low anterior resection and right lateral lymph node dissection (LLND) for rectal cancer presented with right thigh pain, nausea, vomiting, and abdominal pain on postoperative day 17. CT revealed dilated small bowel in the pelvis, and a small bowel loop was detected outside the internal iliac artery branch. Emergent laparoscopic surgery revealed the migration of the small bowel into the space beneath the right obturator nerve. The herniated bowel was reduced, and the obturator nerve was sharply dissected from the herniated bowel and preserved. The hernial orifice was left unrepaired. Postoperative recovery was uneventful, and the right thigh pain disappeared. It is important to consider the possibility of internal herniation beneath the obturator nerve after minimally invasive lateral lymph node dissection for rectal cancer.

A rare case of peritoneal deposits with carbon pigmentation after preoperative endoscopic tattooing for sigmoid colon cancer.

PURPOSE: We report a case in which pigmented peritoneal deposits were found during laparoscopic surgery following preoperative endoscopic tattooing for sigmoid colon cancer. METHODS: The patient's clinical, endoscopic, and histological data from the Niigata City General Hospital were reviewed, as well as the literature on laparoscopic surgery involving the preoperative endoscopic tattoo, with a focus on the relevance of peritoneal deposits and tattooing ink. RESULTS: A 71-year-old man presented to our hospital complaining of vomiting and abdominal distention. Abdominal computed tomography revealed obstructive sigmoid colon cancer. An emergency endoscopic colon stenting procedure and injection of 0.2 ml India ink to the submucosal layer of the tumor's anal side were performed. Laparoscopic-assisted sigmoid colectomy was done 14 days after stenting. At surgery, seven small peritoneal deposits were seen in the rectovesical pouch and at the site adjacent to the tumor. All peritoneal deposits were stained by the ink. Gross leakage of the ink into extraintestinal sites was seen. The seven peritoneal deposits were resected under laparoscope. Histological findings revealed that the seven peritoneal deposits were composed of adenocarcinoma and carbon pigments. Immunohistochemical staining for cluster of differentiation 163 showed that the carbon pigments in the peritoneal deposits were within macrophages. CONCLUSIONS: The possibility of the tattooing procedure causing peritoneal dissemination cannot be completely denied, but it can be hypothesized that the carbon pigmentation was transferred to peritoneal deposits by macrophages. In the future, we hope that this phenomenon becomes a keystone for diagnoses and treatments for peritoneal dissemination.

Computational study on acetophenone in amorphous polyethylene.

Polyethylene (PE) is widely used as an electrical insulating material. Acetophenone (AP) is a major residue in PE and is considered one of the causes of insulation deterioration. However, the physicochemical explanation of the influence of AP is still unknown. Therefore, in the present study, the behavior of AP molecules in amorphous PE was investigated using molecular dynamics (MD) simulations and quantum chemical calculation. First, the basic properties of the AP molecule were evaluated from the viewpoint of molecular electrostatic potential (MEP), molecular orbitals, and energy levels. Subsequently, an amorphous PE system containing AP molecules was studied using MD simulations. The results clearly indicate that AP does not greatly change the density and radius of gyration of amorphous PE. Quantum computations were performed using a part of the structure obtained from the MD simulations, suggesting that AP acts as a trap site in amorphous PE. It was also revealed that under the external electric field, the total density of state (DOS) changes with a dependence on the applied direction. Results of these calculations help in explaining previous experimental results.

A positive detecting code and its decoding algorithm for DNA library screening.

The study of gene functions requires high-quality DNA libraries. However, a large number of tests and screenings are necessary for compiling such libraries. We describe an algorithm for extracting as much information as possible from pooling experiments for library screening. Collections of clones are called pools, and a pooling experiment is a group test for detecting all positive clones. The probability of positiveness for each clone is estimated according to the outcomes of the pooling experiments. Clones with high chance of positiveness are subjected to confirmatory testing. In this paper, we introduce a new positive clone detecting algorithm, called the Bayesian network pool result decoder (BNPD). The performance of BNPD is compared, by simulation, with that of the Markov chain pool result decoder (MCPD) proposed by Knill et al. in 1996. Moreover, the combinatorial properties of pooling designs suitable for the proposed algorithm are discussed in conjunction with combinatorial designs and d-disjunct matrices. We also show the advantage of utilizing packing designs or BIB designs for the BNPD algorithm.

Analysis of the spacial requirements for RNA-protein interactions within the N antitermination complex of bacteriophage lambda.

In bacteriophage lambda, formation of a transcriptional antitermination complex consisting of the lambda N protein, nut RNA transcript (boxA-boxB), host factors, and RNA polymerase is mediated by the interaction of the boxB RNA with the RNA-binding domain of N. In order to understand the spacial requirements of this boxB/N interaction within the complex, the effects of changes in the length of the nut site linker, the boxB stem, and the peptide spacer connecting the RNA-binding domain and activation domain of N were examined using a bacterial reporter system. As a result, we found that the requirements for the boxB stem length and N peptide linker length were optimized and strict. In contrast, when the boxB/N interaction was replaced by heterologous RNA/peptide interactions, the strict requirement for the length of the peptide linker and the RNA stem was relaxed, presumably due to the absence of the interaction between boxB/N and the host factor NusA in the wild-type complex. It was also shown that the decrease in activity upon stem lengthening could be partially suppressed by simultaneous lengthening of the RNA spacer, suggesting that a further understanding of the organization of the antitermination complex may provide insights into the engineering of functional ribonucleoprotein complexes.

Replacement of the lambda boxB RNA-N peptide with heterologous RNA-peptide interactions relaxes the strict spatial requirements for the formation of a transcription anti-termination complex.

In bacteriophage lambda, formation of a transcriptional anti-termination complex involving the elongating RNA polymerase is mediated by the interaction of boxB RNA with the RNA-binding domain of the N protein (N peptide). In an attempt to understand the spatial requirements for boxB/N peptide interaction within the anti-termination complex, the effects of changes in the distance between boxA and boxB RNA, the length of the boxB stem, and the distance between the N peptide and remainder of the N protein were examined using a bacterial reporter system. It was found that the requirements for boxB stem length and the distance between N peptide and the remainder of N were optimized and strict. In contrast, replacement of the boxB/N interaction by heterologous RNA-peptide interactions appeared to relax the strict requirement for RNA stem length and the orientation of the RNA-binding peptide, presumably due to the absence of the cooperative interaction between boxB/N and the host factor NusA. In addition, the decrease in activity upon stem lengthening could be partially suppressed by simultaneous lengthening of the RNA spacer. A further understanding of the structural organization of the anti-termination complex may provide insights into how functional ribonucleoprotein complexes may be engineered.