Experimental and Simulation Study of Solar-Powered Air-Gap Membrane Distillation Technology for Water Desalination.

This work aimed to investigate temperature polarization (TP) and concentration polarization (CP), which affect solar-powered air-gap membrane distillation (SP-AGMD) system performance under various operating conditions. A mathematical model for the SP-AGMD system using the experimental results was performed to calculate the temperature polarization coefficient (τ), interface temperature (Tfm), and interface concentration (Cfm) at various salt concentrations (Cf), feed temperatures (Tf), and flow rates (Mf). The system of SP-AGMD was simulated using the TRNSYS program. An evacuated tube collector (ETC) with a 2.5 m2 surface area was utilized for solar water heating. Electrical powering of cooler and circulation water pumps in the SP-AGMD system was provided using a photovoltaic system. Data were subjected to one-way analysis of variance (ANOVA) and Spearman's correlation analysis to test the significant impact of operating conditions and polarization phenomena at p < 0.05. Statistical analysis showed that Mf induced a highly significant difference in the productivity (Pr) and heat-transfer (hf) coefficients (p < 0.001) and a significant difference in τ (p < 0.05). Great F-ratios showed that Mf is the most influential parameter. Pr was enhanced by 99% and 146%, with increasing Tf (60 °C) and Mf (12 L/h), respectively, at a stable salt concentration (Cf) of 0.5% and a cooling temperature (Tc) of 20 °C. Also, the temperature increased to 85 °C when solar radiation reached 1002 W/m2 during summer. The inlet heat temperature of AGMD increased to 73 °C, and the Pr reached 1.62 kg/(m2·h).

Prognostic factors affecting survival after pancreaticoduodenectomy for pancreatic adenocarcinoma (single center experience).

BACKGROUND: Pancreatic cancer is considered to have the worst prognosis of the periampullary carcinomas. This retrospective study was to determine prognostic factors for survival after pancreaticoduodenectomy in patients had pancreatic carcinoma. METHODS: We retrospectively studied all patients who underwent PD for pancreatic adenocarcinoma originating from the head, neck or uncinate process from January 1996 to January 2011 in our center. Preoperative variables, intraoperative variables and postoperative variables were collected. RESULTS: The study included 480 patients (282 males and 198 females with a median age of 53 years. At the time of analysis, 180 (37.5%) patients were still alive. The median survival was 19 months. This corresponded to a 1-, 3-, and 5-year actuarial survival of 44 %, 20%, and 15% respectively. Mass size less than 2 cm (P=0.0001), lymph node ratio (P=0.0001), safety margin (P=0.0001), perineural, perivascular infiltration, age above 60 years (P=0.03), gender, preoperative bilirubin, SGPT, liver status, pre and postoperative CEA, CA19- 9 (P=0.0001) were significant predictors of survival. CONCLUSION: Mass size less than 2 cm, lymph node ratio, safety margin, perineural, perivascular infiltration, age above 60 years, gender, liver status, pre and postoperative CEA, CA19-9 are important predictors of survival in patients undergoing PD for pancreatic cancer.

Impact of cirrhosis on surgical outcome after pancreaticoduodenectomy.

AIM: To elucidate surgical outcomes of pancreaticoduodenectomy (PD) in patients with liver cirrhosis. METHODS: We studied retrospectively all patients who underwent PD in our centre between January 2002 and December 2011. Group A comprised patients with cirrhotic livers, and Group B comprised patients with non-cirrhotic livers. The cirrhotic patients had Child-Pugh classes A and B (patient's score less than 8). Preoperative demographic data, intra-operative data and postoperative details were collected. The primary outcome measure was hospital mortality rate. Secondary outcomes analysed included duration of the operation, postoperative hospital stay, postoperative morbidity and survival rate. RESULTS: Only 67/442 patients (15.2%) had cirrhotic livers. Intraoperative blood loss and blood transfusion were significantly higher in group A (P = 0.0001). The mean surgical time in group A was significantly longer than that in group B (P = 0.0001). Wound complications (P = 0.02), internal haemorrhage (P = 0.05), pancreatic fistula (P = 0.02) and hospital mortality (P = 0.0001) were significantly higher in the cirrhotic patients. Postoperative stay was significantly longer in group A (P = 0.03). The median survival was 19 mo in group A and 24 mo in group B. Portal hypertension (PHT) was present in 16/67 cases of cirrhosis (23.9%). The intraoperative blood loss and blood transfusion were significantly higher in patients with PHT (P = 0.001). Postoperative morbidity (0.07) and hospital mortality (P = 0.007) were higher in cirrhotic patients with PHT. CONCLUSION: Patients with periampullary tumours and well-compensated chronic liver disease should be routinely considered for PD at high volume centres with available expertise to manage liver cirrhosis. PD is associated with an increased risk of postoperative morbidity in patients with liver cirrhosis; therefore, it is only recommended in patients with Child A cirrhosis without portal hypertension.

Virtual CT colonoscopy versus conventional colonoscopy: a prospective study.

BACKGROUND/AIMS: Diagnosis of colorectal diseases might be a challenge. This prospective study aimed to evaluate virtual CT colonoscopy (CT colonography) as a new diagnostic modality in colorectal diseases. METHODOLOGY: Thirty-two patients (22 males and 10 females, mean age 47 years) with different colorectal complaints were investigated by CT colonography. Scanning parameters were collimation of 5mm, table speed of 6.25mm/s and pitch of 1.25. All images were evaluated in axial slices, reformatted images with endoluminal and extraluminal views. All patients were re-examined by the conventional colonoscope. The CT colonography and the colonoscopy findings were correlated. RESULTS: CT colonography suspected colorectal malignancy in 14 patients, diagnosed colorectal polyps in 4 (out of 6), suspected inflammatory bowel diseases in 5 (out of 6), showed colonic diverticulae in 3 (out of 4), and found no abnormality in 2 patients. CT colonography displayed the proximal colon above the obstructing lesion in extraluminal views, fungating mass in endoluminal view and accurately localized the lesion. In inflammatory bowel diseases, segmental (in 4 patients) or skipped (one patient) wall thickening, loss of colonic haustration (3 patients) and pseudopolyps (one patient) were detected. Superficial ulcers were missed. Endoluminal images displayed the orifices of the diverticulae in 3 patients. The CT colonography sensitivity was 86.7% and its specificity was 100%. CONCLUSIONS: The high resolution and multiple image display of CT colonography allow detection of many colorectal lesions. CT colonography is also a noninvasive imaging modality that is particularly valuable in poor risk patients and for colorectal examination proximal to an obstructing lesion.