Structural conversions of rhodamines in solution

A study has been made of the acidic ionization, structural conversions, and prototropic tautomerism of rhodamine chromogens in methanol and dimethyl sulfoxide, using IR, ¹³ C NMR, and electronic spectroscopy. The lactone structure has been established for the colorless form of rhodamines in DMSO. For rhodamine B in mixtures of water with DMSO, the lactone/zwitterion ratio has been estimated.V. I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Russian Academy of Sciences, Moscow 117975. Khar'kov State University, Khar'kov 310077. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 3, pp. 512–521, March, 1992.     

Active control of extended Van der Pol equation

We study in this paper the active control of a driven class of Van der Pol oscillator which exhibits three limit cycles. We begin by investigating the dynamics and stability analysis of the system under active control. We also analyze the effects of a time periodic perturbation included in the control process. In all these cases the domain of control gain parameters leading to a good control is obtained and verified numerically.     

Higher discriminants of binary forms

We propose a method for constructing systems of polynomial equations that define submanifolds of degenerate binary forms of an arbitrary degeneracy degree. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 153, No. 2, pp. 147–157, November, 2007.     

Nuclear Excitation by X-Ray Emission of Femtosecond Laser Plasma

The proposed model of laser plasma emission spectrum formation enables us to determine the absolute value of the laser pulse to plasma emitted radiation conversion factor, profile of the emission spectrum, and frequency distribution of the intensity and energy in the emitted spectra. This is of interest for laser plasma diagnostics and provides a means for direct calculation of the number of excited nuclei in dependent on the parameters of laser pulse. This revised version was published online in August 2006 with corrections to the Cover Date.     

Analyzing the effect of the inventory policy on order and inventory variability with linear control theory

In this paper we apply linear control theory to study the effect of various inventory policies on order and inventory variability, which are key drivers of supply chain performance. In particular, we study a two-echelon supply chain with a stationary demand pattern under the influence of three inventory policies: an inventory-on-hand policy that bases orders on the visible inventory at an installation, an installation-stock policy that bases orders on the inventory position (on-hand plus on-order inventory) at an installation, and an echelon-stock policy that bases orders on the inventory position at that installation and all downstream installations. We prove analytically that the inventory-on-hand policy is unstable in practical settings, confirming analytically what has been observed in experimental settings and in practice. We also prove that the installation-stock and echelon-stock policies are stable and analyze their effect on order and inventory fluctuation. Specifically, we show the general superiority of the echelon-stock in our setting and demonstrate analytically the effect of forecasting parameters on order and inventory fluctuations, confirming the results in other research.     

Inclusion of cinnamaldehyde in modified γ-cyclodextrins

This work deals with the formation of inclusion complexes between cinnamaldehyde and two synthetic alkylcarbonates of γ-cyclodextrin, namely ethylcarbonate-γ-CD and octylcarbonate-γ-CD. Complexation was monitored by phase-solubility studies, by FT-IR spectroscopy and by DSC and TG analysis. The diffusion of cinnamaldehyde through a cellulose membrane was investigated in the absence and in the presence of each of the two γ-CD alkylcarbonates. Studies on photostability and stability over time were carried out on different cosmetic formulations containing pure cinnamaldehyde or an equivalent amount of cinnamaldehyde complexed with the two alkylcarbonates. Phase-solubility diagrams, DSC, FTIR and TGA analysis suggested the formation of inclusion complexes. The diffusion of cinnamaldehyde through the cellulose membrane decreased in the presence of the two alkylcarbonates confirming the interaction of this molecule with the inclusion agents. Moreover the stability of cinnamaldehyde to light and heat resulted increased by complexing this fragrance material with the two alkylcarbonates.     

First synthesis of magnesacyclopentadienes from acetylenes by treatment with BuMgHlg in the presence of Zr complexes

Treatment of internal acetylenes and allenes with BuMgHlg (Hlg = Cl, Br) in the presence of Cp₂ZrCl₂ selectively leads to the formation of substituted magnesacyclopenta-2,4-dienes and alkylidenemagnesacyclopentenes.     

Evaluation ofwaste perlite fines in the production of construction materials

The use of supplementary cementitious materials (SCM) is a well established practice worldwide in the manufacture of Portland cement (PC)-based construction materials. While utilisation of industrial by-products has been successful, the potential of mining wastes is yet to receive adequate attention in the context of construction materials. In an expanded form perlite, which is a naturally occurring, hydrated volcanic siliceous glass, is an ideal material as a lightweight aggregate for use in a wide range of construction materials including concrete. The mining and processing of the grades of perlite required for the production of lightweight aggregate results in the creation of a fine grained waste which currently has no economic value. This paper reports preliminary data on the utilisation of waste perlite fines as a SCM in calcium silicate-based construction material and discusses the potential of this mining waste to reduce the environmental impact of the production of conventional cement-based construction materials.