Impeller Stall Induced By Reverse Propagation Of Non-Uniform Flow Generated At Return Channel

LectureIn the case of centrifugal compressors, minor non-uniform flow upstream of the impeller is induced by an asymmetrical configuration in the circumferential direction at the compressor suction casing. This non-uniform flow is transmitted to the impeller discharge, but this minor non-uniform flow does not usually cause an adverse effect on the impeller stage performance. However, we found this is amplified at the return channel due to flow separation at reduced flows (depending on return channel geometry), and the amplified non-uniform flow did induce impeller stall by reverse propagation from the return channel to the impeller. These non-uniform flows caused a significant operating range reduction for a large flow coefficient impeller. The aerodynamics issues were mitigated using CFD analysis techniques, and eventually confirmed by the compressor performance during shop performance testing. The OEM conducted the CFD analyses using two (2) return channel geometries with several CFD models to verify the effect of the return channel geometry on impeller stall and to confirm the most suitable CFD modeling method for stall evaluation. Shop performance tests utilizing both return channel geometries were conducted and compared to the CFD analyses. These studies were conducted while collaborating with the end-user. The steady CFD calculation was conducted with frozen rotor interface between full annulus impeller and stator parts. The modeling of diffuser and return channel was varied as follows: 1) 1-pitch model for the return channel with mixing plane at diffuser 2) Full-annulus model for the return channel with a mixing plane at the diffuser 3) Full-annulus model for the return channel without a mixing plane at the diffuser. From the above studies and the shop performance testing, it was confirmed that the proposed CFD modeling method could simulate the measurements taken during the shop performance tests and that the CFD modeling method utilized was key to properly evaluating stall phenomena

Aesthetic pectoral muscle flap repair for refractory enterocutaneous fistula after salvage esophagectomy in a female patient

Anastomotic leakage is a severe complication of esophagectomy. Development of an enterocutaneous fistula after anastomotic leakage often occurs after subcutaneous-route reconstruction at esophagectomy. Pectoralis myocutaneous flap (PMCF) repair has recently been performed when an enterocutaneous fistula was refractory to conservative treatment. However, this procedure requires a conspicuous incision and results in deformity of the breast especially in female patient. We performed pectoralis muscle flap (PMF) repair for a 50-year-old woman with a refractory enterocutaneous fistula after salvage esophagectomy. We made an oblique incision along the inframammary crease in order to avoid a conspicuous scar and moved the PMF under the mammary gland to the site of anastomosis. This method was effective for repairing a refractory enterocutaneous fistula, with especially good aesthetic results in a female patient

Surgical assessment system reflexes and facilitates the developing the surgical skills of trainees for the Laparoscopic Distal Gastrectomy

Background: To assess laparoscopic distal gastrectomy (LDG) for gastric cancer (GC), the Japanese Operative Rating Scale (JORS) for LDG has been developed. This study evaluated the learning curve of the initial experience of LDG for GC using JORS-LDG.Methods: Thirty-one cases of LDG were performed by a trainee. The trainee and an instructor scored the surgical performance using JORS-LDG immediately after LDG. The 31 cases were evenly divided into early phase (EP), middle phase (MP), and late phase (LP).Results: The trainee successfully completed all cases of LDG without any complications. There were also no severe postoperative complications with Clavien–Dindo classification grade III or higher. The average JORS-LDG points were stable after 24 cases of experience in the CUSUM analysis. The median JORS-LDG points in EP were significantly lower than those in LP (EP: MP: LP = 43.5: 44.3: 45.5, P = 0.02). In operative data, procedure time, bleeding, and the drain fluid amylase level were correlated with the JORS-LDG points.Conclusion: The JORS-LDG scoring system is a practical tool to evaluate surgical performance in the initial LDG experience

High serum alpha-fetoprotein and positive immunohistochemistry of alpha-fetoprotein are related to poor prognosis of gastric cancer with liver metastasis

Abstract Liver metastasis in gastric cancer is incurable. Alpha-fetoprotein-producing gastric cancer has a poor prognosis and is prone to liver metastasis. We investigated the association between preoperative serum alpha-fetoprotein levels, liver metastasis, and expression of primitive enterocyte phenotype markers. We reviewed the medical records of 401 patients with gastric cancer who underwent curative surgical resection and immunohistochemically evaluated the primitive phenotype markers. The preoperative serum alpha-fetoprotein levels were elevated and normal in 8 and 393 patients, respectively. Liver metastasis was more frequent in patients with higher preoperative alpha-fetoprotein levels. The 5-year postoperative recurrence-free survival and overall survival rates were significantly worse in patients with higher preoperative serum alpha-fetoprotein levels. Although alpha-fetoprotein and Glypican3 and Spalt-like transcription factor 4 tended to be stained with high preoperative serum alpha-fetoprotein levels, these markers were also positive in some patients with normal alpha-fetoprotein levels. In summary, patients with gastric cancer and high preoperative serum alpha-fetoprotein levels have a poor prognosis and high incidence of liver metastasis. Alpha-fetoprotein can help detect liver metastasis relating to the primitive enterocyte phenotype

Aesthetic pectoral muscle flap repair for refractory enterocutaneous fistula after salvage esophagectomy in a female patient

Anastomotic leakage is a severe complication of esophagectomy. Development of an enterocutaneous fistula after anastomotic leakage often occurs after subcutaneous-route reconstruction at esophagectomy. Pectoralis myocutaneous flap (PMCF) repair has recently been performed when an enterocutaneous fistula was refractory to conservative treatment. However, this procedure requires a conspicuous incision and results in deformity of the breast especially in female patient. We performed pectoralis muscle flap (PMF) repair for a 50-year-old woman with a refractory enterocutaneous fistula after salvage esophagectomy. We made an oblique incision along the inframammary crease in order to avoid a conspicuous scar and moved the PMF under the mammary gland to the site of anastomosis. This method was effective for repairing a refractory enterocutaneous fistula, with especially good aesthetic results in a female patient

Gallium-Catalyzed Reductive Chlorination of Carboxylic Acids with Copper(II) Chloride

Described herein is the direct chlorination of carboxylic acids using copper­(II) chloride via a gallium­(III)-catalyzed reduction in the presence of a hydrosiloxane. During this reductive chlorination, the counteranions of CuCl₂ functioned as a chloride source

Immunological milieu in the peritoneal cavity at laparotomy for gastric cancer

AIM: To investigate the immunological repertoire in the peritoneal cavity of gastric cancer patients

Indium-Catalyzed Reductive Bromination of Carboxylic Acids Leading to Alkyl Bromides

The combination of 1,1,3,3-tetramethyldisiloxane (TMDS) and trimethylbromosilane (Me₃SiBr) with a catalytic amount of indium bromide (InBr₃) undertook direct bromination of carboxylic acids, which produced the corresponding alkyl bromides in good to excellent yields. The reducing system was tolerant to several functional groups