Strong Concentration Research Articles

Technological Entrepreneurship and Rural Development: A Binomial to Combat Depopulation in Spain

Objective: This study aims to characterise the phenomenon of depopulation in the rural environment from the point of view of the opportunities offered by technology-based rural entrepreneurship as a lever that promotes population fixation and the economic dynamisation of the most depressed territories subject to the economic and social imbalances generated by depopulation. Research Design & Methods: The research approach is based on the application of case studies as an empirical research technique. In particular, the strategy for the promotion of rural start-ups in CyL – the largest European region and one of the Spanish regions most affected by the negative consequences of depopulation – is analysed. Findings: Empirical evidence has shown that economic conditions have impacted the extent and duration of migration flows from rural areas to a more industrialised urban environment. Thus, in recent decades, the spatial distribution of the population has taken shape characterised by strong concentrations in large cities as opposed to the dispersion and low density of the population in large areas of the territory. Implications / Recommendations: The promotion of rural entrepreneurship through the development of specific actions to encourage the creation of start-up companies could be a solution to the demographic challenge. Contribution / Value Added: The creation of a regional entrepreneurial ecosystem has been possible owing to the financing, growth, scaling, and business internationalisation programmes promoted by the regional government.

Background Modeling Combined With Multiple Features in the Fourier Domain for Maritime Infrared Target Detection

To detect ship targets in dynamic sea backgrounds, a robust foreground detection method based on background modeling combined with multiple features in the Fourier domain (BMMFF) is proposed. Because the fluctuation of seawater is similar to a sine wave, the amplitude spectrum of the seawater in the Fourier domain has strong energy concentration, and the background model is built in the Fourier domain. The local statistical characteristics can effectively reflect the properties of a specific position, and the target frequency points are extracted by comparing the local statistical characteristic differences between the amplitude spectrum of the test frame and the updated background. Additionally, two different strategies are used to update the background for cases with or without sudden waves in two adjacent test frames. When the target and seawater have different contrast in different scenes, the threshold is set according to the seawater's fluctuation degree, which is classified into three different levels in the training stage. Moreover, the linear correlation feature between the test frame and the updated background and the oscillation feature of the test frame's amplitude spectrum are proposed in the Fourier domain, which can better segment targets in relatively calm and violent sea scenes, respectively. Thus, the two features are combined with the background model with a reasonable strategy to further improve the detection accuracy. The experimental results demonstrate that BMMFF outperforms related comparison algorithms in different challenging sea scenes. The average false alarm rate of BMMFF is reduced by approximately 30% in the case where its average detection rate is similar to that of other algorithms.

Tuning the catalytic properties of La-Mn perovskite catalyst via variation of A- and B-sites: effect of Ce and Cu substitution on selective catalytic reduction of NO with NH3.

Perovskites with flexible structures and excellent redox properties have attracted considerable attention in industry, and their denitration activities can be further improved with metal substitution. In order to investigate the effect of Ce and Cu substitution on the physicochemical properties of perovskite in NH3-SCR system, a series of La1−xCexMn1−yCuyO3 (x = 0, 0.1, y = 0, 0.05, 0.1, 0.2, 0.4) catalysts were prepared by citrate sol-gel method and employed for NO removal in the simulated flue gas, and the physical and chemical properties of the catalysts were studied using XRD, SEM, BET, XPS, DRIFT characterizations. The Ce substitution on A-site cation of LaMnO3 can improve the denitration activity of the perovskite catalyst, and La0.9Ce0.1MnO3 displays NO conversion of 86.7% at 350 °C. The characterization results indicate that the high denitration activity of La0.9Ce0.1MnO3 is mainly attributed to the larger surface area, which contributes to the adsorption of NH3 and NO. Besides, the appropriate Cu substitution on B-site cation of La0.9Ce0.1MnO3 can further improve the denitration activity of perovskite catalyst, and La0.9Ce0.1Mn0.8Cu0.2O3 displays the NO conversion of 91.8% at 350 °C. Although the specific surface area of La0.9Ce0.1Mn0.8Cu0.2O3 is lower than La0.9Ce0.1MnO3, the Cu active sites and the Ce3+ contents are more developed, making many reaction units formed on the catalyst surface and redox properties of catalyst improved. In addition, strong metal interaction (Ce4+ + Mn2+ + Cu2+ ↔ Ce3+ + Mn3+/Mn4+ + Cu+) and high concentrations of chemical adsorbed oxygen and lattice oxygen both strengthen the redox reaction on catalyst surface, thus contributing to the better denitration activity of La0.9Ce0.1Mn0.8Cu0.2O3. Therefore, appropriate cerium and copper substitution will markedly improve the denitration activity of La–Mn perovskite catalyst. We also reasonably conclude a multiple reaction mechanism during NH3-SCR denitration process basing on DRIFT results, which includes the Eley–Rideal mechanism and Langmuir–Hinshelwood mechanism.

The role of the USA aviation industry in the development of general aviation

The history of a relatively little-studied sub-sector of aircraft manufacturing is described: the development and production of general purpose airplanes. Data on 2690 aircraft models and their production are collected by the author. It is shown that the USA share in the production in the 20th century exceeds 80 %, although in 1930–1945 European countries were the leaders. Assumptions are made about the reasons for the change of leaders. The definition of “general purpose airplane” is given with references to the regulatory documents of the USA, European Union and Russia. It is shown that the most popular subclass of such airplanes is four-seaters, its share in the total production of aircraft with the number of seats from 3 to 11 exceeds 50 %. For the first time, the year-by-year dynamics of the development and production of general purpose airplanes in the 20th century in the world is published. Strong declines in production are mentioned during the Great Depression and in the first half of the 1980s. It is shown that the demand for general purpose airplanes decreased significantly during the aggravation of the political situation, which correlates with the confidence of potential buyers in their future. Probably, such dependence should be observed for other long-time used consumer goods. The development of new models of general-purpose aircraft was also studied. It is shown that the peak of its intensity falls on 1929, and the post-war decline in the number of developments began even during the period of growth in production – in the mid-1960s. A very strong geographic concentration has been found: almost half of all general purpose airplanes in the world are built in one town (Wichita, Kansas), where more than a dozen airplane manufacturers have located their enterprises.

Insight into Dynamics of Hydromagnetic Flow of Micropolar Fluid Containing Nanoparticles and Gyrotactic Microorganisms at Weak and Strong Concentrations of Microelements: Homotopy Analysis Method

The mathematical model of bioconvection flow of micropolar fluid through a vertical surface containing nanoparticles and gyrotactic microorganisms is presented in this study. In the study, weak and strong concentrations of microstructures are explored. In the energy and concentration equations, the Catteneo-Christov diffusion models are used to explain temperature and concentration diffusions with thermal and solutal relaxation durations, respectively. The governing equations describing the fluid flow are transformed and parameterized through similarity variables. The approximate analytical solution is obtained by using Homotopy Analysis Method (HAM). The impacts of relevant parameters on the various distributions are investigated and illustrated. It is discovered that increasing the value of the micropolar parameter results in an increase in the microrotation distribution for strong concentrations of microstructures while decreasing the microrotation distribution for weak concentrations of microstructures.

Spinodal Decomposition of an Alloy with a Strong Concentration Dependence of the Mutual Diffusion Coefficient

It is shown that the kinetics of decomposition of an alloy with a strong concentration dependence of the mutual diffusion coefficient is qualitatively different from the widely known kinetics of spinodal decomposition, since it includes the formation of metastable (in the kinetic sense) precipitates of the intermediate composition. Concentration dependence of the mutual diffusion coefficient is particularly due to the difference in impurity diffusion coefficients, as well as component self-diffusion coefficients, and it increases as temperature decreases. The calculations use an expression for the flow of component atoms in the absence of the substance flow, obtained previously under the kinetic theory of vacancy diffusion ("hole gas method"). Keywords: spinodal decomposition, mutual diffusion coefficient, precipitates of intermediate composition.

Global steel production in the first two decades of the 21st century: a period of economic fluctuations and attempts to control globalisation processes

Based on World Steel Association statistical data, this study brings together changes in the geographical pattern of global steel production in the first two decades of the 21st century and its fluctuations during economic and social crises. The analysis indicates a strong concentration of production in several countries, and among them, China has become the leader in the last two decades. Since 2017, it has produced more than half of all steel globally, and in 2019 its annual production exceeded one billion tonnes. In 2020 the largest Chinese concern, China Baowu Group, ousted ArcelorMittal from its leading position in the ranking of the world’s largest steel concerns. Such an intense concentration of steel production in one country and the strategies of internal consolidation of Chinese steel producers are a clear signal that China is taking control of the global market for this raw material, essential for many economic sectors.

Inequality, welfare and punishment. Comparative notes between the Global North and South

In this paper, I will describe how two strong connections between, on the one hand, income inequality and welfare generosity, and, on the other, punitiveness, have been built in both theoretical and empirical explorations in the contemporary comparative literature on the sociology of punishment. Then, I will point out the strong concentration of these explorations on national cases from the Global North as a potential limitation. From there, I will try to ‘southernize’ this debate, through three empirical exercises related to a region of the Global South, Latin America. First, I will include this region in a global comparison of clusters of countries to define whether there is an association between the levels of income inequality and welfare generosity and the levels of punitiveness, both now and in the recent past. Second, I will analyse if the same relationships exist within Latin America countries, both now and in the recent past. Finally, I will examine whether these same relationships are relevant for understanding the evolution of the levels of punitiveness in Latin America over the last three decades. Based on the results of these three exercises, I will examine the shortcomings stemming from assuming these strong statements as universal, placeless and timeless, warning that the styles of comparison that have generated them have to be taken as starting points rather than as arrival points of the analysis and stressing that our analyses about contemporary penal differences, while taking macroscopic dimensions into account, should give a strong centrality to the ‘proximate’ processes that mould penal actions and results.

Intermittent pH control strategy in sludge anaerobic fermentation: Higher short-chain fatty acids production, lower alkali consumption, and simpler control

The pH control to promote short-chain fatty acids (SCFAs) production during anaerobic alkaline fermentation basically focused on constant pH control. In this study, a simple and consumption-reducing intermittent pH control strategy at moderate temperature (23 ± 2 °C) was investigated with adjusting pH to 10 when naturally reduced to 8. The intermittent pH control strategy could alleviate the inhibition of acid-producing bacteria by strong alkaline and high FA concentration. Meanwhile, microbial diversity promoted by 6% and 69% while the relative abundance of acid-producing bacteria increased by 36% and 61% compared to blank and constant pH fermenters. The relative genes abundance related to amino acid metabolism and fatty acid production were mostly promoted and led to enhanced SCFAs production. In the long-term fermenter, the intermittent pH control strategy could result in a 68% reduction in alkali consumption and a 37% increase in SCFAs production compared to that of the constant pH at 10.

Preparation of effective lithium-ion sieve from sludge-generated TiO2

A potential adsorbent for Li+ extraction from liquid resources is titanium-type lithium-ion sieves (LISs) because of their structural stability and high adsorption capacity. However, the adsorption efficiency and recycling stability of LISs produced with various TiO2 precursors vary significantly. Additionally, traditional TiO2 is often produced using chemical-intensive methods, resulting in large amounts of effluent containing strong acids and high concentrations of chloride/sulfate ions, posing a threat to the environment. Hence, in this study, the LIS precursors, Li2TiO3, were synthesized utilizing novel environment-friendly anatase titania made from flocculated sludges of synthetic secondary sewage effluent (S-LTO) and dye wastewater (D-LTO). The physicochemical characteristics and adsorption capacities of the synthesized LISs were then investigated. The results indicated that sludge-generated LISs could be effectively produced and had a high Li+ adsorption capacity of 35.43 mg/g for S-LTO and 34.97 mg/g for D-LTO. For the synthesized LISs, the adsorption kinetics and isotherms verified a fixed energy-based monolayer chemisorption. Furthermore, the H2TiO3 generated from sludge was extremely stable after acid pickling, reusable (4 regeneration cycles exhibited minimal performance degradation), and highly selective to Li+ in an aqueous medium, suggesting enormous industrial potentials such as seawater and brine for aqueous Li+ recovery.

Ultra-thin plasmonic detectors

Plasmonic materials, and their ability to enable strong concentration of optical fields, have offered a tantalizing foundation for the demonstration of sub-diffraction-limit photonic devices. However, practical and scalable plasmonic optoelectronics for real world applications remain elusive. In this work, we present an infrared photodetector leveraging a device architecture consisting of a “designer” epitaxial plasmonic metal integrated with a quantum-engineered detector structure, all in a mature III-V semiconductor material system. Incident light is coupled into surface plasmon-polariton modes at the detector/designer metal interface, and the strong confinement of these modes allows for a sub-diffractive ( ∼ λ 0 / 33 ) detector absorber layer thickness, effectively decoupling the detector’s absorption efficiency and dark current. We demonstrate high-performance detectors operating at non-cryogenic temperatures ( T = 195 K ), without sacrificing external quantum efficiency, and superior to well-established and commercially available detectors. This work provides a practical and scalable plasmonic optoelectronic device architecture with real world mid-infrared applications.

Charge carrier mediation and ferromagnetism induced in MnBi6Te10 magnetic topological insulators by antimony doping

A new kind of intrinsic magnetic topological insulator (MTI) MnBi2Te4 family has shed light on the observation of novel topological quantum effects such as the quantum anomalous Hall effect (QAHE). However, strong anti-ferromagnetic (AFM) coupling and high carrier concentration in the bulk hinder practical applications. In closely related materials MnBi4Te7 and MnBi6Te10, the interlayer magnetic coupling is greatly suppressed by Bi2Te3 layer intercalation. However, AFM is still the ground state in these compounds. Here, by magnetic and transport measurements, we demonstrate that a Sb substitutional dopant plays a dual role in MnBi6Te10, which can not only adjust the charge carrier type and concentration, but also induces the solid into a ferromagnetic (FM) ground state. The AFM ground state region, which is also close to the charge neutral point, can be found in the phase diagram of Mn(Sb x Bi1−x )6Te10 when x ∼ 0.25. An intrinsic FM-MTI candidate is thus demonstrated, which may take us a step closer to realizing a high-quality and high-temperature QAHE and related topological quantum effects in the future.

The HectoMAP Cluster Survey: Spectroscopically Identified Clusters and their Brightest Cluster Galaxies (BCGs)

Abstract We apply a friends-of-friends (FoF) algorithm to identify galaxy clusters and we use the catalog to explore the evolutionary synergy between brightest cluster galaxies (BCGs) and their host clusters. We base the cluster catalog on the dense HectoMAP redshift survey (2000 redshifts deg−2). The HectoMAP FoF catalog includes 346 clusters with 10 or more spectroscopic members within the range 0.05 < z < 0.55 and with a median z = 0.29. We list these clusters and their members. We also include central velocity dispersions (σ *,BCG) for the FoF cluster BCGs, a distinctive feature of the HectoMAP FoF catalog. HectoMAP clusters with higher galaxy number density (80 systems) are all genuine clusters with a strong concentration and a prominent BCG in Subaru/Hyper Suprime-Cam images. The phase-space diagrams show the expected elongation along the line of sight. Lower-density systems include some low reliability systems. We establish a connection between BCGs and their host clusters by demonstrating that σ *,BCG /σ cl decreases as a function of cluster velocity dispersion (σ cl), in contrast, numerical simulations predict a constant σ *,BCG/σ cl. Sets of clusters at two different redshifts show that BCG evolution in massive systems is slow over the redshift range z < 0.4. The data strongly suggest that minor mergers may play an important role in BCG evolution in clusters with σ cl ≳ 300 km s−1. For lower mass systems (σ cl < 300 km s−1), major mergers may play a significant role. The coordinated evolution of BCGs and their host clusters provides an interesting test of simulations in high-density regions of the universe.

Unequal geographies of the Italian tertiary education system. Mapping the disparities at regional scale

Abstract. In the last decade, the tertiary education system in Italy has shrinked and a larger heterogeneity has emerged among universities located in different areas of the country, with a strong concentration of increasingly scarce resources in a narrow and geographically concentrated number of institutions. The less developed areas, such as those in Southern Italy have been hit the most, in terms of enrolled students, academic staff, financial resources, courses offered.In this work we investigate these issues by adopting a cartographic approach. We highlight these polarizing dynamics, disentangling the possible causes. We focus, particularly, on the role of new regulatory policies and the funding mechanisms based on performance indicators as producers of inequalities.

Identification and Classification of the Tea Samples by Using Sensory Mechanism and Arduino UNO

Tea is the most popular hot beverageworldwide. In 2020, the value of the global tea market was almost USD 200 billion, and is estimated to reach up to USD 318 billion by the year 2025. Tea has been included as part ofa regular diet for centuries because of its various health benefits. However, tea is acidic, and over-consumption causes heat problems, disturbance of the sleep cycle, tooth erosion, and low calcium absorption in the body. Strong tea concentration is very harmful and toxic. The safe consumption of tea should be guaranteed. The treatment applied in this research work is on sensory mechanisms and Arduino UNO. The objective of this paper is to find out community interest in a particular tea species and inform them about tea overdose.The acidity is mapped with tea taste in terms of strong, medium, and low flavors. Based on the data analysis, the results differentiatethe acidity level of black tea (pH: 3.89–4.08) as very high, green tea (pH: 4.68–4.70) is in the 2nd position, and the energy drink Herbalife Nutrition (pH: 5.59–5.64) is the least acidic comparatively, with a proportion ratio 1:10 of tea to water. Experimental analysis reveals that in the additives, lemon is most acidic, followed byginger, lemongrass, and Tulasi.

Modification of Laser Marking Ability and Properties of Polypropylene Using Silica Waste as a Filler.

Polypropylene (PP) belongs to the group of polymers characterized by low susceptibility to absorption of electromagnetic radiation in the infrared range (λ = 1064 nm). This research consisted of assessing the possibility of using silica waste from the metallurgic industry as an additive for PP laser marking. The modifier was introduced into the polymer matrix in the range from 1 to 10 wt%. The effects of laser radiation were assessed based on colorimetric tests and microscopic surface analysis. The mechanical properties of the composites were determined during the static tensile tests. The thermal properties were investigated via differential scanning calorimetry. It was found that the introduction of silica waste into polypropylene allows for the effective marking of sample surfaces with the use of a laser beam. The greatest contrast between the graphic symbol and the background was obtained for silica contents of 3 and 5 wt%, with the use of a low-speed laser head and a strong concentration of the laser beam. The application of silica caused an increase in the modulus of elasticity and the tensile strength of the composite samples. Increases in the crystallization temperature and the degree of crystallinity of the polymer matrix were also observed. It was found that silica waste can act as multifunctional additive for polypropylene.

Large seasonal fluctuations of groundwater radioiodine speciation and concentrations in a riparian wetland in South Carolina

Recent studies evaluating multiple years of groundwater radioiodine (129I) concentration in a riparian wetland located in South Carolina, USA identified strong seasonal concentration fluctuations, such that summer concentrations were much greater than winter concentrations. These fluctuations were observed only in the wetlands but not in the upland portion of the plume and only with 129I, and not with other contaminants of anthropogenic origin: nitrate/nitrite, strontium-90, technecium-99, tritium, or uranium. This unexplained observation was hypothesized to be the result of strongly coupled processes involving hydrology, water temperature, microbiology, and chemistry. To test this hypothesis, an extensive historical groundwater database was evaluated, and additional measurements of total iodine and iodine speciation were made from recently collected samples. During the summer, the water table decreased by as much as 0.7 m, surface water temperature increased by as much as 15 °C, and total iodine concentrations were consistently greater (up to 680%) than the following winter months. Most of the additional iodine observed in the summer could be attributed to proportional gains in organo-iodine, and not iodide or iodate. Furthermore, 129I concentrations were observed to be two-orders-of-magnitude greater at the bottom of the upland aquifer than at the top. A coupled hydrological and biogeochemical conceptual model is proposed to tie these observations together. First, as the surface water temperature increased during the summer, microbial activity was enhanced, which in turn stimulated the formation of mobile organo-I. Hydrological processes were also likely involved in the observed iodine seasonal changes: (1) as the water table decreased in summer, the remaining upland water entering the wetland was comprised of a greater proportion of water containing elevated iodine concentrations from the low depths, and (2) water flow paths in summer changed such that the wells intercepted more of the contaminant plume and less of the diluting rainwater (due to evapotranspiration) and streamwater (as the lower levels promote a predominantly recharging system). These results underscore the importance of coupled processes influencing contaminant concentrations, and the need to assess seasonal contaminant variations to optimize long-term monitoring programs of wetlands.

The Zinshaus market and gentrification dynamics: The transformation of the historic housing stock in Vienna, 2007–2019

This article intends to contribute to the debate on the quantification of gentrification, which is constrained by two main obstacles: firstly, the operationalisation of displacement of socially weak households, which appears as an elusive phenomenon. Secondly, the consideration of the specific urban context, in particular the regulation of the housing market. Based on a case study for Vienna, this paper introduces a new empirical approach, which does not focus on households, but on the tenement conversion of the historic housing stock. Here, the transformation as legal conversion and demolition of historic tenement houses (German: Zinshäuser) serve as an alternative indicator for the operationalisation and quantification of displacement processes. The empirical analysis of Zinshaus transformations observed for 2007-2019 for the first time provides an estimation of gentrification dynamics in Vienna. Results point to a pronounced cyclicality in transformation dynamics. Hence, spatial cluster and hotspot analyses reveal a strong concentration of Zinshaus transformations and a clear shift from central bourgeois to peripheral working-class neighbourhoods. Further, a multilinear regression model confirms the impact of Zinshaus transformations on the social dynamics in these neighbourhoods. However, data do not indicate a social shift triggered by upper-class households, but by new migrant groups and well-educated middle-class households. Beyond the case of Vienna, this analysis underlines the relevance of quantitative gentrification approaches based on housing-market segments and their conversion. It proposes applying the Zinshaus as an indicator to make the variety of the urban context visible.

Optical properties, concentration and thermal quenching of luminescence of Dy3+- doped La2O3-Na2O-ZnO-TeO2 glasses

Tellurite glasses of the chemical composition: xDy2O3-(7-x)La2O3–3Na2O-25ZnO-65TeO2, where (0 < x ≤ 7) were obtained by the melt quenching technique. The spectroscopic characteristic of Dy3+- doped title glasses was carried out based on absorption and luminescence spectra as well as luminescence decay kinetics measurements. The Judd-Ofelt intensity parameters Ωλ (λ= 2, 4, 6) have been evaluated from the absorption spectrum and subsequently used to calculate the spontaneous emission probabilities, luminescence branching ratios and radiative lifetime of 4F9/2 emitting level of Dy3+. The emission cross-sections for Dy3+ transitions in the visible range have been determined applying Füchtbauer-Ladenburg formula. The luminescence decay measurements revealed strong concentration quenching of Dy3+ emission. The non-exponential decay curves have been fitted in the frame of Inokuti-Hirayma model, indicating that the dipole-dipole interaction plays an important role in luminescence quenching of 4F9/2 level. The temperature dependence of luminescence decay times of 4F9/2 state of Dy3+ has been investigated.

Effect of coronavirus (COVID-19) pandemic on orthopedic trauma patients presenting in the emergency department of a maximum care hospital and level 1 trauma center

IntroductionWhile overcrowding of emergency departments was often reported in the recent years, during the early phase of the pandemic, a reduction in patient numbers was seen. The aim of the current study was to describe the orthopedic trauma patient cohort presenting to the emergency department (ED) during the early pandemic period as compared to the cohort from the analogue time period 2019.Materials and methodsA single-center case–control study was performed. All the consecutive orthopedic trauma patients > 12 years presenting to the ED were included. Patients in the same time period in 2019 served as the control group.ResultsCompared to 2019, in 2020, 33% less patients presented in the emergency department. Patients treated in 2020 were significantly older, significantly more often brought to ED by emergency medical services and significantly more often admitted. The number of fractures and diagnoses requiring surgical treatment decreased only slightly and the proportion of these patients among all the patients was significantly higher during the pandemic than in the control period. Furthermore, a higher percentage of polytrauma patients could be found in 2020 as well. Analysis of Manchester Triage System showed significantly less not urgent patients in 2020.ConclusionThe present study shows a significant decline in the number of patients treated in the ED during the pandemic period but at the same time almost identical numbers of patients with fractures or diagnoses requiring surgical treatment. In the context of an overall decline in patient numbers, a stronger concentration on level 1 trauma centers seems to be evident during the pandemic.