PIV measurements in an aerated tank stirred by a down- and up-pumping axial flow impeller

Liquid phase hydrodynamics in an aerated tank stirred by a down- and an up-pumping pitched blade turbine have been investigated using Particle Image Velocimetry. The effect of agitator configuration and the gas phase on the mean velocity fields and turbulent quantities in the vessel have been investigated. The global mean gas holdup has also been evaluated for the two pumping conditions. For the gas flow rate used, the presence of gas only slightly alters the liquid flow patterns produced by both the down- and up-pumping configurations and causes a general decrease in the mean liquid velocities. The turbulent kinetic energy in the impeller discharge region was not affected by the presence of gas, but in the bulk of the tank, aeration caused a decrease in this value. Global gas holdup was found to be ~36% greater for the up-pumping impeller and a large amount of gas was found to be entrained by the primary circulation loop

Towards the design of an intensified coagulator

This study compares the hydrodynamics in three millimeter-scale continuous reactor geometries that can be easily used in laboratories and industries – a straight tube, a coiled tube and a Dean-Hex reactor – via numerical simulations and analyses the data in a way that is specifically relevant to coagulation processes, thereby offering insights for engineers to develop new coagulation reactors. A numerical approach based on Lagrangian particle tracking is presented to better understand the impact of the geometry and flow on properties that influence coagulation. The results show that the Dean-Hex meandering geometry provides narrower residence time and shear rate distributions, as well as higher mean average shear rates and Camp number distribution than the other geometries. This is attributed to the generation of transverse flows and radial mixing in the Dean-Hex reactor and suggests that a faster and more homogenous coagulation can be expected

The ADMR Receptor Mediates the Effects of Adrenomedullin on Pancreatic Cancer Cells and on Cells of the Tumor Microenvironment

Adrenomedullin (AM) is highly expressed in pancreatic cancer and stimulates pancreatic cancer cells leading to increased tumor growth and metastasis. The current study examines the role of specific AM receptors on tumor and cells resembling the tumor microenvironment (human pancreatic stellate--HPSC, human umbilical vein-- HUVEC and mouse lung endothelial cells--MLEC).AM receptors ADMR and CRLR were present in HPSC, HUVEC and MLECs while PDAC cells possessed only ADMR receptors as assessed by RT-PCR and western blotting. All cell lines expressed and secreted AM as indicated by ELISA. The growth of each of the cell lines was stimulated by exogenous AM and inhibited by the antagonist AMA. AM also stimulated in vitro angiogenesis assessed by polygon formation of endothelial cell lines. SiRNA-mediated silencing of ADMR, but not CRLR, reduced basal growth of all cells examined and reduced polygon formation of endothelial cells in vitro. Orthotopic tumors developed with shADMR bearing cancer cells had dramatically reduced primary tumor volume (>90%) and lung and liver metastasis compared to shControl bearing cells. To validate ADMR as a potential therapeutic target, in vivo studies were conducted using neutral nanoliposomes to systemically deliver human siRNA to ADMR to silence human cancer cells and mouse siRNA to ADMR to silence mouse tumor stromal cells. Systemic silencing of both human and mouse ADMR had no obvious adverse effects but strongly reduced tumor development.ADMR mediates the stimulatory effects of AM on cancer cells and on endothelial and stellate cells within the tumor microenvironment. These data support the further development of ADMR as a useful target treatment of pancreatic cancer

Adrenomedullin and tumour angiogenesis

The angiogenic activity of peptide adrenomedullin (AM) was first shown in 1998 . Since then, a number of reports have confirmed the ability of AM to induce the growth and migration of isolated vascular endothelial and smooth muscle cells in vitro and to promote angiogenesis in xenografted tumours in vivo. In addition, knockout murine models point to an essential role for AM in embryonic vasculogenesis and ischaemic revascularisation. AM expression is upregulated by hypoxia (a typical feature of solid tumours) and a potential role as a regulator of carcinogenesis and tumour progression has been proposed based on studies in vitro and in animal models. Nevertheless, translational research on AM, and in particular, confirmation of its importance in the vascularisation of human tumours has lagged behind. In this commentary, we review current progress and potential directions for future research into the role of AM in tumour angiogenesis

Plasma and cellular fibronectin: distinct and independent functions during tissue repair

Fibronectin (FN) is a ubiquitous extracellular matrix (ECM) glycoprotein that plays vital roles during tissue repair. The plasma form of FN circulates in the blood, and upon tissue injury, is incorporated into fibrin clots to exert effects on platelet function and to mediate hemostasis. Cellular FN is then synthesized and assembled by cells as they migrate into the clot to reconstitute damaged tissue. The assembly of FN into a complex three-dimensional matrix during physiological repair plays a key role not only as a structural scaffold, but also as a regulator of cell function during this stage of tissue repair. FN fibrillogenesis is a complex, stepwise process that is strictly regulated by a multitude of factors. During fibrosis, there is excessive deposition of ECM, of which FN is one of the major components. Aberrant FN-matrix assembly is a major contributing factor to the switch from normal tissue repair to misregulated fibrosis. Understanding the mechanisms involved in FN assembly and how these interplay with cellular, fibrotic and immune responses may reveal targets for the future development of therapies to regulate aberrant tissue-repair processes

Le Centre de Recherches Agronomiques de Bambey et le machinisme agricole

Le présent rapport de mission avait pour objectifs : - d'étudier avec le Directeur du CRA et son chef de la Division Machinisme Agricole et Génie Rural (MDR) comment pourraient être coordonnées les méthodes et les techniques utilisées dans les essais de machines agricoles par le CEEMAT rt par la Division MGR; - de faire le point des activités du CRA en matière de machinisme, et de déterminer les développements possibles de la collaboration CRA-CEEMAT avec l'accord du Gouvernement Sénégalais; - enfin de prendre en contact avec les stations régionales dépendant du CRA ainsi qu'avec les entreprises agricoles administratives, et para-administratives fortement mécanisées; - étudier dans quelle mesure les études de machines peuvent être introduites dans ce réseau d'expérimentatio