Structural Change Research Articles

Evolution of cavitation clouds under cavitation impinging jets based on three-view high-speed visualization

Cavitation cloud is an important index for evaluating the unsteady behaviour of cavitation water jets. However, when cavitation jets are applied in a restricted space, the optimal standoff distance is not applied. To study the evolution and collapse mechanisms of cavitation clouds at small standoff distances, this study conducted visualization research on the behaviour of submerged cavitation water jet impacting the target surface at three standoff distances from three-view using a high-speed visualization system. The effect of the optimal standoff distance and the small standoff distance on the morphology of cavitation clouds was explored by observing their shedding behaviour and evolution on the target surface, obtaining a pattern for the morphological evolution of cavitation clouds. The evolution of cavitation clouds under impact flow conditions can be divided into stages: incipient cavitation, ring vortex cavitation, spindle-shaped cavitation cloud, mushroom-type cavitation cloud, cavitation ring, ring vortex cavitation, and collapse. The periodicity of cavitation clouds on the target surface was confirmed by monitoring the grayscale change at the center of the target. Furthermore, the changing of cavitation jet structures is illustrated through Proper Order Decomposition (POD) analysis, showing that the frequency of cavitation clouds increased with the decrease of standoff distance within a certain range. The behaviour of cavitation flow impinging on the target surface at optimal standoff distance and small standoff distance was simulated using the Large Eddy Simulation (LES) turbulence model combined with the Zwart-Gerber-Belamri (ZGB) cavitation model. The results show that the numerical simulation can capture the high-pressure zone generated when the cavitation cloud collapses, and the area of the high-pressure zone increases with the standoff distance within a certain range, the concentration of cavitation bubbles on the target surface did not represent the intensity of erosion. The transient vortex structures of the flow field at different standoff distances were investigated based on the Q-criterion. The findings of this study not only provide critical technical support for the application of cavitation jets in confined spaces, but also contribute to a broader understanding of the erosion mechanism of cavitation jets.

Necessary, burdensome, or threatening? Awareness of Black-White disparities in health care access and self-rated health for Black and White Americans.

Awareness of racial health care inequities is one prerequisite to eliminating them. Although extant research has described awareness of racial health care inequities in the United States, the health impacts of such awareness on communities that are most impacted by these inequities remains unknown. Therefore, we examined associations between awareness of Black-White racial health care inequities and self-rated health for Black and White adults in the United States. We used survey data from non-Hispanic Black and White participants (N = 6,449) who responded to the national American Health Values Survey (2015-2016) to test associations between awareness of Black-White inequities in health care and self-rated health. Accurate awareness of health care inequities was associated with 47% higher odds of poorer self-rated health for Black individuals. Inaccurate awareness was associated with 36% higher odds of poorer self-rated health for White individuals. Accurate awareness may be adaptive, yet place an additional burden on Black individuals. Inaccurate awareness may harm White individuals' health. Health care system changes and alleviation of racism-related stress may be preventive supports for the health of Black individuals. Accurate awareness should be a goal for White individuals, not only to prevent health risks, but to also facilitate structural change for racial equity. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

V-type granular starches prepared by maize starches with different amylose contents: An investigation in structure, physicochemical properties and digestibility

V-type granular starches (VGSs) were prepared via an ethanol-alkaline (EA) method using maize starch with different amylose contents, specifically, high amylose (HAM), normal maize starch (MS), and waxy maize starch (WS). The X-ray diffraction pattern of the native starch was completely transformed into a V-type pattern after the EA treatment, indicating a structural change in the starch granules. The VGSs prepared by HAM had highest relative crystallinity (31.8°), while the VGSs prepared by WS showed amorphous diffraction pattern. Excessive NaOH, however, would disrupt the formation of V-type structures and cause granular shape rupture. The quantity of double-helical structures, particularly those formed by amylopectin at the starch granules' periphery, significantly decreased. Conversely, single-helical structures formed by amylose increased. A notable rise in the relative crystallinity of V crystals. Four VGS samples, characterized by granular integrity, were chosen for the next investigation of physicochemical and digestive properties. VGS prepared from HAM exhibited higher granular integrity, lower cold-water swelling extent (59.0 and 161.0 cP), improved thermal stability (the value of breakdown as lower as 57.67 and 186.67 cP), and higher resistance to digestion (RS content was up to 10.38 % and 9.00 % higher than 5.86 % and 5.66 % of VGS prepared from WS and MS). The results confirmed that amylose content has a substantial impact on the microstructural and physicochemical properties of VGSs.

A modified Qian-Liu constitutive model based on advanced packaging underfill materials

—The high integration and multifunctionality of microsystem packaging have led to a gradual reduction in packaging size, bringing changes in materials, structures, and processes. This has resulted in numerous issues related to structural reliability and signal integrity. To address the problems of stress concentration during chip packaging, underfill materials are typically introduced beneath the chip. Therefore, the appropriate underfill selection significantly impacts chip reliability. In this work, a modified Qian-Liu constitutive model is proposed to describe the viscoplastic deformation of underfill. The new model accurately predicted the overall trend of stress-strain behavior for the temperature range from 298K to 398K and the strain rate range from 0.0001s−1 to 0.00ls-1. Constitutive parameters of the underfill over a wide temperature range based on the modified Qian-Liu model were obtained. A comparison between the experiment and simulation verified that the modified Qian-Liu model reasonably simulated the viscoplastic stress-strain relationships for underfill materials.

The 2-month lockdown and commuting behavior transformation in Shanghai: A phone signal data-based analysis

Research on COVID-19's influence on urban mobility often compares pre-pandemic patterns with those during or post-pandemic, emphasizing the decline due to lockdowns and recovery after vaccinations. However, the pandemic's impact on urban mobility and commuting trends, extending beyond the virus's immediate presence, is multifaceted, particularly considering its three-year span and diverse lockdown policies. Our study delves deeper into the effects of Shanghai's 2-month lockdown in 2022, from early April to end of May. Leveraging granular phone signal data, we meticulously compared and analyzed the geospatial dynamics of commuting between May 2021 and July 2022. Our findings revealed a notable contraction in commuting distances. Regions previously characterized by extensive long-distance commuting lost their allure post-lockdown. Intriguingly, administrative boundaries emerged as new impediments to commuting, an outcome that cannot be solely attributed to COVID-19 apprehensions. The empirical evidence suggests the possibility of a structural change in the commuting behavior of people in Shanghai, which is unlikely to be a consequence of the virus itself and more a result of stringent and arguably excessive lockdown protocols.

CO2 and Lignin‐Based Sustainable Polymers with Closed‐Loop Chemical Recycling

AbstractThis work highlights the conversion method of chaining up greenhouse gas CO2 with biomass lignin to develop new sustainable, recyclable polymers from abundant and non‐food based renewable resources. A cyclic carbonate monomer has synthesized using a cost‐effective, non‐phosgene‐based, and greener approach under atmospheric pressure and room temperature. The fully programable ring‐opening polymerization is accomplished by varying the catalyst (DBU and TBD), catalyst loading (0.5–5.0%) and reaction time (2–40 min). The best polymer is obtained in 1% TBD with a 30‐min reaction. The precise characterization of the synthesized cyclic carbonate monomer and polymers' structure are established using spectroscopic analyses including 1H, 13C, and 2D HSQC NMR, FT‐IR, and GPC. The new polymers exhibit high molecular weights (Mn: 120.34–154.58 kDa) and adequate thermal stabilities (Td5%: 244–277 °C from TGA and Tg: 33–52 °C from DSC), rendering them advantageous for practical applications. Significantly, the CO2 and lignin‐based polymers have successfully recycled to the monomer for a circular plastic economy by heating at 90 °C for 12 h in the presence of DBU. This process yields original monomers for another polymerization without unwanted changes in chemical structures, presenting an ultimate sustainable solution.

Succulent-Inspired Implicit Structural Change for Smart "ON/OFF" Switchable and Flexible EMI Shielding Coating.

Modern miniaturized intelligent electronics call for smart switchable and flexible electromagnetic interference (EMI) shielding material for highly precise applications. However, most switchable EMI shielding materials are based on an explicit structural change. Herein, we report a succulent-inspired smart switchable MXene (WR-MXene) coating film realized by inner implicit structural change, which benefits from the insertion of our reversible large-cavity yolk-shell biomicrospheres. The novel switchable yolk-shell biomicrospheres contain a soft N-isopropylacrylamide (PNIPAM) hydrogel core, an "ON/OFF" switchable cavity (over 30% volume fraction), and a porous polydopamine (p-PDA) shell. The yolk-shell biomicrospheres can be obtained by a facile two-step polymerization and a simple drying-dehydration treatment. Because of the "ON/OFF" switchable void space brought by the smart biomicrospheres and conductive framework of MXene, an optimized ultralight and flexible WR-MXene coating film (vWR-coating film) showed both large switchable change (over 60 dB) and extraordinary EMI shielding effectiveness, reaching 95 and over 50 dB in the whole X band (8.2-12.4 GHz). These novel reversible yolk-shell biomicrospheres and the succulent-inspired switchable coating films are promising for smart flexible wearable devices and many advanced multifunctional systems needing dynamic real-time response.

Spin-Flip via Subtle Electronic Perturbation in Axially Ligated Diiron(III) Porphyrin Dimer.

Spin state switching in the metal center is a crucial phenomenon in many enzymatic reactions in biology. The spin state alteration, a critical step in cytochrome P450 catalysis, is driven most likely through a weak perturbation upon substrate binding in the enzyme, which is still not well clarified. In the current work, the spin state transition of iron(III) from high to intermediate via an admixed state is observed upon a subtle electronic perturbation to the sulphonate moieties coordinated axially to a diiron(III)porphyrin dimer. While electron-donating substituents stabilize the high-spin state of iron(III), strongly electron-withdrawing groups stabilize an intermediate-spin state, whereas the moderate electron-withdrawing nature of axial ligands resulted in an admixed state. Confirmation of the molecular structures and their spin states have been made utilizing single-crystal X-ray structure analysis, Mössbauer, magnetic, EPR, and 1 H NMR spectroscopic investigations. The position of the signals of the porphyrin macrocycle in the paramagnetic 1 H NMR is found to be very characteristic of the spin state of the iron center in solution. The Curie plot for the pure high-spin complexes shows the signals' temperature dependency in line with the Curie law. Conversely, the pure intermediate-spin state of iron exhibits an anti-Curie temperature dependence, whereas the admixed-spin state of iron displays significant curvature of the lines in the Curie plot. An extensive DFT analysis displays a linear dependence between the energy difference between d and d orbital versus Fe-Npor distance for the complexes reported here. Furthermore, a strong linear correlation between the Fe-O distance and the spin density over the oxygen atom, as well as the Fe-Npor distance for the complexes, has been observed. Thus, a slight electronic perturbation at the axial ligand of the diheme resulted in a large change in the electronic structures with a spin-flip. This is at par with the metalloenzymes, which employ minute perturbations around the periphery of the active sites, leading to spin state transitions.

Causal clauses as source of sentential complementation: cross-linguistic evidence and methodological issues

Abstract In many languages, causal clause markers can also function as – or are formally identical to – complement markers (e.g., Bulgarian če, Twi se, or Latin quod). This isomorphism is often explained as the result of independent developments from a common source (interrogatives, relativizers, etc.). By contrast, it is also frequently accepted that in some cases the aforementioned identity originates in a type of structural change by which causal clauses are eventually reanalysed as factive complements. However, the nature of the proposed CAUSE > COMPLEMENT development, involving both semantic adjustments and syntactic integration, is not yet fully understood, and it remains unclear how recurrent this phenomenon might be from a cross-linguistic perspective. This article aims to shed light on these questions by analysing diachronic and cross-linguistic data and assessing some of the evidence given for the development of complementation from causal adverbial clauses. The observations reveal significant documentation gaps for postulated models of the emergence of complement clauses and highlight methodological issues that qualify previous explanations about the diachronic relationship between causal and complement clauses.

Structure and Functioning of Urban Local Bodies in Infrastructure and its Challenges

India's society is now characterised by widespread urbanisation. Millions of people are moving to cities in search of employment because cities are the main benefactors of globalisation and are growing in population. This shows that Indian cities must act as the engine for the country's economy's structural change. Infrastructure has to be improved and upgraded, which necessitates active cooperation from both the state and federal governments. The 73rd and 74th Amendments to the Constitution, which aim to establish an institutional framework for bringing about grass- roots democracy through the use of genuinely self-governing local bodies in both urban and rural areas of the nation, provide a clear mandate for democratic decentralisation in addition to the directive principle of state policy. The subjects covered in this research study include various urban local bodies, their relevance, their organisation, their tasks and responsibilities, and their problems and difficulties. Urban Local Bodies must deal with issues such financial scarcity, unplanned urbanisation, excessive state government control, and the proliferation of agencies, Low level of People’s Participation in socio-economic development. And how can the financial independence of urban local governments be increased? By incorporating technology, e-governance, financial instruments like municipal bonds, ensuring active citizen participation, and improving grievance redressal mechanisms. Keywords—urban local bodies, municipal corporation, municipal council, municipal bonds

Structural change, labour reallocation, and productivity growth in post-reform China

Abstract Why has the structural bonus been so small during China’s post-reform era? This article explains the puzzle by exploiting the heterogeneity in structural-change patterns across Chinese provinces. Using an original database covering production and factor inputs in 8 sectors and 31 provinces over 1993–2016, I show only those provinces where labour was reallocated from agriculture to manufacturing and services benefited from a structural bonus on labour productivity growth. In the other provinces, this structural-change effect was minimal or negative. Regarding the structural-change effect on total factor productivity (TFP) growth, I find both labour and capital reallocation played a limited role. Labour reallocation has little potential in boosting aggregate TFP growth, as marginal labour returns are similar across sectors. Capital reallocation has a far greater potential but remains restrained, suggesting substantial reallocation frictions. China’s TFP growth is mostly explained by within-sector technological progress, which has been dissipating since 2008, leading to declining TFP growth.

Elly versus Giorgia? The political leadership of Elly Schlein and Giorgia Meloni between myth and reality

ABSTRACT 2023 has been a year marking a turning point, with two women in leading positions for the first time in Italian politics. Elly Schlein was elected leader of the Democratic Party in February 2023, while a few months earlier Giorgia Meloni, leader of the radical right Brothers of Italy, became prime minister. When Schlein and Meloni celebrated their victory with the identical phrase ‘They [the men] didn’t see us coming’, both leaders showed great awareness that their rise shook the traditionally Italian male dominated political environment. Will the election of the two leaders result in a more structural change? The article seeks to address this issue, focusing on three key aspects: the historical roots of the women’s exclusion from Italian politics; the distinctive political careers of Meloni and Schlein; and the success of the radical right Meloni government in defending the traditional family, while Schlein is facing difficulties to revive the party and to build a single opposition.

Infrastructure and Structural Change in Africa

Abstract Past investments in electricity, Internet, and road infrastructure, in isolation and bundled, have contributed to structural transformation and economic development in Africa. Using new data on the expansion of the road, electricity, and Internet networks over the past two decades, the paper shows that having access to both paved roads and electricity has led to a significant reallocation of labor from agricultural to both manufacturing and services. Adding access to fast Internet has had a major impact on structural change, with an even larger impact on reallocating labor away from agriculture. The paper then uses a spatial general-equilibrium model to quantify the impacts of future regional transport investments, bundled with electricity and Internet investments, on economic development in countries in the Horn of Africa and Lake Chad region.

The structural change and determinants of global carbon footprint network embodied in international migration: A social network analysis

The carbon footprint embodied in international population mobility has a complex spatial correlation, which exacerbates the difficulty of global climate governance. However, the features, changing trends, and determinants of the carbon footprint flow embodied in global population migration are poorly understood. This study employed social network analysis and the exponential random graph model (ERGM) to investigate the structural changes and drivers of the carbon footprint network embodied in global migration from 1995 to 2015. The results showed that approximately 50% of carbon footprint flow embodied in international migration flowed from developing to developed countries. The spatial connections between countries in the network were becoming increasingly close, displaying a typical small-world structure, and showing low reciprocity and negative assortativity. Moreover, centrality analysis highlighted the United States and the European Union as being at the core of the network, whereas some emerging economies (e.g., China, India, and South Africa) were shown as having an increasing influence on the network. The determinants of network formation were divided into three effects. For node attribute effect, countries with developed economy, high proportion of industrial value added, urbanization and openness were becoming the destinations of carbon inflows from immigrants, while countries with high consumption of renewable energy and energy intensity had a trend of carbon outflows with emigrants over periods. As for exogenous network effect, the significance of economic integration on the formation of the network was strengthening, while that of geographical proximity and cultural similarity was declining. Additionally, the positive impact of self-organizational effect on the network was decreasing. This study provided guidance for countries to formulate policies to reduce the carbon emissions embodied in international migration.

Structural effects of water clusters on viscosity at high shear rates.

In this study, we use molecular dynamics simulations of liquid water to investigate how shear thinning affects the viscosity of liquid water by structural changes of the hydrogen bond network. The effect of shear on viscosity can be divided into two parts: shear-induced destruction of the hydrogen bond network and the influence of the water structure on shear viscosity. First, strong shear destroys tetrahedral structures and thus reduces the connectivity of the hydrogen bond network. It is mainly because shear deformation, characterized by compression and expansion axes, respectively, triggers the destruction and formation of hydrogen bonds, resulting in anisotropic effects on water structures. At the same time, shear destroys large clusters and enhances the formation of small ones, resulting in a decrease in average cluster sizes. Second, the change of viscosity obeys a power law relationship with the change of hydrogen bond structures, highlighting a one-to-one correspondence between structure and property. Meanwhile, in order to explain why the structure affects viscosity, we define hydrogen-bond viscosity and find that the cooperative motion of the water structures can promote momentum transfer in the form of aggregations. Hydrogen-bond viscosity accounts for 5%-50% of the total viscosity. Our results elucidate that water structures are the important structural units to explain the change of water properties.

Electroencephalogram-Based Metastability in Mild Cognitive Impairment Alzheimer's Disease.

Background: In this study, we analyze metastability, a feature of brain dynamics in subjects experiencing mild cognitive impairment Alzheimer's disease (MCI-AD) under eyes open (EO) and eyes closed (EC) conditions. Alzheimer's disease (AD) is a critically prolonged brain disorder that interrupts neural synchronization and desynchronization. Thus, studying metastability under EO and EC conditions would help in understanding the cortical dynamics and its impact in early-stage AD. Methods: Metastability is investigated using three methods namely frequency variance analysis, Kuramoto order parameter, and through meta-state activation patterns. Frequency variance estimated from 21 electroencephalogram (EEG) channels was clustered into three regions namely anterior, central, and posterior to study the regional metastability analysis. Global metastability was assessed from Kuramoto order parameter and meta-state activation patterns by collating the 21 EEG channels. Results: Reduction in metastability was observed in central regions of MCI-AD subjects through the study of frequency variance analysis. There was a marked reduction in global metastability in the patient group under the resting EO condition. Reduction in meta-state activation properties such as temporal activation sequence complexity, modularity, and leap size in MCI-AD condition under the EO condition indicates an overall reduction in brain flexibility. Conclusion: Taken together, the study infers an underlying structural change in neuronal dynamics influencing the reduction of metastability under the MCI-AD condition. The study further revealed that this reduction in metastability is more pronounced in the EO condition.

Optical and soft X-ray light-curve analysis during the 2022 eruption of U Scorpii: Structural changes in the accretion disk

Abstract We present our optical photometric observations of the 2022 eruption of the recurrent nova U Scorpii (U Sco) using 49152 data points over 70 d following the optical peak. We have also analyzed its soft X-ray (0.3–1 keV) light curve by the Neil Gehrels Swift Observatory. During the 2022 eruption, the optical plateau stage started 13.8–15.0 d and ended 23.8–25.0 d after the optical peak. The soft X-ray stage started 14.6–15.3 d and ended 38.7–39.5 d after the optical peak. Both stages started later and had shorter durations, and the soft X-ray light curve peaked earlier and was less luminous compared to those during the U Sco 2010 eruption. These points suggest that there were differences in the envelope mass between the different cycles of the nova eruption. Furthermore, we have analyzed the optical eclipses during the 2022 eruption. The primary eclipse was first observed 10.4–11.6 d after the optical peak, earlier than the beginning of the optical plateau stage. This sequence of events can be explained by the receding ejecta photosphere associated with the expanding nova ejecta. We have determined the ingress and egress phases of the primary eclipses and estimated the outer radius of the optical light source centered at the white dwarf (WD). During the optical plateau stage, the source radius remained ∼1.2 times larger than the Roche volume radius of the primary WD, being close to the L1 point. When the optical plateau stage ended, the source radius drastically shrank to the tidal truncation radius within a few orbital periods. This previously unresolved phenomenon can be interpreted as a structural change in U Sco where the temporarily expanded accretion disk due to the nova wind returned to a steady state.

Effect of Mixing Intensity on Electrochemical Performance of Oxide/Sulfide Composite Electrolytes

Despite the variety of solid electrolytes available, no single solid electrolyte has been found that meets all the requirements of the successor technology of lithium-ion batteries in an optimum way. However, composite hybrid electrolytes that combine the desired properties such as high ionic conductivity or stability against lithium are promising. The addition of conductive oxide fillers to sulfide solid electrolytes has been reported to increase ionic conductivity and improve stability relative to the individual electrolytes, but the influence of the mixing process to create composite electrolytes has not been investigated. Here, we investigate Li3PS4 (LPS) and Li7La3Zr2O12 (LLZO) composite electrolytes using electrochemical impedance spectroscopy and distribution of relaxation times. The distinction between sulfide bulk and grain boundary polarization processes is possible with the methods used at temperatures below 10 °C. We propose lithium transport through the space-charge layer within the sulfide electrolyte, which increases the conductivity. With increasing mixing intensities in a high-energy ball mill, we show an overlay of the enhanced lithium-ion transport with the structural change of the sulfide matrix component, which increases the ionic conductivity of LPS from 4.1 × 10−5 S cm−1 to 1.7 × 10−4 S cm−1.

Repression breeds resistance: A call for a methodology of radical solidarity and love to respond to the prison industrial complex and academia's eugenic tendencies

This collaborative autoethnographic article traces psychology's complicity in systems of oppression while highlighting pathways toward liberation. An expression and embodiment of radical solidarity, this article is the product of a research collaboration between an incarcerated justice advocate and a critical psychologist. Critical autoethnographic methods are leaned on to lift experiences of prison as an oppressive institution and illuminate forms of resistance. We strategically and deliberately co-created this methodological approach to joyfully render prison walls metaphorically porous, to seep through surveillance mechanisms (both within the prison and academia), and to build liberatory worlds through our words. Situating mass incarceration as an extension of colonial displacement and enslavement, we dialogically examine how psychology has upheld white supremacy through the illusion of objectivity and neutrality. Psychological concepts like critical consciousness and resilience are re-theorized to center embodied, collective struggles. Calling for psychology to move beyond apologies toward deep structural change and distributive justice, we advocate for centering the experience of those historically excluded in knowledge construction, resource allocation, and leadership. Imagining a psychology of love and solidarity, we urge dismantling oppressive institutions through pedagogies of radical solidarity. Our collaboration—across prison walls—models methodologies of mutual aid, conscientization, and power sharing to build a liberatory psychology.

Effects of Fe Ions, Ultraviolet Irradiation, and Heating on Microscopic Structures of Black Lacquer Films.

The chemical reaction between Fe and lacquer has been used to create the black color in lacquer coatings since ancient times. Here, the effects of Fe ion addition, UV irradiation, and heating on the microscopic structures of black lacquer films were investigated by using X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), Fourier transform-infrared spectroscopy (FT-IR), small-angle X-ray scattering (SAXS), and small angle neutron scattering (SANS). The EXAFS result indicated that heating and UV irradiation made the coordination structure of Fe3+ in the lacquer nonuniform, and that heating caused the greatest nonuniformity. The FT-IR, SAXS, and SANS results demonstrated that the microscopic structural changes in the black lacquer films were induced by both heating and UV irradiation, but the changes were different. Heating caused a substantial structural change on the nanoscale, and UV irradiation mainly caused changes in the molecular binding mode. The results provide important knowledge for analyzing archeological lacquer samples and for developing lacquer-based materials. This work also demonstrates the utility of the complementary use of XANES, EXAFS, FT-IR, SAXS, and SANS for nondestructive analysis of black lacquer in precious cultural relics.