Synthesis,X‐ray powder structure analysis and biological properties of a mononuclear Cu(II) complex of N‐2‐hydroxyhippuric acid

A mononuclear copper (II) complex of N‐2‐hydroxyhippuric acid (2HHA), [Cu(HA)(H₂O)₂], has been synthesized and characterized by spectroscopic and X‐ray powder diffraction studies. Crystal structure of [Cu(HA)(H₂O)₂] reveals a distorted square‐pyramidal geometry around the metal center. The crystal packing in the complex exhibits a three‐dimensional framework formed by intermolecular O? ; H···O and C? H···O hydrogen bonds. Toxicity and antitumor properties of the complex have been studied in vivo. The complex, capable of depleting glutathione (GSH) at nontoxic doses, may be utilized to sensitize drug‐resistant cells where resistance is due to an elevated level of GSH. Copyright © 2009 John Wiley & Sons, Ltd.     

Existence of infinitely many solutions for a nonlocal elliptic PDE involving singularity

Positivity - In this article, we will prove the existence of infinitely many positive weak solutions to the following nonlocal elliptic PDE. $$\begin{aligned} (-\Delta )^s u&= \frac{\lambda...     

Structural basis of BMP-2 and BMP-7 interactions with antagonists Gremlin-1 and Noggin in Glioblastoma tumors

In Glioblastoma (GBM) brain tumors, both Gremlin-1 and Noggin are reported to bind to BMP and inhibit BMP-signaling, thereby allowing the cell to maintain tumorous morphology. Enlisting the interfacial residues important for protein–protein complex formation between BMPs (BMP-2 and BMP-7) and antagonists (Gremlin-1 and Noggin), we analyzed the structural basis of their interactions. We found possible key mutations that destabilize these complexes, which may prevent GBM development. It was also observed that when the interfacial residues were either mutated to histidine or tryptophan, it led to higher destabilization energy values. Besides, our study of the Noggin interactive model of BMP-2 suggested preferential binding at binding site II over binding site I. In the case of Gremlin-1 and BMPs, our research, along with few previous studies, indicates a close-ended cis-trans interactive model.     

Predicting solar cycle 24 with a solar dynamo model

Whether or not the upcoming cycle 24 of solar activity will be strong is being hotly debated. The solar cycle is produced by a complex dynamo mechanism. We model the last few solar cycles by "feeding" observational data of the Sun's polar magnetic field into our solar dynamo model. Our results fit the observed sunspot numbers of cycles 21-23 reasonably well and predict that cycle 24 will be about 35% weaker than cycle 23.     

Symmetries and conservation laws of the damped harmonic oscillator

We work with a formulation of Noether-symmetry analysis which uses the properties of infinitesimal point transformations in the space-time variables to establish the association between symmetries and conservation laws of a dynamical system. Here symmetries are expressed in the form of generators. We have studied the variational or Noether symmetries of the damped harmonic oscillator representing it by an explicitly time-dependent Lagrangian and found that a five-parameter group of transformations leaves the action integral invariant. Amongst the associated conserved quantities only two are found to be functionally independent. These two conserved quantities determine the solution of the problem and correspond to a two-parameter Abelian subgroup.      

Aminomethyl psoralens. Electrophilic substitution of hydroxymethylphthalimide on linear furocoumarins

A new synthetic route to aminomethylpsoralens, substituted on the furan-ring, has been developed by electrophilic substitution of N-hydroxymethylphthalimide and subsequent hydrazinolysis. Hydroxy and methoxy activating functions on the psoralens lead to multi-site substitution and the products of these phthalimido-methylations resist simple cleavage with hydrazine. The two-step introduction of a single CH₂NH₂ group is successful in psoralens containing only methyl substituents.     

A study of an arbitrary Stokes flow past a fluid coated sphere in a fluid of a different viscosity

A general method to discuss the problem of an arbitrary Stokes flow (both axisymmetric and non-axisymmetric flows) of a viscous, incompressible fluid past a sphere with a thin coating of a fluid of a different viscosity is considered. We derive the expressions for the drag and torque experienced by the fluid coated sphere and also discuss the conditions for the reduction of the drag on the fluid coated sphere. In fact, we show that the drag reduces compared to the drag on a rigid sphere of the same radius when the unperturbed velocity is either harmonic or purely biharmonic, i.e., of the form ${r^2\vec{\textbf{v}}}$ , where ${\vec{\textbf{v}}}$ is a harmonic function. Previously Johnson (J Fluid Mech 110:217–238, 1981), who considered a uniform flow showed that the drag on the fluid coated sphere reduces compared to the drag on the uncoated sphere when the ratio of the surrounding fluid viscosity to the fluid-film viscosity is greater than 4. We show that this result is true when the undisturbed velocity is harmonic or purely biharmonic, uniform flow being a special case of the former. However, we illustrate by an example that the drag may increase in a general Stokes flow even if this ratio is greater than 4. Moreover, when the unperturbed velocity is harmonic or purely biharmonic, and the ratio of the surrounding fluid viscosity to the fluid-film viscosity is greater than 4 for a fixed value of the viscosity of the ambient fluid, we determine the thickness of the coating for which the drag is minimum.     

Unsymmetrical Disulfides Synthesis via Sulfenium Ion

An umpolung approach for the synthesis of unsymmetrical disulfides via sulfenium ion is reported. In situ generated electrophilic sulfenium ion from electron‐rich thiols reacted with second thiols to yield unsymmetrical disulfides. Using an iodine catalyst and 4‐dimethylaminopyridine (DMAP)/water as promoter, the target syntheses were achieved in one pot under aerobic condition.     

Noether-Symmetry Analysis using Alternative Lagrangian Representations

We have sought to work with an approach to Noether symmetry analysis which uses the properties of infinitesimal point transformations in the space-time (q, t) variable to establish the association between symmetries and conservation laws of a dynamical system. In this approach symmetries are expressed in the form of generators. We have studied the variational or Noether symmetries of two uncoupled Harmonic oscillators and two such oscillators coupled by an interaction. Both these systems can have alternative Lagrangian representations. We have studied in detail how the association between symmetries and conservation laws changes as one alters the analytic or Lagrangian representation. This analysis is carried out with a view to explicitly demonstrate that the correlation between symmetry transformation and corresponding invariant quantity depends crucially on the choice of the analytic representation. PACS 45.20.Jj, 45.20.df, 45.20.dh