Kinetics and mechanisms of oxidations by metal ions. Part 17. Oxidation of formate ion by alkaline osmium tetroxide

Summary The oxidation of formate ion by alkaline osmium tetroxide, such that [HCO _inf2 ^p– ] [Os^VII], exhibits first-order dependence in [Os^VII], an order less than unity in [HCO _inf2 ^p– ], and zero-order in [OH^–]. HCO^2– reacts as an ion-pair formed with an alkali metal ion and [OsO₄(OH)₂]^2– is the reactive species of Os^VII. The formation of an intermediate Os^VII-HCO₂M complex is substantiated by the rapid-scan spectra of the reaction mixture. Anions (Cl^–, ClO _inf4 ^p– ) have no effect on the rate. The close agreement between the observed k _H/k _D = 7.1 and the theoretically calculated value (7.0), based on the stretching frequencies of C-H and C-D bonds in the free molecule, indicates an outer-sphere mechanism.Author to whom all correspondence should be directed.     

Scandium triflate as an efficient and useful catalyst for the synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines under solvent-free conditions

A simple and efficient method has been developed for the synthesis of β-amino alcohols by ring opening of epoxides in the presence of a catalytic amount of Sc(OTf)₃ at room temperature under solvent-free conditions. The reaction works well with both aromatic and aliphatic amines. High regio-, and diastereoselectivity can be considered as a noteworthy advantage of this method.     

Fabrication and Characterization of Cysteine-Functionalized Zinc Oxide Nanoparticles for Enzyme Immobilization

A green approach is reported for the synthesis of cysteine-functionalized zinc oxide nanoparticles using potato extract as a nontoxic and economical reducing agent. The cysteine-functionalized nanoparticles were used as a support for enzyme immobilization. The structural morphology, crystallinity, and surface functionalization were characterized by scanning electron microscopy, X-ray diffraction, and infrared spectroscopy, respectively. Spherical nanoparticles from 150 to 200?nm were used to evaluate the immobilization efficiency for urease through covalent attachment on the glutaraldehyde-activated amino group of cysteine. In comparison to the unmodified nanoparticles, 62.9% enzyme loading with 72.45% of enzyme specific activity was recovered which was 56% higher than on bare zinc oxide nanoparticles. The point of addition of cysteine during the nanoparticle synthesis had a direct effect on the immobilization efficiency. The immobilized enzyme-specific activity was reduced to 34.32% when cysteine was added following the nanoparticle synthesis. With a facile synthesis procedure and significant immobilization efficiency, cysteine-functionalized zinc oxide nanoparticles were shown to be suitable for various clinical and industrial applications.     

Ionic size dependent electroosmosis in ion‐selective microchannels and nanochannels

Electrokinetics in salt‐free media (in which counterions are only present) is central to the performance of many systems of modern technological relevance, ranging from ion‐selective nanopores to electronic papers. Here, we introduce an analytical theory to describe the size dependence of electroosmosis in such typical scenarios, exhibiting an interesting confluence of the implications of interdependence of the electroosmotic transport mechanisms, ionic sizes, and confinement dimensions along with the counterion concentration. Our results do reveal that the concerned mobility parameter, describing the strength of electroosmotic transport, increases simultaneously with increments in the surface charge density as well as an ionic size factor (also known as the steric factor), bearing far‐ranging consequences in microfluidic and nanofluidic technology.     

Vibrational dynamics of Ni-glassy alloys

The well known model potential is used to investigate the vibrational properties of some Ni-based binary glassy alloys using three theoretical models. Different local field correction functions are employed to see the effect of exchange and correlation in the aforesaid properties and have been found successful.     

Distributed self-tuning of sensor networks

This work is motivated by the need for an ad hoc sensor network to autonomously optimise its performance for given task objectives and constraints. Arguing that communication is the main bottleneck for distributed computation in a sensor network we formulate two approaches for optimisation of computing rates. The first is a team problem for maximising the minimum communication throughput of sensors and the second is a game problem in which cost for each sensor is a measure of its communication time with its neighbours. We investigate adaptive algorithms using which sensors can tune to the optimal channel attempt rates in a distributed fashion. For the team problem, the adaptive scheme is a stochastic gradient algorithm derived from the augmented Lagrangian formulation of the optimisation problem. The game formulation not only leads to an explicit characterisation of the Nash equilibrium but also to a simple iterative scheme by which sensors can learn the equilibrium attempt probabilities using only the estimates of transmission and reception times from their local measurements. Our approach is promising and should be seen as a step towards developing optimally self-organising architectures for sensor networks. Aditya Karnik obtained his B.E. from the University of Pune, Pune, India, and M.E. and Ph.D. (2004) in electrical communication engg. from the Indian Institute of Science, Bangalore, India. He is currently a postdoctoral fellow at the University of Waterloo, Waterloo, Canada. He was a recipient of the IBM Research Fellowship. His research interests are in performance evaluation, optimisation and control of communication networks. Anurag Kumar obtained his B.Tech. degree from the Indian Institute of Technology at Kanpur, and the PhD degree from Cornell University, both in Electrical Engineering. He was then with Bell Laboratories, Holmdel, N.J., for over 6 years. Since 1988 he has been with the Indian Institute of Science (IISc), Bangalore, in the Dept. of Electrical Communication Engineering, where he is now a Professor, and is also the Chairman of the department. From 1988 to 2003 he was the Coordinator at IISc of the Education and Research Network Project (ERNET), India’s first wide-area packet switching network. His area of research is communication networking, specifically, modeling, analysis, control and optimisation problems arising in communication networks and distributed systems. Recently his research has focused primarily on wireless networking. He has been elected Fellow of the IEEE, and the Indian National Science Academy (INSA), both from 2006, and has been a Fellow of the Indian National Academy of Engineering (INAE) since 1998. He is an associate editor of IEEE Transactions on Networking, and of IEEE Communications Surveys and Tutorials. He is a coauthor of the advanced text-book “Communication Networking: An Analytical Approach,” by Kumar, Majunath and Kuri, published by Morgan-Kaufman/Elsevier. Vivek Borkar got his B. Tech. (Elec. Engg.) from Indian Institute of Technology, Mumbai, in 1976, M. S. (Systems and Control) from Case Western Reserve Uni. in 1977, and Ph.D. (Elec. Engg. and Computer Sci.) from the Uni. of California, Berkeley, in 1980. He was with TIFR Centre, Bangalore (1982–1989) and Indian Institute of Science (1989–1999) before taking up his present position at the School of Technology and Computer Science, Tata Inst. of Fundamental Research, Mumbai. He is a Fellow of the Indian Academy of Sciences, Indian National Science Academy, Indian National Academy of Engineers and the IEEE. His research interests are stochastic control, stochastic algorithms and applications. He is on the editorial boards of Sadhana, Systems and Control Letters, SIAM J. Control and Optim., and Applicationes Mathematicae. He is the author of ‘Optimal Control of Diffusion Processes’ (Longman, 1989), ‘Topics in Controlled Markov Chains’ (Longman, 1991), ‘Probability Theory: An Advanced Course’ (Springer, 1995).