Distant C-H Activation/Functionalization: A New Horizon of Selectivity Beyond Proximity

Activation/functionalization of inert C-H bond has undergone rapid growth in last decade and provides novel retro-synthetic disconnections for the synthesis of valuable molecules. The selectivity is often achieved by the use of directing group and is mainly limited to the proximal C-H bond. Initially, meta C-H activations were based on electronic or steric control and now it can be achieved by employing nitrile-based end-on-template as the directing group. The compilation of the remote C-H activation strategy will provide the useful linkage to the scientific community. This article is focused on recent progress in remote C-H activation, mechanistic understanding, and its applications in the field of total synthesis of targeted molecules.     

Paris: An approach to integrated high-speed private networks

This paper describes a design of a high-speed packet switching system for integrated voice, video and data communications. The system makes use of a simplified network architecture in order to achieve the low packet delay and high nodal throughput necessary for the transport of voice and video. A prototype of this system has been implemented and is now being tested under a variety of packet traffic loads. We have demonstrated that this system provides a cost-effective solution for private integrated networks.     

On program testing issues in software reliability—A survey

On account of various difficulties encountered with establishing the proof of correctness for software systems; the program testing seems to be the only sure way to prevent malfunctions from occurrence and thus to improve the software reliability. Whereas program proving is a reductive process; program testing is an affirmative process since everything done in testing can potentially contribute information about the quality of program being tested. Testing is the process of executing programs with representative input data or conditions, for which the correct results are known to determine whether incorrect results occur. This paper makes an attempt to provide a cross-section of current program testing technology—ranging from philosophical issues to research and development concepts to the extent that the known literature permits.     

Hardware vs software maintainability: A comparative study

The rapid technological advances in microelectronics, microprocessors and computer science, accompanied by the increasing use of digital techniques in system designs, have resulted in a transition of system problems from hardware to software. Software costs now generally exceed hardware costs. The use of the words reliability and maintainability for software are taken in a completely different context than for hardware. Significant differences exist between hardware R & M (reliability and maintainability) and software R & M in the basic concepts, understanding, principles, analytic models and design techniques used. Some recent papers 1., 5., 9. point out some of these differences with respect to reliability. This paper discusses hardware and software with respect to maintainability, to point out their similarities and differences in both conceptual and practical terms.     

Preparation, characterization and thermolysis of phenylenediammonium dinitrate salts

Four phenylenediammonium dinitrate salts were prepared and characterized by elemental, Infrared spectroscopy (IR), Ultraviolet spectroscopy (UV) and gravimetric methods. These dinitrates find application in propellant, explosives and pyrotechnics. Their thermal decomposition has been studied using thermogravimetry (TG) and simultaneous thermogravimetry-differential scanning calorimetry (TG–DSC). Kinetics parameters were evaluated by model fitting and isoconversional methods. Their thermolytic pathways have also been suggested, which involves decomposition followed by ignition.     

Mass transfer study of the electropolishing of vertical cylinders with active ends under natural convection conditions

Rates of electropolishing of vertical copper cylinders with active ends in H₃PO₄ were studied by measuring the limiting current under natural convection. Variables studied were H₃PO₄ concentration, cylinder diameter and aspect ratio. The rate of polishing of the whole cylinder was represented by the mass transfer equation $$Sh = 0.33(Sc Gr)^{0.32}$$ for the range 1.17 × 10¹⁰ < Sc Gr < 5.11 × 10¹¹. Rates of mass transfer were measured also at vertical cylinder with insulated ends, and the upward facing surface (disc). Data for the vertical cylindrical surface were represented for the range 8.75 × 10⁹ < Sc Gr < 1.1 × 10¹² by the equation $$Sh = 1.206(Sc Gr)^{0.255}$$ while data at the upward facing disc were correlated for the range 0.11 × 10¹⁰ < Sc Gr < 46 × 10¹⁰ by the equation $$Sh = 0.17Sc^{0.396} (Sc Gr)^{0.146}$$ A comparison between the measured rate of mass transfer at the whole cylinder and the value calculated by adding the rates of mass transfer at the separate surfaces of the cylinder shows that the measured value deviates from the calculated value, the degree of deviation increases with increasing Sc × Gr. Deviation was attributed to flow interaction at the different cylinder surfaces.     

A copper-base brazing alloy for electronics industries

A copper-based alloy with suitable additives has been developed. Major applications are envisioned in the electronics and vacuum-tube industries. The developed alloy with only half the quantity of silver is less expensive than the standard Ag-Cu eutectic alloy and possesses comparable brazing characteristics.