Two-phase flow and oxygen transport in the perforated gas diffusion layer of proton exchange membrane fuel cell

Liquid water transport in perforated gas diffusion layers (GDLs)is numerically investigated using a three-dimensional (3D)two-phase volume of fluid (VOF)model and a stochastic reconstruction model of GDL microstructures. Different perforation depths and diameters are investigated, in comparison with the GDL without perforation. It is found that perforation can considerably reduce the liquid water level inside a GDL. The perforation diameter (D = 100 μm)and the depth (H = 100 μm)show pronounced effect. In addition, two different perforation locations, i.e. the GDL center and the liquid water break-through point, are investigated. Results show that the latter perforation location works more efficiently. Moreover, the perforation perimeter wettability is studied, and it is found that a hydrophilic region around the perforation further reduces the water saturation. Finally, the oxygen transport in the partially-saturated GDL is studied using an oxygen diffusion model. Results indicate that perforation reduces the oxygen diffusion resistance in GDLs and improves the oxygen concentration at the GDL bottom up to 101% (D = 100 μm and H = 100 μm)

Sound radiation from a perforated unbaffled plate

A model to calculate the sound radiation from an unbaffled perforated plate is proposed. This is achieved by modifying an existing model of an unbaffled plate to include the effect of perforation in terms of a continuously distributed surface impedance to represent the holes. Results are compared with those of an idealised situation, a perforated plate in an equally perforated baffle. At low perforation ratios, the radiation efficiency is lower for the unbaffled case but as the perforation ratio increases, the results for both conditions become similar. The effect of perforation increases as the perforation ratio increases and also as the hole diameter reduces. Comparison with existing measurement is also found to give a good agreement

Bowel Perforation in the Emergency Department Related to Bevacizumab Therapy and Recurrent Ovarian Cancer

Case Presentation: We describe the presentation to the emergency department of a patient with recurrent ovarian cancer treated with bevacizumab with the complication of bowel perforation. Discussion: We review the frequency and outcomes of bevacizumab-related bowel perforation. We also report the patient’s imaging findings, including the radiologic presentation of free intraperitoneal air and portal venous gas, both indicative of bowel perforation and the need for emergent surgical evaluation. Our case also illustrates the potentially catastrophic side effects of bevacizumab and other targeted oncologic therapies of which emergecny physicians may not be aware

Role of Membrane GM1 on Early Neuronal Membrane Actions of Aβ During Onset of Alzheimer\u27s Disease

The ability of beta-amyloid peptide (Aβ) to disrupt the plasma membrane through formation of pores and membrane breakage has been previously described. However, the molecular determinants for these effects are largely unknown. In this study, we examined if the association and subsequent membrane perforation induced by Aβ was dependent on GM1levels. Pretreatment of hippocampal neurons with D-PDMP decreased GM1 and Aβ clustering at the membrane (Aβ fluorescent-punctas/20 μm, control = 16.2 ± 1.1 vs. D-PDMP = 6.4 ± 0.4, p \u3c 0.001). Interestingly, membrane perforation with Aβ occurred with a slower time course when the GM1 content was diminished (time to establish perforated configuration (TEPC) (min): control = 7.8 ± 2 vs. low GM1 = 12.1 ± 0.5, p \u3c 0.01), suggesting that the presence of GM1 in the membrane can modulate the distribution and the membrane perforation by Aβ. On the other hand, increasing GM1 facilitated the membrane perforation (TEPC: control = 7.8 ± 2 vs. GM1 = 6.2 ± 1 min, p \u3c 0.05). Additionally, using Cholera Toxin Subunit-B (CTB) to block the interaction of Aβ with GM1 attenuated membrane perforation significantly. Furthermore, pretreatment with CTB decreased the membrane association of Aβ (fluorescent-punctas/20 μm, Aβ: control = 14.8 ± 2.5 vs. CTB = 8 ± 1.4, p \u3c 0.05), suggesting that GM1 also plays a role in both association of Aβ with the membrane and in perforation. In addition, blockade of the Aβ association with CTB inhibited synaptotoxicity. Taken together, our results strongly suggest that membrane lipid composition can affect the ability of Aβ to associate and subsequently perforate the plasma membrane thereby modulating its neurotoxicity in hippocampal neurons

Uterine Perforation With Subtotal Small Bowel Prolapse – A Rare Complication of Dilatation and Curettage

Uterine perforation is the well known complication of induced abortion. We report a rare case of uterine perforation with subtotal prolapse of small bowel following first trimester abortion by an unqualified physician. Early surgical exploration with resection and anastomosis of bowel performed. Patient discharged uneventfully after postoperative recovery

Perforated small intestine in a patient with T-cell lymphoma; a rare cause of peritonitis

The nontraumatic perforations of the small intestine are pathological entities with particular aspects in respect to diagnosis and treatment. These peculiarities derive from the nonspecific clinical expression of the peritonitis syndrome, and from the multitude of causes that might be the primary sources of the perforation: foreign bodies, inflammatory diseases, tumors, infectious diseases, etc. Accordingly, in most cases intestinal perforation is discovered only by laparotomy and the definitive diagnosis is available only after histopathologic examination. Small bowel malignancies are rare; among them, lymphomas rank third in frequency, being mostly B-cell non Hodgkin lymphomas. Only 10% of non-Hodgkin lymphomas are with T-cell. We report the case of a 57 years’ old woman with intestinal T-cell lymphoma, whose first clinical symptomatology was related to a complication represented by perforation of the small intestine. Laparotomy performed in emergency identified an ulcerative lesion with perforation in the jejunum, which required segmental enterectomy with anastomosis. The nonspecific clinical manifestations of intestinal lymphomas make from diagnosis a difficult procedure. Due to the fact that surgery does not have a definite place in the treatment of the small intestinal lymphomas (for cases complicated with perforation), and beyond the morbidity associated with the surgery performed in emergency conditions, prognosis of these patients is finally given by the possibility to control the systemic disease through adjuvant therapy

Impact of Race and Insurance on Door-to-Appendectomy Time among Pediatric Patients

Racial and ethnic disparities in the rate of appendiceal rupture have been widely reported among the pediatric population. The main reasons for this remain largely unknown given that previous explanations pointing to signs of poor health care access have recently been shown to account for only a small percentage of the difference in perforation rates between white and minority children. Because the risk of perforation increases with time, racial disparities in time delay from emergency department presentation to OR appendectomy may help account for the higher appendiceal perforation rates observed among minority children. This is the first study dedicated to analyzing racial differences in door-to-appendectomy time. Insurance status and language barriers were also considered as variables of interest. Retrospective, observational study using admission and treatment data of 607 consecutive children less than or equal to 18 years of age with surgical confirmation of appendicitis. Patients were admitted from February 2, 2013 (start of electronic medical record use) to April 27, 2017. A significant association was found between race and perforation rate (p0.05 for all). Door-to-appendectomy times were also not significantly longer for Medicaid/uninsured patients (613 minutes) compared to private insurance patients (597 minutes) (p=0.60), nor for patients with language barriers (545 minutes) compared to patients without (612 minutes) (p=0.23). While there was a higher appendiceal perforation rate among minority children, it was not due to differences in door-to-appendectomy time. Insurance status and language barriers also did not lead to differential treatment among pediatric patients

Nasal manifestations in granulomatosis with polyangiitis: a case report and review of the literature

Granulomatosis with polyangiitis (GPA) is an anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides of medium and small arteries, characterized by necrotizing granulomatous inflammation of the upper and lower respiratory tract with coexist- ing glomerulonephritis. We report a case of GPA in a patient presenting with a six-month history of spontaneous epistaxis, nasal obstruction and frontal headache. Nasal endoscopy showed a large nasal septum perforation and an anterior translucid mass in the right nasal fossa. Findings were confirmed by computed tomography (CT) scan with contrast. The patient underwent func- tional transnasal endoscopic removal of the mass; histological examination showed tissue features suggestive of GPA; dosage of c-ANCA e p-ANCA antibodies confirmed GPA diagnosis. Nasal septum perforation has long been recognized as a feature of GPA, in which granulomatous destruction of nasal cartilage can result in perforation and saddle-nose deformity. Prompt diagno- sis of GPA is important to initiate therapy which may be life-saving and organ sparing