Investigation of the hot side contacts to nanostructured LASTt(T) material. Part I

Results on fabrication and characterization of metal hot side electrical contacts to nanostructured AgPb _m SbTe_{2 + m} and Ag(PbSn) _m SbTe_{2 + m} materials by using SnTe diffusion bonding are presented.     

Osmotolerant yeast species differ in basic physiological parameters and in tolerance of non‐osmotic stresses

Osmotolerance is the ability to grow in an environment with a high osmotic pressure. In this study we compared the physiological parameters and tolerance to osmotic and non‐osmotic stresses of three osmotolerant yeast species, Debaryomyces hansenii, Pichia farinosa (sorbitophila) and Zygosaccharomyces rouxii, with those of wild‐type Saccharomyces cerevisiae. Although the osmotolerant species did not differ significantly in their basic parameters, such as cell size or growth capacity, they had different abilities to survive anhydrobiosis, potassium limitation or the presence of toxic cationic drugs. When their osmotolerance was compared, the results revealed that some of the species isolated as sugar/polyol‐tolerant (e.g. P. farinosa) are also highly tolerant to salts and, vice versa, some strains isolated from an environment with high concentration of salt (e.g. Z. rouxii ATCC 42981) tolerate high concentrations of sugars. None of the tested strains and species was osmophilic. Taken together, our results showed that P. farinosa (sorbitophila) is the most robust species when coping with various stresses, while Z. rouxii CBS 732, although osmotolerant in general, is not specifically salt‐tolerant and is quite sensitive to most of the tested stress conditions. Copyright © 2014 John Wiley & Sons, Ltd.     

Do the best scholars attract the highest speaking fees? An exploration of internal and external influence

This study investigates whether academics can capitalize on their external prominence (measured by the number of pages indexed on Google, TED talk invitations or New York Times bestselling book successes) and internal success within academia (measured by publication and citation performance) in the speakers’ market. The results indicate that the larger the number of web pages indexing a particular scholar, the higher the minimum speaking fee. Invitations to speak at a TED event, or making the New York Times Best Seller list is also positively correlated with speaking fees. Scholars with a stronger internal impact or success also achieve higher speaking fees. However, once external impact is controlled, most metrics used to measure internal impact are no longer statistically significant.     

A network-based approach to coauthorship credit allocation

We introduce and evaluate a novel network-based approach for determining individual credit of coauthors in multi-authored papers. In the proposed model, coauthorship is conceptualized as a directed, weighted network, where authors transfer coauthorship credits among one another. We validate the model by fitting it to empirical data about authorship credits from economics, marketing, psychology, chemistry, and biomedicine. Also, we show that our model outperforms prior alternatives such as fractional, geometric, arithmetic, and harmonic counting in generating coauthorship credit allocations that approximate the empirical data. The results from the empirical evaluation as well as the model’s capability to be adapted to domains with different norms for how to order authors per paper make the proposed model a robust and flexible framework for studying substantive questions about coauthorship across domains.     

The study of deoxynivalenol and its masked metabolites fate during the brewing process realised by UPLC–TOFMS method

The co-occurrence of deoxynivalenol (DON) and deoxynivalenol-3-glucoside (DON-3-Glc) has been recently reported in malt and beer. In this study, the concentration changes were monitored within the brewing process of four beer brands: light, dark tap and two lagers, produced from ground malt mixtures differing in composition, and also mycotoxins content. A simple and rapid method employing DON-dedicated immunoaffinity columns (IAC) for the selective pre-concentration, followed by ultra-performance liquid chromatography coupled to a time-of-flight mass spectrometer (UPLC–TOFMS) system for the reliable quantification at (ultra)trace levels, was validated for all experimental matrices. The results document the key role of the malt contamination nature. While in the first monitoring period a significant increase of both DON and DON-3-Glc occurred (up to 250% and 450%, respectively), fairly different trends were observed when new malts were used for identical technological processing (in some beers a decrease of DON and only a small increase of DON-3-Glc occurred). Worth noticing, that the outcome of the brewing process was surprisingly reproducible for a particular malt mixture. In the final phase, a small monitoring study comparing Czech and Austrian alcohol-free and conventional beers was carried out.     

A first principles study of the optical properties of BxCy single wall nanotubes

The optical properties of small radius (<1 nm) single wall carbon nanotubes (SWCNTs) alloyed with boron were examined using relaxed C-C bond length ab initio calculations in the long wavelength limit. The magnitude of the static dielectric constant essentially depends on the B concentration as well as the direction of polarization. The maximum value of the absorption coefficient is shown to strongly depend on the concentration of B in a non-linear way with a minimum at a critical concentration of 0.40 for both the parallel polarization and the un-polarized cases and of 0.29 for perpendicular polarization of the electromagnetic field. The peak of the loss function in parallel polarization and unpolarized cases shifts to a lower frequency with increasing concentration up to 50% but then shifts to a higher frequency. The non-linear fits to the plasma resonance frequency variation with B concentration indicate the existence of a unique minimum. All these factors may shed light on the nature of collective excitations in B-alloyed SWCNTs.     

Effects of length of dry period on yields of milk fat and protein, fertility and milk somatic cell score in the subsequent lactation of dairy cows

The objective was to utilize data from modern US dairy cattle to determine the effect of days dry on fat and protein yield, fat and protein percentages, days open, and somatic cell score in the subsequent lactation. Field data collected through the dairy herd improvement association from January 1997 to December 2003 and extracted from the Animal Improvement Programs Laboratory national database were used for analysis. Actual lactation records calculated from test-day yields using the test-interval method were used in this study. The model for analyses included herd-year of calving, year-state-month of calving, previous lactation record, age at calving, and days dry as a categorical variable. Fat and protein yield was maximized in the subsequent lactation with a 60-d dry period. Dry periods of 20 d or less resulted in substantial losses in fat and protein yield in the subsequent lactation. In contrast to yields, a short dry period was beneficial for fat and protein percentages. Short dry periods also resulted in fewer days open in the subsequent lactation; however, this was entirely due to the lower milk yield associated with shortened dry period. When adjusted for milk yield, short dry periods actually resulted in poorer fertility in the subsequent lactation. Long days dry improved somatic cell score in the subsequent lactation. Herds with mastitis problems should be cautious in shortening days dry because short dry periods led to higher cell scores in the subsequent lactation compared with 60-d dry.     

Effect of γ-irradiation on antioxidant activity of black pepper (Piper nigrum L.)

Antioxidant activity and EPR investigations of irradiated ground black pepper (Piper nigrum L.) were evaluated. The black pepper was exposed to γ-irradiation at doses from 5 to 30 kGy. The effect of irradiation on antioxidant properties of black pepper extracts was investigated by radical-scavenging effect on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, by determination of reducing power and content of thiobarbituric acid-reactive substances. Some significant changes were observed in creation of thiobarbituric acid-reactive substances (TBARS). Difference between non-irradiated and irradiated samples at the legal European limit dose of 10 kGy reached, on average, 23% and, at the Food and Drug Administration (FDA) 30 kGy limit, 33%. Irradiation affected significantly the DPPH radical-scavenging activity and reducing power of ground black pepper extracts. The γ-radiation treatment of ground black pepper samples observed by EPR, resulted in the production of three paramagnetic species (GI–GIII) characterized by different origin, thermal behaviour and stability. The axially symmetric EPR resonances, GI and GII, were assigned to the carbohydrate radical structures. The spin Hamiltonian parameters of GIII possessed the characteristic features of “cellulosic” radical species. The EPR measurements, performed 20 weeks after the radiation process, confirmed that temperature increase from 298 to 353 K, caused significant decrease of integral EPR signal intensity for γ-irradiated samples (∼40%), compared to the reference (non-irradiated) ground black pepper, where only 13% drop was found. Significant correlation between EPR and thiobarbituric acid methods was assessed by study of antioxidant activity changes in relation to irradiation doses and also in the case of spice storage, between EPR and reducing power methods.     

Oxidation of aromatic and aliphatic hydrocarbons by OH radicals photochemically generated from H2O2 in ice

Oxidation of aromatic and saturated aliphatic hydrocarbons (c = 10(-3)-10(-5) mol L(-1)) by the hydroxyl radicals, photochemically produced from hydrogen peroxide (c = 10(-1)-10(-5) mol L(-1)), in frozen aqueous solutions was investigated in the temperature range of -20 to -196 degrees C. While aromatic molecules (benzene, phenol, naphthalene, naphthalen-2-ol, or anthracene) underwent primarily addition-elimination reactions to form the corresponding hydroxy compounds, saturated hydrocarbons (cyclohexane, butane, methane) were oxidized to alcohols or carbonyl compounds via hydrogen abstraction and termination reactions. The results suggest that these photoreactions, taking place in a highly concentrated liquid or solidified layers covering the ice crystals, are qualitatively similar to those known to occur in liquid aqueous solutions; however, that probability of any bimolecular reaction in the environment ultimately depends on organic contaminant concentrations and oxidants availability at specific locations of the ice matrix, temperature, wavelength, and photon flux. They, moreover, support hypotheses that oxidation of organic impurities in the snowpack can produce volatile hydroxy and carbonyl compounds, which may consequently be released to the atmosphere.     

Production of organic acids by Lactobacillus strains in three different media

Ten strains of Lactobacillus (Lb). casei, Lb. rhamnosus, Lb. plantarum, Lb. paracasei and Lb. curvatus species were chosen to determine the production of organic acids after cultivation in skimmed milk, MRS broth and Jerusalem artichoke (JA) medium. The highest acidity was obtained in MRS broth and the weakest acidification was found in skimmed milk. Lb. casei Shirota produced the highest amount and Lb. rhamnosus VT1 the lowest amount of substances being estimated as titratable acidity. All strains produced lactic acid in the investigated broth and most of the strains produced acetic acid in MRS broth except Lb. curvatus 2768 and Lb. casei Shirota, in JA broth except Lb. paracasei SF1 and in skimmed milk except Lb. casei 2750, Lb. curvatus 2768, Lb. curvatus 2775 and Lb. casei Shirota. All strains, except Lb. plantarum 01, produced butyric acid in MRS broth. Beside the lactic and acetic acids, formic, citric, succinic and glutamic acids were also produced in MRS broth; formic and succinic acids were produced in skimmed milk and succinic acid in JA broth. Some strains showed change in their fermentation profile from homofermentative to mix-acid fermentation in milk. The antifungal efficiency of the lactic and acetic acid in the amount produced by lactobacilli was investigated. None of the investigated aspergilli were inhibited. The inhibitory effect of acids against Fusarium increased unequivocally with the increasing concentration. The study pointed at the dissimilarity of organic acid production of Lactobacillus strains, which was considerably influenced by the media.