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Coronavirus disease 2019 (COVID-19) has rapidly spread around the world since the early 2020. Recently, a second wave of COVID-19 has resurged in many countries. The transmission dynamics and infectiousness of the COVID-19 pandemic remain unclear, and developing strategies to mitigate the severity of the pandemic is a top priority for global public health. According to the infection mechanism of COVID-19, a novel susceptible-asymptomatic-symptomatic-recovered (SASR) model with control variables in a patchy environment was proposed not only to consider the key characteristics of asymptomatic infection and the effects of seasonal variation but also to incorporate different control measures for multiple transmission routes. The basic reproduction number \begin{document}$ R_{0} $\end{document} was established to describe the spreading behavior in the natural state over a long time horizon, and the natural reproduction number \begin{document}$ R_{n} $\end{document} , which describes the development trend of the disease during a short time in the future, was defined according to the actual propagation characteristics. In addition, the effective reproduction number \begin{document}$ R_{e} $\end{document} considering the control strategies was proposed to evaluate the impact of non-pharmaceutical interventions. The results of numerical simulations for COVID-19 cases in Wuhan, China, based on the SASR model indicate that \begin{document}$ R_{0} $\end{document} was 3.58, \begin{document}$ R_{n} $\end{document} ranged from 2.37 to 4.91, and \begin{document}$ R_{e} $\end{document} decreased gradually from 4.83 on December 8, 2019 to 0.31 on March 8, 2020, reaching 1.40 on January 23, 2020, when the lockdown was lifted in Wuhan. We further concluded that the total number of infections, including asymptomatic infections, was approximately 301, 804 as of March 8, 2020, in Wuhan, China. In particular, this article proposes a dynamic method to distinguish the impact of natural factors and human interventions on the development of the pandemic, and provides a theoretical basis for fighting the global COVID-19 pandemic.

There are different types of skin diseases due to chronic injuries that impede the natural healing process of the skin. Tissue engineering has focused on the development of bioengineered skin or skin substitutes that cover the wound, providing the necessary care to restore the functionality of injured skin. There are two types of substitutes: acellular skin substitutes, which offer a low response to the body, and cellular skin substitutes (CSSs), which incorporate living cells and appear as a great alternative in the treatment of skin injuries due to their greater interaction and integration with the rest of the body. For the development of a CSS, it is necessary to select the most suitable biomaterials, cell components, and methodology of biofabrication for the wound to be treated. Moreover, these CSSs are immature substitutes that must undergo a maturing process in specific bioreactors, guaranteeing their functionality. The bioreactor simulates the natural state of maturation of the skin by controlling parameters such as temperature, pressure, or humidity, allowing a homogeneous maturation of the CSSs in an aseptic environment. The use of bioreactors not only contributes to the maturation of the CSSs but also offers a new way of obtaining large sections of skin substitutes or natural skin from small portions acquired from the patient, donor, or substitute. Based on the innovation of this technology and the need to develop efficient CSSs, this work offers an update on bioreactor technology in the field of skin regeneration. Impact Statement The manufacture of functional cellular skin substitutes (CSSs) is one of the current goals in the field of tissue engineering to improve the treatment of chronic skin injuries, thus favoring skin repair and regeneration. The main advances in the development of innovative and effective CSSs are largely focused on the selection of more adequate cellular components, biomaterials, and biofabrication techniques to be used in their biofabrication. However, the maturation of CSSs should be an essential step in obtaining a functional substitute capable of replacing the native skin. The sequential procedure from the design of the CSS to its maturation process will be reviewed. In the context of the manufacturing of novel CSSs, different technologies to biofabricate functional structures and how their maturation can be carried out by specific devices are addressed, as well as key challenges facing the design and development of CSSs.

The article is devoted to the analysis of the problems of obligations in the light of the natural legal concepts of John Locke and Jan-Jak Russo. Thus, within his theory of the social contract, John Locke notes about the natural state of people, from which the law of nature follows, is obligatory for everyone. Such the obligation comes from the human nature or from the harmony between natural law and the rational human nature. The reason for the formation of a civil society is to prevent a state of war, when force, not supported by law, is used contrary to natural law. Therefore, John Locke assigns obligations to the supreme authority, to which people entrusted a part of their freedom in order to fulfill the goals of the state - to ensure peace,security and welfare of the people. Thus, John Locke mainly considers the obligation through the prism of laws - first of all natural (not to cause harm to others), and later also civil, which is established by the supreme authority. The individual in the state is entrusted with the obligation to carry out the prescriptions determined by the government, while the government is supposed to ensure peace, protect property, and justly resolve (through judicial institutions) disputes between citizens. In this way, the freedom of individuals is guaranteed by the state, because real freedom, according to the thinker, is possible only in a legal state. On the example of the concept of Jan-Jak Russo’s social contract а certain feature can be traced. It is about a significant strengthening of the collective factor over the individual one, when a union of individuals who have mutual rights and obligations in relation to each other is formed in the manner of a corresponding contract. Obligation, therefore, is not only what binds a person, subjecting him to the supreme authority, but, above all, what serves as a factor of cooperation of people in a perfect union. Based on the concept of popular sovereignty, the principles of direct democracy, which the French thinker advocated, individuals should not just fulfill certain prescriptions, but also be called to be active participants in the state-legal reality, in particular, to participate in the creation of laws. Such laws, as the personification of the expressions of the general will, can ensure justice, equality and freedom of individuals., Стаття присвячена аналізу проблематики обов’язків у світлі природно-правових концепцій Дж. Локка та Ж.-Ж. Руссо. Так, у межах своєї теорії суспільного договору Дж. Локк зазначає про природний стан людей, з якого випливає закон природи, обов’язковий для кожного. Така обов’язковість походить від самої природи людини чи від гармонії між природнім законом і раціональною природою людини. Причина ж формування громадянського суспільства зводиться до того, щоб запобігти стану війни, коли всупереч закону природи (розуму) застосовується сила, не підкріплена правом. Відтак, Дж. Локк покладає обов’язки на верховну владу, якій люди доручили частину своєї свободи задля сповнення цілей держави – забезпечення миру, безпеки і блага народу. Таким чином, у Дж. Локка обов’язок переважно розглядається крізь призму законів – спершу природного (не спричинювати шкоди іншому), а згодом і громадянського, що встановлюється верховною владою. На індивіда в державі покладається обов’язок виконувати визначені владою приписи, тоді як на саму владу – забезпечувати мир, охороняти власність, а також справедливо вирішувати (через судові установи) спори між громадянами. У такий спосіб свобода індивідів отримує гарантування від держави, адже дійсна свобода, на думку мислителя, можлива лише у правовому стані. На прикладі ж концепції суспільного договору Ж.-Ж. Руссо простежується певна особливість. Йдеться про суттєве посилення колективного фактору перед індивідуальним, коли в спосіб відповідного договору формується, дійсно, єднання індивідів, які мають по відношенню одне до одного взаємні права та обов’язки. Обов’язок, звідси, це не тільки те, що зв’язує людину, підкорюючи її верховній владі, але, передусім, те, що слугує фактором кооперації людей у досконале об’єднання. Виходячи з концепції народного суверенітету, принципів безпосередньої демократії, які відстоював французький мислитель, особи не просто повинні виконувати визначені приписи, але і покликані бути активними учасниками державно-правової дійсності, зокрема, брати участь у творенні законів. Саме такі закони як уособлення виразників загальної волі і можуть забезпечити справедливість, рівність та свободу індивідів.

Resumo: O presente artigo procura demonstrar que há uma forte similaridade entre a maneira pela qual o escritor norte-americano J.D. Salinger construiu os vários personagens criança de Nine Stories (1953) – especialmente aquele nomeado Teddy – e a poética romântica da infância, inaugurada por autores ingleses como William Blake e William Wordsworth, onde a criança é representada como uma entidade sagrada, portadora de uma pureza e sabedoria celestiais. Para tanto, operamos uma análise direta dos contos de Salinger – pela qual exploramos suas personagens e técnicas literárias –, mas também uma ampla revisão bibliográfica que visa rastrear os motivos que levaram ao surgimento dessa poética literária da infância no século XVIII e sua continuidade até o século XX, além de identificar algumas das interinfluências das doutrinas filosóficas, teológicas e psicanalíticas que debateram a infância durante os últimos séculos. Desta forma, o presente artigo transita por questões como: desenvolvimento e educação infantil, o pecado original, inocência, experiência social e mundana, pureza de intenções e estado natural, iluminação espiritual, Salvação Cristã e Nirvana Zen-Budista. Elementos que se vinculam à sacralização da infância operada por diversos autores de textos literários, a exemplo de Blake, Wordsworth e, claro, Salinger.

Groundwater studies were carried out between two geological groups to evaluate factors that influences groundwater geochemistry. To achieve this, 30 groundwater samples were collected. Parameters such as pH, Electrical Conductivity (Ec), Total Dissolved Solids (TDS), Total Hardness (TH), and hydrochemical characteristics (Na 2+ , K + , Ca 2+ , Mg 2+ , HCO 3 ¯, NO 3 ¯, Cl¯, CO 2 3 ¯, and SO 4 2 ¯) of groundwater were determined. Findings revealed that the pH value for Asu River Group ranges from 5.3 to 7.5, and that of Eze Aku Group ranges from 4.1 to 7.9. It was observed that areas around the mines had low pH values. Analyzed results that were obtained were interpreted using various hydrogeochemical models. Parson plots reflected that groundwater within the two geological groups fell within Ca˗Mg˗SO 4 and Ca˗Mg˗Cl. Results from End˗member plots showed that 96% of groundwater samples analyzed were categorized under carbonate weathering, 4% fell silicate weathering. Gibbs plots revealed that interactions between groundwater and surrounding host rocks are mostly the main processes responsible for chemical characteristics of groundwater, Diamond field plots suggested that groundwater within the study were categorized to be high in Ca + Mg & SO 4 + Cl, the plot of Ca 2+ /(HCO 3 ¯+SO 4 2 ¯) against Na+/Cl¯ revealed that groundwater was considered to be within the natural state for the two group. The plot of TDS against TH showed that groundwater is classified as soft freshwater. The study revealed there was no significant difference between factors that influence groundwater within the two geological.

PURPOSE The threat of serious radiation exposures to members of the public from radiological incidents and nuclear events has led to intensive study of a number of emergency dosimetry techniques for purposes of triage. As such, a national laboratory of retrospective dosimetry was established in our institute. The purpose of this work is to provide a summary of the well-established and already implemented retrospective physical dosimetry techniques based on thermoluminescence (TL), optically stimulated luminescence (OSL) and neutron activation including their specifics. Moreover, we present some new results of the experimental work, in which we compared dosimetry potential of various dental repair materials and human teeth. MATERIALS AND METHODS At first, an overview of already established retrospective physical retrospective methods including their main features was compiled. As regards recent research, an experimental comparative study was performed under defined conditions. The materials used were aliquots prepared from both pure and repaired teeth and aliquots of unused dental ceramics of known type. Following irradiation, we compared TL and OSL curves of the materials. We also compared dosimetry characteristics of OSL signal as reproducibility, dose dependence and fading. RESULTS After irradiation, the teeth aliquots of dental enamel and dentin exhibited very low OSL and TL signals compared with aliquots containing some dental repair materials or aliquots of pure dental ceramics. With a few exceptions, the OSL signal of dental enamel and dentin aliquots irradiated to 2 Gy was hardly distinguishable from OSL signal corresponding to unirradiated aliquots. In contrast, aliquots of teeth containing some dental repair material and aliquots of pure dental ceramics provided a well reproducible OSL signal exhibiting linear dose response. All the materials tested exhibited a significant fading of the OSL signal. The loss of OSL signal during the first 24 hours after irradiation was from 20 to 99% of its original value obtained immediately after the irradiation. CONCLUSIONS The already established physical methods of retrospective dosimetry use a spectrum of verified materials and techniques for dose assessment in the aftermath of serious radiological incidents and nuclear events. In the comparative study, we found that the dosimetry potential of teeth in natural state is much worse compared to teeth repaired with dental ceramics or dental cement fillings. Teeth restored with dental repair materials exhibited relatively favorable dosimetry characteristics. However, they can be usable for a dose reconstruction only on condition that the main practical problems connected with fading and optical bleaching were solved.

The health benefits of purple sweetpotato, which is used as an edible food in its natural state and in processed foods and as a natural color pigment, have been recognized. In Japan, sweetpotato has been economically produced in regions below 36°4ʹN latitude; however, cultivation areas are beginning to expand further north. The anthocyanin and polyphenolics in three purple sweetpotatoes cultivated in different locations; I (42°92ʹN, 143°04ʹE) and II (31°72ʹN, 131°03ʹE), were compared over two years. Total anthocyanin and polyphenolic contents in purple sweetpotatoes tended to be high in location I. The anthocyanin and polyphenolic compositions differed between locations. The peonidin/cyanidin ratios were higher in location II compared with I in all varieties. The relative amount of 3,4- and 4,5-di-O-caffeoyolquinic acids were higher in location II. Their contents and composition also differed between years. These results suggest that the variability of the anthocyanin and polyphenolic content and composition was influenced by climate conditions, probably temperature during cultivation. This study indicates that northern areas in Japan are an alternative production area and may yield higher amounts of anthocyanin and polyphenolics.

Mount Iyang-Argopuro is one of the geothermal working areas in the East Java. Mount Iyang-Argopuro has the potential of 185 MWe of reserves and 110 MWe of resources. It is estimated to have a liquid dominated reservoir with temperature up to 250-275 oC. An early 3D natural state numerical model of Mount Iyang-Argopuro Field is created using TOUGH2 simulator in order to identify the undisturbed condition of reservoir and resource assessment. Since Mount Iyang-Argopuro geothermal area is still in the exploration stage, the model created based on based on geological, geophysical, and geochemical data. The model has an area 14 km x 8.2 km and 9180 m in thickness. The model consists of 7410 of rectangular cell blocks with the roughest cell size is 1000 m x 1000 m and the finest is 200 m x 500 m. The model is verified by matching the model temperature and pressure profiles to the calculated geothermometer temperature and pressure, which shows good match enough.

PURPOSE Squats are among the basic exercises that have become an integral part of exercise programs. It is commonly used by athletes in many sports. Its potential is shown in the development of strength, power, and overall sports performance. The aim of the study was to verify inconsistent views on deep squats, technical design, and related health risks. METHODS For the purposes of the review, the terms "squat, knee, biomechanics, deep, patellofemoral, back squat, performance, arthritis, health, injury, risk" were used. RESULTS It turns out that the technique of performing a deep squat has its strict principles, which must be respected and which have a significant impact on the benefits and risks. From loading, the lower position represents an increase in compressive and shear forces on the patellofemoral joint, however, this is a natural state that is not risky. Health hazards cannot be based on analytical-mathematical models, which are insufficient in this aspect. Extreme long-term exposure carries the risk of permanent consequences in the form of osteoarthritis. For prophylaxis or convalescence, it is possible to use effective aids like sleeves, kinesio taping, bandage or "knee savers". CONCLUSIONS With optimal technique and sensible exercise selection, there is no greater risk in healthy individuals without degenerative anatomical changes. In order to assess the effects of the squat forces on the ankle, knee, hip, spine, it is necessary to consider the technique and also individual anatomical differences.

Cilj ovoga rada je analiza Rousseauove misli i njezine posljedice po pitanju slobode pojedinca unutar društvenog stanja. Primarno korištena metoda jest kombinacija analize i sinteze. Tako smo u prvom poglavlju govorili o životu i djelu autora, iz čega smo saznali kako on u prvoj fazi života gleda negativno na društvo i napredak. Tako smo u drugome poglavlju prikazali njegovo poimanje slobode te ideal slobode kao moralno djelovanje čovjeka, uz što veće pridržavanje prirodnosti. No, da bismo uopće pričali o prirodnosti kod Rousseaua, morali smo detaljno obraditi njegova dva glavna pojma prirodnog i društvenog stanja. Potom smo se bavili položajem pojedinca spram opće volje unutar države i time došli do zaključka i rezultata rada. Rezultat rada do kojeg smo došli nalaže da treba oprostiti Rousseau na nejasnoći i problemima koje nam zadaje svojim pisanjem, imajući na umu intenciju s kojom je stvarao svoja djela. Ukoliko zažmirimo na njegove mane u pisanju, možemo uvidjeti kako se ispod svega toga nalazi autor koji prognozira nevolje koje krije predstavnička demokracija te pokušava dati svoje moguće rješenje. Aim of this paper is analysis of Rousseau’s thought, and its consequences regarding individual’s freedom once inside the social state. Method primarily used is a combination of analysis and synthesis. In the first chapter we talked about author’s life and work, from which we realized that in the first stage of his life, Rousseau has a negative view upon society and progress. In the second chapter we have shown his understanding of freedom and the ideal of freedom as moral action of a man who stays, as much as possible, true to his nature. If we wanted to talk about nature in Rousseau’s thought, we had to provide detailed explanation of his two main ideas of natural and social state. Then we took upon explaining the position of individual against general will inside the state and with that, came to conclusion and the results of this paper. The result that this paper provided us, demands that we forgive Rousseau for being unclear in his writings, bearing in mind the intention that accompanies his entire work. If we close our eyes on his obvious flaws in writing, we can truly see that underneath all those initial issues, there is an author who prognosed issues that stand behind the representative democracy, and tries to provide us with his own ideas of solutions.

“Willow Withes Repairing Bone” (WWRB) is an ancient and mysterious technique in traditional Chinese medicine. In the 1950s, researchers of Chinese medicine made a lot of efforts hoping to revive the technique, but due to the poor osteogenic ability of willow withes, the research ended in a negative conclusion. Nonetheless, given the inherent advantages of the structure of willow withes, the authors of this paper decided to investigate the possibility of improving their osteogenicity. The results show that willow withes in a natural state show little ability to support HA biomineralization. Phosphorylation of the withes, however, can induce a significant degree of HA mineralization on their surface and in their pores by introducing phosphate groups through esterification, resulting in a remarkable improvement of the withes’ osteogenicity. Even better, phosphorylation does not affect the pore structure and biocompatibility of the withes. It does reduce their mechanical strength, but the amount of reduction is acceptable. This study should act as a step toward the revival of the WWRB technique.

The creation of the new “Ferry-Free Coastal Highway Route E39” in southwest Norway entails the production of a remarkable quantity of crushed rocks. These resources could be beneficially employed as aggregates in the unbound courses of the highway itself or other road pavements present nearby. Two innovative stabilizing agents, organosilane and lignosulfonate, can significantly enhance the key properties, namely, resilient modulus and resistance against permanent deformation, of the aggregates that are excessively weak in their natural state. The beneficial effect offered by the additives was thoroughly evaluated by performing repeated load triaxial tests. The study adopted the most common numerical models to describe these two key mechanical properties. The increase in the resilient modulus and reduction in the accumulated vertical permanent deformation show the beneficial impact of the additives. Furthermore, a finite element model was created to simulate the repeated load triaxial test by implementing nonlinear elastic and plastic constitutive relationships.

This work presents the physical-chemical, geotechnical and mechanical characterization of a sample of mine tailings from the state of Zacatecas, Mexico with the objective of evaluating their possible use as a construction material for pavement support layers or as an aggregate of a hydraulic concrete. The material analyzed was classified as a poorly graded silty sand (SP-SM) according to the SUCS classification and is composed mainly of quartz and calcite. The analyzed sample satisfies the necessary requirements, according to current Mexican regulations, to be used as i) a subgrade layer in a pavement, without the addition of virgin aggregates, or ii) as fine aggregates in the production of hydraulic concrete, previously sieved to correct its grain-size distribution. The mining residues studied do not require stabilization because the material transported in the leaching process is below the permissible limits for heavy metals according to Mexican regulations; this may be caused by the neutral pH of the sample, demonstrating a high adsorption of the heavy metals that avoids potential leaching. However, the sample was stabilized with Portland cement with 3 and 5% respectively to corroborate the decrease in heavy metal transport based on the consulted bibliography; the concentrations of the analyzed elements decreased except for chrome due to its presence in the stabilizing material and an increase in the pH value was observed.

Sedum aizoon L. is a medicinal plant that contains various flavonoids and phenolic acids, and plays positive roles in lowering blood pressure, hemostasis, anti-bacterial and anti-inflammatory. However, the clinical application of Sedum aizoon L. is limited because of its low yield in natural state. Here, we aim to explore the application of adventitious root culture technology in Sedum aizoon L., further to improve the yield of Sedum aizoon L. and the production of secondary metabolites. We found that the callus of Sedum aizoon L. could be induced in MS medium containing 2.0 mg L−1 2,4-D and 0.5 mg L−1 BA. Then, the adventitious roots were obtained in Sedum aizoon L. with maximum induction rate (98.32%) when the callus were cultured in a stratified combination MS medium supplemented with 4.0 mg L−1 IBA, 1.0 mg L−1 KT, 1.0 mg·L−1 NAA and 60 mmol L−1 NO3−/NH4+ (5:1 ratio). Furthermore, the production of flavonoids in adventitious roots of S. aizoon L. (16.32±0.51 mg·g−1 DW) was obviously higher than those in the callus (3.66±0.65 mg g−1 DW). In conclusion, we determined that adventitious roots culture might be an effective alternative in improving the potential application of Sedum aizoon L..

PURPOSE: The main purpose of the article was to assess the level of integration in the supply chain in the herbal industry. The specific objectives were to identify entities operating in the herbal industry and to analyse the relationship between individual links in the supply chain., DESIGN/METHODOLOGY/APPROACH: The research period covered the years 2016-2019. The source material was the primary data. The interviews were conducted with entities representing two links in the supply chain - suppliers of herbal raw materials from field crops and from the natural state of the Lubelskie and Podlaskie voivodeships, as well as a plant for processing herbal raw materials. The Supply Chain Integration’s Degree Measure (SCIDM) indicator was used to achieve the main purpose., FINDINGS: The empirical results show that before 2001 the return in the U.S. was high and when the dollar was appreciated, after 2001, the same return became negative and the dollar was depreciated, but after 2004 the returns have growing positively for the U.S., and the returns for the Euro-zone are falling., PRACTICAL IMPLICATIONS: It was found that the level of integration in the supply chain in the herbal industry was low, which was influenced by the limited relationships and the type of dependencies between the participants of the chain. The factor contributing to the low level of integration was the significant fragmentation and collection of herbs by hundreds of individual collectors from natural sites. The situation was slightly better on the side of recipients, where the degree of integration was in the middle range., ORIGINALITY/VALUE: Development of a herbal supply chain model and assessment of its level of integration. Individual links in the studied supply chain were described and the relations between them were identified., Financial support from Henry George Research Funds (Robert Schalkenbach Foundation) is gratefully acknowledged. The usual disclaimer applies., peer-reviewed

Large reservoirs can alter the natural thermal regime and result in the delivery of water with unseasonal water temperatures downstream. Establishing a detailed understanding how a river’s thermal regime has changed from its natural state is a critical step required before mitigation options can be investigated. Our study focussed on one of Australia’s most iconic rivers, the Snowy River which is regulated by multiple headwater regulating structures. We used mean daily pre-dam water temperature (1962–1967) data from the Snowy River to develop generalized additive models (GAMs) to predict the natural (daily mean, max and min) water temperatures in the Snowy River. Daily modelled natural water temperatures were compared with daily observed water temperatures in the regulated Snowy River and two nearby analogue reference streams. Using the GAMs, we identified a reduced thermal range (max and min) and water temperatures ≥ 2 °C warmer than natural between the cooler months of April and July for at least 50 % of the study period. Temperatures rarely ( 2 °C) requires further investigation.

Most business cycle theories originate from a paradigmatic vision with a two fold simplicity. The first of which is that firms are bound through simple relations in which they influence each other anonymously via prices but not directly through non-price rivalrous competition. And the second is that firms have immutable and transparent cores. These presumptions yield an economy whose natural state is one of stability. Macroeconomic dynamics, or change more generally, is brought about by exogenous shocks. This paper develops an alternate vision for understanding business cycle dynamics. We consider the dynamics that emerge from micro changes that originate from deep within firms. Each firm is surprised by externally visible innovations of other firms because they cannot observe each others’ high dimensional interiors. Innovations can cascade because of the complex microeconomic interrelations between the plans of firms. The interaction between external-observable attributes and internal-unobservable active cores of firms is capable of generating change without exogenous shocks.

Over-exploitation and sand-gravel mining affect groundwater resources in terms of both quantity and quality. Groundwater level and well yields in and around the sand-gravel pits significantly decrease. Sand-gravel mining also changes the turbidity levels and temperature of groundwater. Reduction and destruction of valuable aquifers are significant issues. In this case, the natural state of the aquifer disappears. The Kazan Plain in central Turkey is a dramatic example of these kinds of results. The productive sand-gravel aquifer in the Kazan plain has been substantially damaged due to intensive sand-gravel mining since the 1980s. Additionally, over-exploitation has caused notable declines in groundwater levels, particularly in the 2000s. This study focuses on the hydrogeochemical situation of the Kazan Plain alluvium aquifer after intensive sand-gravel mining and over-exploitation. Groundwater samples were collected seasonally in 2015, five years after the over-exploitation and heavy sand-gravel mining. The decline reached 20 m (about half of the saturated thickness of the sand-gravel aquifer) in the region where the intensive groundwater abstraction lasted until 2010. Some quarries continued to operate until 2010, but after that mining activity continued only at a minimum level. Today, groundwater quality has been significantly degraded due to the over-exploitation of sand-gravel mining and also the cessation of recharge from fresh river water.

Study on the effect of acoustic wave on droplet collision-coalescence process is interesting and helps to better understand acoustic agglomeration mechanism. This study designs and carries out a microscopic experiment to investigate the effect of acoustic wave on wall droplet collision-coalescence process. The derived microscopic images of droplets under the action of different sound waves at different moment are processed and analyzed by binaryzation with iterative threshold, cavity filling, morphological open arithmetic processing, and identification of connected regions, etc. Using a newly defined parameter, equivalent droplet size, the growth rates of the droplets in natural state and under the action of different acoustic parameters are compared and analyzed. The results show that the effect of sound wave greatly accelerates the collision-coalescence process of the droplet, and comparing with sound pressure level (SPL), the frequency of the sound wave is a more effective parameter in promoting the collision-coalescence process of wall droplets, and the lower the acoustic wave frequency results in larger collision-coalescence rate.