Synthesis and Characterization of 2-Aminobenzothiazol and 1-Methylisatin Co-Сrystal

Crystallography Reports - A co-crystal of 2-aminobenzothiazol and 1-methylisatin (III) was synthesized and characterized by elemental analysis, Fourier-transform infrared spectroscopy, nuclear...     

Weakly Coordinating,Ketone-Directed (η5-Pentamethylcyclopentadienyl)cobalt(III)- and (η5-Pentamethylcyclopentadienyl)rhodium(III)-Catalyzed C−H Amidation of Arenes: A Route to Acridone Alkaloids

The weakly coordinating, ketone-directed, regioselective monoamidation of aromatic ketones, chalcone, carbazole, and benzophenones was achieved by employing high-valent cobalt and rhodium catalysis to access numerous biologically important molecular building blocks. This amidation proceeded smoothly with a variety of ketones and several amidating partners. The application of the products in the synthesis of various heterocycles, including acridones, indoles, quinoline, quinolones, quinolinones, and quinazolines, was also explored. The total synthesis of acridone-based alkaloids, namely, toddaliopsin A, toddaliopsin D, and arborinine, and the formal synthesis of acronycine and noracronycin were also accomplished by applying this method. A mechanistic study revealed this amidation reaction follows a base-assisted intermolecular electrophilic substitution pathway.     

Novel radioassay for anti-thyroperoxidase autoantibodies using protein A coupled magnetizable cellulose particles as an immunoadsorbent

Journal of Radioanalytical and Nuclear Chemistry - Autoantibodies against thyroid peroxidase (TPO); described initially as thyroid microsomal antigen, are found in most of the patients with...     

A metal-free iodine-mediated conversion of hydroxamates to esters

Abstract

A metal-, oxidant-, and additive-free conversion of hydroxamates to esters have been achieved using molecular iodine as the reagent using a novel but not-so-explored heron-type rearrangement. The reaction proceeds with almost equal facility with substrates having either electron-donating or electron-withdrawing substituent. Similarly, α,ß-unsaturated, and sterically hindered ortho-substituted hydroxamates also undergo the desired transformation smoothly.     

Center or limit cycle: renormalization group as a probe

Based on our studies done on two-dimensional autonomous systems, forced non-autonomous systems and time-delayed systems, we propose a unified methodology – that uses renormalization group theory – for finding out existence of periodic solutions in a plethora of nonlinear dynamical systems appearing across disciplines. The technique will be shown to have a non-trivial ability of classifying the solutions into limit cycles and periodic orbits surrounding a center. Moreover, the methodology has a definite advantage over linear stability analysis in analyzing centers.     

Ultra-low-frequency dust-electromagnetic modes in self-gravitating magnetized dusty plasmas

Obliquely propagating altra-low-frequency dust-electromagnetic waves in a self-gravitating, warm, magnetized, two fluid dusty plasma system have been investigated. Two special cases, namely, dust-Alfvén mode propagating parallel to the external magnetic field and dustmagnetosonic mode propagating perpendicular to the external magnetic field have also been considered. It has been shown that effects of self-gravitational field, dust fluid temperature, and obliqueness significantly modify the dispersion properties of these ultra-low-frequency dust-electromagnetic modes. It is also found that in parallel propagating dust-Alfvén mode these effects play no role, but in obliquely propagating dust-Alfvén mode or perpendicular propagating dust-magnetosonic mode the effect of self-gravitational field plays destabilizing role whereas the effect of dust/ion fluid temperature plays stabilizing role.     

Extensions de la filtration de Saito

We extend Saito's filtration to the Chow groups of a representable morphism of presheaves on Sch_C${\mathit{Sch}}_{\mathbb{C}}$, the category of schemes over C$\mathbb{C}$. Moreover, for a presheaf on the category of smooth and projective schemes over C$\mathbb{C}$, we define its higher Chow groups along with their filtrations.     

Synchronization in coupled Ikeda delay systems

In this work, we demonstrate the use of a Field Programmable Gate Array (FPGA) as a physical platform for realizing chaotic delay differential equations (DDE). Moreover, using our platform, we also experimentally study the synchronization between two time delayed systems. We illustrate two different experimental approaches – one is hardware co-simulation (using a Digilent Atlys with a Xilinx Spartan-6 FPGA) and the other is analog output (using a Terasic DE2-115 with an Altera Cyclone IV E FPGA).     

Experiments with an ion-neutral hybrid trap: cold charge-exchange collisions

Due to their large trap depths (～1 eV or 10,000 K), versatility, and ease of construction, Paul traps have important uses in high-resolution spectroscopy, plasma physics, and precision measurements of fundamental constants. An ion-neutral hybrid trap consisting of two separate but spatially concentric traps [a magneto-optic trap (MOT) for the neutral species and a mass-selective linear Paul trap for the ionic species] is an ideal apparatus for sympathetic cooling. However, over the past few years, hybrid traps have proven most useful in measuring elastic and charge-exchange rate constants of ion-neutral collisions over a wide temperature range from kilo-Kelvin to nano-Kelvin. We report some initially surprising results from a hybrid trap system in our laboratory where we have loaded the Paul trap with Ca⁺ ions in the presence of a Na MOT (localized dense gas of cold Na atoms). We find a strong loss of Ca⁺ ions with MOT exposure, attributed to an exothermic, non-resonant ion-neutral charge-exchange process with an activation barrier, which leads to the formation of Na⁺ ions. We propose a detailed mechanism for this process. We obtain an estimated measure of the rate constant for this charge exchange of ～2 × 10^?11  cm³/s, much less than the Langevin rate, which suggests that the Langevin assumption of unit efficiency in the reaction region is not correct in this case.     

Uniqueness and set sharing of derivatives of meromorphic functions

We prove some uniqueness theorems concerning the derivatives of meromorphic functions when they share two or three sets which will improve some existing results.