Effects of inorganic and organic lead compounds on chromosomal length in human lymphocytes

In vitro exposure of human lymphocyte cultures to spindle inhibitors reduce the average chromosome length^1,2. In this report chromosome length measurements were used for indirect but quantitative evaluation of the effects of inorganic and organic lead compounds on spindle function. The data indicate that organic compounds are much more powerful spindle inhibitors than inorganic lead compounds, almost as potent as colchicine. Occupational exposure to organic lead compounds may result in partial spindle inhibition, leading to a high probability of nondisjunction.     

The measurement of the absorption spectra of chlorine e 6 photosensitizer and hemoglobin in whole blood by multiple light scattering

The potential of using multiple light scattering methods to monitor the state and concentration of photosensitizer and hemoglobin in whole blood is demonstrated. Samples of whole blood with various contents of chlorine e ₆ photosensitizer were studied in the spectral region of 620–850 nm. On the basis of experimentally measured coefficients of diffuse reflection and transmission, absorption spectra of blood with and without the photosensitizer and the concentrations of oxy-, deoxy-, and methemoglobin in the samples are calculated. On the basis of this information, the absorption spectrum of chlorine e ₆ in whole blood is reconstructed and its state and concentration are estimated for the first time. It is found that chlorine e ₆ in whole blood occurs mainly in the monomer form.     

Topology optimization of microfluidic mixers

This paper demonstrates the application of the topology optimization method as a general and systematic approach for microfluidic mixer design. The mixing process is modeled as convection dominated transport in low Reynolds number incompressible flow. The mixer performance is maximized by altering the layout of flow/non‐flow regions subject to a constraint on the pressure drop between inlet and outlet. For a square cross‐sectioned pipe the mixing is increased by 70% compared with a straight pipe at the cost of a 2.5 fold increase in pressure drop. Another example where only the bottom profile of the channel is a design domain results in intricate herring bone patterns that confirm findings from the literature. Copyright © 2008 John Wiley & Sons, Ltd.     

Gold(III) six-membered N^C^N pincer complexes: synthesis, structure, reactivity and theoretical calculations

The first six-membered gold(III) N^C^N pincer complex was obtained in good yield, under very mild conditions, by transmetalation of [Hg(κC-N^C^N)Cl] (N^CH^N = 1,3-bis(pyridin-2-ylmethyl)benzene, HL(1)) with Na[AuCl(4)]. The X-ray crystal structure of [Au(N^C^N)Cl][PF(6)] showed that the fused six-membered metallacycles each exist in a strongly puckered boat conformation. As shown by the (1)H NMR spectra in various solvents, the same structure is also retained in solution: no inversion of the six-membered metallacycles is observed in DMSO up to 95 °C. This correlates well with a reaction barrier of 17.5 kcal/mole, as determined by quantum chemical calculations. The reactivity of the present pincer complex is compared to that of the analogous 1,3-bis(2-pyridyl)benzene, HL(2), derivative, which has five-membered fused metallacycles. Sharp differences are found in the reactions with phosphines, such as PPh(3) and dppe (1,2-bis-diphenylphosphino-ethane), and with silver salts. Theoretical calculations were carried out on the two pincer complexes in order to try to understand these differences, and we found that the gold-chlorine bond is significantly stronger in the case of the complex containing five-membered metallacyclic rings.     

An NMR thermometer for cryogenic magic-angle spinning NMR: the spin-lattice relaxation of (127)I in cesium iodide

The accurate temperature measurement of solid samples under magic-angle spinning (MAS) is difficult in the cryogenic regime. It has been demonstrated by Thurber et al. (J. Magn. Reson., 196 (2009) 84-87) [10] that the temperature dependent spin-lattice relaxation time constant of ⁷⁹Br in KBr powder can be useful for measuring sample temperature under MAS over a wide temperature range (20–296 K). However the value of T₁ exceeds 3 min at temperatures below 20 K, which is inconveniently long. In this communication, we show that the spin-lattice relaxation time constant of ¹²⁷I in CsI powder can be used to accurately measure sample temperature under MAS within a reasonable experimental time down to 10 K.     

Nonlinear soliton matching between optical fibers

In this Letter, we propose a generic nonlinear coupling coefficient, η(NL)2=η|γ/β?|(fiber2)/|γ/β?|(fiber1), which gives a quantitative measure for the efficiency of nonlinear matching of optical fibers by describing how a fundamental soliton couples from one fiber into another. Specifically, we use η(NL) to demonstrate a significant soliton self-frequency shift of a fundamental soliton, and we show that nonlinear matching can take precedence over linear mode matching. The nonlinear coupling coefficient depends on both the dispersion (β?) and nonlinearity (γ), as well as on the power coupling efficiency η. Being generic, η(NL) enables engineering of general waveguide systems, e.g., for optimized Raman redshift or supercontinuum generation.     

3D ultrasound reconstruction algorithms from analog and digital data

Freehand 3D ultrasound is increasingly being introduced in the clinic for diagnostics and image-assisted interventions. Various algorithms exist for combining 2D images of regular ultrasound probes to 3D volumes, being either voxel-, pixel- or function-based. Previously, the most commonly used input to 3D ultrasound reconstruction has been digitized analog video. However, recent scanners that offer access to digital image frames exist, either as processed or unprocessed data. To our knowledge, no comparison has been performed to determine which data source gives the best reconstruction quality. In the present study we compared both reconstruction algorithms and data sources using novel comparison methods for detecting potential differences in image quality of the reconstructed volumes. The ultrasound scanner used in this study was the Sonix RP from Ultrasonix Medical Corp (Richmond, Canada), a scanner that allow third party access to unprocessed and processed digital data. The ultrasound probe used was the L14-5/38 linear probe. The assessment is based on a number of image criteria: detectability of wire targets, spatial resolution, detectability of small barely visible structures, subjective tissue image quality, and volume geometry. In addition we have also performed the more “traditional” comparison of reconstructed volumes by removing a percentage of the input data. By using these evaluation methods and data from the specific scanner, the results showed that the processed video performed better than the digital scan-line data, digital video being better than analog video. Furthermore, the results showed that the choice of video source was more important than the choice of tested reconstruction algorithms.     

Optimum fiber tapers for increasing the power in the blue edge of a supercontinuum-group-acceleration matching

We demonstrate how the gradient of the tapering in a tapered fiber can significantly affect the trapping and blueshift of dispersive waves (DWs) by a soliton. By modeling the propagation of a fundamental 10?fs soliton through tapered fibers with varying gradients, it is shown that the soliton traps and blueshifts an increased fraction of the energy in its DW when the gradient is decreased. This is quantified by the group-acceleration mismatch between the soliton and DW at the entrance of the taper. These findings have direct implications for the achievable power in the blue edge of a supercontinuum generated in a tapered fiber and explain observations of a lack of power in the blue edge.     

Maintaining the Regular Ultra Passum Law in data envelopment analysis

The variable returns to scale data envelopment analysis (DEA) model is developed with a maintained hypothesis of convexity in input–output space. This hypothesis is not consistent with standard microeconomic production theory that posits an S-shape for the production frontier, i.e. for production technologies that obey the Regular Ultra Passum Law. Consequently, measures of technical efficiency assuming convexity are biased downward. In this paper, we provide a more general DEA model that allows the S-shape.     

Synthesis of Simple Multivalent β-D-GalNAc-(1→4)-β-D-Gal Oligomers as Probes for Investigating the Interactions of P. Aeruginosa Pili with Multivalent Receptors

ABSTRACT

Five multivalent β-D-GalNAc-(1→4)-β-D-Gal oligomers were selected and synthesized as probes for investigating the adhesin-receptor interactions of P. aeruginosa pili with multivalent receptors. They were synthesized by the amide coupling reactions of 8-(N-2-aminoethyl)carboxamidooctyl 4-O-(2-acetamido-2-deoxy-β-D-galactopyranosyl)-β-D-galactopyranoside (7) with EDTA dianhydride, EDTA, Kemp's triacid and adipic acid with EDC, DIC and DCC combined with HOBt as coupling reagents and by the reaction of per-O-acetylated 7 with 1,3,5-benzenetricarbonyl trichloride followed by de-O-acetylation. These resulting multivalent compounds contain flexible C₉ spacer arms as linkers attached to either flexible hydrophilic moieties or rigid hydrophobic cores.