Global Stability of Enzymatic Chains of Full Reversible Michaelis-Menten Reactions

We consider a chain of metabolic reactions catalyzed by enzymes, of reversible Michaelis-Menten type with full dynamics, i.e. not reduced with any quasi-steady state approximations. We study the corresponding dynamical system and show its global stability if the equilibrium exists. If the system is open, the equilibrium may not exist. The main tool is monotone systems theory. Finally we study the implications of these results for the study of coupled genetic-metabolic systems.     

A New Trigonometric Spline Approach to Numerical Solution of Generalized Nonlinear Klien-Gordon Equation

The generalized nonlinear Klien-Gordon equation plays an important role in quantum mechanics. In this paper, a new three-time level implicit approach based on cubic trigonometric B-spline is presented for the approximate solution of this equation with Dirichlet boundary conditions. The usual finite difference approach is used to discretize the time derivative while cubic trigonometric B-spline is applied as an interpolating function in the space dimension. Several examples are discussed to exhibit the feasibility and capability of the approach. The absolute errors and error norms are also computed at different times to assess the performance of the proposed approach and the results were found to be in good agreement with known solutions and with existing schemes in literature.     

The structure of the antitumor complex cis-(diammino) (1,1-cyclobutanedicarboxylato)-Pt(II): X ray and nmr studies

X-ray crystallography shows that Pt(NH₃)₂(CBDCA) is a square-planar complex with the dicarboxylate chelate ring in the boat conformation and a planar cyclobutane ring. ¹H and ¹³C nmr studies suggest that rapid chelate ring flipping occurs in solution. The value of ¹⁹⁵Pt nmr combined with ¹⁵N labeling as an informative new method of studying carboxylate coordination is illustrated. nmr results are also reported for the analogous ethylmalonate complex.     

Top-Down Nanofabrication and Characterization of 20 nm Silicon Nanowires for Biosensing Applications

A top-down nanofabrication approach is used to develop silicon nanowires from silicon-on-insulator (SOI) wafers and involves direct-write electron beam lithography (EBL), inductively coupled plasma-reactive ion etching (ICP-RIE) and a size reduction process. To achieve nanometer scale size, the crucial factors contributing to the EBL and size reduction processes are highlighted. The resulting silicon nanowires, which are 20 nm in width and 30 nm in height (with a triangular shape) and have a straight structure over the length of 400 μm, are fabricated precisely at the designed location on the device. The device is applied in biomolecule detection based on the changes in drain current (I_ds), electrical resistance and conductance of the silicon nanowires upon hybridization to complementary target deoxyribonucleic acid (DNA). In this context, the scaled-down device exhibited superior performances in terms of good specificity and high sensitivity, with a limit of detection (LOD) of 10 fM, enables for efficient label-free, direct and higher-accuracy DNA molecules detection. Thus, this silicon nanowire can be used as an improved transducer and serves as novel biosensor for future biomedical diagnostic applications.     

Marine algae that display anti-tumorigenic activity against Agrobacterium tumefaciens

Abstract Thirty-five extracts representing different seasonal growths of 17 marine algal species collected from the Alexandria coast were tested for anti-tumorigenic activity against Agrobacterium tumefaciens galls on potato discs. Eleven extracts (nine species) displayed > 20% inhibition of tumor initiation, with three of these ( Codium tomentosum , winter; Jania rubens , summer; Padina pavonia , winter) displaying relatively high activity. Bacterial viability tests showed that the inhibitory effects were directly due to anti-tumorigenesis rather than an indirect result of anti-bacterial activity.