Liquid chromatographic determination of 4,4'-dinitrocarbanilide, the active component of the infertility agent nicarbazin, in chicken, duck, goose, and snake eggs

4,4'-Dinitrocarbanilide (DNC) was extracted from chicken, duck, goose, and snake eggs and isolated by reversed-phase liquid chromatography. DNC was detected by ultraviolet absorbance at 347 nm and quantitated by comparison with a calibration standard. Recoveries of DNC from fortified control chicken, duck, goose, and snake egg samples were determined for DNC levels of 0.16, 10, and 16 microg/g. The mean recoveries from chicken, duck, goose, and snake eggs were 92 +/- 4, 88 +/- 9, 87 +/- 7, and 95 +/- 6%, respectively. The method limits of detection for DNC in chicken, duck, goose, and snake eggs ranged from 0.015 to 0.035 microg/g. The reported method is much simpler than and equally efficient as previous methods developed for the determination of DNC residues in egg contents.     

Linearization of the interaction principle: Analytic Jacobians in the “Radiant” model

In this paper we present a new linearization of the Radiant radiative transfer model. Radiant uses discrete ordinates for solving the radiative transfer equation in a multiply-scattering anisotropic medium with solar and thermal sources, but employs the adding method (interaction principle) for the stacking of reflection and transmission matrices in a multilayer atmosphere. For the linearization, we show that the entire radiation field is analytically differentiable with respect to any surface or atmospheric parameter for which we require Jacobians (derivatives of the radiance field). Derivatives of the discrete ordinate solutions are based on existing methods developed for the LIDORT radiative transfer models. Linearization of the interaction principle is completely new and constitutes the major theme of the paper. We discuss the application of the Radiant model and its linearization in the Level 2 algorithm for the retrieval of columns of carbon dioxide as the main target of the Orbiting Carbon Observatory (OCO) mission.     

Low-loss chalcogenide waveguides on lithium niobate for the mid-infrared

We demonstrate low-loss chalcogenide (As(2)S(3)) waveguides on a LiNbO(3) substrate for the mid-IR wavelength (4.8 μm). Designed for single-mode propagation, they are fabricated through photolithography and dry-etching technology and characterized on a mid-IR measurement setup with a quantum cascade laser. For straight waveguides, propagation loss as low as 0.33 dB/cm is measured and low-loss bends on the order of 100 μm are simulated, with measurement results showing <3 dB for a 250 μm bend radius. The coupling efficiency is estimated to be 81%. In addition, the influences of variations in width and bend radius are also investigated.     

Structure, morphology, and thermal properties of nanocomposites based on polyamido imide and hydrosilicate nanotubes

New nanocomposites based on heat-resistant poly[(diphenyl oxide)amido-N-phenylphthalimide] with Mg₃Si₂O₅(OH)₄ hydrosilicate nanoparticles of tubular structure were prepared. The structure, morphology, and thermal properties of the nanocomposites were studied in relation to the content of hydrosilicate nanotubes.     

Calculation of Jacobians for inverse radiative transfer: An efficient hybrid method

We present an accurate and numerically efficient procedure of calculating Jacobians by finite difference that consists of two components: (1) a method employing the saving of atmospheric layers that accelerates the solution to the equation of radiative transfer for solvers that use the Discrete Space formulation and (2) a method of perturbing the eigenmatrix spectrum associated with a reduced attenuation matrix. The procedure eliminates the need to call the eigenmatrix package, here, LAPACK a second time and provides insights into the fundamental properties of the attenuation matrix, useful for characterizing the accuracy of the derivatives calculated by finite difference methods. The computational complexity of the perturbation method is 8n³+22n², where n is one half the number of streams in the radiance field as opposed to 16n³ using LAPACK. The method is not limited to the calculation of base state radiances I(ω) and those associated with an ‘infinitesimal’ perturbation I(ω+δω) (from which the numerical derivative of I(ω+δω) with respect to δω may be approximated), but is also useful in the calculation of radiances associated with a ‘finite’ perturbation I(ω+Δω) from which a sensitivity can be calculated.     

The acoustic and perceptual effects of two noise-suppression algorithms

Internal noise generated by hearing-aid circuits can be audible and objectionable to aid users, and may lead to the rejection of hearing aids. Two expansion algorithms were developed to suppress internal noise below a threshold level. The multiple-channel algorithm's expansion thresholds followed the 55-dB SPL long-term average speech spectrum, while the single-channel algorithm suppressed sounds below 45 dBA. With the recommended settings in static conditions, the single-channel algorithm provided lower noise levels, which were perceived as quieter by most normal-hearing participants. However, in dynamic conditions "pumping" noises were more noticeable with the single-channel algorithm. For impaired-hearing listeners fitted with the ADRO amplification strategy, both algorithms maintained speech understanding for words in sentences presented at 55 dB SPL in quiet (99.3% correct). Mean sentence reception thresholds in quiet were 39.4, 40.7, and 41.8 dB SPL without noise suppression, and with the single- and multiple-channel algorithms, respectively. The increase in the sentence reception threshold was statistically significant for the multiple-channel algorithm, but not the single-channel algorithm. Thus, both algorithms suppressed noise without affecting the intelligibility of speech presented at 55 dB SPL, with the single-channel algorithm providing marginally greater noise suppression in static conditions, and the multiple-channel algorithm avoiding pumping noises.     

Comparison of direct and indirect calculations of laryngeal airway resistance in connected speech

Direct measures of subglottal pressure obtained through a tracheal puncture were used to calculate laryngeal airway resistance. Six subjects completed tasks including syllable trains and more natural speech samples produced at three loudness levels. Direct calculations of natural speech resistance values were compared with indirect estimates obtained during syllable train production. The degree of correspondence between direct and indirect calculations varied by subject. Overall, the smallest relative errors among calculations occurred for syllable trains, with higher relative errors for the monologue and sentence. For loudness conditions, the smallest and largest relative errors occurred for soft and loud productions, respectively. The clinical utility of indirect estimation is questioned and suggestions for improving its validity are provided.     

A Carbohydrate Approach to the Enantioselective Synthesis of 1,3-Polyols

Treatment of per-O-benzoyl-D-glycero-D-gulo-heptono-1,4-lactone (2) with tertiary amines afforded selectively and with good yields the (5H)-furan-2-one derivatives 3, 4, and 5, formed by controlled elimination of one, two, or three molecules of benzoic acid, respectively. The stereochemistry for the exocyclic double bonds of 4 and 5 was determined by means of NMR techniques. Particularly, the furanone 4 was obtained from 2 ( approximately 90% yield) as a mixture of the E and Z diastereoisomers, which were separated by column chromatography or, more efficiently, by HPLC. The catalytic hydrogenation of compounds 4-E and 4-Z took place diastereoselectively, due to the chiral induction of the stereocenter located in the lateral chain. Thus, hydrogenation of 4-E led to a mixture of the 4,5-dihydro-(3H)-furan-2-ones having 3R,5S,2'S (D-xylo, 6) and 3S,5R,2'S (D-arabino, 7) configurations, with 6 as the major product; whereas the 4-Z isomer gave the same mixture, but being 7 preponderant. On hydrogenation of the original 4-E/Z mixture, compound 6 was obtained pure after recrystallization. O-Debenzoylation of 6gave 9, which was reduced with NaBH(4) to the 3,5-dideoxy-meso-xylo-heptitol (11). The peracetate (12) and perbenzoate (13) of the latter were prepared, and the 1-(tert-butyldiphenylsilyl)oxy derivative (16) was also synthesized via the 3'-(silyloxy)-4,5-dihydro-(3H)-furan-2-one 14. Chemoselective reduction of the lactone function of 6 with diisoamylborane gave the 2,5,6-tri-O-benzoyl-3,6-dideoxy-D-xylo-heptofuranose (17). The 3,5-dideoxy-D-arabino-heptitol (18), a diastereoisomer of 11, was also isolated and characterized.