A versatile high-permittivity phantom for EIT

Phantoms are frequently used in medical imaging systems to test hardware, reconstruction algorithms, and the interpretation of data. This report describes and characterizes the use of powdered graphite as a means of adding a significant reactive component or permittivity to useful phantom media for electrical impedance imaging. The phantom materials produced have usable complex admittivity at the electrical impedance tomography (EIT) frequencies from a few kilohertz to 1 MHz, as measured by our EIT system (ACT4) and by a commercial bioimpedance analyzer (BIS 4000, Xitron). We have also studied a commercial ultrasound coupling gel, which is highly electrically conductive and semisolid but that permits objects to move within it. The mixture of agar–graphite and gel–graphite, increases in permittivity and conductivity are proportional to the graphite concentration. We also report the use of a porous polymer membrane to simulate skin. A thin layer of this membrane increased resistance and the characteristic frequency of the phantoms, providing a promising candidate to simulate the effect of skin and the layered structure of a breast or other anatomical structure. The graphite also provides a realistic level of “speckle” in ultrasound images of the phantom, which may be useful in developing dual-mode imaging systems with ultrasound and the EIT.      

The monolithic multicell: a tool for testing material components in dye‐sensitized solar cells

A multicell is presented as a tool for testing material components in encapsulated dye‐sensitized solar cells. The multicell is based on a four‐layer monolithic cell structure and an industrial process technology. Each multicell plate includes 24 individual well‐encapsulated cells. A sulfur lamp corrected to the solar spectrum has been used to characterize the cells. Efficiencies up to 6·8% at a light‐intensity of 1000 W/m^su2 (up to 7·5% at 250 W/m²) have been obtained with an electrolyte solution based on γ‐butyrolactone. Additionally, a promising long‐term stability at cell efficiencies close to 5% at 1000 W/m² has been obtained with an electrolyte based on glutaronitrile. The reproducibility of the cell performance before and after exposure to accelerated testing has been high. This means that the multicell can be used as an efficient tool for comparative performance and stability tests. Copyright © 2006 John Wiley & Sons, Ltd.     

1D-photonic crystals prepared from the amorphous chalcogenide films

We describe the preparation and optical properties of the 15-layer chalcogenide dielectric mirrors with the first order stop bands in near infrared range. The high refractive index Sb–Se and low refractive index Ge–S layers were deposited on silicon and glass substrates using thermal evaporation method. To centre the stop bands of the prepared chalcogenide mirrors at 1.55 μm, the layer thicknesses, d(Sb–Se) = 117 and d(Ge–S) = 183 nm, were calculated from the quarter wave stack condition. The optical reflectivity measurements revealed the total reflection from the 15-layer chalcogenide mirrors in the range of 1,400–1,600 nm for the unpolarized light with normal incidence. The effect of annealing on the optical properties of the prepared chalcogenide mirrors was studied as well. Using spectral ellipsometry, we examined the angular dependence of the multilayers reflectivity for the light with s- and p-polarization. The preparation of the dielectric mirrors for near infrared region from chalcogenide films seems to be possible exploiting good optical quality of chalcogenide films and their simple deposition.     

Interactions between human neutrophils and mucin-coated surfaces

Recently, we showed microscopically that bovine (BSM), porcine (PGM) and human (MG1) mucin coatings could suppress the adhesion of neutrophils to a polyethylene terephthalate-based model biomaterial (Thermanox). Here, using the release of reactive oxygen species (ROS) as a marker of material-induced neutrophil activation, the strong surface-passivating effects of these mucin coatings were corroborated. Under optimal adsorption conditions, all mucin species performed equally well, thus indicating a high degree of functional homology between the mucins. Cell adhesion and morphology correlated well with the release of ROS. Quartz crystal microbalance (QCM-D) analysis linked low neutrophil activation to efficient mucin surface-shielding. Interestingly, the shielding power appeared equal for thick expanded and thin compact mucin coatings. Combined mucin-serum coatings were found to be highly surface-passivating. Particularly, since our data suggested partly synergistic mucin-serum action, we highlight the possibility that pre-adsorbed mucins could provide favorable support for adsorbing host components.     

Predictors of driving after alcohol and drug use among adolescents in Valencia (Spain)

Background

Driving under the influence of alcohol and drugs has been identified as a risk factor for road traffic crashes. We have assessed the prevalence and predictor factors for driving after alcohol and drug use by adolescents.

Methods

A cross-sectional survey involving 11,239 students aged 14–18 years from 252 private and public schools in the Valencia region of Spain was conducted. The prevalence and predictors of driving after alcohol use, alcohol and drug use, or drug use during the previous 6 months were measured.

Results

Of the students who reported driving (20%), 45.1% indicated driving after alcohol and drug use. The consumption of various drugs was higher among students who drove a vehicle compared with those who did not. The likelihood of driving after consuming alcohol, or alcohol and drugs, increased in line with the number of standard drink units per week, reports of any lifetime alcohol- or drug-related problems, and poor family relationship. In addition, masculine gender and early alcohol use increased the likelihood of driving after consuming alcohol.

Conclusions

Driving after alcohol and drug use is quite prevalent among adolescents in the Valencia region of Spain. There is a need for implementation of targeted policies for adolescents. This should focus on education and information on alcohol/drug use and driving.     

Aggregation Condition–Structure Relationship of Mouse Prion Protein Fibrils

Prion diseases are associated with conformational conversion of cellular prion protein into a misfolded pathogenic form, which resembles many properties of amyloid fibrils. The same prion protein sequence can misfold into different conformations, which are responsible for variations in prion disease phenotypes (prion strains). In this work, we use atomic force microscopy, FTIR spectroscopy and magic-angle spinning NMR to devise structural models of mouse prion protein fibrils prepared in three different denaturing conditions. We find that the fibril core region as well as the structure of its N- and C-terminal parts is almost identical between the three fibrils. In contrast, the central part differs in length of β-strands and the arrangement of charged residues. We propose that the denaturant ionic strength plays a major role in determining the structure of fibrils obtained in a particular condition by stabilizing fibril core interior-facing glutamic acid residues.     

High-speed, high-resolution monolithic capillary LC-MALDI MS using an off-line continuous deposition interface for proteomic analysis

High-speed, high-resolution LC separations, using a poly(styrene-divinylbenzene) monolithic column, have been coupled to MALDI MS and MS/MS through an off-line continuous deposition interface. The LC eluent was mixed with alpha-cyano-4-hydroxycinnamic acid matrix solution and deposited on a MALDI plate that had been precoated with nitrocellulose. Deposition at subatmospheric pressure (80 Torr) formed a 250-microm-wide serpentine trace with uniform width and microcrystalline morphology. The deposited trace was then analyzed in the MS mode using a MALDI-TOF/TOF MS instrument. Continuous deposition allowed interrogation of the separation with a high data sampling rate in the chromatographic dimensions, thus preserving the high resolution of narrow peaks (3-5-s peak width at half-height) of the fast monolithic LC. No extracolumn band broadening due to the deposition process was observed. Over 2000 components were resolved in a 10-min linear gradient separation of the model sample, and 386 unique peptides were identified in the subsequent MS/MS analysis. The continuous deposition interface allows the coupling of high-resolution separations to MALDI MS without degradation in separation efficiency, thus enabling high-throughput proteome analysis.     

Thermal vaporization-vacuum ultraviolet laser ionization time-of-flight mass spectrometry of single aerosol particles

Single aerosol particles of ethylene glycol and oleic acid are vaporized on a heater at temperatures between 500 and 700 K, and the resulting vapor plume is ionized by a 10.5-eV vacuum ultraviolet (VUV) laser. The mass spectra are compared to those obtained by CO2 laser vaporization followed by VUV laser ionization. The relative intensities of the parent and fragment ion peaks are remarkably similar for the two modes of vaporization. A Maxwell-Boltzmann distribution of speeds accurately describes the dependence of the signal as a function of the VUV laser pulse timing. The signal levels obtained with this design are sufficient to obtain good-quality mass spectra.     

Zur Verfestigung von Schüttgütern – Mikroprozesse und Kinetikmodelle

Storage tanks are important elements of a self-operating closed processing system. The reliability and availability of storage equipment essentially depends on the flow behaviour of particulate solids in storage containers. A wide residence time distribution (i.e. too long a storage time at rest) in silos, bunkers or transportation containers, respectively, can lead to the hazardous problem of so-called “time consolidation” of particulate solids. During this hardening process, solid bridges are forming with resulting solidification and solid properties of bulk material. In principle, there are four main physico-chemical effects in bulk materials storing and handling which can produce solid briding between the particle contacts due to crystallisation, chemical reactions, solidification of high-viscous bonding agents and sintering. Generally, new adhesion force based models are presented to describe the consolidation kinetics of particulate solids. Preliminary solutions of kinetic model equations are discussed and compared with new test results and practical conclusions are drawn concerning the reliable processing, storage and transportation of bulk materials.