alpha-Sarcin catalytic activity is not required for cytotoxicity

Background  

α-Sarcin is a protein toxin produced by Aspergillus giganteus. It belongs to a family of cytotoxic ribonucleases that inactivate the ribosome and inhibit protein synthesis. α-Sarcin cleaves a single phosphodiester bond within the RNA backbone of the large ribosomal subunit, which makes the ribosome unrecognizable to elongation factors and, in turn, blocks protein synthesis. Although it is widely held that the protein synthesis inhibition caused by the toxin leads to cell death, it has not been directly shown that catalytically inactive mutants of α-sarcin are non-toxic when expressed directly within the cytoplasm of cells. This is important since recent studies have cast doubt on whether protein synthesis inhibition is sufficient to initiate apoptosis.     

Magnetohydrodynamic oblique stagnation-point flow

Laminar two-dimensional stagnation flow of a viscous and electrically conducting fluid obliquely impinging on a flat plate in the presence of a uniform applied magnetic field is formulated as a similarity solution of the Navier-Stokes equations. The relative importance of this flow is measured by the dimensionless strain rate and magnetohydrodynamic parameters γ and M. The viscous problem is reduced to a coupled pair of ordinary differential equations governed by γ and M. It is found that the parameter M causes a shift in the position of the point of zero skin friction along the wall.     

Synthesis, alignment, and magnetic properties of monodisperse nickel nanocubes

This Communication describes the synthesis of highly monodispersed 12 nm nickel nanocubes. The cubic shape was achieved by using trioctylphosphine and hexadecylamine surfactants under a reducing hydrogen atmosphere to favor thermodynamic growth and the stabilization of {100} facets. Varying the metal precursor to trioctylphosphine ratio was found to alter the nanoparticle size and shape from 5 nm spherical nanoparticles to 12 nm nanocubes. High-resolution transmission electron microscopy showed that the nanocubes are protected from further oxidation by a 1 nm NiO shell. Synchrotron-based X-ray diffraction techniques showed the nickel nanocubes order into [100] aligned arrays. Magnetic studies showed the nickel nanocubes have over 4 times enhancement in magnetic saturation compared to spherical superparamagnetic nickel nanoparticles.     

Automated method for measuring globin adducts of acrylamide and glycidamide at optimized Edman reaction conditions

The general population is exposed to acrylamide, a potential human carcinogen, through food and cigarette smoke. The assessment of human exposure to acrylamide is important in the evaluation of health risks associated with this chemical. Hemoglobin adducts of acrylamide (AA-Hb) and its primary metabolite glycidamide (GA-Hb) are established biomarkers of acrylamide exposure and methods to measure these biomarkers using modified Edman reaction are described. Only limited information about the optimal Edman reaction conditions such as pH or temperature is available for these adducts and the existing methods do not allow automation needed in biomonitoring studies. In this study, the yield of Edman products of AA-Hb and GA-Hb between pH 3-10 and at 35-55 degrees C at different time intervals, and the applicability of liquid-liquid extraction on diatomaceous earth for analyte extraction, were assessed and results were used in a new optimized method. The applicability of our optimized method was assessed by comparing results obtained with a convenience sample from 96 individuals with a conventional method. Maximum yield of Edman products was obtained between pH 6-7, heating the reaction solution at 55 degrees C for 2 h resulted in the same yields as with conventional conditions, and use of diatomaceous earth was found suitable for automated analyte extraction. Using these conditions, no difference was observed between our optimized and a conventional method. The median globin adduct values in the convenience sample are 129 pmol/g globin (range: 27-453 pmol/g globin) and 97 pmol/g globin (range: 27-240 pmol/g globin) for AA-Hb and GA-Hb, respectively. The GA-Hb/AA-Hb ratio decreases significantly with increasing AA-Hb values indicating that measurement of AA-Hb as well as GA-Hb are needed to appropriately assess human exposure to acrylamide.     

On the use of a Pohlhausen method in three dimensional boundary layers

Summary The paper deals with the problem of a three dimensional boundary layer flow on the inner surface of a cone when the flow external to the boundary layer is due to a potential line vortex on the axis of the cone together with a radial flow parallel to the cone generators.The momentum integral equations are solved using a Pohlhausen method. An asymptotic solution of the boundary layer equations is used to overcome the arbitrariness which commonly arises in this type of approach and, together with a discussion of certain other boundary conditions, lays a foundation for the use of the method.

---

Zusammenfassung Die Arbeit behandelt das dreidimensionale Grenzschichtproblem der Strömung entlang des Inneren an einem Kegel, wobei die Strömung ausserhalb der Grenzschicht durch einen Potentialwirbel entlang der Kegelachse und durch Radialbewegung entlang der Kegel-Generatoren gebildet wird.Die Momenten-Integral-Gleichung wird mit einer Pohlhausen-Methode gelöst. Eine asymptotische Lösung der Grenzschichtgleichung wird dazu benützt, eine gewisse Willkür zu beseitigen, die gewöhnlich bei solchen Methoden auftritt, und gibt zusammen mit der Diskussion von gewissen Grenzbedingungen die Grundlage der Methode.

     

Free-convection boundary layer on an isothermal horizontal cylinder

The free convection on a horizontal circular cylinder whose temperature is suddenly increased is studied at large Grashof number. An accurate numerical method is described for determining the solution of the time-dependent boundary-layer equations. The development of the various physical properties of the flow are calculated and compared with their values at small and large times as obtained from the previously obtained analytical solutions.

---

Résumé Cette étude considère la convection libre à nombre de Grashof élevé au dessus d'un cylindre horizontal de section circulaire lorsqu'on augmente brusquement sa température. On présente une méthode numérique qui permet de déterminer avec précision la solution des équations instationnaires de la couche limite. Le développement des caractéristiques physiques de l'écoulement est calculé et les résultats sont comparés avec ceux qui ont été déjà obtenus analytiquement pour les petites et grandes valeurs de la variable du temps.

     

Retrieval of Spacewise Dependent Hydraulic Properties of Anisotropic Rocks from Transient Flow Experiments

An inverse finite-difference method (FDM) is developed to characterise the spatially dependent components of the hydraulic conductivity tensor together with the specific storage for anisotropic materials, using experimental data generated from the direct FDM. This simulated surface data serves as additional information to a genetic algorithm (GA) optimisation procedure, using a modified least squares functional, that minimises the difference between the experimental data and the FDM-predicted boundary pressure and/or average hydraulic flux measurements based on current hydraulic conductivity tensor and specific storage estimates.