Inactivation of gram-negative bacteria in milk and banana juice by hen egg white and lambda lysozyme under high hydrostatic pressure

The effect of hen egg white lysozyme (HEWL) and bacteriophage lambda lysozyme (LaL) in combination with high pressure (HP) treatment on the inactivation of four gram-negative bacteria (Escherichia coli O157:H7, Shigella flexneri, Yersinia enterocolitica and Salmonella typhimurium), was studied in skim milk (pH 6.8; a(w) 0.997) and in banana juice (pH 3.8; a(w) 0.971). In the absence of lysozymes, S. flexneri was more sensitive to HP in milk than in banana juice, while the opposite was observed for the other three bacteria. In combination with HP treatment, LaL was more effective than HEWL on all bacteria in both milk and banana juice. Depending on the bacteria, inactivation levels in banana juice were increased from 0.4-2.7 log units by HP treatment alone to 3.6-6.5 log units in the presence of 224 U/ml LaL. Bacterial inactivation in milk was also enhanced by LaL but only by 0.5-2.1 log units. Under the experimental conditions used, LaL was more effective in banana juice than in milk, while the effectiveness of HEWL under the same conditions was not significantly affected by the food matrix. This effect could be ascribed to the low pH of the banana juice since LaL was also more effective on E. coli in buffer at pH 3.8 than at pH 6.8. Since neither LaL nor HEWL are enzymatically active at pH 3.8, we analysed bacterial lysis after HP treatment in the presence of these enzymes, and found that inactivation proceeds through a non-lytic mechanism at pH 3.8 and a lytic mechanism at pH 6.8. Based on these results, LaL may offer interesting perspectives for use as an extra hurdle in high pressure food preservation.     

Axial and radial distribution of thermal and epithermal neutron fluxes in irradiation channels of the Ghana Research Reactor-1 using foil activation analysis

The experimental method (foil activation) was used to determine the neutron fluxes in two outer irradiation channels of the Ghana Research Reactor-1. In the experimental procedure, it was observed that the fluxes rise to a peak before falling and then finally leveling out, axially. Axially and radially, it was also observed that the fluxes in the center of the channels were lower than those on the sides. Radially, the fluxes dipped in the center while they increased monotonically towards the sides of the channels. The results have shown that there are flux variations within the irradiation channels at both axial and radial directions.     

Type systems equivalent to data-flow analyses for imperative languages

We show that a large class of data-flow analyses for imperative languages are describable as type systems in the following technical sense: possible results of an analysis can be described in a language of types so that a program checks with a type if and only if this type is a supertype of the result of applying the analysis. Type-checking is easy with the help of a certificate that records the “eureka”-bits of a typing derivation. Certificate-assisted type-checking amounts to a form of lightweight analysis à la Rose. For secure information flow, we obtain a type system that is considerably more precise than that of Volpano et al., but not more sophisticated. Importantly, our type systems are compositional.     

Effect of urbanization on stream hydraulics

Urbanization results in major changes to stream morphology and hydrology with the latter often cited as a primary stressor of urban stream ecosystems. These modifications unequivocally alter stream hydraulics, but little is known about such impacts. Hydraulic changes due to urbanization were demonstrated using two‐dimensional hydrodynamic model simulations, comparing urban and non‐urban stream reaches. We investigated three ecologically relevant hydraulic characteristics: bed mobilization, retentive habitat, and floodplain inundation, using hydraulic metrics bed shear stress, shallow slow‐water habitat (SSWH) area, and floodplain inundation area. We hypothesized that urbanization would substantially increase bed mobilization, decrease retentive habitat, and due to increased channel size would decrease floodplain inundation. Relative percent area of bed disturbance was 4 times higher, compared with that of the non‐urban stream at bankfull discharge. SSWH availability rapidly diminished in the urban stream as discharge increased, with SSWH area and patch size 2 times smaller than the non‐urban stream for a frequently occurring flow 0.7 times bankfull discharge. Floodplain inundation decreased in frequency and duration. These results demonstrate changes in hydraulics due to urbanization that may impact on physical habitat in streams. New “water sensitive” approaches to stormwater management could be enhanced by specification of hydraulic regimes capable of supporting healthy stream habitats. We propose that a complete management approach should include the goals of restoration and protection of natural hydraulic processes, particularly those that support ecological and geomorphic functioning of streams.     

Multi-level privacy analysis of business processes: the Pleak toolset

International Journal on Software Tools for Technology Transfer - Privacy regulations, such as GDPR, impose strict requirements to organizations that store and process private data....     

Amylose and amylopectin molecular fractions and chain length distribution of amylopectin in 12 varieties of Ghanaian sweet potato (Ipomoea batatas) flours

Sweet potato (Ipomoea batatas) is a commonly cultivated root crop in tropical and subtropical regions, including Ghana. Different varieties of sweet potato have been bred, in order to expand its utilisation within the food and industrial sector. This study analysed flours made from 12 recently developed Ghanaian sweet potato varieties in terms of their amylose and amylopectin molecular fractions and amylopectin chain length distribution. Starch content of the sweet potato flours ranged from 49 to 77 g/100 g dry matter, with 11 of the varieties containing above 60 g/100 g dry matter. An orange-fleshed variety, Apomuden, had the lowest amount of starch (48.9 g/100 g dry matter), while the cream-fleshed variety Histarch had the highest (77.3 g/100 g dry matter). The flours from the 12 sweet potato varieties had intermediate amounts of amylose, within the range 10–30 g/100 g dry matter, and showed typical molecular distribution according to size-exclusion chromatography (SEC). The fine structures of amylopectin, as revealed by anion-exchange chromatography, contained features common for starches of C-type X-ray pattern, but some structural differences were also observed.     

Voltage standards for testing ac voltage calibrators

Conclusions The V1-14 setup allows ac voltage measurement within the range from 0.1 to 300 V by the indirect comparison method and in the 0.1 to 100 mV range by substitution combined with comparison.The V1-14 setup conforms to 1st-class standards and can be used to test and certify both locally produced and imported voltage standards (calibrators), digital voltmeters, and also 2nd-class or less accurate thermoelectric converters.Translated from Izmeritel'naya Tekhnika, No. 2, pp. 65–66, February, 1978.     

1T’ RexMo1−xS2–2H MoS2 Lateral Heterojunction for Enhanced Hydrogen Evolution Reaction Performance

The imperfect interfaces between 2D transition metal dichalcogenides (TMDs) are suitable for boosting the hydrogen evolution reaction (HER) during water electrolysis. Here, the improved catalytic activity at the spatial heterojunction between 1T’ Re_xMo_1−xS₂ and 2H MoS₂ is reported. Atomic-scale electron microscopy confirms that the heterojunction is constructed by an in-situ two-step growth process through chemical vapor deposition. Electrochemical microcell measurements demonstrate that the 1T’ Re_xMo_1−xS₂–2H MoS₂ lateral heterojunction exhibits the best HER catalytic performance among all TMD catalysts with an overpotential of ≈84 mV at 10 mA cm⁻² current density and 58 mV dec⁻¹ Tafel slope. Kelvin probe force microscopy shows ≈40 meV as the work function difference between 2H MoS₂ and 1T’ Re_xMo_1−xS₂, facilitating the electron transfer from 2H MoS₂ to 1T’ Re_xMo_1−xS₂ at the heterojunction. First-principles calculations reveal that Mo-rich heterojunctions with high structural stability are formed, and the HER performance is improved with the combination of increased density of states near the Fermi level and optimal ΔG_H* as low as 0.07 eV. Those synergetic effects with many electrons and active sites with optimal ΔG_H* improve HER performance at the heterojunction. These results provide new insights into understanding the role of the heterojunction for HER.