Ti: sapphire-based picosecond visible-infrared sum-frequency spectroscopy from 900-3100 cm-1

Visible-infrared sum-frequency spectroscopy is ideally suited to the study of surfaces and interfaces. This paper introduces new sum-frequency spectroscopy instrumentation that we have developed with two novel features: (1) stable and robust infrared generation in the 900-3100 cm(-1) (11-3.2 microm) region using an amplified Ti : sapphire oscillator with a home-built OPG/OPA, and (2) continuous tuning over either 900-2700 cm(-1) (11-3.7 microm) or 1800-3100 cm(-1) (5.5-3.2 microm) in a single experiment. All practical details of baseline correction issues due to the picosecond pulses (including variation in infrared (IR) energy, spatial and temporal overlap, Fresnel coefficients) are addressed while demonstrating signal throughout this region from an amorphous gold surface. A sum-frequency spectrum from an oriented polymer is shown as a complete example of the data treatment, which reveals the vibrational modes accessible in this wavelength region.     

Central modulation of Brewer''s yeast-induced peripheral inflammation by neuropeptides bradykinin and substance P

This study reports the results of some voluntary Italian radiologists performing 103 proficiency tests in clinical (100 patients, 32 cancers) and screening mammography (150 patients, 17 cancers). Relative to the average accuracy of a panel of expert radiologists, 12 of 49 readers (27%) and 32 of 54 readers (56%) passed the clinical and screening mammography test, respectively. The results were significantly correlated with the readers' previous experience (years of mammographic practice [< 2, 2-4, > 4] and number of mammograms read [< 5,000, 5-10,000, > 10,000]). The rate of passed test was: < 2 years = 0%, 2-4 years = 40%, > 4 years = 66.6% (P = 0.002); < 5,000 mammograms read = 15.3%, 5-10,000 = 28.5%, > 10,000 = 69.2% (P = 0.02). The best results were achieved by the readers with a previous reading experience of at least 10,000 mammograms, a figure which might be used as the reference for a future criterion of accreditation on a national basis. Proper training before reporting mammography is fundamental to ensure a good diagnostic performance. The low number of tests performed in most Italian mammographic practice facilities makes local training highly questionable and requires quite a long time. Reference centers, adequately equipped for training, should be identified for this purpose. Proficiency tests such as those described in the present study are useful to assess individual performance and should be a part of a training program.     

Production and characterization of ITO-Pt semiconductor powder containing nanoscale noble metal particles catalytically active in dye-sensitized solar cells

Doped indium tin oxide (ITO) samples of a surface area around 60 m²/g have been synthesized. As doping component platinum and gold atoms were utilized, respectively. The powders were produced by pyrolyzing mixed metal oxide precursors in a first zone in a flame consisting of hydrogen and air, metering a noble metal compound and reducing gas into a second zone of the flame and separating off the solid obtained in a third zone. Well-defined solid phases In₂Pt and In₂Au in ITO were obtained, respectively. The production of a mixture with discrete SnO₂ entities could be avoided. The mixed oxide powder doped with platinum can be used as a catalyst. The structure and composition of materials obtained at different levels of platinum dosing into a flame reactor has been determined. The size of the noble metal-containing entities ranged at about 3.5–5.5 nm. The catalytic properties of these oxides containing noble metal have been utilized in the fabrication of dye-sensitized solar cells (DSCs). Long term stability of DSCs containing liquid electrolytes requires a glass sealing of the two electrodes at a temperature of over 600 °C. Such high temperatures are detrimental to the catalytic activity of the conventional platinum layers in the counter electrode. Improved catalytic activity could be achieved by platinum entities bound to indium tin oxide. This catalytic material can effectively be used in the DSCs with glass sealing, the sealing temperature being over 600 °C. Spray pyrolysis in a flame reactor is highly suitable to produce noble metal-containing oxides in one single production step. Platinum-containing ITO particles from flame pyrolysis production exhibit superior catalytic activity in dye-sensitized solar cells compared to material from conventional thermal decomposition.     

Inputs from low threshold muscle and cutaneous afferents of hand and forearm to areas 3a and 3b of baboon's cerebral cortex

The posterior wall of the central sulcus in forelimb area of SI has been expolred with extracellular micro-electrodes in baboons lightyl anaesthetized with nitrous oxide and sodium thiopentone. 2. The excitatory responses of 130 single units to low intensity electrical stimulation of the deep radial (muscle) and the superficial radial (cutaneous) nerves have been investigated. 3. Units that responded only to muscle nerve stimulation were located in area 3a but overlapped into area 3b. Units that responded only to cutaneous nerve stimulation were found mainly in area 3b but a number occurred in area 3a. Units that responded to both muscle and nerve stimuli (convergent units) were found throughout area 3a and the rostral part of area 3b. 4. Latency analyses of all three response groups revealed a single population of units responding to low threshold muscle nerve stimulation (mean latency 8.5 msec), and both early and late populations responding to low threshold cutaneous nerve stimulation (mean latencies 9.5 and 13.6 msec respectively). A number of the convergent units had very similar latencies for both inputs. 5. Electrical stimulation within area 3a deminstrated a projection from areas 1 and 3b to area 3a; such a pathway may provide a route for excitation of the late skin population which was found mainly in area 3a. 6. In area 3a units commonly responded to light touch, local pressure or deep pressure but only rarely to movement of hairs. A number of the convergent units responded to natural stimulation of cutaneous receptors.     

A Scalable Framework For Segmenting Magnetic Resonance Images

A fast, accurate and fully automatic method of segmenting magnetic resonance images of the human brain is introduced. The approach scales well allowing fast segmentations of fine resolution images. The approach is based on modifications of the soft clustering algorithm, fuzzy c-means, that enable it to scale to large data sets. Two types of modifications to create incremental versions of fuzzy c-means are discussed. They are much faster when compared to fuzzy c-means for medium to extremely large data sets because they work on successive subsets of the data. They are comparable in quality to application of fuzzy c-means to all of the data. The clustering algorithms coupled with inhomogeneity correction and smoothing are used to create a framework for automatically segmenting magnetic resonance images of the human brain. The framework is applied to a set of normal human brain volumes acquired from different magnetic resonance scanners using different head coils, acquisition parameters and field strengths. Results are compared to those from two widely used magnetic resonance image segmentation programs, Statistical Parametric Mapping and the FMRIB Software Library (FSL). The results are comparable to FSL while providing significant speed-up and better scalability to larger volumes of data.     

Electrochemical lithiation synthesis of nanoporous materials with superior catalytic and capacitive activity

Nanoporous materials have attracted great technological interest during the past two decades, essentially due to their wide range of applications: they are used as catalysts, molecular sieves, separators and gas sensors as well as for electronic and electrochemical devices. Most syntheses of nanoporous materials reported so far have focused on template-assisted bottom-up processes, including soft templating (chelating agents, surfactants, block copolymers and so on) and hard templating (porous alumina, carbon nanotubes and nanoporous materials) methods. Here, we exploit a mechanism implicitly occurring in lithium batteries at deep discharge to develop it into a room-temperature template-free method of wide applicability in the synthesis of not only transition metals but also metal oxides with large surface area and pronounced nanoporosity associated with unprecedented properties. The power of this top-down method is demonstrated by the synthesis of nanoporous Pt and RuO2, both exhibiting superior performance: the Pt prepared shows outstanding properties when used as an electrocatalyst for methanol oxidation, and the RuO2, when used as a supercapacitor electrode material, exhibits a distinctly better performance than that previously reported for non-hydrated RuO2 (refs 19,20).     

Dual-modulator broadband infrared Mueller matrix ellipsometry

A broadband mid-infrared Mueller matrix ellipsometer is described based on two photoelastic modulators and a step-scan interferometer. The data are analyzed using a combination hardware-software double Fourier transformation. Obtaining spectra of the Mueller matrix elements requires that the infrared wavelength-dependent retardation amplitude of the modulators be known through calibration and subsequently incorporated into the data processing. The spectroscopic capability of the instrument is demonstrated in transmission and reflection geometries by the measured Mueller matrices of air, an anisotropic quartz crystal, and the ZnSe-water interface, each from 2500-4000 cm^-1.     

Heterogeneously doped polyethylene glycol as nano-composite soft matter electrolyte

We have applied the concept of heterogeneous doping [1] to prepare and examine composite electrolytes, consisting of silica particles, low molecular weight polyethylene glycol solvents and lithium perchlorate salt. These “soggy sand” electrolytes combine high ionic conductivities (on the order of mS cm⁻¹) and high Li transference numbers (typically 60–80%) with improved mechanical properties. They were characterized using differential scanning calorimetry, dc-polarization and ac-impedance spectroscopy, zeta potential measurements and viscosimetry. Oxide, size and concentration as well as solvent molecular weight were varied to better understand the influence of ceramic oxide fillers on the ion conduction in these systems. As regarding the filler content, we observe that both conductivity and transference number of Li⁺ start increasing already at low volume fractions of oxide particles, reach a maximum and subsequently decrease to low values. The percolating network is – after initial partial coarsening – found to be stable within the time periods of the measurements.     

Children's residential exposure to chlorpyrifos: application of CPPAES field measurements of chlorpyrifos and TCPy within MENTOR/SHEDS-Pesticides model

The comprehensive individual field-measurements on non-dietary exposure collected in the Children's-Post-Pesticide-Application-Exposure-Study (CPPAES) were used within MENTOR/SHEDS-Pesticides, a physically based stochastic human exposure and dose model. In this application, however, the model was run deterministically. The MENTOR/SHEDS-Pesticides employed the CPPAES as input variables to simulate the exposure and the dose profiles for seven children over a 2-week post-application period following a routine residential and professional indoor crack-and-crevice chlorpyrifos application. The input variables were obtained from a personal activity diary, microenvironmental measurements and personal biomonitoring data obtained from CPPAES samples collected from the individual children and in their homes. Simulation results were compared with CPPAES field measured values obtained from the children's homes to assess the utility of the different microenvironmental data collected in CPPAES, i.e. indicator toys and wipe samplers to estimate aggregate exposures that can be result from one or more exposure pathways and routes. The final analyses of the database involved comparisons of the actual data obtained from the individual biomarker samples of a urinary metabolite of chlorpyrifos (TCPy) and the values predicted by MENTOR/SHEDS-Pesticides using the CPPAES-derived variables. Because duplicate diet samples were not part of the CPPAES study design, SHEDs-Pesticides simulated dose profiles did not account for the dietary route. The research provided more confidence in the types of data that can be used in the inhalation and dermal contact modules of MENTOR/SHEDS-Pesticides to predict the pesticide dose received by a child. It was determined that we still need additional understanding about: (1) the types of activities and durations of activities that result in non-dietary ingestion of pesticides and (2) the influence of dietary exposures on the levels of TCPy found in the urine.