EFFECT OF CHILLING AND FREEZING ON SURVIVAL OF VIBRIO PARAHAEMOLYTICUS ON FISH FILLETS1

Vibrio parahaemolyticus is a foodborne pathogen isolated from coastal waters of the United States, and from seafoods including fish. No information is available on the viability of V. parahaemolyticus on raw, chilled and frozen fish. A three‐strain mixture of V. parahaemolyticus was inoculated on fish fillets (pH 6.4) to obtain a bacterial load of 10⁴ (high) or 10³ (low) CFU/fillet, and stored at 4C or 8C for 9 days or at – 18C for seven weeks. At 4C and 8C, and at both levels of inoculation, V. parahaemolyticus survived on the fillets for the entire duration of the study. However, there was a significant reduction (P < 0.01) in V. parahaemolyticus population on the fillets by 9 days of storage. In the frozen fillets, there was a sharp decline (P < 0.01) in the population of V. parahaemolyticus by day 5 of storage. Although chilling and freezing significantly (P < 0.01) inactivated high numbers of V. parahaemolyticus on fish, they cannot be relied upon as a method to reduce V. parahaemolyticus on fish, since the time and magnitude of reduction depends on the initial load of the pathogen and the storage temperature.     

eVEREst—SUPPORTING ESTIMATION OF REAL ESTATE VALUE

Enhanced Value Estimation of Real Estates (eVEREst) is the project carried out at the Department of Management Information Systems at the Poznań University of Economics. The paper presents the idea and the architecture of a system that supports the real estate registry with additional information that enables more precise estimation of real estate value.     

Thermal Denaturation and Aggregation of Proteins in Minced Fish as Studied by a Thermomechanical Method

A thermomechanical method of heating and mixing, was developed to study directly protein denaturation and aggregation in minced fish. It is based on simultaneous and continuous measurement of torque and temperature in a meat sample mixed while being heated. The torque and temperature were continuously recorded. From curves thus obtained, thermal denaturation temperatures of minced samples from 6 marine fish species were determined. The curves showed 4-6 peaks at 32-38°C, 44-46°C, 52-56°C, and 62-75°C, presumably corresponding to denaturation of myosin, actomyosin, sarcoplasmic proteins, and actin, respectively. The temperature range of peak 1 was 4-5°C higher in fatty fish (herring, mackerel) than in lean fish (cod, blue whiting).     

Experimental and numerical assessment of fracture toughness of dual-phase austempered ductile iron

The effects of the microstructure topology on the fracture toughness of dual-phase austempered ductile iron are studied in this paper by means of finite element modelling and experimental testing. To this end, specimens with matrix microstructures ranging from fully ferrite to fully ausferrite were studied and the preferential zones and phases for crack propagation were identified in every case. The effectiveness of the ausferrite phase as a reinforcement of the ferritic matrix via the encapsulation of the brittle and weak last-to-freeze (LTF) zones was confirmed. The toughening mechanism is consequence of the increment in the crack path longitude as it avoids the encapsulated LTF zones. Besides, the presence of small pools of allotriomorphic ferrite increase the crack propagation resistance of the ausferrite-ferrite matrices.     

A discussion on “On the solution of a class of fuzzy system of linear equations”

The paper is a discussion on the results obtained by Salkuyeh in the article (Sādhānā 40(2):369–377, 2015). Salkuyeh considers the solution of the fuzzy system of linear equations (FSLE) and gives numerical examples where the results of FSLE are calculated. It was shown that the results by Salkuyeh are not full solutions and do not satisfy equivalent forms of the analysed FSLE. The paper presents a multidimensional approach to finding the solution of the FSLE. On the basis of the notation of the horizontal fuzzy number, a full solution that satisfies the FSLE and its equivalent forms is obtained.     

Stabilization of Lipids in Minced Fish by Freeze Texturization

Minced meats of Baltic cod (Gadus morhua) with added krill (Euphausia superba D.), krill precipitate, or bream (Abramis brama) were freeze-textured or frozen conventionally. Lipid composition and oxidation were analyzed after 6–8 mo storage at –20°C. Analyses included peroxide value, fluorescence, lipid classes (thin-layer chromatography), and fatty acid composition (gas chromatography). Peroxide value was 4–9 times lower in freeze-textured meat minces than in conventionally frozen samples. Docosahexaenoic acid (DHA) was higher, by 22% in bream minces to 80% in cod minces without additives, in all freeze-textured minces than in conventionally frozen samples. Texturization could reduce lipid oxidation in minced fish during frozen storage.     

Integrability and non-integrability in quantum mechanics

The concepts of integrability, non-integrability and chaos in quantum mechanics are examined, and it is indicated that they all are sensibly definable only in connection with the corresponding properties of their classical analogues. The concrete examples concern the quantum and classical properties of dynamic systems on SU₃ algebra and classically integrable but quantum nonintegrable system with two degrees of freedom.     

Influence of the control mode on overlapping commutation of thyristors in a series inverter†

The paper describes the effects of changes in the triggering frequency on the maximum working frequency of a series inverter. Inverters differ in the type of load and in the mutual coupling existing between two commutation inductors in the circuit. It has been shown that the transient state is a result of changes in thyristor commutation from natural or critical to overlapping, and is dependent on the mode of change of the triggering frequency. The region of overlapping commutation has been determined by using two types of frequency change: fast (by keying modulation) and slow (by frequency modulation). The results show that slow changes in thyristor commutation permit a higher maximum working frequency than do fast changes. The region of overlapping commutation of thyristors is defined by new limit curves. The results may, for example, be applied in the design of an ultrasonic generator operating with frequency modulation.     

Scanning and transmission electron microscopy microstructure characterization of mechanically alloyed Nb–Ti–Al alloys

Results are presented of an investigation of the microstructure development during mechanical alloying and following consolidation of an Nb15Ti15Al alloy. The alloy was synthesized from elemental as well as pre‐alloyed powders. The microstructure of this material was examined by transmission electron microscopy, scanning electron microscopy and X‐ray diffraction. The use of pre‐alloyed TiAl powder for synthesis of the Nb15Ti15Al alloy meant that a much shorter time was required to complete the mechanical alloying process compared with the synthesis of elemental powders. The investigation indicates that three phases were present in the consolidated materials: the Nb solid solution, the Nb₃Al intermetallic phase and the dispersoid.