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Latter Situation (latter + situation)

Distribution by Scientific Domains

Medical Sciences	40%
Chemistry	40%

Selected Abstracts

Microdimensional Polyaniline: Fabrication and Characterization of Dynamics of Charge Propagation at Microdisk Electrodes

ELECTROANALYSIS, Issue 17 2004
Karolina Caban
Abstract We describe fabrication of microdimensional polyanilne films in a controlled manner by voltammetric potential cycling or controlled potential electrolysis on platinum microdisk electrodes. The film grows in a form of hemispherical microdeposits, and its size largely exceeds the size of a Pt microdisk. Consequently, the film covers both the Pt substrate as well as the surrounding glass seal. Since the adhering polyaniline layer is conducting, the latter situation may lead to an increase in the effective electrode surface area. The lateral growth of polyaniline films outside the microdisk has also been demonstrated by performing diagnostic voltammetric experiments with use of a double microdisk set-up in which independent polarization of each disk is feasible. Microelectrode-based chronocoulometry, that involves an uncomplicated well-defined reduction potential step starting from the emeraldine (conducting) form and ending at leucoemeraldine (nonconducting) form, yields (upon application of a sufficiently short pulse) a well-defined linear response of charge versus square root of time that is consistent with the linear effective diffusion as the predominant charge propagation mechanism. When describing the system kinetics in terms of the effective (apparent) diffusion coefficient, we expect this parameter to be on the level of 10,8,cm2 s,1 or lower. The relative changes in dynamics of charge transport are discussed with respect to the polyaniline film loading, the size of microdisk electrode, expansion of the active electrode area, and the choice of electrolyte (strong acid) anion. The results are consistent with the view that when Pt microelectrode is modified with PANI deposit exceeding the size of the microdisk substrate, it behaves in a way as if its surface area is effectively much larger than the geometric area of Pt microdisk. [source]

A laboratory model of splash-form tektites

METEORITICS & PLANETARY SCIENCE, Issue 9 2003
Linda T. ELKINS-TANTON
However, no detailed fluid dynamical investigation of their form and stability has yet been undertaken. Here, we review the dynamics and stability of spinning, translating fluid drops with a view to making inferences concerning the dynamic history of tektites. We conclude that, unless the differential speed between the molten tektite and ambient is substantially less than the terminal velocity, molten tektites can exist as equilibrium bodies of revolution only up to sizes of 3 mm. Larger tektites are necessarily non-equilibrium forms and so indicate the importance of cooling and solidification during flight. An examination of the shapes of rotating, translating drops indicates that rotating silicate drops in air will assume the shapes of bodies of rotation if their rotational speed is 1% or more of their translational speed. This requirement of only a very small rotational component explains why most splash-form tektites correspond to bodies of revolution. A laboratory model that consists of rolling or tumbling molten metallic drops reproduces all of the known forms of splashform tektites, including spheres, oblate ellipsoids, dumbbells, teardrops, and tori. The laboratory also highlights important differences between rolling drops and tumbling drops in flight. For example, toroidal drops are much more stable in the former than in the latter situation. [source]

Schistosomiasis and liver fibrosis

PARASITE IMMUNOLOGY, Issue 11 2009
Z. A. ANDRADE
Summary Schistosoma mansoni infection invariably results in liver fibrosis of the host. This fibrosis may be represented by small focal areas of chronic inflammation and excess extracellular matrix deposited in periovular granulomas, distributed in variable numbers at the periphery of the portal vein system. This is the outcome of 90% of the infected population in endemic areas. Conversely, a minority of infected individuals develop extensive disease with numerous granulomas along the entire extension of the portal spaces. This latter situation is mainly dependent on special hemodynamic changes created by a heavy worm load, with the subsequent production of numerous eggs and represents a severe form of a peculiar chronic hepatopathy. Thus, host,parasite interactions in schistosomiasis help us to understand a number of important features of liver fibrosis: its initiation and regulation, the significance of accompanying vascular changes, the dynamics of fibrosis formation and regression with antiparasitic treatment; host genetic and immunological contributions, and the pathophysiology of portal hypertension. [source]

Synthesis and Two-photon Photolysis of 6-(ortho -Nitroveratryl)-Caged IP3 in Living Cells

CHEMBIOCHEM, Issue 1 2006
Srinivas Kantevari Dr.
Abstract The synthesis of a photolabile derivative of inositol-1,4,5-trisphosphate (IP3) is described. This new caged second messenger (6- ortho -nitroveratryl)-IP3 (6-NV-IP3) has an extinction coefficient of 5000,M,1,cm,1at 350 nm, and a quantum yield of photolysis of 0.12. Therefore, 6-NV-IP3 is photolyzed with UV light about three times more efficiently than the widely used P4(5) -1-(2-nitrophenyl)ethyl-caged IP3 (NPE-IP3). 6-NV-IP3 has a two-photon cross-section of about 0.035 GM at 730 nm. This absorbance is sufficiently large for effective two-photon excitation in living cells at modest power levels. Using near-IR light (5 mW, 710 nm, 80 MHz, pulse-width 70 fs), we produced focal bursts of IP3 in HeLa cells, as revealed by laser-scanning confocal imaging of intracellular Ca2+concentrations. Therefore, 6-NV-IP3 can be used for efficient, subcellular photorelease of IP3, not only in cultured cells but also, potentially, in vivo. It is in the latter situation that two-photon photolysis should reveal its true forte. [source]

Intravenous immunoglobulins in infectious diseases: where do we stand?

CLINICAL MICROBIOLOGY AND INFECTION, Issue 5 2003
L. Mouthon
Intravenous immunoglobulins (IVIg) are therapeutic preparations of normal human IgG that have been used for more than 20 years for substitutive therapy in patients with primary antibody deficiencies. Recent studies pointed out the need to obtain normal residual levels of IgG (i.e. 8 g/L) in order to reduce the number and severity of bacterial infections in these patients. The IVIg are also prescribed for the substitutive therapy of secondary immunodeficiencies such as chronic lymphoid leukemia and multiple myeloma with hypogammaglobulinemia and severe and/or recurrent infections, and human immunodeficiency virus (HIV)-infected children with recurrent bacterial infections before the era of highly active antiretroviral agents. However, in the latter situation, no recent study has evaluated IVIg therapy in acquired immunodeficiency syndrome (AIDS) children receiving highly active antiretroviral agents (HAART), and the use of IVIg must probably be restricted to the currently rare clinical situation in Western Europe of children with AIDS who develop recurrent infections despite the administration of HAART and prophylactic cotrimoxazole. IVIg have also been reported to prevent infections, interstitial pneumonia and graft-vs. host disease during the first 90 days post-transplant in allogeneic bone-marrow transplant recipients. However, this result was not confirmed by two recent studies and IVIg therapy should probably only be proposed for a subgroup of bone-marrow allografted patients such as those with hypogammaglobulinemia and sepsis. With the exception of erythrovirus B19 infection with erythroblastopenia, no clear benefit of IVIg therapy has been reported for the curative management of other infectious diseases. [source]