Remote sensing of pollutants using femtosecond laser pulse fluorescence spectroscopy

The fluorescence spectrum of ethanol molecules induced by femtosecond laser pulses has been recorded as the fingerprint of the molecules. It was demonstrated that, if this is combined with a LIDAR technique, the fluorescence from pollutants in the atmosphere could be detected over a long distance. PACS 42.68.Wt; 42.62.Fi; 42.65.Re     

Normalizability of one-dimensional quasi-exactly solvable Schrödinger operators

We completely determine necessary and sufficient conditions for the normalizability of the wave functions giving the algebraic part of the spectrum of a quasi-exactly solvable Schrödinger operator on the line. Methods from classical invariant theory are employed to provide a complete list of canonical forms for normalizable quasi-exactly solvable Hamiltonians and explicit normalizability conditions in general coordinate systems.Supported in Part by DGICYT Grant PS 89-0011Supported in Part by an NSERC GrantSupported in Part by NSF Grant DMS 92-04192     

Tissue self-affinity and polarized light scattering in the born approximation: a new model for precancer detection

Light scattered from biological tissues can exhibit an inverse power law spectral component. We develop a model based on the Born approximation and von Karman (self-affine) spatial correlation of submicron tissue refractive index to account for this. The model is applied to light scattering spectra obtained from excised esophagi of normal and carcinogen-treated rats. Power law exponents used to fit dysplastic tissue site spectra are significantly smaller than those from normal sites, indicating that changes in tissue self-affinity can serve as a potential biomarker for precancer.     

KF/clinoptilolite nanoparticles as a novel catalyst for the green synthesis of chromens using three component reactions of 4‐hydroxycoumarins: Study of antioxidant activity

In this research, the green synthesis of chromen derivatives in good yields is described via three‐component reactions of 4‐hydroxycumarine, aldehydes or ketones, and methyl ketones in the presence of KF/clinoptilolite nanoparticles (KF/CP‐NPs) under solvent‐free conditions at 50°C in low time. The present methodology suggests some advantages such as low reaction time, easy and simple procedure, green method, inexpensive catalyst, high yield of product, and existence of different substrates for performing these reactions. In addition, it should be mentioned that antioxidant activity was studied for some prepared compounds, such as 4a–4d, by DPPH radical trapping and reducing potential tests of ferric ion and then comparing results with TBHQ and BHT as synthetic antioxidants. In this study, compounds 4c was shown to have moderate DPPH radical trapping, and compounds 4b and 4d displayed good reducing power of ferric ion.     

Spatiotemporal patterns of stable isotopes and hydrochemistry in springs and river flow of the upper Karkheh River Basin,Iran

Karst springs of the Zagros Mountains contribute a significant amount to agricultural and human water demands of western and south-western Iran. For an adequate management of available water resources in semi-arid and arid regions, sufficient hydrological monitoring is needed, and hydro-chemical and isotope hydrological data provide important additional information. About 350 water samples were collected from precipitation, river water, and karst springs of the upper part of the Karkheh River Basin (20,895 km²) located between 33°35^′ and 34°55^′ North and 46°22^′ and 49°10^′ East with elevations ranging from 928 to 3563 m above sea level. Sampling was conducted in monthly time resolution from August 2011 to July 2012. All samples were analysed for hydro-chemical parameters (pH, electrical conductivity, and major ions) and stable isotopes (deuterium, oxygen-18). Isotope values of precipitation indicate a local meteoric water line (Zagros MWL δ²H=6.8 δ¹⁸O+10.1; R²=0.99) situated between the Mediterranean MWL and Global MWL. Spring and river water isotope values vary between?7.1 and?4.1 ‰, and?38 and?25 ‰ for δ¹⁸O and δ²H, respectively, responding to winter snowmelt and evaporation. This work implements stable isotopes and hydro-chemical information of springs and river water to understand hydrological and hydro-geological interrelations in karstic semi-arid areas and helps to improve the current water resources management practices of western Iran.     

Interdependence of primary and Johari-Goldstein secondary relaxations in glass-forming systems

We report evidence from broadband dielectric spectroscopy that the dynamics of the primary alpha- and secondary Johari-Goldstein (JG) beta-processes are strongly correlated in different glass-forming systems over a wide temperature T and pressure P range, in contrast with the widespread opinion of statistical independence of these processes. The alpha-beta mutual dependence is quantitatively confirmed by (a) the overall superposition of spectra measured at different T-P combinations but with an invariant alpha-relaxation time; (b) the contemporary scaling of the isothermal-pressure and isobaric-temperature dependences of the alpha-and beta-relaxation times as plotted versus the reduced variable Tg(P)/T where Tg is the glass transition temperature. These novel and model-independent evidences indicate the relevance of the JG relaxation phenomenon in glass transition, often overlooked by most current theories.     

Kiwifruit Actinidin: A Proper New Collagenase for Isolation of Cells from Different Tissues

Actinidin is a cysteine protease abundant in Kiwifruit. This enzyme is known as a meat-tenderizing protease. In this project, actinidin was purified from kiwifruit by salt precipitation and ion exchange chromatography. Collagenolytic effect of the purified enzyme was tested in four different buffer systems. Thereafter, the enzyme was used for isolation and culture of cells from three different tissues: endothelial cells from human umbilical vein, hepatocytes from rat liver, and thymic epithelial cells from rat thymus. Our results revealed that actinidin can hydrolyze collagen types I and II at neutral and alkaline buffers. Furthermore, actinidin compared with type II or IV collagenase isolated intact human umbilical vein endothelial cells, hepatocytes, and thymic epithelial cells with viability more than 90%. These results address a novel and valuable collagenase, which can be used efficiently for hydrolysis of collagen and isolation of different cell populations from various solid tissues.     

Ethylene glycol,an efficient and recoverable medium for copper-catalyzed N-arylation of diazoles under microwave irradiation

Ethylene glycol was used as an efficient and recoverable medium for the reaction of diazoles with aryl iodides and aryl bromides in the presence of CuCl₂ as the catalyst and K₂CO₃ as the base. Consequently, imidazole, benzimidazole, and pyrazole reacted readily under microwave irradiation to give good to excellent yields of their corresponding N-arylated products in relatively short time periods. Apparently, ethylene glycol plays a dual role by activating the catalyst and also providing a homogenous medium for the processes. The reaction medium consisting of the solvent, the base, and the copper salt was recovered and reused successfully in the next several reactions.