Migratory effect of middle predator in a tri‐trophic food chain model

A tri‐trophic food chain model in a two‐patch environment is considered. Although tri‐trophic food chain model is well studied, the study considering migration of middle predator is lacking. To the best of our knowledge, the present investigation is the first study in this direction. Both prey and predator density‐dependent migrations are considered to observe the effects on stability and persistence of the system. We observe that migration of middle predator has the ability to control chaos in tri‐trophic food chain model. Our results indicate that the chance of predator extinction enhances for prey density‐dependent middle predator migration. Copyright © 2010 John Wiley & Sons, Ltd.     

Expanding the Arsenal of PtIV Anticancer Agents: Multi‐action PtIV Anticancer Agents with Bioactive Ligands Possessing a Hydroxy Functional Group

Most multi‐action Pt^IV prodrugs have bioactive ligands containing carboxylates. This is probably due to the ease of carboxylating the OH axial ligands and because following reduction, the active drug is released. A major challenge is to expand the arsenal of bioactive ligands to include those without carboxylates. We describe a general approach for synthesis of Pt^IV prodrugs that release drugs with OH groups. We linked the OH groups of gemcitabine (Gem), paclitaxel (Tax), and estramustine (EM) to the Pt^IV derivative of cisplatin by a carbonate bridge. Following reduction, the axial ligands lost CO₂, rapidly generating the active drugs. In contrast, succinate‐linked drugs did not readily release the free drugs. The carbonate‐bridged ctc‐[Pt(NH₃)₂(PhB)(Gem‐Carb)Cl₂] was significantly more cytotoxic than the succinate‐bridged ctc‐[Pt(NH₃)₂(PhB)(Gem‐Suc)Cl₂], and more potent and less toxic than gemcitabine, cisplatin, and co‐administration of cisplatin and gemcitabine.     

Light-Induced Formation of Thymine-Containing Mercury(II)-Mediated Base Pairs

By applying caged thymidine residues, DNA duplexes were created in which Hg^II-mediated base pair formation can be triggered by irradiation with light. When a bidentate ligand was used as the complementary nucleobase, an unprecedented stepwise formation of different metal-mediated base pairs was achieved.     

Chromenone-rhodamine conjugate for naked eye detection of Al3+ and Hg2+ ions in semi aqueous medium

Chromenone-rhodamine conjugate 1 has been synthesized and its metal ion binding properties have been studied in CH₃CN/water (3:1, v/v; 10 mM HEPES buffer; pH = 6.85). Compound 1 senses multiple metal ions such as Al³⁺ and Hg²⁺ by exhibiting turn on fluorescence and color change (colorless to pink). Al³⁺ and Hg²⁺ ions have been distinguished with the aid of tetrabutylammonium iodide (TBAI). While in the presence of I^? the pink color of the 1.Hg²⁺ complex was completely discharged; under identical conditions the pink color of 1.Al³⁺ complex was retained.     

Sequential detection of Cu2+ and cysteine using an imidazole‐based chemosensor in aqueous solution

A highly substituted imidazole‐based colorimetric and fluorogenic chemosensor, 2‐methoxy‐4‐(4,5‐diphenyl‐1H‐imidazol‐2‐yl)phenol (L), for the detection of Cu²⁺ ion and subsequent colorimetric detection of an amino acid, cysteine, was investigated. L exhibited a distinct color change from colorless to red in the presence of Cu²⁺ in an aqueous medium. The L‐Cu²⁺ complex can also be used to detect cysteine by the naked eye over a series of amino acids. The receptor L behaves as a highly selective colorimetric and fluorescent sensor for Cu²⁺ ions at concentrations as low as 4.33 and 2.25 μM, respectively. These values are much less compared to the WHO recommended limit of 30 μM for Cu²⁺ in drinking water. From Job's plot and the ESI‐MS spectrum, a 1:1 stoichiometric complex between L and Cu²⁺ ions can readily be reckoned. This binding was also substantiated by the EPR spectrum and magnetic susceptibility measurements. Additionally, the binding of L with Cu²⁺ ions was also manifested in the detection of B16F10 cells. This was substantiated through fluorescence microscopy. The spectrum of the L‐Cu²⁺ entity was also attempted to reproduce theoretically. The probable structure of this was also propounded through Density Functional Theory.     

Controlling the isomerization dynamics of iodide acetonitrile dimer complex by optimally designed electromagnetic field: A wave packet based approach

Both symmetric and asymmetric forms of the iodide acetonitrile dimer complex are known to exist with a higher stability shown by the symmetric isomer. Dynamics of this isomerization has been investigated on reduced dimensional surface in absence/presence of external electromagnetic field using Gaussian wave packet as the starting wave function. When the symmetric isomer has been taken as the initial structure, isomerization does not takes place without the external field due to high energy barrier, whereas with the asymmetric isomer as the starting one, isomerization takes place spontaneously with an equal population of both isomers. Our target in this study has been to get a dominant population of asymmetric isomer which is not possible without the application of electromagnetic field. However, it has also been seen that a simple monochromatic field cannot achieve this goal. Only by application of optimally designed polychromatic field the dominating population of asymmetric isomer can be obtained.     

Isotropic Brans-Dicke cosmology with dust distribution

A simple approach for finding the exact solution of the matter dust distribution in the Brans-Dicke cosmology has been attempted. The condition for obtaining a complete exact solution is presented.     

Alpha radioactivity in human blood and its possible correlation to ailment pattern

Journal of Radioanalytical and Nuclear Chemistry - Human blood, beside its multi-functional activities, may carry different ionizing radiation emitters to the whole body, spatially alpha emitters,...     

An audio encryption based on distinct key blocks along with PWLCM and ECA

This paper presents a robust audio encryption scheme based on three consecutive phases, accomplished as cyclic shift followed by ciphering and wound up by shuffling, to break the high correlation amongst the neighbouring region of a plain audio. To encrypt a plain audio, the entire audio is split into different blocks of 64 bytes each and distinct key blocks are used for those audio blocks in the foregoing three phases. At first, the correlation of each audio block is reduced by the cyclic shift; thereafter, these shifted blocks are ciphered with piecewise linear chaotic map (PWLCM) along with elementary cellular automata (ECA) and finally, turns up with shuffling of ciphered bytes for better diffusion. The significant feature of this scheme is to generate distinct key blocks, which are highly sensitive to the secret key, a combination of the 64-byte external key along with the plain audio-dependent value. Moreover, these key blocks are derived using PWLCM from the secret key along with the preceding key block and previous encrypted block to achieve resistance against the known plain-text attack. It uses key space as large as \(2^{576}\) to resist brute-force attacks. The robustness as well as competence of this scheme is established with statistical analyses, cryptanalysis, randomness analysis and comparisons with existing schemes.