Solidification of binary aqueous solution cooled from above

金沢大学環日本海域環境研究センターエコテクノロジー研究部門Freezing and melting phenomena are important in many different fields, including crystal growth, casting, metallurgy, geophysics, and oceanography. Solidification of a multi-component solution is the one often observed in nature. In order to investigate basic features of the freezing processes of binary systems, we conducted a series of laboratory experiments in a rectangular box cooled from above using aqueous NaNO3 solution. During the freezing, the solid phase always grows into many needle-like crystals called the mushy layer. We measured the growth of the mushy layer thickness, the solid fraction, the temperature, and the concentration distributions. The average solid fraction is found to increase with time in the mushy layer. This causes a slow descent of the released solute in the mushy layer and its eventual fall into the liquid region below because of gravity. We propose a one-dimensional model to explain the horizontally-averaged mushy layer growth. In the model, the estimate of a heat flux at the mushy-liquid interface due to natural convection is found essential for a correct prediction. The proposed theory predicts well the growth of the mushy-layer and the average solid fraction, once the convective heat flux is properly given. © 2009 Wiley Periodicals, Inc

Impact of a learning health system on acute care and medical complications after intracerebral hemorrhage

Introduction: Patients with stroke often experience pneumonia during the acute stage after stroke onset. Oral care may be effective in reducing the risk of stroke‐associated pneumonia (SAP). We aimed to determine the changes in oral care, as well as the incidence of SAP, in patients with intracerebral hemorrhage, following implementation of a learning health system in our hospital. Methods: We retrospectively analyzed the data of 1716 patients with intracerebral hemorrhage who were hospitalized at a single stroke center in Japan between January 2012 and December 2018. Data were stratified on the basis of three periods of evolving oral care: period A, during which conventional, empirically driven oral care was provided (n = 725); period B, during which standardized oral care was introduced, with SAP prophylaxis based on known risk factors (n = 469); and period C, during which oral care was risk‐appropriate based on learning health system data (n = 522). Logistic regression analysis was performed to evaluate associations between each of the three treatment approaches and the risk of SAP. Results: Among the included patients, the mean age was 71.3 ± 13.6 years; 52.6% of patients were men. During the course of each period, the frequency of oral care within 24 hours of admission increased (P < .001), as did the adherence rate to oral care ≥3 times per day (P < .001). After adjustment for confounding factors, a change in the risk of SAP was not observed in period B; however, the risk significantly decreased in period C (odds ratio 0.61; 95% confidence interval 0.43‐0.87) compared with period A. These associations were maintained for SAP diagnosed using strict clinical criteria or after exclusion of 174 patients who underwent neurosurgical treatment. Conclusions: Risk‐appropriate care informed by the use of learning health system data could improve care and potentially reduce the risk of SAP in patients with intracerebral hemorrhage in the acute stage

A Case of Small Bowel Obstruction Caused by Bezoars Diagnosed with Double Balloon Enteroscopy

Primary small bowel bezoars are rare and cause acute abdomen due to small bowel obstruction (SBO). A 69-year-old Japanese man presented with epigastric pain associated with fullness. Physical examination of the abdomen showed no marked signs of peritoneal irritation. An erect X-ray film of the abdomen showed small bowel obstruction. Computed tomography (CT) showed a dilated small bowel loop proximal to the site of the obstruction. Retrograde double balloon enteroscopy (DBE) was performed and showed yellow, hard bezoars blocking the distal ileum. At surgery, a bezoar was found impacted in the distal ileum, and enterotomy with extraction was performed. After 9 days, the patient was discharged from our hospital in satisfactory condition. DBE also appears to be a safe and useful diagnostic tool in patients with SBO, and the findings of DBE influence the strategy of therapy in patients in whom the cause of SBO could not be determined by conventional radiography

Laparoscopic Resection of Schwannoma of the Ascending Colon

Schwannomas of the colon are rare and difficult to diagnose preoperatively. We report a case of schwannoma of the ascending colon that was resected laparoscopically. A 64-year-old woman was referred to our hospital by her local clinic for further evaluation and management of a submucosal tumor of the ascending colon. A definitive preoperative diagnosis could not be reached despite examinations. Gastrointestinal stromal tumor, leiomyoma and lymphoma were the differential diagnoses. We performed a laparoscopic right hemicolectomy with D2 lymph node dissection. Histological findings with hematoxylin-eosin staining revealed spindle-like tumor cells, and immunohistochemical analysis showed that the tumor was positive for S-100 but negative for c-kit, CD34, smooth muscle actin and desmin, with a Ki-67 index of <5%. Thus, the diagnosis in this case was benign schwannoma of the ascending colon

Laparoscopic Resection of Schwannoma of the Ascending Colon

Schwannomas of the colon are rare and difficult to diagnose preoperatively. We report a case of schwannoma of the ascending colon that was resected laparoscopically. A 64-year-old woman was referred to our hospital by her local clinic for further evaluation and management of a submucosal tumor of the ascending colon. A definitive preoperative diagnosis could not be reached despite examinations. Gastrointestinal stromal tumor, leiomyoma and lymphoma were the differential diagnoses. We performed a laparoscopic right hemicolectomy with D2 lymph node dissection. Histological findings with hematoxylin-eosin staining revealed spindle-like tumor cells, and immunohistochemical analysis showed that the tumor was positive for S-100 but negative for c-kit, CD34, smooth muscle actin and desmin, with a Ki-67 index of <5%. Thus, the diagnosis in this case was benign schwannoma of the ascending colon

Report of a case: Retroperitoneal mucinous cystadenocarcinoma with rapid progression

Introduction: Retroperitoneal mucinous cystic neoplasms are uncommon, and little is known about the etiology of the disease. Malignant forms of these are extremely rare. Here, we report a case of primary retroperitoneal mucinous cystadenocarcinoma (PRMC), which demonstrated unexpectedly aggressive progression despite finding only a limited area of adenocarcinoma. Presentation of case: A 62-year-old woman with a complaint of abdominal discomfort was admitted to the hospital. Abdominal CT and MRI showed multiple large retroperitoneal cysts dislocating the right kidney nearly to the center of the abdomen. Transabdominal resection of the cysts was performed. Those cysts contained 1100 ml of mucinous fluids in total. Cytological examination of those fluids revealed no malignant cells. The cyst wall was lined with mucinous epithelial cells, and contained some ovarian-type stroma. Also, there was a focal area of adenocarcinoma in the cyst wall, and the lesion was diagnosed as primary retroperitoneal mucinous cystadenocarcinoma. Eight months later, the patient developed lumbar bone metastasis. Chemotherapy with S-1, an oral fluoropyrimidine, and docetaxel had been begun immediately; however, the disease had rapidly spread in the retroperitoneum. Eventually, the patient died of the disease 15 months after surgery. Discussion: Retroperitoneal mucinous cystic neoplasms are considered to be metaplasia of embryonal coelomic epithelium. Complete excision without rupture is essential. However, variance of biological aggressiveness might exist in PRMCs. Conclusion: Retroperitoneal mucinous cystadenocarcinoma is a rare tumor, and it is urgently necessary to elucidate the etiology of an effective therapy for the disease