Spectroscopic Study of New Fluorescent Probes

Abstract— Various newly synthesized substances containing the same chromophore as PRODAN were subjected to a spectroscopic study. The new substances, ω-[6-( N -meth-yl- N -alkylamino)naphthoyl]alcanoic acids (MANA), possess polar groups and alkyl chains of variable length that make them potentially useful as fluorescent probes in membrane studies. This paper reports on their spectroscopic properties in various pure solvents. Their Stokes shifts are given and related to different physicochemical properties of the solvents. A theoretical study of the behavior of the new substances is also presented.     

Spectrophotometric determination of cyanide by unsegmented flow methods

Photometric methods for cyanide determination by normal and reversed FIA techniques and by completely continuous monitoring are proposed. The sampling rates for the first two techniques are 20 and 28/hr, respectively, the r.s.d. being less than 0.8% in both cases. A simulation of cyanide control in industrial waste waters shows the usefulness of the continuous monitoring method.     

Generalized inverses on normed vector spaces

We extend the concepts, introduced by C.R. Rao for Euclidean norms, of minimum g-inverses and least square g-inverses, using arbitrary norms. We give a characterization of such generalized inverses and an application to the case in which the norm is l_∞. As a result of this application we obtain that when $\text{A?}\text{C}{}^{\mathrm{(n+1)\times n}}$ has rank n, there exists a generalized inverse of A, which serves the same purpose as the Moore-Penrose inverse, when the norm is l_∞.     

Characterization of the Suzuki phase in doped alkali halides by Raman spectroscopy

The symmetries and frequencies of the Raman active modes of the Suzuki phase in the systems 6NaCl:CdCl₂; and 6NaCl:MnCl₂, have been calculated. Three of the four peaks allowed by symmetry (A_1g and 2F_g) agree to within 25% in position with the experimental values presented here and with other experimental results. The fourth peak (E_g) seems to be associated with a very soft mode, which explains why this peak has not been observed. The features of the Raman spectrum depend mainly upon the chlorine ions.     

Higgs masses in the standard,multi-Higgs and supersymmetric models

Theoretical constraints and limits on the masses of Higgs scalars in the standard electroweak model, in electroweak models with additional Higgs doublets and in various supersymmetric models are presented. In the standard model, the lower limit on the Higgs mass, based on vacuum stability arguments, is reviewed in detail, as are “upper limits” based on perturbative constraints. In most grand unified and all supersymmetric models, however, at least two doublets are needed. The masses of the various Higgs scalars in the two-doublet model are discussed and constraints on their masses are found, including the generalization of the above limits. The results are then generalized to models with more than two doublets. Finally, recent attempts at constructing models with low-energy supersymmetry are reviewed and it is shown that in many models, fairly stringent tree-level mass relations among the Higgs scalars can be found. These relations are interesting in that they do not refer to the supersymmetric partners of ordinary particles, and they are most restrictive in models in which the supersymmetry is explicitly broken, i.e., via arbitrary mass terms.     

Quasi-particle density of states of the one-dimensional Anderson-Hubbard Hamiltonian

The quasi-particle density of states of the one-dimensional Anderson-Hubbard Hamiltonian has been calculated. The effect of correlation on the local density of states of a disordered chain is shown to depend critically on the energy region.     

Enhancing sonochemical activity in aqueous media using power-modulated pulsed ultrasound: an initial study

Relatively little is known about the effects of pulsed ultrasound on the facilitation of chemical reactivity. Previous studies have indicated that sonochemistry using pulses is generally less effective than continuous ultrasonic irradiation. However, the pulse trains employed were such that the peak power of the pulses was the same as the maximum power used in continuous irradiation. As a result, less acoustic energy was transmitted to the solutions over the same period of time. The effectiveness of ultrasound when the pulse is adjusted so that the same amount of acoustic energy is input compared to continuous irradiation over a given time has not been previously explored. In this study we have embarked on an examination of the efficacy of power-modulated pulsed (PMP) sonochemistry. Specifically, we have explored the effects of pulse type and pulse frequency on the oxidation of potassium iodide and the degradation of acid orange, a common industrial colorant. A rate increase by a factor of three was observed compared with continuous irradiation under conditions of equivalent acoustic input power.     

Scaling exponents and probability distributions of DNA end-to-end distance

The scaling of the average gyration radius of polymers as a function of their length can be experimentally determined from ensemble measurements, such as light scattering, and agrees with analytical estimates. Ensemble techniques, yet, do not give access to the full probability distributions. Single molecule techniques, instead, can deliver information on both average quantities and distribution functions. Here we exploit the high resolution of atomic force microscopy over long DNA molecules adsorbed on a surface to measure the average end-to-end distance as a function of the DNA length, and its full distribution function. We find that all the scaling exponents are close to the predicted 3D values (upsilon=0.589+/-0.006 and delta=2.58+/-0.77). These results suggest that the adsorption process is akin to a geometric projection from 3D to 2D, known to preserve the scaling properties of fractal objects of dimension df<2.     

Locally periodic Timoshenko rod: experiment and theory

The flexural vibrations of a locally periodic rod, which consists of N unit cells, are discussed both from the experimental and theoretical points of view. Timoshenko's beam theory and the transfer matrix method are used to calculate the normal-mode frequencies and amplitudes. The theoretical values are then compared with the experimental ones, which are obtained using an electromagnetic acoustic transducer (EMAT). Good agreement between the numerical results and the experimental measurements is obtained. It is shown that as N grows, a band spectrum emerges.