Recent Advances in Transition Metal‐Catalyzed Hydrogenation of Nitriles

Amines are important building blocks possessing various applications in agrochemicals, the fine chemical industry, pharmaceuticals, materials science and biotechnology. The catalytic hydrogenation of nitriles is an important reaction for the one‐step synthesis of diverse amines. However, significant amounts of side product formation during the course of the reaction is a major issue. In recent years, an enormous amount of work has been reported using both homogeneous and heterogeneous transition metal complex catalysts for the selective reduction of nitriles. Transition metal catalysts are the most crucial factor that controls the selectivity in this reaction. Therefore, transition metal catalysts are the central point of this review. We have also briefly discussed the effect of reaction parameters, selectivity to different substrate structures and reaction mechanisms. This review provides an overview of recent developments in transition metal‐catalyzed nitrile reduction along with examples which highlight its vast potential in organic transformations.

     

Triplex Formation by Oligonucleotides Containing Organomercurated Base Moieties

Homothymine oligonucleotides with a single 5‐mercuricytosine or 5‐mercuriuracil residue at their termini have been synthesized and their capacity to form triplexes has been examined with an extensive array of double‐helical targets. UV and circular dichroism (CD) melting experiments revealed the formation and thermal denaturation of pyrimidine ? purine*pyrimidine‐type triple helices with all oligonucleotide combinations studied. Nearly all triplexes were destabilized upon mercuration of the 3′‐terminal residue of the triplex‐forming oligonucleotide, in all likelihood due to competing intramolecular Hg^II‐mediated base pairing. Two exceptions from this general pattern were, however, observed: 5‐mercuricytosine was stabilizing when placed opposite to a T ? A or A ? T base pair. The stabilization was further amplified in the presence of 2‐mercaptoethanol (but not hexanethiol, thiophenol or cysteine), suggesting a stabilizing interaction other than Hg^II‐mediated base pairing.     

Trends in Power Quality Monitoring

This letter introduces two Pade/spl acute/ approximation schemes that, when combined, enable the ABCD parameters of multiconductor transmission lines to be accurately and efficiently evaluated directly in the phase domain for application to harmonic analysis studies. Since the solution is obtained directly in the phase domain, modal decompositions are completely avoided.     

Regulation of Reproduction in the Primitively Eusocial Wasp <Emphasis Type="Italic">Ropalidia marginata</Emphasis>: on the Trail of the Queen Pheromone

Queens and workers are not morphologically differentiated in the primitively eusocial wasp, Ropalidia marginata. Upon removal of the queen, one of the workers becomes extremely aggressive, but immediately drops her aggression if the queen is returned. If the queen is not returned, this hyper-aggressive individual, the potential queen (PQ), will develop her ovaries, lose her hyper-aggression, and become the next colony queen. Because of the non-aggressive nature of the queen, and because the PQ loses her aggression by the time she starts laying eggs, we hypothesized that regulation of worker reproduction in R. marginata is mediated by pheromones rather than by physical aggression. Based on the immediate loss of aggression by the PQ upon return of the queen, we developed a bioassay to test whether the queen’s Dufour’s gland is, at least, one of the sources of the queen pheromone. Macerates of the queen’s Dufour’s gland, but not that of the worker’s Dufour’s gland, mimic the queen in making the PQ decrease her aggression. We also correctly distinguished queens and workers of R. marginata nests by a discriminant function analysis based on the chemical composition of their respective Dufour’s glands.     

One-pot PEG-mediated syntheses of 2-(2-hydrazinyl) thiazole derivatives: novel route

Thiazoles are important sulfur-containing molecules that are widely used in diverse fields such as pharmaceuticals, agrochemicals, and material sciences. This is the first report on the PEG-300-mediated one-pot synthesis of 2-(2-hydrazinyl) thiazole derivatives from ketones, thiosemicarbazide, and α-halo ketones. Here PEG-300 acts as a solvent as well as supporting catalyst. Formation of compounds was confirmed by IR, ¹H NMR, ¹³C NMR, and mass spectroscopic studies.

A series of 2-(2-hydrazinyl) Thiazole derivatives have been synthesized from substituted ketones, thiosemicarbazide & α-halo ketones using PEG-300 as a reaction medium via one-pot approach.     

Application of AHP for Ranking of Total Productive Maintenance Pillars

Total Productive Maintenance—TPM is widely being used in industries for manufacturing excellence. TPM is based on its eight pillars. Successful Implementation of TPM from its kick-off to final stage depends on in-depth knowledge of these pillars. The purpose of the paper is to rank eight pillars of TPM according to their importance with respect to four parameters: Productivity, Cost, Quality and Delivery in Time, by using Analytic Hierarchy Process (AHP) a multiple criteria decision-making methodology. A pairwise comparison of TPM pillars is done by use of AHP method, by considering a case of automotive industries in India. Ranking of TPM pillars is proposed to set guidelines to decide the weightage of each pillar in terms of major factors to improve Overall Equipment Efficiency. This in terms will guide management to give proper preference and allocate fund at proper time to proper pillar. The ranking suggested suites for automotive sector and assembly lines. By varying the judgmental rating the new ranking can be obtained from the suggested guidelines on similar basis.     

用椰壳制活性炭吸附去除三价铋离子(英文)

In present study,we report the preparation of coconut shell activated carbon as adsorbent and its appli-cation for Bi(Ⅲ) removal from aqueous solutions.The developed adsorbent was characterized with scanning elec-tron microscope(SEM),Fourier Transform Infrared(FTIR),C,H,N,S analyzer,and BET surface area analyzer.The parameters examined include agitation time,initial concentration of Bi(Ⅲ),adsorbent dose and temperature.The maximum adsorption of Bi(Ⅲ)(98.72%) was observed at 250 mg·L-1 of Bi(Ⅲ) and adsorbent dose of 0.7 g when agitation was at 160 r·min-1 for 240 min at(299±2) K.The thermodynamic parameters such as Gibb’s free energy(△Gθ),enthalpy(△Hθ) and entropy(△Sθ) were evaluated.For the isotherm models applied to adsorption study,the Langmuir isotherm model fits better than the Freundlich isotherm.The maximum adsorption capacity from the Langmuir isotherm was 54.35 mg?g?1 of Bi(Ⅲ).The kinetic study of the adsorption shows that the pseudo second order model is more appropriate than the pseudo first order model.The result shows that,coconut shell ac-tivated carbon is an effective adsorbent to remove Bi(Ⅲ) from aqueous solutions with good adsorption capacity.     

Gelatin–κ-carrageenan polyelectrolyte complex hydrogel compositions for the design and development of extended-release pellets

Present investigation was aimed to develop Zaltoprofen-loaded extended-release (ER) pellets formulation for prolonged release. The matrix type of pellets was prepared by extrusion-spheronization technique using calcium chloride-mediated gelatin–κ-carrageenan (G–κ-Carr) polyelectrolyte complex (PEC) hydrogel using rotatable central composite design. The pellets were characterized for physicochemical, morphological, solid-state characterization and flow properties. The formulations were also estimated for drug release and mucoadhesion potential. The optimized formulation (F1) containing 5:5 ratio of G–κ-Carr showed a drug release up to 98.2% and mucoadhesion of 95%. Optimized formulation showed acceptable release pattern, and hence would be viable alternative to ER type of formulations.     

Inelastic X-ray scattering experiments on B4C under high static pressures

Boron K-edge inelastic X-ray scattering experiments were performed on clean B₄C and shock impact recovered boron carbide up to 30 GPa and at ambient temperature to understand the pressure induced bonding changes. The spectral features corresponding to the boron site in the interlinking chain remained unchanged up to 30 GPa. The results of our experiments indicate that pressure induces less distortion to the boron sites and the local amorphization observed in the previous reports are due to the rearrangement of carbon atoms under extreme conditions without affecting the boron environment.     

Modular Models of Intelligence – Review, Limitations and Prospects

AI applications are increasingly moving to modular agents, i.e.,systems that independently handle parts of the problem based on smalllocally stored information (Grosz and Davis 1994), (Russell and Norvig 1995). Many suchagents minimize inter-agent communication by relying on changes in theenvironment as their cue for action. Some early successes of thismodel, especially in robotics (``reactive agents'), have led to adebate over this class of models as a whole. One of theissues on which attention has been drawn is that of conflicts betweensuch agents. In this work we investigate a cyclic conflict thatresults in infinite looping between agents and has a severedebilitating effect on performance. We present some new results inthe debate, and compare this problem with similar cyclicity observedin planning systems, meta-level planners, distributed agent models andhybrid reactive models. The main results of this work are:(a) The likelihood of such cycles developing increasesas the behavior sets become more useful.(b) Control methods for avoiding cycles such asprioritization are unreliable, and(c) Behavior refinement methods that reliably avoidthese conflicts (either by refining the stimulus, or by weakeningthe action) lead to weaker functionality.Finally, we show how attempts to introduce learning into thebehavior modules will also increase the likelihood of cycles.