Structural Change Research Articles

Structural Predictors of Lung Function Decline in Young Smokers with Normal Spirometry.

Rationale: Chronic obstructive pulmonary disease (COPD) due to tobacco smoking commonly presents when extensive lung damage has occurred. Objectives: We hypothesized that structural change would be detected early in the natural history of COPD and would relate to loss of lung function with time. Methods: We recruited 431 current smokers (median age, 39 yr; 16 pack-years smoked) and recorded symptoms using the COPD Assessment Test (CAT), spirometry, and quantitative thoracic computed tomography (QCT) scans at study entry. These scan results were compared with those from 67 never-smoking control subjects. Three hundred sixty-eight participants were followed every six months with measurement of postbronchodilator spirometry for a median of 32 months. The rate of FEV1 decline, adjusted for current smoking status, age, and sex, was related to the initial QCT appearances and symptoms, measured using the CAT. Measurements and Main Results: There were no material differences in demography or subjective CT appearances between the young smokers and control subjects, but 55.7% of the former had CAT scores greater than 10, and 24.2% reported chronic bronchitis. QCT assessments of disease probability-defined functional small airway disease, ground-glass opacification, bronchovascular prominence, and ratio of small blood vessel volume to total pulmonary vessel volume were increased compared with control subjects and were all associated with a faster FEV1 decline, as was a higher CAT score. Conclusions: Radiological abnormalities on CT are already established in young smokers with normal lung function and are associated with FEV1 loss independently of the impact of symptoms. Structural abnormalities are present early in the natural history of COPD and are markers of disease progression. Clinical trial registered with www.clinicaltrials.gov (NCT03480347).

Deciphering the adaptive conformational evolution of dihydrophenazine derivatives in the confined space of a semi-rigid macrocyclic host

Exploring the conformational evolution of organic molecules is a long-pursuit theme in the field of chemistry. Herein, interests are endeavored to unveil the conformational evolution of conformationally flexible dihydrophenazines with environment-sensitive and continuously-changeable fluorescence in the confined space exerted by the semi-rigid macrocyclic host ExBox4+. Co-crystals of the ExBox4+ and dihydrophenazines are obtained via vapor diffusion, facilitating direct clarification of the structural variations of the host and guests. The adaptive ground-state conformational evolution of the guests is fully deciphered via 1H NMR titration, crystallography analysis as well as systematic theoretical calculations. In contrast to the much smaller structural change of the well-noted conformationally adaptive host, the conformational variation in the central dihedral angle of the guest can be up to 22° in the crystal of the host-guest complex, which is completely different from the cases when ExBox4+ interacting with the rigid guests. Dynamic information encryption has been further achieved by harnessing the distinct fluorescence behaviors before and after host-guest complexation. This work not only provides new insights into the understanding of mutual interactions between a semi-rigid host and conformationally flexible guests, but also offers an alternative scheme for advanced information encryption based on the luminescent host-guest complexes.

Classification of Parkinson’s disease EEG signals using 2D-MDAGTS model and multi-scale fuzzy entropy

Parkinson’s disease (PD) is a neurodegenerative disorder that causes changes in neurons, behavior, and physiological structures. However, these changes are very subtle in the early stages of PD, making diagnosis and treatment challenging. To overcome this challenge, we propose a multi-scale fuzzy entropy (MSFEn) fusion method. MSFEn can be used as an EEG feature to quantify the complexity and irregularity of the EEG signal. We also propose a two-dimensional multiple dual attention gated temporal-separable (2D-MDAGTS) model for PD automatic detection. This model integrates temporal separable convolution (TSCN), gated recurrent unit (GRU), and dual attention network (DANet) to improve PD detection performance. TSCN can mine multi-level information in timing sequence and output processed features. Then the GRU is operated in parallel with the DANet to further integrate feature information. GRU can capture long-term dependencies of time series data and DANet can adjust the weight of features through the attention mechanism to better focus on the features related to PD. Two datasets were used to evaluate the proposed methods. In the classification of healthy subjects and drug-free PD patients, our results achieved an accuracy of 98.68% on the San Diego dataset and 99.30% on the UNM dataset. In the classification of healthy subjects and PD patients on medication, our results achieved an accuracy of 99.01% on the San Diego dataset and 99.31% on the UNM dataset. The results showed that this method is superior in the diagnosis of PD patients. The application of this method is expected to provide support for early diagnosis and disease monitoring.

Do electromagnetic fields significantly affect thyroid cells and their functions? – A systematic review

Background: This review aimed to emphasize the effects, mechanisms involved, conditions required to trigger impacts, and the adapted responses of EMF on thyroid gland. Methods: The included literatures were collected from the Oceania Radiofrequency Scientific Advisory Association (ORSAA) database which were published before April 2021. The searched was then refined with keyword ‘thyroid’. Results: A total of 15 experimental studies, 10 observational studies, 4 review articles, and 1 medical hypothesis were included. Hypothyroidism is the most reported functional abnormality. The identified morphological abnormalities of the thyroid gland include increased follicular epithelial and interfollicular tissue, decreased colloid volume of cubic cells, follicular fluid, interfollicular space, changes in lysosomes, granular endoplasmic reticulum, cell nuclei, changes in glandular structures including cell hypotrophy, glandular hypertrophy, and increased apoptosis via caspase-dependent pathways. The observational studies reported an increase in thyroid cancer incidence and the diameter of the left anteroposterior of the thyroid gland. Postulation that thyroid cancer is associated with thyroid cancer EMF exposure, is suggested by a medical hypothesis paper. The possibilities of hypothyroidism, thyroid cancer, and cell apoptosis due to EMF exposure have been highlighted in the review articles. Conclusion: Despite these findings, critical elements, such as the effects and mechanisms of EMF exposure on thyroid hormone transporters, genomic and non-genomic actions, conditions required for the effect to occur, and the resultant adapted responses, have not been explored suggesting the need of further research.

Role of promoter on the catalytic activity of novel hollow bimetallic Ni–Co/Al2O3 catalyst in the dry reforming of methane process: Optimization using response surface methodology

In this research, the effect of promoter addition and its type on the catalytic performance and morphology properties of bimetallic Ni–Co catalysts on the novel hollow Al2O3 support was investigated in the dry reforming of methane (DRM) process. The response surface method (RSM) based on the optimal custom model was employed for maximizing CH4 and CO2 conversions, as well as H2 and CO yield. Four independent variables including Co to Ni mass ratio (0, 0.5, 1), DRM temperature (600, 650, 700 °C), CH4/CO2 molar ratio (1, 1.5, 2), and catalyst type (without promoter, with Mg or Y promoter) were selected for this purpose. Among three suggested optimized catalysts by the design expert, the yttrium-promoted one with 1 Co/Ni mass ratio (1Ni–Co–Y/Al) depicted the highest CH4 conversion of 86.50 %, CO2 conversion of 92.00 %, H2 yield of 85.11 %, and CO yield of 93.54 % at lower temperature of 679 °C and equal CH4/CO2 mole ratio of 1. The structural characterizations confirmed that the high activity of 1Ni–Co–Y/Al could be due to the better dispersed active sites and higher surface area of this catalyst compared with un-promoted and Mg-promoted samples. The time-on-stream performance of optimized catalysts at their optimized conditions was also compared experimentally, results of which showed more stability and activity of the Y-promoted sample during 12 h DRM reaction. The TGA, EDX, XRD, FESEM, and N2 physisorption techniques demonstrated the lower structural change and deposited carbon on the 1Ni–Co–Y/Al surface after reaction, which may be because of higher oxygen storage capacity (OSC) of this catalyst.

Is natural resource dependence a blessing or curse for sustainable energy blueprint? An empirical insight towards achieving sustainable environment

AbstractNatural resources have become the centerpiece of global discussion recently in an effort to achieving sustainable development. There are arguments that as much as natural resources are inevitable for development; they are disastrous to factors that promote sustainability of the global environment of which the transition to sustainable energy stands out. That notwithstanding, studies have been largely engrossed in verifying the roles natural resources on economic growth and the environment. Consequently, this research provides the first empirical evidence on the impacts of natural resources on sustainable environment in a global dataset for 73 countries from 1997 to 2019. To extend the frontier of knowledge, the roles of technological advancement, structural change, regulatory quality, and foreign direct investment are considered in the empirical model. The empirical evidence relies on cross‐sectional autoregressive distributed lag, augmented mean group; common correlated effects mean group and method of moment quantile regression. The preliminary analyses show that the world is presently in a renewable energy deficit while recording a gradual shift from relying on natural resources. Feedbacks from the model evaluated expose that natural resource dependence curses sustainable energy through its militating impacts. Besides, technological advancement, structural change, regulatory quality, and foreign direct investment significantly and positively drive sustainable energy. Besides, the quantile regression analysis provides diverging magnitudes. Policies that promote sustainable energy are suggested.

Exploration and Improvement Path of Local Government Debt Risk Warning Mechanism Based on KMV Model: Taking Bengbu, Anhui as an Example

This article is based on the KMV model and explores methods for improving the local government debt risk warning mechanism under the backdrop of the pandemic, with a case study of Bengbu City in Anhui Province, China. In the context of an economic downturn and the impact of the COVID-19 pandemic, accurately understanding and effectively managing the fiscal risks of local governments is particularly important. The study focuses on analyzing the impact of changes in fiscal revenue and expenditure structures during the pandemic on local debt risks, using the KMV model for in-depth analysis. By comparing fiscal data from different time periods, the effectiveness of the existing local government debt risk warning mechanisms was evaluated. This paper also discusses how to improve risk management and proposes specific strategies and suggestions. These recommendations aim to enhance the efficacy of local government debt warning systems, especially considering the unique challenges brought about by the pandemic and economic changes. The study shows that by improving fiscal risk management and optimizing warning mechanisms, it is possible to better respond to various economic challenges that may arise in the future, providing local governments with more robust and reliable financial risk control plans.

A pilot study of antimicrobial effects and ototoxicity of a Norway spruce (Picea abies) resin-based canine otic rinse product.

Norway spruce (Picea abies) resin-based products are used in human medicine. A resin-based otic rinse also could be useful in supportive care of canine otitis externa (COE), yet information on its antimicrobial effect against canine pathogens or ototoxicity is lacking. To investigate the antimicrobial properties and ototoxicity of a commercial resin-based otic product. Antimicrobial effect was evaluated using a standardised challenge test on Staphylococcus pseudintermedius, Corynebacterium auriscanis, Pseudomonas aeruginosa, Escherichia coli, Malassezia pachydermatis, and Streptococcus halichoeri strains to measure reduction in growth after 24 h exposure to the product. Effect on cell morphology was investigated by exposing S. pseudintermedius, C. auriscanis, P. aeruginosa and M. pachydermatis to the product in 20% and 100% (v/v) concentrations for 6, 24 and 48 h, and evaluating cells by transmission (TEM) and scanning (SEM) electron microscopy. An invitro microbial kill-rate assay also was performed. Auditory brain stem response test, clinical evaluation and postmortem histological evaluation of ear canals were undertaken on experimental guinea pigs treated with the test product or saline controls. The product showed >log 5 growth reduction for all strains in the challenge test. TEM and SEM images showed clear changes in the cells' inner structures and deterioration of cells, and 100% (v/v) test product exposure induced microbial killing in 1-2 h. Ototoxicity was not detected in guinea pigs. The product may be an option in supportive care of COE because of antimicrobial effects and lack of ototoxic properties in a guinea pig model.

The structure and potential allergenicity of peanut allergen monomers after roasting.

Given that roasted peanut (Ro) products are commonly used in daily life, peanut allergenicity is a foremost concern. Analyzing the changes in the structure and potential allergenicity of individual allergens can promote the exploration of the structural basis of the alterations in the potential allergenicity of Ro. This work focused on four major allergens in raw peanut (Ra) and Ro. Structural changes were analyzed on the basis of circular dichroism, ultraviolet and fluorescence spectroscopy, and molecular dynamic simulation. The IgE recognition capability of allergens was assessed via western blot analysis. The IgE binding capacity of allergens was detected by conducting enzyme-linked immunosorbent assay. The potential allergenicity of allergens was evaluated using the KU812 cell degranulation model. The results showed that roasting induced different changes in the overall structures of allergens and altered the structures and electrostatic potential of IgE epitopes, especially Ara h 1 and Ara h 6. These alterations affected the potential allergenicity of allergens. Ara h 1 and Ara h 6 in Ro showed significantly enhanced IgE binding capacities and abilities to elicit KU812 cell degranulation, while Ara h 2 and Ara h 3 did not change significantly. For total protein, the roasted peanut protein showed decreased abilities to elicit KU812 cell degranulation. The results indicated that different allergens in Ro showed different changes of structures and potential allergenicity and that the conformational structure plays a crucial role in potential allergenicity of allergens.

Focusing on structural changes and future risks of ecosystems: An opportunity-cost based ecosystem service account for riparian ecosystems and its case study

The riparian is a buffer zone between the river and human society, and improper land development will increase the ecological vulnerability of the river basin. Different evaluation methods for the ecological impact of development behavior will produce different value perception results, which in turn will affect the judgment and choice of decision-makers and the public. Based on the construction of an opportunity-cost-based monetary valuation method in the SEEA-EA (System of Environmental Economic Accounting-Ecosystem Accounting), this study took the riparian under the influence of the Xiaolangdi Project of the Yellow River from 1990 to 2020 as the research object, and evaluated the impact of land development decisions on ecosystem services under the superimposed influence of major projects, policies and socio-economic changes. The results show that: (1) The inclusion of opportunity costs can reduce the distortion of ecological value caused by economic factors and supply–demand state. In the case study, the opportunity cost of each 5-year accounting period in 30 years reduced the total accounting value respectively by 196.76, 25.88, 80.57, 84.33, 27.96, and 577.48 million yuan. (2) Opportunity cost can effectively reflect the ecological profit and loss caused by land transformation between different ecosystem types caused by decision-making in different periods. From 2015 to 2020, the opportunity cost of ecosystems was high when the total ecological land in the riparian increased, which reflected the drastic changes in land use during the decision-making period. (3) Opportunity costs are included in the monetary account as part of the “stock reduction”, which directly reflects the risk of ecological land reduction and structural change caused by development behavior. This mixed account of physical and monetary stocks can reflect both physical changes in ecosystem services and ecological risks, thereby improving stakeholders’ scientific understanding of the fluctuations in the value of ecosystem services caused by riparian land use.

A graphitic C3N4 nanocomposite-based fluorescence platform for label-free analysis of trace mercury ions.

In this study, a nanocomposite consisting of graphitic carbon nitride nanosheets loaded with graphitic carbon nitride quantum dots (CNQDs/CNNNs) was synthesized via a one-step pyrolysis method. This nanocomposite exhibited excellent thermal stability, photobleaching and salt resistance. Then a new fluorescence sensing platform based on CNQDs/CNNNs was constructed, which showed high sensitivity and selectivity towards trace mercury ions (Hg2+). By using X-ray photoelectron spectroscopy, UV-vis diffuse reflectance spectra and density functional theory, the fluorescence response mechanism was elucidated where Hg2+ could interact with CNQDs/CNNNs, causing a structural change in the nanocomposite, further affecting its bandgap structure, and finally leading to fluorescence quenching. The linear range for detecting Hg2+ was found to be 0.025-4.0 μmol L-1, with a detection limit of 7.82 nmol L-1. This strategy provided the advantages of a rapid response and a broad detection range, making it suitable for quantitative detection of Hg2+ in environmental water.

Are financial stocks driven by substantive factors or virtual factors? Comparing Taiwan and China markets

This study employs information economics and the financial intermediary theory to explore the influences of private information in virtual communities and financial technology (fintech) derived from virtual currency on financial stocks. The paper conducts robust analyses on 67,166 data observations of the stock markets in China and Taiwan and finds that virtual currency development causes a structural change in the financial industry. The financial stocks in Taiwan are obviously driven by virtual factors, whereas those in China are subject to both pull from substantial factors and push from virtual factors. The research findings also suggest that the non-fundamental herding behavior driven by private information interferes with the value of financial stocks. However, financial innovations boost the competitiveness of the financial industry. It is advised to establish a policy to closely monitor the diffusion of private information and the exchange rate volatility between cryptocurrencies and home currencies to facilitate proactive financial risk management.

Comprehensive understanding of the crystal structure of perovskite-type Ba3Y4O9 with Zr substitution: a theoretical and experimental study.

We previously reported that Zr substitution improves the chemical stability of Ba3Y4O9 and nominally 20 mol% Zr-substituted Ba3Y4O9 is an oxide-ion conductor at intermediate temperatures (500-700 °C). However, the influence of Zr substitution on the structural properties of Ba3Y4O9 was poorly understood. This paper aims to comprehensively understand the crystal structure of Ba3Y4O9 with Zr substitution by powder X-ray diffraction (XRD), extended X-ray absorption fine structure (EXAFS) measurements, and first-principles calculations. From the results, firstly we found that the hexagonal unit cell of Ba3Y4O9 reported in the database should be revised as doubled along the c-axis in terms of the periodicity of oxide-ion positions. The revised unit cell of Ba3Y4O9 consists of 18 layers of BaO3 and 24 layers of Y which periodically stack along the c-axis. In this work, we focused on the cationic lattice and noticed that the periodical stacking of Ba and Y layers comprises a similar sequence to that in the body-centered cubic (BCC) structure. There are two regions in the Ba3Y4O9 structure: one is a hetero-stacking region of Ba and Y layers (Ba-Y-Ba-Y-Ba) and the other is a homo-stacking region (Ba-Y-Y-Ba). It is noteworthy that the former region is similar to a cubic perovskite. In Zr-substituted Ba3Y4O9, Zr ions preferentially substitute for Y ions in the hetero-stacking region, and therefore the local environment of Zr ions in Ba3Y4O9 is quite similar to that in BaZrO3. Besides, the Zr substitution for Y in Ba3Y4O9 increases the fraction of the cubic-perovskite-like region in the stacking sequences. The structural change in the long-range order strongly affects the other material properties such as chemical stability and the ionic-conduction mechanism. Our adopted description of perovskite-related compounds based on the stacking sequence of the BCC structure should help in understanding the complex structure and developing new perovskite-related materials.

The likelihood ratio test for structural changes in factor models

A factor model with a break in its factor loadings is observationally equivalent to a model without changes in the loadings but with a change in the variance of its factors. This approach effectively transforms a high-dimensional structural change problem into a low-dimensional problem. This paper considers the likelihood ratio (LR) test for a variance change in the estimated factors. The LR test implicitly explores a special feature of the estimated factors: the pre-break and post-break variances can be a singular matrix under the alternative hypothesis, making the LR test diverging faster and thus more powerful than Wald-type tests. The better power property of the LR test is also confirmed by simulations. We also consider mean changes and multiple breaks. We apply this procedure to the factor modeling of the US employment and study the structural change problem using monthly industry-level data.

Development of frontal boundaries during the extratropical transition of tropical cyclones

AbstractThis study seeks to characterize the development of atmospheric fronts during the extratropical transition (ET) of tropical cyclones (TCs) as a function of their evolution during ET. Composite histograms indicate that the magnitude of the lower atmospheric frontogenesis and average sea‐surface temperature is different based on the nature of the TC's structural change during ET. We find that the development of cold and warm fronts evolves as expected from conceptual models of extratropical cyclones. Composites of these fronts relative to the completion of ET show that azimuth, storm motion, and deep‐layer shear all appear to have equal influence on the frontal positions. TCs that have more fronts at the time of ET onset complete ET more quickly, suggesting that pre‐existing fronts before ET begins may contribute to a shorter ET duration. The orientations of fronts at ET completion in the North Atlantic and west Pacific align with the climatological distributions of the sea‐surface temperatures associated with the western boundary currents in each of those basins. These results provide a perspective on the locations of frontal development within TCs undergoing ET.

“Seven Weeks Is Not a Lot of Time”: Temporal Work and Institutional Change in Australian Football

Recognizing the importance of timing in efforts to drive institutional change, this study examined how actors engage in “temporal institutional work” in their attempts to disrupt inequitable institutions in sport. A qualitative case study was conducted on football (soccer) in Australia wherein significant gender equity reforms have been enacted. The findings revealed how the temporal activities of entraining (e.g., capitalizing on external interventions), constructing urgency (e.g., through advocacy), and enacting momentum (e.g., through consensus-based leadership) allowed actors to exploit a time-sensitive window of opportunity for change, quickly foster a perception of irreversibility that structural change would occur, and generate synchronicity with broader reforms. Inspired by the breakthroughs in Australian football, this research highlights temporal-based strategies for combating gender inequity in sport. Theoretically, this study extends research on institutional work in sport by illuminating the key role that timing norms play during institutional change.

In vitro effect of Er: YAG laser irradiation in caries cavity preparation on biobehaviors of adjacent human dental pulp cells in the pulp chamber.

The erbium-doped yttrium aluminum garnet (Er: YAG) laser has been successfully applied in caries removal; however, little is known about proper parameters of Er: YAG laser on different conditions of caries removal, especially the influence of Er: YAG irradiation on human dental pulp cells (hDPCs). Here, we tested the effects of Er: YAG laser at different output energy levels (100, 200, 300, 400, and 500 mJ) on biobehaviors of hDPCs. To simulate clinical deep caries conditions, hDPCs were cultured on the pulpal side of 500-μm-thick dentin disks in an in vitro pulp chamber model. Temperature change, structural change, and ablation depth of dentin disk were also recorded. The findings suggested that the biological behaviors of hDPCs are strongly correlated with the energy output of the Er: YAG laser. Er: YAG laser irradiation at 100 mJ may be proper and safe for deep caries removal since it would not cause any adverse effect on hDPCs biobehaviors.

Where to Save Matters: Impact of Aging-induced Saving on Structural Change and Growth

Where to Save Matters: Impact of Aging-induced Saving on Structural Change and Growth

Electronic band structure change with structural transition of buckled Au2X monolayers induced by strain.

This study investigates the strain-induced structural transitions of η ↔ θ and the changes in electronic band structures of Au2X (X = S, Se, Te, Si, Ge) and Au4SSe. We focus on Au2S monolayers, which can form multiple meta-stable monolayers theoretically, including η-Au2S, a buckled penta-monolayer composed of a square Au lattice and S adatoms. The θ-Au2S is regarded as a distorted structure of η-Au2S. Based on density functional theory (DFT) calculations using a generalized gradient approximation, the conduction and the valence bands of θ-Au2S intersect at the Γ point, leading to linear dispersion, whereas η-Au2S has a band gap of 1.02 eV. The conduction band minimum depends on the specific Au-Au bond distance, while the valence band maximum depends on both Au-S and Au-Au interactions. The band gap undergoes significant changes during the η ↔ θ phase transition of Au2S induced by applying tensile or compressive in-plane biaxial strain to the lattice. Moreover, substituting S atoms with other elements alters the electronic band structures, resulting in a variety of physical properties without disrupting the fundamental Au lattice network. Therefore, the family of Au2X monolayers holds potential as materials for atomic scale network devices.

Modeling methamphetamine use disorder in mammals: Sex differences in behavioral, biochemical, and transcriptional consequences.

Methamphetamine (METH) is the most commonly misused amphetamine-type stimulant throughout the globe. METH is very rewarding, and its misuse can lead to a diagnosis of METH use disorder (MUD). Although METH use is observed in both sexes, there are, however, reported differences in the clinical manifestations of METH use and its consequences. These observations indicate the need for more research on the long-term sex-dependent consequences of METH taking in both preclinical and clinical settings. In effect, sex is a biological variable that can impact conclusions drawn from various basic and clinical studies. Thus, the present chapter provides a succinct review of the current state of the research on METH and its sex-associated consequences. In addition to behavioral and cognitive aspects of METH use, we discuss METH-induced changes in neurotransmitter systems and structures in the brain. Thus, the book chapter serves to highlight the significance of sex as a critical element that needs to be considered during discussions of novel therapeutic approaches to MUD.