Frequently it is useful to compare experimental values of the hyperpolarizabilities β and γ with calculated values. It is also often helpful to compare experimental values of β obtained from dc-electric field induced second harmonic generation (dc-SHG) experiments, e.g., with values obtained using the solvatochromism method. In order to do this the hyperpolarizabilities must be defined using consistent conventions. In this paper, four commonly used conventions are discussed and simple factors for converting between them presented. In addition, the sum-over-states expression for the calculation of β and γ is described and its correct use in comparing with hyperpolarizabilities obtained using other experimental and theoretical techniques discussed. As an illustration of the consistent use of conventions, ab initio and semiempirical calculations on para-nitroaniline are compared with experimental dc-SHG values. This comparison highlights the difference between theoretical values of the hyperpolarizability with the molecule in a gas phase environment and experimental values obtained in polar solvents−a difference that has in the past been obscured by inconsistent choice of conventions.

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The first and second hyperpolarizabilities ͑␤ and ␥͒ of eight molecules at a fundamental wavelength of 1064 were measured by gas-phase electric-field-induced second-harmonic generation ͑EFISH͒, gas-phase hyper-Rayleigh scattering ͑HRS͒, and liquid-phase HRS experiments. The EFISH measurements give accurate values of ␤ and ␥ for these molecules in the gas phase, and the HRS measurements show that the effective ␤ of these molecules in the liquid is enhanced over the gas-phase value by a factor which varies from Ϸ0.4 to 2.0, over and above the Lorentz local field factors. Combining all of the measurements provides an accurate, absolute determination of the effective ␤ for HRS in the liquid phase. The results for CCl 4 , suitable as reference standards, are ͗␤ VV 2 ͘ 1/2 ϭ18.6Ϯ0.7 au in the liquid phase and ␤ xyz ϭ20.7Ϯ1.6 au in the gas phase. Comparison of measurements between hydrogenated and deuterated molecules indicates that vibrational contributions to ␤ are small.

Supplements and growth promotants containing steroid hormones are routinely administered to beef cattle to improve feeding efficiency, reduce behavioral problems, and enhance production. As a result, beef cattle manure will contain both synthetic steroids as well as a range of endogenous steroids including androgens, estrogens, and progestogens. A two-year controlled study was conducted in which beef cattle were administered steroid hormones via subcutaneous implants and feed additives and the occurrence of 16 endogenous and synthetic steroid hormones and metabolites was evaluated in runoff from beef cattle feedlots and in manure and soil collected from feedlot surfaces. Samples were extracted and analyzed using liquid chromatography tandem mass spectrometry for metabolites of the synthetic androgen trenbolone acetate, 17α-trenbolone, 17β-trenbolone, for the nonsteroidal semisynthetic estrogen agonist, α-zearalanol, and the synthetic progesterone melengesterol acetate, as well as a wide range of endogeneous estrogens, androgens, and f usarium metabolites. Synthetic steroids including trenbolone metabolites and melengestrol acetate were detected in fresh manure and in feedlot surface soils from cattle administered synthetic steroids at concentrations up to 55 ± 22 ng/g dry weight (dw) (17α-trenbolone) and 6.5 ± 0.4 ng/g dw (melengesterol acetate). Melengesterol acetate was detected in 6% of runoff samples from feedlots holding cattle administered synthetic steroids at concentrations ranging up to 115 ng/L. The presence of melengesterol acetate in runoff from beef cattle feeding operations has not been previously reported. Synthetic steroids were not detected in manure or runoff from control cattle. A wide range of endogenous hormones were detected in runoff and feedlot surface soils and manure from cattle given synthetic steroids and from control cattle, with no statistically significant differences in concentration. These results indicate that runoff from confined animal production facilities is of environmental and public health concern regardless of the use of growth promotants.

Articles you may be interested inComparison between optical nonlinearity relaxation times from coherent secondharmonic generation and from incoherent hyperRayleigh scattering Hyperpolarizabilities of the msubstituent phenyl amine based chromophores determined from the hyperRayleigh scattering and two photon absorption induced fluorescence Determination of first hyperpolarizability of nonlinear optical chromophores by second harmonic scattering using an external reference Hyper-Rayleigh light scattering measurements at incident wavelengths of 1064 and 1319 nm are reported for several organic nonlinear optical chromophores in solution with approximately 5%-10% uncertainty in the relative first hyperpolarizabilities. The measured chromophores include representatives from C 1 , C s , C 2V , and D 3 molecular point groups and include both neutral and ionic compounds. The measurements were made with 2-5 cm Ϫ1 spectral resolution and include polarization analysis of the incident and scattered light. Polarization ratios were measured with 2%-3% uncertainty for each molecule, and relative magnitudes of the hyperpolarizability components were deduced. Two-photon induced fluorescence from several chromophores was observed to overlap with the scattered second harmonic light spectrum. The use of a scanning monochromator, however, generally allows the separation of these two sources of photons. The measured first hyperpolarizabilities are consistent with previous electric field induced second harmonic generation measurements of the same compounds, provided that the standard reference value for the nonlinear susceptibility of quartz is taken to be d 11 ϭ0.30Ϯ0.02 pm/V at 1064 nm.