Permanent Components Research Articles

XANTHOPHYLL CONCENTRATION IN LYMNAEA STAGNALIS CAUSED BY CHROMIUM IONS

Currently the pollution of natural waters by heavy metal ions is a particularly serious problem which results in the disruption of the balance of food chains and the overall ecosystem balance. In this regard the study of the reaction of the biotic components of the hydroecosystem to toxic effects is relevant, and will allow to expand the understanding of the adaptive mechanisms of aquatic organisms and to determine sensitive test objects and test functions for assessing the degree of pollution of natural waters.
 The influence of chromium ions (Cr3+ and Cr2O72-) in concentrations corresponding to 0.5 and 2 TLV in fish farming water basins was studied based on the concentration of xanthophylls in hemolymph, hepatopancreas, mantle and leg of Lymnaea stagnalis, which is a permanent component of most hydrobiocenoses of Zhytomyr Polissia. The dynamics of the discussed carotenoids at different durations of exposure (2, 7, 14 and 21 days) of the studied shellfish in a toxic environment were observed.
 It was found that 48-hour exposure of shellfish in solutions of chromium ions (Cr3+ and Cr2O72- ) regardless of their concentration (0.5 and 2 TLV) causes 2.45–3.23 times increase of xanthophylls in all the studied organs and tissues of L. stagnalis (p ≤ 0.001) which indicates the development of an immediate reaction of animals to toxic elements. Further prolongation of exposure to chromium ions (7, 14, and 21 days) resulted in non-linear organ-dependent dynamics of the xanthophyll content which is related to the specificity of the action of ions, the duration of exposure of animals to toxic solutions, and the metabolic features of the studied organs and tissues. It is shown that the content of xanthophylls in the body of L. stagnalis is characterized by tissue-organ specificity. The minimum amounts of the discussed carotenoid were recorded in the hemolymph of animals and the maximum values varied significantly between the studied components depending on the experimental conditions.

Determinants of commodity market liquidity

AbstractUsing positions data for 18 commodity futures during 2001–2020, we examine systematic and idiosyncratic determinants of Amihud price impact and microstructure noise proxying for permanent and transitory components of commodity futures liquidity. Idiosyncratic factors have the largest economic impact: while excess hedging demand increases PI and noise, active position‐taking (by market‐makers) in excess of the hedging demand reduces noise. Systematic factors, including the lack of competition among liquidity providers, adversely impact liquidity, but this effect is mitigated if liquidity providers are well‐capitalized. Supplementary leverage ratio (SLR) makes holding inventory costlier and is associated with lower liquidity.

Solidarity in the Context of Migration: A Philosophical Perspective

Solidarity is a permanent component of social life. In this sense, it becomes a transformative value that clearly connects people and their projects with others. The current situation in the world sharpens the issue of human solidarity. War, migration crises, aggressive globalization, territorial elitism, consumerism, populism, and the ideologization of social discourse lead to the distortion or elimination of the idea of solidarity. Nowadays, there are multi-level and multi-directional changes and transformations in individual and social ethos. Therefore, understanding solidarity requires an analysis of the context in which it is applied, as well as basic scientific assumptions. The article addresses this issue in the context of migration. It consists of three main elements: 1/ Firstly, it explains the philosophical phenomenon of solidarity as a very complex and multi-faceted individual and social reality; 2/ It portrays solidarity as a European virtue and value, which today seems to be experiencing certain difficulties in the EU’s migration policy, particularly revealed by the refugee crisis; 3/ It presents several ways of reflecting on solidarity in the light of representatives of contemporary philosophy and theoreticians of political thought (H.G. Gadamer, J. Dean, A. Grimmel, J. Tischner). These proposals can become an opportunity and a call to reflect on solidarity in times of its axiological and actual deficit.

Magnetic signature reproduction of ferromagnetic ships at arbitrary geographical position, direction and depth using a multi-dipole model

The reproduction of magnetic signatures is an important issue concerning the safety of ship traffic, as well as the identification and classification of vessels. Moreover, military applications of magnetic signatures and their reproduction refer to the activation or protection against activation of magnetic naval mines. Previous works on this subject focused on recording and replicating the signatures under the same conditions as those under which they were measured, e.g., on the same ship courses. In this article, much greater capabilities of the multi-dipole model are presented, including simultaneous identification of permanent and induced magnetism. Determining the dipole values using the data from cardinal directions gives the possibility of determining the magnetic field density at any trajectory (position), direction, or depth, with further reconstruction of the entire magnetic field on the basis of residual measurements. For the purpose of this article, a numerical test model of a corvette-type ship has been modelled in Opera simulation software for different geographical positions. The synthetic data from the simulator served as the data source for determining the parameters of the multi-dipole model and the reference data for the verification of the signatures reconstructed for other positions, directions, and depths than those used to determine the model parameters. To determine all permanent magnetization components, data sets were used for two different values of the external magnetic field vertical component. Finally, as a culmination of the demonstration of model universality, the entire magnetic field around the ship was reproduced for different control points on Earth, and for different courses and depths. Investigating the possibility of reconstructing the magnetic signature at a different geographic location than the place where the measurement was made for model synthesis is the main original issue considered in this paper.

고령층 소득의 비선형적 지속성 분석

This study estimates income risk observed among the elderly using the Korean Retirement and Income Study data. In order to decompose household income into permanent and transitory components, the quantile-based panel data framework is employed. The permanent component is assumed to follow a first-order Markov process, and the transitory component is assumed to be independent over time and also independent of the persistent components. I estimate the income persistence from the estimated permanent income component, and analyze the dynamic effects of permanent income shocks on income through simulations. The results show the presence of nonlinear persistence in the household income of the elderly. Furthermore, it is observed that the dynamic effects of permanent income shocks vary depending on the past income history. These findings differ from studies focused on the age groups participating in the labor market. In particular, the permanent income shocks have a significant impact on the income of elderly households. In particular, the permanent income shocks have a significant impact on the income of elderly households.

Phytoremediation Technology for Heavy Metal Removal from the Environment

Anthropogenic activities, industrialization, and urbanization have contributed extensively to the enhanced pollution levels in theenvironment. Along with soil and water pollution, air pollution is also escalating and contamination with heavy metals (HMs) isdangerous for the environment since it has negative impacts on people, animals, plants, and the ecosystem. HMs derive their origin from natural and anthropogenic sources. Commercial activities like processing of metals, mining, automobiles, geothermal energy plants, manufacturing industries, tanning, dyeing and plating are the sources of HM contamination. The non biodegradable, permanent inorganic chemical components recognized as HMs are typically harmful at small doses even in humans. HM toxicity leads to carcinogenic effects, developmental and reproductive damage, cardiovascular ailments, haematological, respiratory and nervous system disorders, inflammation and gastrointestinal troubles etc. The absorption and accretion of these metals cause oxidative stress and molecular damage, cytotoxic and mutagenic effects, growth reduction and physiological disorder in plants. Therefore considering their toxic effects, various mechanical as well as physio-chemical technologies are employed for metal removal from the air, water and soil but these techniques have their own limitations and environmental consequences. Hence, phytoremediation is considered an innovative, potentially promising technology employing majorly green plants. The various phytoremediation techniques involve phytoextraction, phytostabilization, phytodegradation, phytotransformation, phytovolitization, and rhizofiltration. Employing these techniques, plants can remove contaminants through a variety of processes, including adsorption, absorption, transport and translocation, hyper-accumulation, transformation, and mineralization. While phytoremediation of air pollutants is still an emerging technology, assimilation properties of plants to convert a toxicant into non-toxic forms have been used extensively for phytoremediation of air. Plants like Morus alba and Eucalyptus globulus can efficiently remove metallic pollutants from air. Moreover, aquatic macrophytes like Eichhornia crassipes,Spirodela polyrhiza, Pistia stratiotes, Azolla, Lemna minor, and Salvinia herzogii are potentially used for cleanup of the HMs in water, while Brassica juncea, Thlaspi caerulescens, Jatropha curcas, Pteris vittata, Vetiveria zizanioides, Gentiana pennelliana, Ambrossia artemisifolia etc. display tremendous well known phytoremediation activity in soil. Phytoremediation is an innovative, aesthetically pleasing, nonintrusive, sustainable and cost-effective technology. Furthermore, due to the disadvantages like high maintenance cost, extensive labor requirement and risks involved in existing conventional technologies associated with pollution abatement, phytoremediation technique can act as a potential, cost-effective and efficient method for water, soil as well as air pollution control.

ЕЛЕКТРОННА ОСВІТА: СОЦІАЛЬНО-ЕКОНОМІЧНИЙ КОНТЕКСТ

This research can be treated as a kind of pilot, due to the relatively small population of respondents. However, according to the definition of the selection of typical units, such a small population of respondents is sufficient to draw conclusions from the research presented in this text. The purpose of the article is analysis of the main problems and positive aspects of the introduction of electronic educational tools. The methodological basis of the research was the logical methods of information processing, statistical analysis, comparison. The main hypothesis of the study. Teaching and learning with the use of modern telecommunications and information technologies is already a permanent component of the reality of education in and around the world most countries Teaching via the Internet, which is one of the forms of distance education, breaks certain stereotypes regarding the so-called knowledge transfer process. Presenting main material. Innovation is the main driver of economic and social progress. Its absence results in stagnation both in the economy and in various spheres of social life. Economists emphasize the importance of large-scale investments in innovative programs, including education, which will not only help revive the economy in the near term, but also in the long term.. Originality and practical significance of the research. The selected research results presented here were related, as already indicated, to the declarations of current and future employees of the Schools. Undoubtedly, the crisis caused by the COVID-19 pandemic has once again revealed the need for innovation and innovation in education and other areas of social life. Meeting this need requires well-thought-out changes in teacher education and professional development. In preparing teachers for work, it is necessary to move away from the narrowly understood didactic effectiveness in favor of, among others, developing teachers' attitudes in the field of introducing changes in education and their innovative behavior. Conclusions. Conclusions are presented in the form of answers to research problems: Respondents know many remote learning applications and programs, the most popular of which is Teams; The biggest disadvantage of e-education is the lack of direct contact with the teacher and other pupils/students, although these data are not clearly significant; The greatest advantage of e-education is its low organizational, time and financial costs; Respondents have the possibility of using various methods in e-education and are in favor of using activating methods. Unfortunately, they have little knowledge of the existence of a variety of applications.

Commodity price shocks: Order within chaos?

The prices of 27 internationally traded commodities are decomposed into transitory and permanent components by applying an ideal band-pass filter to monthly data during 1970–2022. The two components account roughly equally to price variations, but with wide heterogeneity. The permanent component accounts for two-thirds of the variability in agricultural prices but less than 30 percent in energy prices. The transitory component revealed three medium-term cycles. The first (from the early 1970s to the mid-1980s) and third (from the early 2000s to 2020) exhibit similar duration and involve almost all commodities, while the second (spanning the 1990s) is mostly applicable to metals, with the notable absence of energy. The permanent component differs across commodities, with an upward trend for most industrial commodities and downward trend for agriculture. Moreover, the permanent component of commodities in which investment is irreversible (including energy, metals, and tree crops) exhibits a high degree of nonlinearity, most likely reflecting less flexibility in investment allocation and input use of these commodities. Prices of commodities subjected to widespread policy interventions, such as internationally-coordinated supply management schemes, exhibit persistent deviations from linear trends.

Carillons in the Soundscape of Gdańsk1

From 1561, the chiming of the Main Town Hall automatic carillon bells became a permanent component of the City of Gdańsk soundscape, to which, from 1575, were added the chimes of the St Catherine’s Church tower ‘striking device’ in the Old Town. The first automatic carillon comprised fourteen bells, whereas the other ‘device’ probably had several. It was not until 1738 that St Catherine’s Church acquired a large carillon with a keyboard as well as a mechanism for automatic playing. This article investigates the possible reasons why carillons were built for the Main Town Hall and St Catherine’s Church in Gdańsk, describes the bells and the mechanisms for automatic playing of both instruments and considers the repertoire by which their chiming filled the City of Gdańsk soundscape over the centuries.

The level of discreteness of the signs of the own productivity of repair pigs and the reproductive qualities of sows of different breeding value: criteria for the selection of highly productive animals according to the BLUP index

Products of plant origin, recommended as permanent components of the daily human diet, are rich in vitamins, minerals, plant fibers, as well as various active phytochemicals (polyphenols, flavonoids) and sterols, which have a low calorie content. According to the results of epidemiological and clinical studies, it has been established that the risks of various pathologies are reduced when using a diet that is balanced in terms of nutrients, rich in vegetable fiber and food products of plant origin. The evolution of food technology has led to the appearance on the shelves of Italian supermarkets of products defined as “ready foods” or products – semi-finished products of high quality and safety, which present all the characteristics of freshness, similar to products that have just been harvested. They also include products of vegetable origin, which belong to the fresh-cut category. A limited technological elaboration is applied to this category of products, after which they can be used without further manipulation before consumption. The products of vegetable origin of fresh-cut vegetable have the definition of "potentially dangerous products" due to their possible contamination with pathogenic microorganisms such as Escherichia coli, Salmonella spp. and Listeria monocytogenes. These pathogens very often contaminate fresh-cut vegetable, causing food poisoning in consumers. The main sources of pathogenic contamination by the causative agents of human intestinal infections are the water used for watering plants and exposure to inappropriate temperatures during the storage of plant products. The decisive aspect, without a doubt, remains the sanitary and hygienic characteristics of the product at the time of its consumption. It is fundamental to deepen our knowledge about the transmission, resistance, and growth mechanisms of pathogenic microorganisms in products of the IV range. This will allow the establishment of sampling norms for express diagnostics to reduce the possibility of low-quality products reaching the consumer.

Mirror Surface Nanostructuring via Laser Direct Writing—Characterization and Physical Origins

AbstractThe addition of an optically absorptive layer to otherwise standard dielectric mirrors enables a set of laser direct writing nanostructuring methods that can add functionality to such mirrors while retaining their high reflectivity. A thorough characterization of this method is given in this paper, and its physical origins are investigated. In particular, these measurements show that laser direct writing of such mirrors has a reversible and a permanent component. The reversible process originates from the thermal expansion of the surface and allows a simple yet precise way to temporarily modify the shape of the mirror. Scanning electron microscope cross‐sectional images suggest that the permanent part of the nanostructuring process is due to thermally induced pore formation and enlargement in the tantalum oxide layers of the used dielectric mirror.

EU requirements regarding hygienic and sanitary aspects of products of vegetable origin of category IV range in Italy

Products of plant origin, recommended as permanent components of the daily human diet, are rich in vitamins, minerals, plant fibers, as well as various active phytochemicals (polyphenols, flavonoids) and sterols, which have a low calorie content. According to the results of epidemiological and clinical studies, it has been established that the risks of various pathologies are reduced when using a diet that is balanced in terms of nutrients, rich in vegetable fiber and food products of plant origin. The evolution of food technology has led to the appearance on the shelves of Italian supermarkets of products defined as “ready foods” or products – semi-finished products of high quality and safety, which present all the characteristics of freshness, similar to products that have just been harvested. They also include products of vegetable origin, which belong to the fresh-cut category. A limited technological elaboration is applied to this category of products, after which they can be used without further manipulation before consumption. The products of vegetable origin of fresh-cut vegetable have the definition of “potentially dangerous products” due to their possible contamination with pathogenic microorganisms such as Escherichia coli, Salmonella spp. and Listeria monocytogenes. These pathogens very often contaminate fresh-cut vegetable, causing food poisoning in consumers. The main sources of pathogenic contamination by the causative agents of human intestinal infections are the water used for watering plants and exposure to inappropriate temperatures during the storage of plant products. The decisive aspect, without a doubt, remains the sanitary and hygienic characteristics of the product at the time of its consumption. It is fundamental to deepen our knowledge about the transmission, resistance, and growth mechanisms of pathogenic microorganisms in products of the IV range. This will allow the establishment of sampling norms for express diagnostics to reduce the possibility of low-quality products reaching the consumer.

Unobserved components model estimates of credit cycles: Tests and predictions

This paper estimates unobserved components (UC) models with real and financial trends and business and credit cycles to assess different measures of the credit cycle used by policymakers. The permanent components of the real and financial sectors are a Beveridge–Nelson and local linear trend, respectively. The business and credit cycles evolve jointly as a second-order vector autoregression. Bootstrap methods are applied to UC model estimates retrieved from classical optimization of the predictive likelihood of the Kalman filter. Results indicate the slope of the financial trend better predicts the credit to GDP ratio in the United States than the estimated business and credit cycles and the Basel gap. This suggests policymakers should consider permanent shocks to the financial sector when gauging the state of financial stability.

Growth rate and efficiency-related traits in Kermani lambs: estimations of (co)variance components and genetic parameters.

Using Kermani sheep, the current study estimated (co)variance components and genetic parameters for average daily gain, Kleiber's ratio, growth efficiency, and relative growth rate. Data were analyzed by the average information restricted maximum likelihood (AI-REML) method using six animal models with different combinations of direct and maternal effects. The best-fitting model was determined after testing for improvement in log-likelihood values. The estimates of h2 for average daily gain (ADG), Klieber's ratio (KR), growth efficiency (GE), and relative growth rate (RGR) in pre- and post-weaning phases were 0.13 ± 0.6 and 0.17 ± 0.02, 0.12 ± 0.04, and 0.16 ± 0.03; 0.05 ± 0.05 and 0.07 ± 0.03 and 0.06 ± 0.02 and 0.07 ± 0.01, respectively. Maternal heritabilities (m2) ranged from 0.03 ± 0.01 for relative growth rate in pre-weaning phase to 0.11 ± 0.04 for average daily gain in post-weaning period. The maternal permanent environmental component (Pe2) accounted for 3 to 13% to the phenotypic variance for all the studied traits. Estimated values of additive coefficient of variations (CVA) ranged from 2.79% for relative growth rate at 6 months of age to 23.74% for growth efficiency at yearling age. Genetic and phenotypic correlations among traits were ranged from -0.687 to 0.946 and -0.648 to 0.918, respectively. The result indicated that selection for growth rate and efficiency-related traits would also be less effective in achieving genetic change, because there was little additive genetic variation among Kermani lambs.

Typology and Modeling Profiles of Moving-Class Process-Entity Interactions: Core Types, Relationships, Constraints and Subschemas

Most of scientific research that are immediately concerned with the development of domain digital models, to one degree or another, is aimed at the derivation of reference conceptual and logical constructions covering all pertinent classes of interactions in which real-world objects with concomitant constraints can be involved. This work is directed to forming the core of a structural template that models facts — instances of associates that arise during the movement (transportation) of freights. The multiple alternatives and high variability of any processes logic, including moving-class processes, make their complete unification problematic. Nevertheless, one can come down to process modeling from a system-wide perspective, focusing on the capture of universal permanent processes components, such as source and output sets of objects, associations and constraints. The reality exhibits examples of hierarchical coherence of any classes of generalized processes, which in their sequential development break up into several self-sufficient processes distributed between organizational, calendar and implementation phases. The main focus of the work is on the sequential (from simple to complex) configuration of the structural core of process-entity interactions in the organizational phase, covering route segments, transport and freights, as well as the study of constraints on permissible instances of links incoming into the corresponding associative complex. Conceptual diagrams are presented in simplified and thorough formats. In a simplified format, multi-valued dependencies are modeled by means of weak entities and relators. In a thorough format, weak entities and relators have been replaced with documentary types, the structures of which contain an eXhaustive set of information about all objects, including auXiliary ones that are involved in interactions. The paper also considers the influence of the environment that is represented by classifying sets on the content of bounded relationships operating between the entity and process types. We have ascertained, formalized and described all constraints appearing in the organizational phase of generalized transport process including new constraint kind — split dependent link, resulting from the formation of cycles in conceptual constructions. Similar cycles contain and link together split, entity and (or) process types.

BIM-Based Timber Formwork Design and Modeling

Building information modeling (BIM) is one of the most promising new technological developments that can be used to facilitate design and construction automation. Prior BIM research has primarily focused on permanent building components; temporary structures such as scaffolding and concrete formwork have received little attention. The design and planning of concrete formwork systems, however, would substantially benefit from the capabilities of BIM. Formwork design is repetitive and can be very time-consuming due to the need to analyze multiple parameters of individual permanent components, the latest formwork design guidelines, methods, and procedures, and the available materials. In this study, a BIM-based tool is developed and proposed to assist designers and builders in planning, designing, and generating concrete formwork design models for planning purposes. By integrating the design procedures recommended by the American Concrete Institute (ACI), the streamlining tool automates the design and modeling process for timber concrete formwork through an application programming interface (API) in Revit. The workability of the proposed tool was demonstrated through a case study. The study also employed the survey method to investigate the effectiveness of the proposed tool and its potential for improving worker safety and health from the perspectives of formwork professionals. Using the tool, form designers and planners will be able to determine the most applicable formwork design based on the permanent facility structure along with the availability of construction materials, site conditions present, and worker safety and health considerations. The study also provides contractors with a new tool for planning concrete operations and expands the scope of BIM design.

The Post Pandemic Future: Nursing in the Region of the Americas and Mental Health

The transformative and impactful role of nurses has been highlighted throughout the COVID-19 pandemic. The health workforce has endured many particularly difficult challenges during this time, both professionally and in their personal lives, in the effort to respond to the needs of communities, patients, and families. As a result, many nurses and other providers are facing their own mental health challenges due to the prolonged response to address pandemic challenges. In the Region of the Americas, several areas have faced inequities and greater challenge, especially in countries that are low- and middle income. There is a tremendous gap between the number of people who need mental healthcare and those who receive it, even with the current health workforce. Increasing national investments in nursing in the Region of the Americas is necessary and has been addressed by the Pan American Health Organization. A strategic regional focus has been placed to empower healthcare professionals to achieve the levels of education necessary to improve working conditions and to have leadership roles supported and recognized in a model of resilient health systems. Protecting mental health of providers has become an important lesson of the pandemic and an essential and permanent component in the management of health systems and services. This article offers a summary of challenges in the Region of the America as leaders consider the best strategies to support a positive relationship that features resilience, adequate working conditions, and investments in the nursing profession for a post-COVID-19 future that protects workers’ mental health.

A New Approach to Estimating the Natural Rate of Interest

AbstractBuilding upon the insight that M1 velocity is the permanent component of nominal interest rates—see Benati (2020)—I propose a novel, and straightforward approach to estimating the natural rate of interest, which is conceptually related to Cochrane's (1994a) proposal to estimate the permanent component of Gross National Product (GNP) by exploiting the informational content of consumption. Under monetary regimes (such as inflation‐targeting) making inflation I(0), the easiest way to implement the proposed approach is to (i) project the monetary policy rate onto M1 velocity—thus obtaining an estimate of thenominalnatural rate—and then () subtract from this inflation's sample average (or target), thus obtaining therealnatural rate. More complex implementations based on structural vector autoregressions (VARs) produce very similar estimates. Compared to existing approaches, the one proposed herein presents two key advantages: (i) under regimes making inflation I(0), M1 velocity is equal, up to a linear transformation, to the real natural rate, so that the natural rate is, in fact,observed; and (ii) based on a high‐frequency estimate of nominal GDP, the natural rate can be computed at the monthly or even weekly frequency. In the U.S., Euro area, and Canada, the natural rate dropped sharply in the months following the collapse of Lehman Brothers. Likewise, the 1929 stock market crash was followed in the U.S. by a dramatic decrease in the natural rate.

Work-limiting disabilities and earnings volatility

This paper examines how the onset of a work-limiting disability influences male earnings volatility as measured by the variance of transitory earnings. Using data from the 1970 to 2013 survey waves of the Panel Study of Income Dynamics and a semi-parametric error components model, we decompose annual earnings into its permanent and transitory components. Results show that the variance of transitory earnings of disabled and non-disabled men is similar before onset of a work-limiting health condition. Upon onset, earnings volatility increases significantly, and does not return to pre-onset levels until at least five years after the last reported disability. Additional results show that earnings volatility has increased since 1970 for both disabled and non-disabled men. However, the trend in volatility is steeper for those who suffer from a disability. Despite this steeper trend, disability's contribution to the total variance of earnings has remained constant over time at roughly 15%.

Modern Approaches for the Development of New Herbicides Based on Natural Compounds.

Weeds are a permanent component of anthropogenic ecosystems. They require strict control to avoid the accumulation of their long-lasting seeds in the soil. With high crop infestation, many elements of crop production technologies (fertilization, productive varieties, growth stimulators, etc.) turn out to be practically meaningless due to high yield losses. Intensive use of chemical herbicides (CHs) has led to undesirable consequences: contamination of soil and wastewater, accumulation of their residues in the crop, and the emergence of CH-resistant populations of weeds. In this regard, the development of environmentally friendly CHs with new mechanisms of action is relevant. The natural phytotoxins of plant or microbial origin may be explored directly in herbicidal formulations (biorational CHs) or indirectly as scaffolds for nature-derived CHs. This review considers (1) the main current trends in the development of CHs that may be important for the enhancement of biorational herbicides; (2) the advances in the development and practical application of natural compounds for weed control; (3) the use of phytotoxins as prototypes of synthetic herbicides. Some modern approaches, such as computational methods of virtual screening and design of herbicidal molecules, development of modern formulations, and determination of molecular targets, are stressed as crucial to make the exploration of natural compounds more effective.