Copper-free click conjugation of methotrexate to a PAMAM dendrimer platform

The synthesis of a generation 5 (G5) poly(amidoamine) (PAMAM) dendrimer platform having cyclooctyne ligands that were subsequently be used for a copper-free Huisgen 1,3-dipolar cycloaddition (click reaction) with azido modified methotrexate is described. The G5 PAMAM dendrimer was first partially (70%) acetylated and then coupled with 20 cyclooctyne ligands through amide bonds. The remaining primary amine groups on the dendrimer surface were neutralized by acetylation. The platform was then ‘clicked’ with different numbers (5, 10, and 17) of γ-azido functionalized methotrexate. The copper-free click reactions were stoichiometric with excellent yields.     

Tackling HIV through robust diagnostics in the developing world: current status and future opportunities

Over the last thirty years, the world has seen HIV circulate the globe, affecting 33 million people to date and killing 2 million people a year. The disease has affected developed and developing countries alike, and in the U.S., remains one of the top ten leading causes of death. Many regions of the world are highly impacted by this disease, including sub-Saharan Africa, South and South-East Asia, and Eastern Europe. Fortunately, multilateral, global efforts, along with successful developments in diagnostic tools and anti-retroviral drugs (ARVs) have successfully curbed the spread of HIV over the last ten years. In spite of this fact, access to HIV treatment and preventive healthcare is varying and limited in developing countries. A lack of healthcare infrastructure, financial support, and healthcare workers are some logistical factors that are responsible. HIV stigmatization, discrimination, and inadequate education pose additional social challenges that are hindering countries from advancing in HIV prevention. This review focuses on current technological tools that are used for HIV diagnosis and ongoing research that is aimed at addressing the conditions in low-resource settings. Recent developments in microfluidic applications and mobile health technologies are promising approaches to building a compact, portable, and robust device that can provide information-rich, real-time diagnoses. We also discuss the role that governments, healthcare workers, and even researchers can play in order to increase the acceptance of newly introduced devices and treatments in rural communities.     

Instrumentation for beam-foil spectroscopic studies in the UV-visible region

A facility for carrying out beam-foil spectroscopic studies in the UV and visible region using the 400 kV electrostatic ion accelerator at Tata Institute of Fundamental Research, Bombay is described.     

Use of native and derivatized cyclodextrin chiral stationary phases for the enantioseparation of aromatic and aliphatic sulfoxides by high performance liquid chromatography

Summary The enantioselectivity of native and derivatized cyclodextrin stationary phases for aromatic and aliphatic chiral sulfoxides was evaluated using high performance liquid chromatography (HPLC). Many sulfoxide enantiomers could be baseline resolved using the derivatized cyclodextrin stationary phases in the reverse phase mode. The most important factor influencing enantioselectivity is the presence of steric bulk alpha to the chiral center. However, substituents on an aromatic ring bonded to the sulfoxide have less pronounced effects on enantioselectivity. The 2,3-dimethyl β-cyclodextrin exhibits the broadest anantioselectivity for neutral chiral sulfoxides. Native cyclodextrins and hydroxypropyl-β-cyclodextrins were much less effective in separating this class of molecules. The hydrogen bonding ability of the organic modifier does not significantly affect enantioselectivity.     

Determination of traces of rare earth elements in high-purity uranium by ion-exchange separation and neutron activation γ-spectrometry

Neutron activation γ-spectrometry is sufficiently sensitive for the determination of traces of rare earth elements but quantitative separation from uranium is essential. The rare earth elements in 0.2 M ammonium carbonate medium are quantitatively retained on Chelex-100, and are quantitatively separated from uranium by recycling the eluate. When 10-g samples are used, neutron activation provides detection limits of 1–20 μg kg^?1. Recoveries of rare earths, checked by spiking with radiotracers, are essentially complete.     

Formation of self-assembled quantum dots of iron oxide thin films by spray pyrolysis from non-aqueous medium

Quantum dots (QDs) of iron oxide have been deposited onto ITO coated glass substrates by spray pyrolysis technique, using ferric chloride (FeCl₃·7H₂O) in non-aqueous medium as a starting material. The non-aqueous solvents namely methanol, ethanol, propanol, butanol and pentanol were used as solvents. The effect of solvents on the film structure and morphology was studied. The structural, morphological, compositional and optical properties were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive analysis of X-rays (EDAX), and optical absorption measurement techniques.     

Spin squeezing and quantum correlations

We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among the spinors in the coupled state.