Growth and surface engineering of vertically-aligned low-wall-number carbon nanotubes

A novel catalyst of cobalt supported by single crystal MgO was prepared by atomic layer deposition and used for carbon nanotube growth. With CO as carbon source, vertically-aligned carbon nanotubes with predominant double-walled (82%) were produced at 700 °C. Similar carbon nanotube array with a majority of single-walled tubes (62%) was produced at 900 °C using methane as the carbon source. Due to their high flexibility compared with multi-walled carbon nanotubes, the low-wall-number carbon nanotube array could form a 3-dimensional honeycomb-like network when being spread with acetone.     

Involving users in the development of a modeling language for customer journeys

Software and Systems Modeling - Although numerous methods for handling the technical aspects of developing domain-specific modeling languages (DSMLs) have been formalized, user needs and usability...     

Reduction by gaseous ozone of Salmonella and microbial flora associated with fresh-cut cantaloupe

This research investigates the efficacy of gaseous ozone, applied under partial vacuum in a controlled reaction chamber, for the elimination of Salmonella inoculated on melon rind. The performance of high dose, short duration treatment with gaseous ozone, in this pilot system, on the microbial and sensory quality of fresh-cut cantaloupes was also evaluated. Gaseous ozone (10,000 ppm for 30 min under vacuum) reduced viable, recoverable Salmonella from inoculated physiologically mature non-ripe and ripe melons with a maximum reduction of 4.2 and 2.8 log CFU/rind-disk (12.6 cm(2)), respectively. The efficacy of ozone exposure was influenced by carrier matrix. Salmonella adhering to cantaloupe was more resistant to ozone treatment when suspended in skim-milk powder before aqueous inoculation to the rind. This indicated that organic matter interferes with the contact efficiency and resultant antimicrobial activity of gaseous ozone applied as a surface disinfectant. Conversely, in the absence of an organic carrier, Salmonella viability loss was greater on dry exocarp surfaces than in the wetted surfaces, during ozone treatment, achieving reductions of 2.8 and 1.4 initial log CFU/rind-disk, respectively. Gaseous ozone treatment of 5000 and 20,000 ppm for 30 min reduced total coliforms, Pseudomonas fluorescens, yeast and lactic acid bacteria recovery from fresh-cut cantaloupe. A dose Ct-value (concentration x exposure time) of 600,000 ppm min achieved maximal log CFU/melon-cube reduction, under the test conditions. Finally, fresh-cut cantaloupe treated with gaseous ozone, maintained an acceptable visual quality, aroma and firmness during 7-day storage at 5 degrees C. Conclusions derived from this study illustrate that gaseous ozone is an effective option to risk reduction and spoilage control of fresh and fresh-cut melon. Moreover, depending on the timing of contamination and post-contamination conditions, rapid drying combined with gaseous ozone exposure may be successful as combined or sequential disinfection steps to minimize persistence of Salmonella on the surface of cantaloupe melons and transference during fresh-cut processing of home preparation. Based on these results, greater efficacy would be anticipated with mature but non-ripe melons while ripe tissues reduce the efficacy of these gaseous ozone treatments, potentially by oxidative reaction with soluble refractive solids.     

Stable isotope dilution analysis of the Fusarium mycotoxins deoxynivalenol and 3-acetyldeoxynivalenol

Trichothecenes are secondary metabolites produced by several fungi of the Fusarium genus during their growth period. They inhibit protein biosynthesis in eukaryotic cells resulting in numerous toxic effects such as diarrhea, vomiting, and gastro-intestinal inflammation. Considering its occurrence in food and feedstuff, deoxynivalenol (DON) is one of the most important trichothecenes. We report the synthesis of stable isotope labeled 15-d(1)-deoxynivalenol (15-d(1)-DON) from its natural precursor 3-acetyldeoxynivalenol (3-AcDON) as starting material. Furthermore, a method for the analysis of DON and 3-AcDON using HPLC-MS/MS with stable isotope labeled 15-d(1)-DON and 3-d(3)-AcDON as internal standards has been developed. In total, 18 cereal product samples were analyzed with contamination levels ranging from 10-301 microg/kg for DON and 5-14 microg/kg for 3-AcDON. This is the first report of an isotope dilution MS method for the analysis of type B-trichothecenes.     

Development of stable haploid strains and molecular genetic tools for Naumovozyma castellii (Saccharomyces castellii)

The budding yeast Naumovozyma castellii (syn. Saccharomyces castellii) has been included in comparative genomics studies and functional analyses of centromere DNA elements, and has been shown to possess beneficial traits for telomere biology research. To provide useful tools for molecular genetic approaches, we produced stable haploid heterothallic strains from an early ancestral strain derived from the N. castellii collection strain CBS 4310. To this end, we deleted the gene encoding the Ho endonuclease, which is essential for the mating type switching. Gene replacement of HO with the kanMX3 resistance cassette was performed in diploid strains, followed by sporulation and tetrad microdissection of the haploid spores. The mating type (MATa or MATα) was determined for each hoΔ mutant, and was stable under sporulation‐inducing conditions, showing that the switching system was totally non‐functional. The hoΔstrains showed wild‐type growth rates and were successfully transformed with linear DNA using the general protocol. Opposite mating types of the hoΔstrains were mated, resulting in diploid cells that efficiently formed asci and generated viable spores when microdissected. By introduction of a point mutation in the URA3 gene, we created a uracil auxotrophic strain, and by exchanging the kanMX3 cassette for the hphMX4 cassette we show that hygromycin B resistance can be used as a selection marker in N. castellii. These haploid strains containing genetic markers will be useful tools for performing genetic analyses in N. castellii. Moreover, we demonstrate that homology regions of 200–230 bp can be successfully used for target site‐specific integration into genomic loci. Copyright © 2016 John Wiley & Sons, Ltd.     

New method for time-resolved diesel engine exhaust particle mass measurement

The Dekati mass monitor (DMM; Dekati Ltd., Finland), a relatively new real-time mass measurement instrument, was investigated in this project. In contrast to the existing gravimetric filter method also used as a standard for regulation purposes, this instrument provides second-by-second data on mass concentration in the engine exhaust gas. The principle of the DMM is based on particle charging, inertial and electrical size classification, and electrical detection of aerosol particles. This study focuses on the instrument's practical performance. Details on calibration and the theory of operation will be published elsewhere. The exhaust emissions of two heavy-duty engines complying with the Euro III emission standard were measured on a dynamic engine test bench. We looked atthe particle number and mass emissions of the engines in different transient test cycles and steady-state conditions. The ability to follow transient test cycles and the response times of the DMM were investigated. The aerosol mass concentration measured by the DMM was compared with the mass concentration obtained by the standard gravimetric filter method with Teflon-coated glass fiber filters. The total mass concentration (integral over the whole cycle) measured by the DMM is about 20% higher than that measured by the standard gravimetric filter method. The total mass concentration from the DMM was also compared with the volume concentration calculated from the electrical low-pressure impactor (ELPI) measurements. Correlations were made with other particle measuring systems. The DMM correlates very well with the particulate mass (R2 = 0.95) and exhibits good linearity and repeatability. The response time to a well-defined change in exhaust concentration was observed to be fast and stable. The DMM was able to follow transient test cycles and provides good results on a second-by-second basis. The instrument used in this study was still under development, and there is therefore no complete scientific background reference for the DMM. This study therefore focuses more on the measurements than on the scientific background. The measurements have shown thatthe DMM is an adequate instrument for measuring the mass concentration of engine exhaust, with results comparable to those from the standard gravimetric filter method. In addition, the DMM provides real-time second-by-second data of the mass concentration during transient test cycles.     

Mitigating grid voltage harmonics using a line converter with active filtering feature

A line converter equipped with an LCL-line filter is used as an active filter directly compensating grid voltage harmonics. The control of four individual grid voltage harmonics is implemented using an individual control of corresponding harmonic line currents. The knowledge of the grid impedance is essential to efficient control of the grid voltage harmonics. To overcome the problem of an unknown grid impedance an identification method is used. The method uses the converter control system to measure the grid impedance at selected frequencies. The active voltage harmonic cancellation is tested with a 19 kVA line converter by compensating background voltage distortion and distortion caused by a nonlinear load.     

Visual search for grouped versus ungrouped icons in a computer interface

The paradigm of visual search was used to investigate how participants looked for a target file among distracter files in an icon-based computer interface. The purpose of these experiments was to study the effect of icons and spatial grouping on scanning speed. Does spatial grouping of identical icons increase the scanning speed? Do icons themselves speed up the search for a target file when compared with a condition in which the files are indicated with mere textual labels? Our results showed that both the presence of icons and their grouping had a significant positive effect on the scanning speed. Potential applications of this research include the design of graphics-based interfaces, such as the effective arrangement of icons in an interface.