Wavelet-enhanced bayesian classification of surface nanostructures observed in pentacene thin films

In recent years, the wavelet transform has proven to be an extremely powerful image-processing tool. Here, we have developed a wavelet-enhanced Bayesian methodology to analyze the AFM images of organic crystals, such as pentacene, using the Haar wavelet transform. This methodology segments and identifies structures in AFM data and extracts quantitative information such as grain size, perimeter, and orientation. This methodology relies on a Naïve Bayesian classification system, which determines whether each data point corresponds to a peak or a valley with a finite statistical probability based on analysis of a synthetic teaching image. In this work, we apply this technique to AFM images of organic crystal films deposited on three different substrates.     

Methods for rapid separation and concentration of bacteria in food that bypass time-consuming cultural enrichment

The rapid detection of pathogenic organisms that cause foodborne illnesses is needed to insure food safety. Conventional methods for the detection of pathogens in foods are time-consuming and labor-intensive. New advanced rapid methods (i.e., polymerase chain reaction, DNA probes) are more sensitive and selective than conventional techniques, but many of these tests are inhibited by food components, rendering them dependent on slow cultural enrichment. The need for alternative methods that will rapidly separate and concentrate bacteria directly from food samples, thereby reducing the time required for these new rapid detection techniques, is evident. Separation and concentration methods extract target bacteria from interfering food components and/or concentrate bacteria to detectable levels. This review describes several methods used to separate and/or concentrate bacteria in food samples. Several methods discussed here, including centrifugation and immunomagnetic separation, have been successfully used, individually and in combination, to rapidly separate and/or concentrate bacteria from food samples in less time than is required for cultural enrichment.     

Inlet ionization: a new highly sensitive approach for liquid chromatography/mass spectrometry of small and large molecules

Inlet ionization is a new approach for ionizing both small and large molecules in solids or liquid solvents with high sensitivity. The utility of solvent based inlet ionization mass spectrometry (MS) as a method for analysis of volatile and nonvolatile compounds eluting from a liquid chromatography (LC) column is demonstrated. This new LC/MS approach uses reverse phase solvent systems common to electrospray ionization MS. The first LC/MS analyses using this novel approach produced sharp chromatographic peaks and good quality full mass range mass spectra for over 25 peptides from injection of only 1 pmol of a tryptic digest of bovine serum albumin using an eluent flow rate of 55 μL min(-1). Similarly, full acquisition LC/MS/MS of the MH(+) ion of the drug clozapine, using the same solvent flow rate, produced a signal-to-noise ratio of 54 for the major fragment ion with injection of only 1 μL of a 2 ppb solution. LC/MS results were acquired on two different manufacturer's mass spectrometers using a Waters Corporation NanoAcquity liquid chromatograph.     

Gabapentin for smoking cessation: a preliminary investigation of efficacy.

Gabapentin affects the glutamate and gamma amino butyric acid (GABA) neurotransmitters through which it may facilitate smoking abstinence. To obtain preliminary estimates of efficacy of gabapentin for smoking cessation, we conducted a single-arm, open-label study of gabapentin, 1,800-mg/day administered in three equal divided doses for 8 weeks. A total of 50 adult smokers were enrolled. All participants received a brief behavioral intervention at each medication visit. A total of 37 participants completed all follow-up assessments. At end-of-treatment the biochemically confirmed point-prevalence and prolonged smoking abstinence rates were 28% (95% CI=16%-42%) and 24% (95% CI=13%-38%), respectively. At 6 months, the biochemically confirmed point-prevalence and prolonged smoking abstinence rates were 20% (95% CI=10%-34%) and 16% (95% CI=7%-29%), respectively. Among subjects who continued to smoke and completed the follow-up assessments, the reported number of cigarettes smoked per day (mean+/-standard deviation) was significantly less than at baseline: -10.0+/-8.2 (p<.001). Adverse effects were minor and well tolerated. Our results suggest that gabapentin may increase smoking abstinence. An adequately powered randomized clinical trial assessing different doses of this drug against a placebo would be the reasonable next step.     

Role of soil manganese in the oxidation of aromatic amines

Soil-induced oxidation and subsequent polymerization of aromatic amines is an important pathway for reducing the mobility of amines in soils and their hazard potential in the environment. This study assesses the hypothesis that manganese(III/IV) oxides/hydroxides play a significant role in the oxidation of aromatic amines in whole soils. Aromatic amines including alpha-naphthylamine, p-methoxyaniline, and aniline were allowed to react in aqueous whole soil suspensions for 5 d. Irreversible binding and/or transformation of amines were estimated using a rigorous extraction method and extractable transformation products were analyzed by matrix-assisted laser desorption/ ionization mass spectrometry. The Mn speciation shifts in the soil residue after amine-soil reactions were measured using a successive fractionation method and in-situ using X-ray absorption near-edge structure spectroscopy. A fraction of each of the three amines became irreversibly sorbed, and a large polymer formation was observed for alpha-naphthylamine and p-methoxyaniline. The increase in the irreversibly sorbed/transformed amine fraction over time was concomitant with the reduction of Mn(III/IV) to Mn(II), although oxidation by Mn(III/IV) was not sufficient to account for all amine irreversibly lost. Oxidation by soil Mn did contribute to immobilizing amines within organic matter and to the formation of large aromatic amine polymers, which serves to reduce mobility and bioavailability of aromatic amines in the natural environment.     

Statistical efficiency of using two quantitative randomized response techniques to estimate correlation.

Used Monte Carlo techniques to generate sampling distributions of the correlation coefficient between 2 variables, each measured by 2 quantitative models of the randomized response technique (RRT)—the additive constants model and the unrelated question model. As expected, the RRT models yielded less statistically efficient estimates of the population correlation coefficient, and inefficiency increased as the population correlation increased. Comparisons of efficiency between the 2 models favored the additive constants model for constants less than certain limiting values. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The deposition of selenium coatings on beryllium foils

A technique for preparing selenium films on 50.8μm thick beryllium foils is described. The selenium was deposited in vacuum from a resistance heated evaporation source. A water-cooled enclosure was used to minimize contamination of the vacuum system and to reduce the exposure of personnel to toxic and noxious materials. Profilometry measurements of the coatings indicated selenium thicknesses of 5.5, 12.9, 37.5, 49.8 and 74.5 μm. The control of deposition rate and of coating thickness was facilitated using a commercially available closed-loop programmable deposition controller. The X-ray transmission of the coated substrates was measured using a tritiated zirconium source. The transmissivities of the film/substrate combination are presented for the range of energies from 4 to 20 keV.     

Fatigue of Thick Thermal Barrier Coatings

Thick thermal barrier coatings (TTBCs) of plasma-sprayed 8% Y₂O₃–ZrO₂ were fatigued in compression as part of a reliability and durability study to evaluate their potential use in high-performance diesel engines. Test specimens were designed to test the bulk ceramic uniaxialiy, independent of the substrate. A test machine was designed to alleviate the mechanical gripping and alignment difficulties associated with cyclically stressing brittle ceramics in compression. Higher fatigue limits, 375 vs 200 MPa, were observed at 800°C than at room temperature. Specimens tested at room temperature after high-temperature com-pressive cycling also had higher fatigue limits, indicating that the strengthening was permanent. At temperatures of 800°C, the coatings showed evidence of low-temperature, pressure-induced sintering. The extent to which sintering occurred was determined by studying the change in the elastic modulus as a result of the application of varying temperatures and static stresses.     

Normal-Pressure Hot-Pressing of α-Alumina-Diamond Composites

α-Alumina-diamond composites have been developed by normal hot-pressing procedures using a conventional pressure of 32 MPa and 1250°C. Heretofore this type of composite has required a pressure of 6 GPa (60 kbar) to prevent the transformation of diamond to graphite. The mechanical properties, density, and thermal expansion coefficient of these composites have been characterized. The fracture toughness ( K _Ic) of alumina shows a considerable increase with the addition of diamond particles. Diamond additions tend to decrease the thermal expansion coefficient of these composites. The composite properties are dependent on the volume fraction of diamond particles.