Kazimierz Wielki University in Bydgoszcz

About: Kazimierz Wielki University in Bydgoszcz is a education organization based out in Bydgoszcz, Poland. It is known for research contribution in the topics: Luminescence & Population. The organization has 1109 authors who have published 2923 publications receiving 19548 citations. The organization is also known as: Casimir the Great University & Uniwersytet Kazimierza Wielkiego w Bydgoszczy.

High temperature (nano)thermometers based on LiLuF4:Er3+,Yb3+ nano- and microcrystals. Confounded results for core–shell nanocrystals

Abstract: Recent technological developments require knowledge of temperature down to the micro- or even nano-scale. Lanthanide-doped nanoparticles became a popular tool to achieve this. Their temperature sensitive luminescence enables their application as remote thermometers and for mapping temperature profiles with high spatial resolution. Applicability of luminescence thermometry is, however, often limited at high temperatures. In nanoelectronics or chemical reactors, high temperatures above 500 K are common and new approaches for accurate high temperature sensing need to be developed. In this work, we report three different shapes of upconverting LiLuF4:2% Er3+,18% Yb3+ nanocrystals both with and without shells and study the influence of the shell on the thermometric properties. We observed peculiar behavior of the core–shell particles suggesting the presence of the dopants within the protective and ‘undoped’ shells. Coating the nanoparticles with a silica layer extends the operational temperature range. In an upconversion (UC) Yb3+–Er3+ system temperature sensing relies on thermal coupling between the 4S3/2 and 2H11/2 energy levels. At sufficiently high temperatures (>550 K), we observe additional thermal coupling involving the higher 4F7/2 energy levels. The larger energy gap allows to increase the relative sensitivity at elevated temperatures and to sustain a high temperature precision over a wider temperature range than for a two-level Boltzmann thermometer. The thermal coupling between the 4S3/2 and 2H11/2 energy levels is used for lower temperature sensing ( 550 K).

A new approach to assess occupational exposure to airborne fungal contamination and mycotoxins of forklift drivers in waste sorting facilities.

Abstract: The waste management industry is an important employer, and exposure of waste-handling workers to microorganisms is considered an occupational health problem. Besides fungal contamination, it is important to consider the co-occurrence of mycotoxins in this setting. Forklifts with closed cabinet and air conditioner are commonly used in waste industry to transport waste and other products within the facilities, possibly increasing the risk of exposure under certain conditions. The aim of this study was to assess the fungal contamination and mycotoxin levels in filters from the air conditioning system of forklift cabinets, as an indicator to assess occupational exposure of the drivers working in a waste sorting facility. Cytotoxicity was also assessed to understand and characterize the toxicity of the complex mixtures as present in the forklift filters. Aqueous extracts of filters from 11 vehicles were streaked onto 2% malt extract agar (MEA) with chloramphenicol (0.05 g/L) media, and in dichloran glycerol (DG18) agar-based media for morphological identification of the mycobiota. Real-time quantitative PCR amplification of genes from Aspergillus sections Fumigati, Flavi, Circumdati, and Versicolores was also performed. Mycotoxins were analyzed using LC-MS/MS system. Cytotoxicity of filter extracts was analyzed by using a MTT cell culture test. Aspergillus species were found most frequently, namely Aspergillus sections Circumdati (MEA 48%; DG18 41%) and Nigri (MEA 32%; DG18 17.3%). By qPCR, only Aspergillus section Fumigati species were found, but positive results were obtained for all assessed filters. No mycotoxins were detected in aqueous filter extracts, but most extracts were highly cytotoxic (n = 6) or medium cytotoxic (n = 4). Although filter service life and cytotoxicity were not clearly correlated, the results suggest that observing air conditioner filter replacement frequency may be a critical aspect to avoid worker’s exposure. Further research is required to check if the environmental conditions as present in the filters could allow the production of mycotoxins and their dissemination in the cabinet during the normal use of the vehicles.

Perceived social support and life-satisfaction

Abstract: The article concerns the relationship between life-satisfaction and the features of interpersonal relationships and social support. The research presented in this paper concerned the satisfaction with the relationships with family members, friends, colleagues and acquaintances, the extent of the relationships among these groups, and the perceived social support. The aim of the presented research is to assess the impact of these characteristics on life-satisfaction. In addition, the changes that occurred after the social skills training in the level of life-satisfaction and its determinants were examined. The study group consisted of 60 participants. The results show that the strongest determinants of life-satisfaction are practical support and the satisfaction with the relationships with friends. After the social training the structure of the determinants changed. The factors which were relevant before the training appear to be insignificant now; however, the emotional support, satisfaction with family relationships and the number of friends gain in importance. The social skills training was also effective and increased the level of life-satisfaction.

Luminescence of F + and F centers in AI 2 O 3 -Y 2 O 3 oxide compounds

Abstract: We summarize the results of investigation of spectral-kinetic characteristics of the luminescence of F+ and F-centers in Al2O3, YAlO3 (YAP) and Y3Al5O12 (YAG) crystals under excitation by synchrotron radiation in the transmittance and fundamental absorption ranges of these oxides. We show that the luminescence of F+ and F centers in the mentioned crystals can be excited via the corresponding intrinsic 1A→2A, 2B and 3P (F+) and 1S→3P, 1P (F) transitions of these centers, as well as via the radiative relaxation of excitons localized around F+ and F centers. In YAG crystal fast (2.3 ns) emission in the 400 nm band, excited at 3.33, 5.37 and 6.56 eV, arises from the F+-type centers, localized around YAl antisite defects (ADs). In Al2O3 and YAP crystals, the luminescence of excitons localized around F+ centers (LE(F+) centers) is revealed and the energies of formation of such excitons are determined as well. In YAG crystal the observation of the luminescence of LE(F+) centers is obscured due to presence of the large content (~0.2 at.%) of YAl ADs and formation of an excitons localized around YAl ADs and dimer F+-ADs centers.

Technological process planning by the use of neural networks

Abstract: The central objective of the present author's research is to develop a system supporting the design of a technological process (a computer-aided process planning system) that functions similarly to a human expert in the field in question. The use of neural networks makes the creation of such a system possible. The proposed method uses a system of three blocks of neural networks, and involves the creation of neural networks to be used for the selection of machines, tools, and machining parameters. These networks are built for each process operation separately; that is, a set of neural networks is created for each selection. For the construction of models, different types of neural networks (multilayer networks with error backpropagation, radial basis function, and Kohonen) with different structures were employed, and the networks that made the best selections were identified. A method was also developed for the elimination of defects occurring during the production process. When a defect comes to light, this method suggests changes to the technological process, thus improving the quality of that process. Guidelines for the elimination of defects are produced in the form of decision rules. Such a computer-aided process planning system will be especially useful for process engineers who do not yet have sufficient experience in the design of technological processes, or who have only recently joined a particular manufacturing enterprise and are not fully familiar with its machines and other means of production (tools and instrumentation). It should be emphasized that such a system performs an advisory role, and it is always the process engineer who makes the final decision. The neural network models were tested on real data from an enterprise. A computer-aided process planning system based on rules and neural network models enables the intelligent design of technological processes.