Laminar forced convection to a pseudoplastic fluid food in circular and annular ducts

In this manuscript we investigated experimentally the steady-state heat transfer to an important pseudoplastic fluid food, the soursop juice, flowing in laminar regime through circular and concentric annular ducts. The mean convection heat transfer coefficients, determined by measuring the bulk temperatures before and after the heating sections with constant temperatures of the tube walls, were used to correlate simple new empiric expressions to estimate the average Nusselt number in the thermal entrance of the considered geometries. In addition, the thermophysical properties of the tested fluid food, as well as the rheological behavior, being essential for the heat transfer analyses, were experimentally determined. (c) 2006 Elsevier Ltd. All rights reserved.

MOTILIN-IMMUNOREACTIVE CELLS IN THE DUODENUM, PYLORIC STOMACH AND PANCREAS OF CAIMANS (CAIMAN-LATIROSTRIS AND CAIMAN-CROCODILUS, ALLIGATORINAE) - A FURTHER COMPARISON USING REGION-SPECIFIC MOTILIN ANTISERA

Motilin-immunoreactive cells in the duodenum, pyloric stomach and pancreas of Caiman latirostris and Caiman crocodilus were investigated using region specific antisera for porcine and canine motilin molecules. Motilin-immunoreactive cells were found in the duodenum, pyloric stomach and pancreas of both caiman species. These cells were primarily open-type endocrine ones in the epithelium of the duodenum and pyloric stomach. Motilin-immunoreactive cells were observed in both the exocrine and endocrine portions of the pancreas, and frequently exhibited one or more cytoplasmic processes of variable length. Since motilin-immunoreactive cells do not cross-react with serotonin or any of the other pancreatic and gut hormones, they are considered to be cell type independent from any of the other known pancreatic or gut endocrine cells. The molecular similarity between caiman motilin and porcine and canine motilins and the heterogeneity of the motilin molecule in the caiman digestive system is discussed.

DIABETES AND EXPERIMENTAL PREGNANCY IN RATS - COURSE OF MATERNAL BLOOD-GLUCOSE LEVELS AND ITS REPERCUSSIONS ON THE BLOOD-GLUCOSE LEVELS AND PANCREAS OF NEWBORN PUPS

The objective of the present investigation was to determine the course of maternal blood glucose levels in pregnant rats and its repercussions on the glucose levels and pancreas of their newborn pups. Diabetes was induced by alloxan (42 mg/kg body weight) and streptozotocin (40 mg/kg). Sixty-two pregnant Wistar rats weighing 180 to 250 g were divided into a control group and two groups with moderate (120 to 200 mg/dl glucose) and severe diabetes (greater than 200 mg/dl glucose), respectively. Blood glucose levels were measured in the dams on the 1st, 14th, and 21st days of pregnancy and in the pups at birth. The results were pooled for each litter. The fetal pancreases were removed after cesarian section performed on the 21st day of pregnancy, pooled for each litter and processed for histopathologic examination by light microscopy. Maternal blood glucose levels were significantly increased compared with the first day of pregnancy in both normal and diabetic rats starting on the 14th day of pregnancy. Fetal blood glucose levels correlated with maternal levels. The histopathologic changes characterized by vacuolization and basophilia of the cytoplasm of endocrine pancreas of newborn pups from darns with moderate or severe diabetes suggested pancreatic hyperactivity.

Fluctuations of doublet splittings using the annular billiard

We study the statistical distribution of quantum energy splittings due to a dynamical tunneling. The system. The annular billiard, has whispering quasimodes due to a discrete symmetry that exists even when chaos is present in the underlying classical dynamics. Symmetric and antisymmetric combinations of these quasimodes correspond to quantum doublet states whose degeneracies decrease as the circles become more eccentric. We construct numerical ensembles composed of splittings for two distinct regimes, one which we call semiclassical for high quantum numbers and high energies where the whispering regions are connected by chaos, and other which we call quantal for low quantum numbers, low energies, and near integrable where dynamical tunneling is not a dominant mechanism. In both cases we observe a variation on the fluctuation amplitudes, but their mean behaviors follow the formula of Leyvraz and Ullmo [J. Phys. A 29, 2529 (1996)]. A description of a three-level collision involving a doublet and a singlet is also provided through a numerical example.

Early Pancreas Transplant Improves Motor Nerve Conduction in Alloxan-Induced Diabetic Rats

The purpose of this study was to assess the temporal relationship between pancreas transplant and the development of electrophysiological changes in the sciatic and caudal nerves of alloxan-induced diabetic rats. Nerve conduction studies were performed in diabetic rats subjected to pancreas transplantation at 4, 12, and 24 weeks after diabetes onset, using nondiabetic and untreated diabetic rats as controls. Nerve conduction data were significantly altered in untreated diabetic control rats up to 48 weeks of follow-up in all time points. Rats subjected to pancreas transplantation up to 4 and 12 weeks after diabetes onset had significantly increased motor nerve conduction velocity with improvement of wave amplitude, distal latency, and temporal dispersion of compound muscle action potential in all follow-up periods (P<0.05); these parameters remained abnormal when pancreas transplantation were performed late at 24 weeks. Our results suggest that early pancreas transplant (at 4-12 weeks) may be effective in controlling diabetic neuropathy in this in vivo model.

Pancreas damage and intratracheal NiCl2 administration. Effects of nickel chloride.

Changes in activities of Cu-Zn superoxide dismutase (SOD- E.C.1.15.1.1.) and lactate dehydrogenase (LDH- E.C.1.1.1.27.) and levels of copper, total protein, triglycerides, phospholipids and total lipids were investigated in pancreas of rats after intratracheal administration of NiCl2 (8.4 mumol/kg). Nickel chloride induced increased SOD activity in pancreas and erythrocytes. This elevation was related to increased copper and decreased phospholipid content in pancreas of these animals. In conclusion, the ability of an animal to tolerate nickel chloride induced damage was governed by a delicate balance between the generation of cytotoxic agents and the various pancreas defense capabilities.

Integral transform method for laminar heat transfer convection of herschel-bulkley fluids within concentric annular ducts

ABSTRACT: Related momentum and energy equations describing the heat and fluid flow of Herschel-Bulkley fluids within concentric annular ducts are analytically solved using the classical integral transform technique, which permits accurate determination of parameters of practical interest in engineering such as friction factors and Nusselt numbers for the duct length. In analyzing the problem, thermally developing flow is assumed and the duct walls are subjected to boundary conditions of first kind. Results are computed for the velocity and temperature fields as well as for the parameters cited above with different power-law indices, yield numbers and aspect ratios. Comparisons are also made with previous work available in the literature, providing direct validation of the results and showing that they are consistent.

Islet of Langerhans transplantation. A comparative study of two different methods for isolating islet cells from rat pancreas

Two different methods for isolation of islet of Langerhans on control of metabolic abnormalities of alloxan-induced diabetic rat were tested. Sixty rats were randomly assigned to four experimental groups: GI included 10 non-diabetic control rats, GII included 10 diabetic control rats, without treatment, GIII included 20 diabetic rats (10 inbred and 10 outbred rats) that received islet of Langerhans transplantation (ILT) using islet cells prepared by collagenase, and GIV included 20 diabetic rats (10 inbred and 10 outbred rats) submitted to ILT using islet cells prepared by nonenzymatic method. Clinical and laboratory parameters at beginning and 4, 7, 14, 21 and 30 days of follow-up were recorded. Outbred rats were immunosuppressed with cyclosporin A, diabetes was induced by e.v. alloxan administration, and islet cells were isolated from normal donor Lewis rats and injected into the portal vein. ILT corrected the body weight gain, polyuria, polydipsia, polyphagia, and the high levels of blood and urine glucose in 73.7% of rats treated by enzymatic method and in 64.7% of those ones treated by nonenzymatic method. However, there was no significantly difference between the two methods (P > 0.50). We did not also observe significantly difference between the two methods when ILT was performed either in inbred or outbred rats. We concluded that ILT performed by nonenzymatic method may be an alternative treatment for diabetes due to be less expensive and to have possible advantages in the isolation process.

Multidetector CT Evaluation of the Postoperative Pancreas

Several pancreatic diseases may require surgical treatment, with most of these procedures classified as resection or drainage. Resection procedures, which are usually performed to remove pancreatic tumors, include pancreatoduodenectomy, central pancreatectomy, distal pancreatectomy, and total pancreatectomy. Drainage procedures are usually performed to treat chronic pancreatitis after the failure of medical therapy and include the Puestow and Frey procedures. The type of surgery depends not only on the patient's symptoms and the location of the disease, but also on the expertise of the surgeon. Radiologists should become familiar with these surgical procedures to better understand postoperative changes in anatomic findings. Multidetector computed tomography is the modality of choice for identifying normal findings after surgery, postoperative complications, and tumor recurrence in patients who have undergone pancreatic surgery. (C)RSNA, 2012 . radiographics.rsna.org

Experimental investigation of gravitational gas separation in an inclined annular channel

The oil industry uses gas separators in production wells as the free gas present in the suction of the pump reduces the pumping efficiency and pump lifetime. Therefore, free gas is one of the most important variables in the design of pumping systems. However, in the literature there is little information on these separators. It is the case of the inverted-shroud gravitational gas separator. It has an annular geometry due to the installation of a cylindrical container in between the well casing and pioduction pipe (tubing). The purpose of the present study is to understand the phenomenology and behavior of inverted-shroud separator. Experimental tests were performed in a 10.5-m-length inclinable glass tube with air and water as working fluids. The water flow rate was in the range of 8.265-26.117 l/min and the average inlet air mass flow rate was 1.1041 kg/h, with inclination angles of 15 degrees, 30 degrees, 45 degrees, 60 degrees, 75 degrees, 80 degrees and 85 degrees. One of the findings is that the length between the inner annular level and production pipe inlet is one of the most important design parameters and based on that a new criterion for total gas separation is proposed. We also found that the phenomenology of the studied separator is not directly dependent on the gas flow rate, but on the average velocity of the free surface flow generated inside the separator. Maps of efficiency of gas separation were plotted and showed that liquid flow rate, inclination angle and pressure difference between casing and production pipe outlet are the main variables related to the gas separation phenomenon. The new data can be used for the development of design tools aiming to the optimized project of the pumping system for oil production in directional wells. (C) 2012 Elsevier Inc. All rights reserved.