Nontrivial period annuli in the second order ordinary differential equation are continua of periodic trajectories that contain inside more than one critical point. They can appear in conservative equations, which are known to have no attractors. Nevertheless, according to some authors, their behavior may be done chaotic by adding a periodic external force. Is the period of the external force correlated with periods of solutions in period annuli? Is the chaotic behavior of a solution dependent on the initial value and, in turn, on a certain periodic annulus? These, and related questions are studied in the article.

In the process of considering the documented health benefits of Viburnum opulus L. (V. opulus), including its anti-inflammatory and antioxidant activities, the present study was designed to qualitatively and quantitatively evaluate the biochemical profile and antimicrobial potency of four commercially available V. opulus extracts. These extracts were obtained from its flowers, bark, berries, and a mixture thereof by cold ultrasound-assisted extraction. An examination of the V. opulus extracts indicated a relative abundance of group compounds, such as phenolics, flavonoids, tannins, and anthocyanins, which are responsible for antioxidant activity (AOA). The widest range in all of the four group compounds was detected in the V. opulus extract sourced from berries, whereas the narrowest range was found in those obtained from flowers. The HPLC-ESI-TQ-MS/MS technique displayed relative fluctuations in the concentrations of individual amino acids (AAs) over the four V. opulus extracts. The prevalence of proline was marked in the flower-derived extract, which made up 63.3% of the total AAs, while aspartic and glutamic acids dominated in the berry-derived extract by contributing up to 29.2 and 24.4% to the total AA content, respectively. Profiling of the individual phenolic compounds disclosed the superiority of chlorogenic acid (up to 90.3%) in the berry and mixed extracts, as well as catechin (up to 57.7%) and neochlorogenic acid (11.1%) in the bark extract, which conveyed a remarkable contribution toward antimicrobial activity. The lowest content of individual phenolics was found in the flower extract. Owing to its substantially denser bioactive composition, the V. opulus berries and bark extracts exhibited markedly better AOA, which was pinpointed by three independent methods, i.e., DPPH•, FRAP, and ABTS•+, than those obtained from flowers or a mixture of V. opulus morphological parts. As part of the antimicrobial activity testing, the V. opulus extracts exhibited outstanding inhibitory activity and a homeopathic mode of action. The V. opulus extracts obtained from a mixture, bark, and berries were more active against 8 out of 19 selected test microorganisms at minimum inhibitory concentration (MIC) values that ranged from 0.24 to 0.49 µL mL−1. Overall, the extracts of V. opulus were found to be effective against Gram-positive and Gram-negative bacteria. However, their conceivable exploitation as functional or pharmaceutical ingredients must be further clarified within in vivo models.

A two-year trial (2021 and 2022) was performed with five different fungicide and foliar fertiliser application strategies to control apple scab (Venturia inaequalis) in integrated apple orchards in Latvia. A strategy of using inorganic fungicides or combining them with synthetic fungicides was compared to a strategy of applications with only synthetic fungicides and untreated control. Furthermore, two strategies included foliar fertilisers to determine whether they may affect apple scab used alone or combined with synthetic fungicides. The timing of the fungicide applications was based on the risk forecasted by the decision support system RIMpro, and fertilisers were used at certain growth stages of the crop. The disease incidence on untreated fruits on cv. Auksis ranged from 38.3% to 59.6%, and on cv. Ligol from 99.3% to 99.5%. Strategies including synthetic fungicides were the most effective against scab on shoot leaves and fruits. The strategy using only inorganic fungicides was effective for low-inoculum orchards. Combining synthetic and inorganic fungicides provided the best apple scab control strategy on fruits, likely helping reduce the resistance selection pressure and residues of synthetic fungicides. Foliar fertilisers were insufficient to control apple scab; they would supplement existing scab fungicide programs.

Abstract The degradation of chernozems and increased soil erosion led to the search for more advanced methods of tillage, taking into account climatic conditions, the quantity and quality of crop residues, and the volume of fertilizer application. The aim of the study was to establish the effect of various methods of basic tillage in the presence of preceding plant‘s crop residues on the growth and development of spring barley plants. The experiment was carried out in the forest-steppe of Ukraine. During the experiment, the influence of various methods of basic tillage on the agrophysical properties of the soil, its water regime, and weed infestation of spring barley crops was studied. For comparison, the following types of basic tillage were used: dump to a depth of 20–22 cm, chisel tillage to a depth of 14–16 cm, and disc tillage to a depth of 10–12 cm. Dump and chisel processing were characterized by higher grain yield. Chisel tillage provided better moisture accumulation compared to reverse ploughing. In spring, at the time of sowing grain crops in the layer of 0–15 cm, the reserves of productive moisture during chiselling were 145 mm, and during mouldboard processing 122.6 mm. Thus, chisel tillage for spring barley creates the best conditions for moisture supply and guarantees a high level of grain yield and significant profitability of production.

Abstract In this research, a Python algorithm was developed that calculated one of the total concentrations of phenol in vegetable oils using the RGB colour system. The algorithm converts data obtained in the RGB colour system into absorbance values using NumPy, Pandas, Matplotlib and SciPy libraries. It allows for complex data calculations and analyses that are particularly accurate and more efficient than traditional methods such as MS Excel. Algorithm development is divided into six stages: library import, user data input and processing, absorbance calculations, linear regression and calibration curve drawing, data analysis and saving results in Excel format. The algorithm offers flexible use in both local Python development environments and online platforms such as Kaggle (https://www.kaggle.com/). It can also be used in the analyses of other plant extracts or chemical substances, where interpretations of RGB colour system data are used as a basis. This algorithm opens up new possibilities in scientific data analysis by taking advantage of modern technology and programming language.

The swift adoption of digitalization and transformation within enterprises and their operations had commenced prior to the onset of COVID-19, characterized by the shift towards Industry 4.0 and subsequently progressing towards Industry 5.0. However, mandated restrictions significantly amplified the necessity and drive to utilize digital tools for both businesses and consumers. New opportunities previously not utilized have arisen yet are hand in hand with several risks linked to the use of these new digital tools. The bioeconomy sector is not an exception. The study aims to consider the sector representatives’ opinions on the significance of the risks related to digitalization. The empirical results of this study stem from a survey of enterprises in the bioeconomy sector carried out in 2020 and 2021 in Latvia. The research results prove that there are many factors influencing the development of digitalization. The results notably affirm that both entrepreneurs and employees in SMEs recognize the considerable importance of these risks, particularly emphasizing the significance of security and technology risks. While the Chi-Square Test of Independence indicates a notable association between risk evaluation scores and the education level of respondents before the COVID-19 outbreak in 2020, this association diminishes in 2021. Contrary to the hypothesis that individuals with higher education levels are more attentive to risks, the evidence shows inconsistency in their perception, particularly regarding professional challenges of the entrepreneur and employees to use digital tools and other risk categories. However, the relationship between higher education levels and the significance of risks pertaining to security risks, technology risks, and the skills of the clients to use digital tools is partly affirmed.

The seasonal variation of Baltic sprat chemical composition leads to a change in smoked fish texture and color, which may pose challenges for industrial processing. This research aimed to evaluate the dependence of smoked sprat texture and color on the catching season and pre-treatment applied before the smoking of fish, following one year of frozen storage. Various proportions of sodium chloride (NaCl), calcium chloride (CaCl2), and acetic acid were used in the solution for fish pre-treatment. The introduction of salts during the pre-treatment process for late-season fish has been found to enhance the texture of the smoked product. The color components of the lightness (L*) and redness (a*) measured on the smoked fish surface remained consistent throughout the catching season, whereas the yellowness (b*) showed a tendency to decrease towards the end of the season. Moreover, when acetic acid was applied to late-season fish, the yellowness of the smoked sprat surface increased compared to that of the sample without this pre-treatment. These findings suggest that the choice of pre-treatment methods can significantly improve the texture and color attributes of the smoked sprat, which is crucial for maintaining quality standards, especially in the context of industrial processing.

Landscapes play a significant role in the regional development by providing ecosystem services to the local communities. Significant changes in land management due to the political decisions may significantly change the typical landscape in rural areas. Therefore, the aim of this study is to explore how to use the landscape differences to facilitate achievement of national socio-economic and environmental objectives, while avoiding significant changes and safeguarding typical landscapes. Cluster analysis was used to identify relatively homogeneous groups with four socio-economic and environmental indicators, namely, profit, employment, net GHG emissions, habitat quality. Results show that clusters with the highest socio-economic return are located closest to the capital city and carbon sequestration measures may be concentrated in the landscapes that are geographically farthest from the capital city, but then the abandonment of rural areas and the disappearance of typical landscapes may occur. The political decisions related to land use change should be adapted to the specific landscape, so that not only socio-economic and environmental objectives are achieved together with the fulfilment of international obligations, but also the typical landscape of the specific landscape region is preserved.

Restoration of the soil fertility is an important task for scientists and practitioners. Based on the constructed mathematical model of the surface of a screw-type working body, rotating around a fixed horizontal axis, there are determined the work and power of penetration of the screw-type working body into the soil, loosening the soil and overcoming the soil friction. It has been established that the cutting power is proportional to the square root of deepening of the working body (а1/2), and the radius of the working body (R1/2) is directly proportional to the speed of the unit V. On the basis of a complex of experimental studies, regression dependencies were derived to determine the traction resistance when cultivating the soil with a harrow, equipped with screw-type working bodies. It has been found that the dominant impact upon the value of the traction resistance Рх is exerted by the depth of tillage h, then by the angle of attack β of the battery of the screw-type working bodies, but the least impact is made by the change in the speed of the harrow V. The difference between the calculated and the experimental values of the traction resistance ranges from 9.6...11.2%.

In recent decades, cultural ecosystem services have been increasingly studied in the field of ecosystem services. Even more diverse studies have been conducted since the Covid-19 pandemic and today's political situation brings cultural ecosystem services, more specifically identity, symbolic, religious and cultural-historical values even more to the fore. Although the services of cultural ecosystems in general are more and more extensively researched, mostly focusing on tourism issues, the cultural-historical, symbolic, religious and entertainment value as base not only for tourism, but also for strengthening local communities, is still rarely studied in research in the world and in Latvia due to the lack of data and the intangible nature of research. Therefore, a methodological framework for conducting such a research, selecting data from publicly available sources, as well as obtaining missing data in field studies. Also, tools for integrating results from assessment of cultural ecosystem services related to identity, religious and symbolic values into political and decision-making documents are missing. Thus, as a continuation of the study on the assessment of cultural ecosystem services and integration into political and decision-making documents, the aim of the particular article is presentation of a methodological framework developed for the assessment of cultural-historical, symbolic, religious and entertainment values in the landscape. The methodological framework includes seven steps, which are described in this article. The methodological framework created will be tested and validated in future studies, where improvements may be made depending on the situation during the process.