Impact of Ozonation Process on the Microbiological Contamination and Antioxidant Capacity of Highbush Blueberry (Vaccinum corymbosum L.) Fruit during Cold Storage

In the studies conducted, the impact of the innovative ozonation procedure on the microbial state and antioxidant potential of highbush blueberry (Vaccinum corymbosum L.) stored under cold storage conditions was assessed. Microbiological analysis was carried out to determine the total number of mesophilic aerobic bacteria and the total number of fungi during the storage experiment. In addition, changes in the flavonoid, anthocyanins, and vitamin C content and the total antioxidant capacity were monitored during the storage. The degree of fruit infection with gray mold and anthracnose was determined. It was found that daily ozonation of fruits with a dose of 15 ppm for 30 min, every 12 h, for 28 days effectively reduced the development of aerobic mesophilic bacteria and fungi. On the last day of storage, symptoms of the infection by gray mold were observed in 27.5% of the control fruit, while the absence of symptoms was observed in case of the ozonated fruit. On the other hand, ozone was ineffective in case of inhibiting the infection by anthracnose. Nevertheless, the ozonation process allowed maintaining a high antioxidant potential of the fruit and substantially reduced losses of flavonoids, anthocyanins, and vitamin C. The utilized procedure has proved to be effective, providing the possibility of extensive use of ozone as a factor allowing sustaining a high commercial and consumption value of the fruit over extended time.     

Seed Selection for Spread of Influence in Social Networks: Temporal vs. Static Approach

The problem of finding optimal set of users for influencing others in the social network has been widely studied. Because it is NP-hard, some heuristics were proposed to find sub-optimal solutions. Still, one of the commonly used assumption is the one that seeds are chosen on the static network, not the dynamic one. This static approach is in fact far from the real-world networks, where new nodes may appear and old ones dynamically disappear in course of time. The main purpose of this paper is to analyse how the results of one of the typical models for spread of influence - linear threshold - differ depending on the strategy of building the social network used later for choosing seeds. To show the impact of network creation strategy on the final number of influenced nodes - outcome of spread of influence, the results for three approaches were studied: one static and two temporal with different granularities, i.e. various number of time windows. Social networks for each time window encapsulated dynamic changes in the network structure. Calculation of various node structural measures like degree or betweenness respected these changes by means of forgetting mechanism - more recent data had greater influence on node measure values. These measures were, in turn, used for node ranking and their selection for seeding. All concepts were applied to experimental verification on five real datasets. The results revealed that temporal approach is always better than static and the higher granularity in the temporal social network while seeding, the more finally influenced nodes. Additionally, outdegree measure with exponential forgetting typically outperformed other time-dependent structural measures, if used for seed candidate ranking.     

Application of averaged instantaneous power spectrum for diagnostics of machinery operating under non-stationary operational conditions

Vibration analysis of machines operating under non-stationary operational conditions requires special attention. This refers to the necessity of use of order tracking algorithms together with additional advanced signal processing methods, especially when faults indicators of interest are located in resonance frequency ranges.     

Friction welding of ductile iron with stainless steel

The study of mechanical properties and microstructure of friction welded coupe of ductile iron with stainless steel are presented. Scanning electron microscopy (SEM) was used for investigation of the fracture morphology and phase transformations taking place during friction welding process. It was concluded that in case of bainitic ductile iron (BDI) the fracture precedes mainly trough the cleavage planes. Moreover, the distribution of selected elements on both side of the joining interface was studied using EDS line and maps spectrometry. The EDS spectrometry showed some enrichment of ductile iron with Cr and Ni atoms close to the joint. The depth of Cr atoms penetration reached 50 μm. The heat generated locally by friction increased the temperature in the area close to the interface even over the melting point of ductile iron. This was confirmed by metallography which revealed the carbide eutectic enriched with Cr in ductile iron.     

A fast exact algorithm for the allocation of seats for the EU Parliament

In this paper, we analyse the problem of allocation of seats for the EU Parliament. To solve it, we propose a fast exact algorithm which overwhelms limitations of the existing methods. It allows us to examine all feasible allocations of seats within few minutes. On this basis, an in-depth analysis of the problem is provided and some of its properties are revealed (e.g., the number of feasible allocations of seats holding the Treaty of Lisbon), which have never been presented in the scientific literature. Furthermore, the proposed algorithm is not limited to dealing with the problem of allocation of seats for the EU Parliament, but it can be applied in the expert system for any other similar problem, especially under degressive proportionality constraints.     

Solids flow mapping in a high pressure slurry bubble column

Successful design and scale-up of Slurry Bubble Column Reactors (SBCRs) require proper understanding of how operating conditions affect their flow behavior. Presently, there is little information on the flow dynamics of solids (e.g., distribution of velocities and turbulent parameters) in slurry systems that are operated at industrially relevant conditions of high pressure, high superficial gas velocities, and high solids loading.Computer Automated Radio Particle Tracking (CARPT) is widely recognized as one of a few techniques that can be reliably used even in highly turbulent and opaque slurry flows. This work utilizes an improved CARPT technique to investigate the effect of reactor pressure (0.1-1 MPa) and superficial gas velocity (0.08-0.45 m/s) on solids phase velocity and shear stress in a pilot scale 0.16 m diameter stainless steel column using an air-water-glass beads () system. The solids axial velocity and shear stress were found to increase noticeably with pressure and superficial gas velocity in the churn turbulent flow regime.     

6‐Pyridinium benzo[a]phenazine‐5‐oxide derivatives as visible photosensitisers for polymerisation

Several 6‐pyridinium benzo[a]phenazine‐5‐oxide derivatives have been synthesised and characterised by proton nuclear magnetic resonance spectroscopy and mass spectrometry. The spectroscopic and electrochemical properties of these dyes were examined. The dyes were used as reducible sensitisers for selected electron donors (phenylthioacetic acid, phenoxyacetic acid, N‐phenylglycine, and ethyl 4‐N,N‐dimethylaminobenzoate) and as oxidisable sensitisers for electron acceptors (onium and N‐alkoxypyridinium salts). These photoredox pairs were found to be effective visible‐wavelength photoinitiators for the free radical polymerisation of trimethylolpropane triacrylate under visible light. The cationic photopolymerisation of cyclohexene oxide by the studied dyes and the onium salt photoredox pairs was ineffective. The obtained results are discussed on the basis of both free energy change for electron transfer to or from the benzo[a]phenazine dyes and the photochemical properties of the dyes, particularly their photobleaching. The proposed mechanism of dye fading is supported by density functional theory calculations and spectroscopic characterisation of the radical cation of the dye.     

A focus on vision

Eye problems, in general, tend to get overlooked in a crowd of broader health issues such as heart disease and cancer. For this reason, the vision health care community has been working hard in recent years to emphasize the importance of proper eye care.     

The synthesis of novel,visible-wavelength oxidizable polymerization sensitizers based on the 5,12-dihydroquinoxalino[2,3-b]pyridopyrazine skeleton

Novel dyes based on the 5,12-dihydroquinoxalino[2,3-b]pyridopyrazine skeleton were synthesized and subsequently characterized using ¹H NMR. Their electrochemical and spectral properties, such as absorption and emission spectra, quantum yield of fluorescence, and quantum yield of singlet oxygen generation, were also measured. The dyes were useful as photoinitiators for sensitizing compounds to photooxidation. Photoredox pairs comprising dyes and onium salts were found to be effective visible-wavelength initiators of free radical or cationic polymerization.     

The photochemical behaviour of naphthoylenebenzimidazolone dyes in 1-methyl-2-pyrrolidone

The photochemical behaviour of selected naphthoylenebenzimidazolone dyes is discussed in terms of the photobleaching of the dyes in the presence of electron donors (phenylthioacetic acid, N-phenylglycine, ethyl 4-N,N-dimethylaminobenzoate) as well as an electron acceptor (1-methoxy-4-phenylpyridinium tetrafluoroborate) that are used in photoredox systems for light-induced polymerization. The fluorescence quenching of the dyes in the presence of the electron donors and the electron acceptor was also examined.