Conjugation and proton exchange equilibria I. Significant role of proton exchange and homoconjugation equilibria in protonic hetero systems

The significant role of the proton exchange and homoconjugation (formation of AHA^– and A₁HA ₁ ^– complexes) equilibria in protonic hetero systems (HA+A ₁ ^– ) has been shown from analysis of published data and from my own simple experiments. It is concluded that there is a need to reconsider some basic hydrogen bond problems. One of these problems-the existence of heteroconjugates in polar solvents — has been verified and illustrated with suitable experimental evidence (IR and UV-VIS spectra). The most accepted experimental evidence for the double minimum potential in the hydrogen bridge has been questioned as being in disagreement with the equilibrium law. A simple relation between the heteroconjugation constant, the parent homoconjugation constants and the proton exchange constant is also postulated. This relation fulfills important theoretical requirements, however, it is not applicable in extreme cases.To the memory of Bogdan Przybyszewski.     

Generation of low-density plasma by two-step photoionization of barium and its evolution in electric field

Two-color, two-step resonant photoionization has been used to produce low-density (∼10⁶ – 10⁷cm⁻³) barium photoplasma in an atomic beam. The two-photon induced specific absorption coefficient at 355nm for the photoionization process has been measured. The motion of the finite size photoplasma bounded by vacuum is experimentally studied in a static electric field in parallel-plate electrode configuration. It is observed that at sufficiently high electric fields all electrons leave the plasma and the evolution of the left over ion bunch is understood on the basis of independent particle motion.     

Studies on photoinduced effects in pulse-electrodeposited Ag/Hg-1212/CdSe hetero-nanostructures

Metal/superconductor/semiconductor (Ag/Hg-1212/CdSe) hetero-nanostructures have been fabricated using pulse-electrodeposition technique and are characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The junction capacitance of Ag/Hg-1212, Hg-1212/CdSe and Ag/Hg-1212/CdSe heterojunctions is measured in dark and under laser irradiation at room temperature. The nature of the junction formed and built-in-junction potentials were determined. The increase in carrier concentration across the junction due to photo-irradiation has been observed.     

Two-step single-colour photoionization spectroscopy of atomic uranium

The single-colour photoionization spectrum of atomic uranium is recorded in the spectral region from 366 to 371 nm. Most of the 43 observed resonances are found to be associated with the two-step photoionization process. Based on known energy levels seven new transitions have been proposed. Three of these transitions originate either from the ground state or the lowest metastable state at 620 cm^–1.     

Effect of laser irradiation of C-V characteristics of electrodeposited Ag/Tl-2223/CdSe hetero-nanostructures

One of the innovative technological directions for the high-temperature superconductors has been persued by fabricating the heteroepitaxial multilayer structures such as superconductor-semiconductor heterostructures. In the present investigation, metal/superconductor/semiconductor (Ag/Tl-2223/CdSe) hetero-nanostructures have successfully been fabricated using dc electrodeposition technique and were characterized by X-ray diffraction (XRD), full-width at half-maximum (FWHM) and scanning electron microscopy (SEM) studies. The measurement of junction capacitance as a function of biasing voltage was used for the estimation of junction built-in-potential (V _D) and to study the charge distribution in a heterojunction. The Mott-Schottky plots were measured for each junction in dark and under the photo-irradiation. The effect of laser irradiation on C-V characteristics of hetero-nanostructure has been studied.     

Biclosure and bistability in a balanced bipartite graph

The k-biclosure of a balanced bipartite graph wiht color classes A and B is the graph obtained from G by recursively joining pairs of nonadjacent vertices respectively taken in A and B whose degree sum is at least k, until no such pair remains. A property P defined on all the balanced bipartite graphs of order 2n is k-bistable if whenever G + ab has property P and d_G(b) ≧ k then G itself has property P. We present a synthesis of results involving, for some properties, P, the bistability of P, the k-biclosure of G, the number of edges and the minimum degree. © 1995 John Wiley & Sons, Inc.     

Clinical decision support system for dental treatment

BackgroundIn this research, a decision making system, based on fuzzy inference mechanism as proposed by Mamdani, is presented. Literature suggests that there is a lack of consistency among dentists in choosing treatment plan(s). So, this research work aims to facilitate the dentist decide the treatment plan(s) of the broken tooth.MethodsAn expert system based on fuzzy logic has been designed to accept inaccurate and vague values of dental signs and symptoms associated with the broken tooth. We designed a knowledge base with 60 rules and used Mamdani inference algorithm to decide the possible one or more treatment(s) and suggest the same to the dentist.ResultsThe results proposed by the system are compared with the dentists’ suggestions. The Chi-square test of homogeneity is conducted on 100 randomly generated sample cases with the help of three professional dentists. It is found that the results produced by the system are consistent with the treatment plan(s) proposed by the dentists. Chi-square value of the test is 3.843565 which is less than the critical value which is 12.592. Hence, we are unable to reject the null hypothesis that assumes the two populations are homogeneous with respect to treatments.ConclusionsThe accuracy of the proposed decision support system for the treatment of broken tooth enhances the confidence level of the dentists while making decision regarding the treatment plan(s). Simple and interactive GUI makes it easy to use.     

Nanocomposites of polyamide‐11 and carbon nanostructures: Development of microstructure and ultimate properties following solution processing

There is growing interest in the incorporation of nanoparticles into engineering polymers to improve various functional properties. However, ultimate properties of nanocomposites are affected by a large number of factors including the microstructural distributions that are generated during processing. In this work, polyamide‐11 (PA‐11) (also known as nylon‐11) nanocomposites are generated with carbon nanostructures employing a solution crystallization technique at multiple polymer and nanoparticle concentrations, followed by drying, molding, uniaxial stretching and the analysis of the microstructural distributions and tensile properties of the nanocomposites. The morphology of crystals of PA‐11 encapsulating the nanoparticles changed from nano‐hybrid shish‐kebabs at low polymer concentration (0.02 wt % PA‐11 in solvent) to spherulites at high polymer concentration (10 wt % PA‐11 in solvent). The drawing down of nanocomposite films at draw ratios ranging from 2 to 5 at 100 °C resulted in a shift of the PA‐11 polymorph from the generally‐encountered α phase to the technologically interesting γ phase (which is the crystal phase attributed to the piezoelectric and pyroelectric properties of PA‐11). The drawing down also increased of the tensile modulus and yield stress of the nanocomposite films. In contrast, the α phase was conserved at a drawdown temperature of 150 °C, which was attributed to the resulting smaller normal force, i.e., the normal stress difference and the higher temperature allowing the partial relaxation of some of the macromolecules. These findings illustrate how PA‐11 can be structured in the presence of carbon nanotubes and nanofibers to achieve enhanced functionality, which could broaden the application areas and utility of this polymer. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1311–1321, 2011     

玫瑰红与介孔二氧化硅生物光敏复合体的激发态性质

以光动力治疗药物玫瑰红( Rose Bengal,RB)与孔径为2.7nm的介孔二氧化硅MCM-41为主体材料进行结构组装,制备了具有生物光敏功能的介孔复合载体.对介孔复合载体的性质进行了表征,通过紫外吸收和荧光光谱对玫瑰红RB在介孔孔道内的光学性质进行了分析.由于介孔道表面与RB的相互作用,不同结构和性质的内孔道中的...