As is well known, gas consumption and its prices depends on many factors including local factors, geopolitics, the development of the gas transport infrastructure (including liquefied natural gas), distribution and extraction costs – for example unconventional deposits (e.g. shale gas). The global gas market depends primarily on the economic relations between large gas producers and importers e.g. US-China, Middle East/US – Russia etc. (Olayele 2015). In individual countries, the price is also dependent on concluded contracts and delivery directions. Also it should be mentioned that the gas consumption depends on weather conditions, type of day of the year (holiday, business day, month) and economic situation (Kosowski et. al 2010). What impact has the appearance of the COVID-19 epidemic had on the European natural gas market?

The analyzed research problem concerned, in particular, two areas: gas consumption and its prices, in selected European countries in the aspect of the spread of the COVID-19 epidemic with reference to historical data from 2016–2019. Seven European countries belonging to the European Network of Transmission System Operators for Gas (ENTSOG) were selected, for which the highest inland consumption of natural gas by country was observed in the last year. The countries are presented in order or consumption: Germany, the United Kingdom, Italy, France, the Netherlands, Spain, Poland. The data has been downloaded from transmission system operators (TSOs) for each of these countries.

Furthermore the article showed information about the dates of governments restrictions (lockdown), LNG contract volumes, injection/withdrawal volumes (storage).

In 1981, Polish canoeists (members of the Bystrze Academic Travel Club) made the first journey along the waters of the River Colca in the section located in Arequipa Province (Peru), along which the waters flow in a deep canyon. Information on this sporting achievement – and a description of the Canyon and its surrounding area filled the Peruvian press and tourist publications around the world, ensuring that the Colca Canyon became one of the most important goals for tourists anywhere in Peru from that time on. However, mass infl uxes of tourists, noisy trips, the development of hotel infrastructure and other items required in tourism have generated permanent change in the character of the Colca Valley, and done much to influence the lives of its inhabitants.

Ch-chalcedony is a green colored member of the quartz group of gem stones. The appearance of Ch-chalcedony is very similar to that of chrysoprase. Differently, Ch-chalsedonies have a chromium element instead of a nickel element as a trace element. Green quartz used in jewelery as a seal stone, in necklaces and rings and has been one of the most valuable quartz varieties throughout history, with its beautiful green color,more rare than other quartz varieties. The Ch-chalcedonies in the North Anatolian region is yellowish-white, brownish gray, light green to dark green in color ranging from several centimeters to one meter thick in veins and lenses in the Lower-Middle Eocene dolomitic limestones. Ch-chalcedonies are composed of fine-grained and occasionally fibrous needle-like quartz; in some examples, quartz is present together with cristobalite, tridimite and cuspidine minerals. According to geochemical investigations in Ch-chalcedonies, the main oxides that were determined are as follows: SiO2 was observed in the range of 95.86–97.81%, Fe2O3 was observed in the range of 0.61–0.91% and Cr2O3 was observed in the range of 0.125–0.168%. A trace element analysis of Ch-chalcedonies, shows their significant enrichments in: Ni, Mo, Cu, Mn, V, Cr and W, especially in the Cr (up to 705 ppm). The green color of the studied Cr-chalcedonies originates from the element chromium. Taking the possible reserves into account, the hardness, color, massive structures, mineralogical, petrographical and gemological features of Ch-chalcedonies in the region are evaluated together. It is determined that they are suitable for the production of jewelry and ornaments.

Drawing on the stressor–emotion model, the study examines the mechanisms of counterproductive work behavior (CWB) development: specifically (1) the direct effect of job stressor (bullying at work); (2) the moderation effect of the Dark Triad (DT) and job control (JC); and (3) the moderated moderation effect (DT x JC) on the job stressor–CWB link. Data were collected among 763 white- and blue-collar workers. The hypotheses were tested by means of the PROCESS method. As expected in the hypotheses, high job stressor was directly related to high CWB, and DT moderated (increased) the link. JC also moderated the job stressor–CWB link, but the moderation effect was in a direction opposite to expectations. High job control participants were more likely to report CWB when they reported a high level of the stressors. The moderated moderation effect was supported. JC increases the moderation effect of DT on the job stressor–CWB link. The highest level of CWB was observed when DT and JC were high. The findings provide further insight into processes leading to the development of CWB.

Based on a study of Polish migrants living in England and Scotland, this paper explores how Polish families who have decided to bring up their children in the UK make initial school choices. The Polish parents taking part in our study generally had low levels of social and cultural capital (Bourdieu 1986) upon arrival in the UK: they had limited networks (predominantly bonding capital) (Putnam 2000) and a poor command of English, and lacked basic knowledge of the British education system. Meanwhile, this is a highly complex system, very much different from the Polish one; moreover, school choice plays a much more important role within the UK system, especially at the level of secondary education. We found that while some parents acted as ‘disconnected choosers’ (Gewirtz, Ball and Bowe 1995) follow-ing the strategy they would use in Poland and simply enrolling their children in the nearest available school, others attempted to make an informed choice. In looking for schools, parents first and foremost turned to co-ethnic networks for advice and support; nevertheless, parents who attempted to make an informed choice typically lacked ‘insider knowledge’ and often held misconceptions about the British education system. The one feature of the system Polish parents were very much aware of, however, was the existence of Catholic schools; therefore, religious beliefs played a key role in school choice among Polish parents (with some seeking and others avoiding Catholic schools). The ‘active choosers’ also made choices based on first impressions and personal beliefs about what was best for their child (e.g. in terms of ethnic composition of the school) or allowed their children to make the choice. Parents of disabled children were most restricted in exercising school choice, as only certain schools cater for complex needs. All in all, the Polish parents in our sample faced similar barriers to BME (Black Minor-ity Ethnic) parents in exercising school choice in the UK and, regardless of their own levels of education, their school selection strategies resembled those of the British working class rather than of the middle class. However, the risk of ‘bad’ initial school choice may be largely offset by a generally strong pref-erence for Catholic schools and parents’ high educational ambitions for their children.

An efficiency of the nonsingular meshless method (MLM) was analyzed in an acoustic indoor problem. The solution was assumed in the form of the series of radial bases functions (RBFs). Three representative kinds of RBF were chosen: the Hardy’s multiquadratic, inverse multiquadratic, Duchon’s functions. The room acoustic field with uniform, impedance walls was considered. To achieve the goal, relationships among physical parameters of the problem and parameters of the approximate solution were first found. Physical parameters constitute the sound absorption coefficient of the boundary and the frequency of acoustic vibrations. In turn, parameters of the solution are the kind of RBFs, the number of elements in the series of the solution and the number and distribution of influence points. Next, it was shown that the approximate acoustic field can be calculated using MLM with a priori error assumed. All approximate results, averaged over representative rectangular section of the room, were calculated and then compared to the corresponding accurate results. This way, it was proved that the MLM, based on RBFs, is efficient method in description of acoustic boundary problems with impedance boundary conditions and in all acoustic frequencies.

Recently, significant progress has been made in experimental studies on the flow of wet steam, measuring techniques based on recording the phenomenon of extinction of light and ultrasound have been elaborated or improved. The basic value experimentally determined in the final stage was the content of the liquid phase defined as the wetness fraction. The methodology of tests and experimental investigations was presented, as well as the applied and developed measurement systems. Next, some developed designs of new ultrasonic and light extinction measuring probe and their modifications are described. The article presents also some examples of applications of the developed measurement techniques in application to experimental research conducted on wet steam. Examples of comparison between experimental and numerical tests for the extinction method are also provided.

The purpose of this study was to validate the applicability of specialized microbial consortium for the degradation of lipids in wastewater. An experimental model of the process is proposed that enables prediction of the required batch length. This model can be used for supervision of the process and to control cycles of the batch reactor. The study involved 4 reactors with microbial consortium obtained by inoculation from a commercially available biopreparate. Each reactor was fed a different load of lipid containing substrate. The biodiversity, settling characteristics and COD reductions were measured. The biodiversity of the microbial consortium changed within a range of ±15% depending on lipids concentration, as shown by the Shannon index and increasing amount of β-proteobacteria. Higher concentrations of lipids increased the biodiversity suggesting higher growth of microorganisms capable of utilizing lipids as energy and carbon source by producing lipid hydrolyzing enzymes. High lipid concentrations degrade the settling capabilities of the biomass. Higher lipid concentrations (0.5–2.0 [g/l]) increase the final COD (1445–2160 [mg O2/l]). The time necessary for substrate degradation changes with the initial concentration and can be predicted using the proposed model. The study showed that specialized microbial consortium is capable of reducing the lipids containing substrate and maintains its biodiversity suggesting that utilization of such consortia in multiple cycles of a batch reactor is possible. Future research should concentrate on assessing the biodiversity and effectiveness of substrate reduction after an increased number of batch reactor cycles.

Composition effect on electro-optic (EO) properties of a LiNbO₃ (LN) single-crystal has been investigated in a Li₂O-content range of 47.0–49.95 mol%. Some non-congruent LN crystals with different Li₂O-contents were prepared by performing Li-deficient or Li-rich vapour transport equilibration treatments on as-grown congruent LN crystals. Unclamped EO coefficients γ₁₃ and γ₃₃ of these samples were measured by a Mach–Zehnder interferometric method. The measurements show that in the Li-deficient regime both γ13 and γ33 increase by ∼8% as Li₂O-content decreases from the congruent 48.6 mol% to the 47.0 mol% in the Li-deficient regime. The feature is desired for the EO application of the Li-deficient crystal. In the near-stoichiometric regime, both γ₁₃ and γ₃₃ reveal a non-monotonic dependence. As the Li₂O-content increases from the 48.6 mol%, the EO coefficient decreases. Around Li₂O-content 49.5 mol%, a minimum is reached. After that, the EO coefficient recovers slowly. At the stoichiometric composition, it recovers to a value close to that at the congruent point. Comparison shows that different crystal growth methods give rise to different defect structure features and hence different composition effects.

The semiempirical rule, “Rule 07” specified in 2007 for P-on-n HgCdTe photodiodes has become widely popular within infrared community as a reference for other technologies, notably for III-V barrier photodetectors and type-II superlattice photodiodes. However, in the last decade in several papers it has been shown that the measured dark current density of HgCdTe photodiodes is considerably lower than predicted by benchmark Rule 07. Our theoretical estimates carried out in this paper support experimental data. Graphene and other 2D materials, due to their extraordinary and unusual electronic and optical properties, are promising candidates for high-operating temperature infrared photodetectors. In the paper their room-temperature performance is compared with that estimated for depleted P i-N HgCdTe photodiodes. Two important conclusions result from our considerations: the first one, the performance of 2D materials is lower in comparison with traditional detectors existing on global market (InGaAs, HgCdTe and type- II superlattices), and the second one, the presented estimates provide further encouragement for achieving low-cost and high performance HgCdTe focal plane arrays operating in high-operating temperature conditions.