Search

Abstract This paper revisits the relationships among the perceived built environment, travel attitude, perceived value, and consumer travel in the particular era of the changing retail landscape amid advances in information technology. This study thus uses consistent partial least squares structural equation modelling (PLSc-SEM) to estimate the focal parameters on the basis of data from 30 commercial centres in Shanghai, China. Additionally, this inquiry uses multigroup analysis structural equation modelling (MGA-SEM) to evaluate the disparities between two types of consumer travel: purchasing goods and experiencing services. The results show that consumers’ perceived values and travel attitude significantly influence their travel and that these effects are even more apparent for experience services. In addition, the perceived built environment plays a partially positive role in consumer travel. Notably, however, accessibility cannot directly influence consumer travel and only indirectly influences travel attitude, whereas commercial attractiveness positively influences both of these factors. Accordingly, this study offers valuable insights, enabling urban planning, transportation, and commercial services to better address the evolving retail landscape and emerging consumer travel demands.

Abstract Airborne contaminants produced during the laser cutting processes are hazardous substances produced as byproducts during laser cutting or engraving operations. These contaminants include respirable particulates, volatile organic compounds (VOCs), and other toxic substances that pose health risks to humans. As desktop laser cutting/engraving technology gains popularity, addressing the potential health hazards associated with airborne contaminants is critical. This study aimed to evaluate the concentrations of respirable particles, sub-half-micron particles, VOCs, and carbon monoxide (CO) that are emitted during laser cutting or engraving processes. The experimental matrix consisted of four materials (cardboard, wood, plastic, and glass) and three currents (10 amp, 15 amp, 20 amp), while also assessing the efficiency of exhaust ventilation. The results showed that the interaction of materials, currents, and ventilation significantly influenced emission concentrations of respirable particulate matter. Cardboard consistently exhibited the highest concentration of respirable particulate matter of 253.9 ± 47.6 mg m–3 and an average emission rate of sub-half-micron particles of 5.8 × 1010 # min–1, characterized by the smallest geometric mean diameter of 53 nm in the absence of ventilation. The extremely high emission highlighted the potential of ultrafine particle exposures and health risks from cutting cardboard. Conversely, glass demonstrated excellent resilience to thermal cutting, resulting in lower particle emissions. Wood and plastic materials showed intermediate levels of respirable and ultrafine particle production compared to cardboard and glass. Materials with higher carbon content, such as wood and cardboard, generated higher levels of VOCs and CO, compared to plastic (high VOC but no CO emissions) and glass (no VOC nor CO emission). Additionally, implementing ventilation control during laser cutting or engraving processes is highly recommended, as it effectively reduces the emissions of respirable particles and completely removes gaseous contaminants.

The exacerbation of wildfires caused by global warming poses a significant threat to human health and environmental integrity. This review examines the particulate matter (PM) and gaseous pollutants resulting from fire incidents and their impacts on individual health, with a specific focus on the occupational hazards faced by firefighters. Of particular concern is the release of carbon-containing gases and fine particulate matter (PM2.5) from forest fires and urban conflagrations, which exceed the recommended limits and pose severe health risks. Firefighters exposed to these pollutants demonstrate an elevated risk of developing pulmonary and cardiovascular diseases and cancer compared to the general population, indicating an urgent need for enhanced protective measures and health management strategies for firefighters. Through a meticulous analysis of the current research findings, this review delineates future research directions, focusing on the composition and properties of these pollutants, the impacts of fire-emitted pollutants on human health, and the development of novel protective technologies.

Urban vitality is the comprehensive characterization of the activities and processes in the city, which is influenced not only by environmental factors but also by the vitality of surrounding areas. Thus, the spatial effect of urban vitality can be understood under the constraint of the built environment. Taking Xiamen Island as a case, multisource big data are used to measure urban vitality, development intensity, and functional diversity. Spatial weight matrices with different distances are constructed. Through the spatial autoregressive threshold model, the threshold values of development intensity and functional diversity are estimated, and the spatial nonlinear effects of urban vitality based on different spatial weight matrices are analyzed. Results show that: (1) There is a significant spatial spillover effect of urban vitality. The spatial spillover effect is influenced by the built environment conditions and shows the characteristics of nonlinear growth with the change in development intensity and functional diversity; (2) the spatial spillover effect of urban vitality is significantly enhanced with the expansion of influence distance; (3) The development intensity has double thresholds. With the improvement of development intensity, the spatial spillover effect of urban vitality becomes stronger and more significant. The functional diversity has a significant single threshold value. The discussion of functional diversity should be carried out on the premise of density. The conclusion provides a theoretical basis for the optimization of urban vitality and built environment.

In the current field of regional studies, there is a growing focus on regional spatial relationships from the perspective of functional linkages between cities. Inter-city population movement serves as an embodiment of the integrated functionality of cities within a region, and this is closely tied to the socio-economic development of urban areas. This study utilized Location-Based Services (LBSs) to collect the scale of inter-city population movement across 355 cities in China. Additionally, socio-economic data published by local governments were incorporated. By establishing a Multiscale Geographically Weighted Regression (MGWR) model, this research explores the spatial relationships between inter-city population movement and socio-economic influencing factors in China. This study aims to elucidate the spatial scales of the relationships between various variables. Our research findings indicate that the relationship between inter-city population movement and potential socio-economic determinants exhibits spatial non-stationarity. It is better to explore this spatial relationship through the MGWR model as there are different determinants operating on inter-city population movement at different spatial scales. The spatial distribution of the coefficient estimates shows significant regional differences and numerical variations. In China’s economically developed coastal regions, there is relatively balanced development among cities, with advanced manufacturing and producer service industries acting as significant drivers of mobility. In inland regions of China, city size is the most influential variable, directing a substantial flow of human and economic resources towards regional socio-economic hubs such as provincial capitals. The main contribution of this study is the re-examination of the relationship between inter-city population movement and socio-economic factors from the perspective of spatial scales. This approach will help China to consider the heterogeneity of different regions more extensively when formulating regional development policies, thereby facilitating the targeted promotion of regional element flow.

Abstract The COVID-19 pandemic introduced considerable challenges for respiratory protection of different population groups. Disposable medical masks and NIOSH-approved N95 filtering facepiece respirators (FFRs) are typically their only defense against the virus. At the same time, continuous wearing of these devices, especially some N95 FFR models cause damage to the facial skin, such as skin irritation, swelling, and scaling. Skin protectants are becoming increasingly popular and effective in providing a protective barrier for the skin that reduces direct contact between a wearer’s face and respirator. Recent pilot studies involving human subjects have examined the effect of skin protectants on the performance of respirators/masks through fit testing, but their findings are heavily impacted by between-subject variability. This investigation deployed a standardized protocol that utilized the NIOSH advanced static manikin headform connected to a Breathing Recording and Simulation System (BRSS), producing a predetermined breathing pattern. The effect of skin protectants on the total inward leakage (TIL) was evaluated for three N95 FFR models, five different skin protectants, and two breathing flow rates. The aerosol particle concentrations inside and outside the respirator were measured with NaCl serving as the challenge aerosol. The TIL was shown to be significantly affected by the interaction of the skin protectant type, breathing flow rate and FFR models. The data suggest that different skin protectants may influence the performance of disposable N95 FFRs in different ways - by either increasing or decreasing the TIL value relative to one with no skin protectants applied. No negative effects on the TIL was observed for either tape- or gel/cream-type protectants when testing with 3M 8210 or 3M 1870+ FFRs; however, the use of skin protectants of either group with the AOSafety 1050 FFR may compromise its performance as quantified by the TIL.

PM2.5 (particulate matter with aerodynamic diameter ≤ 2.5 μm) is a well-known cytotoxic pollutant that capable to induce severe intracellular oxidative stress while the underlying mechanisms remain unclear. Herein, 4 types of PM2.5 derived from solid fuel burning were selected as stimuli in A549 cells exposure model to evaluate their effects on oxidative stress and inflammatory responses. Although resulting in different responses in cell viability, all PM2.5 exhibited over 50 % higher oxidative stress than control group, expression as intracellular reactive oxygen species, malondialdehyde and superoxide dismutase levels. The Pearson’s correlation results indicated that cations (e.g., Ca2+), heavy metals (e.g., Cr and Pb), nPAHs (nitro-polycyclic aromatic hydrocarbons, e.g., 6-nitrochrysene) and oPAHs (oxygenated PAHs, e.g., 9-fluorenone) were the main functioning toxics (r > 0.6). A key finding was the dual-directional regulation function of ECG (epicatechin gallate), that is, it could either increase the low A549 cell viabilities in coal combustion PM2.5 group or reduce them in charcoal PM2.5 group (P

Changes in temperature during reactor operation may cause changes in physical parameters, leading to core overheating and accidents. It is essential to analyze and assess the safety parameters of the core under different operating conditions. This paper investigates the effects of fuel temperature, moderator density, boron concentration, and control rod state on AP1000 safety parameters. The study uses RMC and NJOY to calculate the changes in reactivity factor, effective delayed neutron fraction, and neutron generation time of the AP1000 reactor under different operating conditions. The changes in reactivity coefficients, neutron fluxes, and relative power densities of AP1000 reactors are analyzed for normal and accidental operating conditions. The results indicated that the reactivity coefficient remained negative under accident conditions, which ensured the safe operation of the reactor. The delayed neutron fraction, neutron flux, and power density distributions are affected by fuel temperature, moderator density, and control rod position. The control rod worth was sufficient for the emergency shutdown of the reactor under accidental conditions. It is demonstrated that the operation of the AP1000 reactor under study conditions is safe and controllable.

Atmospheric PAHs (polycyclic aromatic hydrocarbons) and their derivatives are a global concern that influences environments and threatens human health. Concentrations of 52 PAHs and the main derivatives in six Chinese megacities were measured in the winter of 2019. The concentrations of ∑PAHs (sum of 52 PAHs) ranged from 19.42 ± 7.68 to 65.40 ± 29.84 ng m−3, with significantly higher levels in northern cities (Harbin [HB], Beijing [BJ], and Xi’an [XA]) than southern ones (Wuhan [WH], Chengdu [CD] and Guangzhou [GZ]). Source apportionment of ∑PAHs was conducted by the PMF model and results showed coal combustion and traffic emissions were the two dominant sources, which dominated ∑PAHs in northern and southern cities, respectively. Biomass burning was also characterized as a crucial source of ∑PAHs and showed extremely high contributions in XA (42.5%). Assisted by the individual PAH source apportionment results, the source-depend TEQ (total BaP equivalent) and incremental lifetime cancer risk (ILCR) were firstly reported in these cities. The results highlighted the contributions of coal combustion and biomass burning to both TEQ and ILCR, which were underestimated by ∑PAHs source apportionment. Secondary organic aerosol-derived PAHs were demonstrated to increase the TEQ compared with the fresh PAHs and three parameters, namely temperature, relative humidity, and O3 concentrations were characterized by multiple linear regression as the principal factors influencing secondary reactions of PAHs in winter. This study provides accurate human health-orientated results and potential control measures to mitigate the toxicity of secondary formed PAHs, and significantly decrease the uncertainty level of traditional methods. The results also revealed great progress in air pollution control by the Chinese government in the past 20 years, but still a long way to go to formulate strict emission control strategies from both environmental and human health-protective perspectives.

Abstract Monoterpene is a biogenic volatile organic compound commonly found in cleaning products and air fresheners. It can react rapidly with indoor oxidants, such as ozone (O3), to produce secondary organic aerosols (SOAs) in indoor environments, and the reactions are potentially influenced by ammonia (NH3). This study simulated the reactions of O3 and monoterpene with and without the presence of NH3 in an environmental chamber and investigated the surface characterization (elemental components and carbon states) of the PM2.5 generated by these reactions. We found that the generated particles possessed a higher content of nitrogen-containing organic compounds when NH3 was present. Unsubstituted aromatic carbon and aliphatic carbon were the main carbon structures, exhibited by over 60% of the carbon-containing compounds. Additionally, in the presence of NH3, more amide carbon and carboxylic carbon formed during the reactions. We also examined acute lung injury in mice caused by new particle formation under different reaction conditions. Oxidative stress was observed in the bronchoalveolar lavage fluid of the mice, as evidenced by a decrease in antioxidant enzymes (superoxide dismutase) and antioxidants (glutathione) as well as an increase in malondialdehyde. Moreover, the SOAs generated in the presence of NH3 lowered glutathione levels, indicating a rise in oxidative stress. Hence, fine particles formed by indoor oxidative reactions may trigger acute lung injury in humans, potentially causing further respiratory disease.

PM2.5 Road dust samples were collected from 10 representative cities in southern and northern China for examination of chemical components and oxidative stress levels in A549 cells. Downtown road dust was abundance of heavy metals, EC and PAHs compared to nondowntown road dust. Source apportionment also revealed the relative higher contribution of vehicle emission to downtown (35.8%) than nondowntown road dust (25.5%). Consequently, downtown road dust induced much higher intracellular reactive oxidative species (ROS) levels than that from nondowntown (p

Workers may be at risk of exposure to airborne contaminants, including hexavalent chromium (Cr-(VI)) and particles of diverse shapes and sizes during the laser cutting of leathers because of the extensive chemicals employed in leather tanning processes. Desktop carbon dioxide (CO2) laser engraving machines have gained popularity in various industries; however, airborne contaminant exposure in the laser cutting process of leathers remains unclear. This study investigated Cr-(VI) and particle emissions during laser cutting/engraving of leather treated with various tanning methods. Six tanning methods (chrome 1-, chrome 2-, vegetable 1-, vegetable 2-, oil-, and alum-tanned) were studied at three laser power settings (15, 45, and 75%). A personal air sampler coupled with a sampling cassette and ISO 17075-2 evaluation were used to sample and analyze airborne Cr-(VI) concentrations, respectively. Two real-time aerosol monitors were utilized to assess particulate concentrations and size distributions from 10 nm to 10 μm. High concentrations of Cr-(VI) were detected in chrome-tanned leathers when the ventilation system was off, indicating the critical role of ventilation. The particle number concentrations were statistically significantly affected by various leather tanning methods and laser powers. Chrome 1-tanned leather exhibited the highest concentration of nanoparticles (<420 nm) at low (14,733 #/cm³) and medium (20,725 #/cm³) laser powers, while veg 2-tanned leather produced the highest micrometer-sized particle (>0.3 μm) concentration, over 1,600 #/cm³ at all laser powers. The medium laser power exhibited higher nanoparticles than other powers when laser cutting most tanned leathers. The higher power resulted in the generation of smaller-sized particles for chrome-, oil-, and alum-tanned leathers. These findings underscore the importance of adequate ventilation and controlled laser power settings in minimizing health risks during the leather laser cutting processes. [ABSTRACT FROM AUTHOR]

Background: The health effects of heavy solid fuel use in winter in rural China are of concern. The effects of air pollution resulting from domestic solid fuel combustion in rural households on rural homemakers’ biomarkers were revealed in this study. Methods: In total, 75 female homemakers from rural areas of Guanzhong Basin, the Fenwei Plain, People’s Republic of China, were randomly selected and divided into three groups (biomass users, coal users, and nonusers of solid fuel user [control group]). The differences in biological indicators, including 8-hydrox-2′-deoxyguanosine (8-OHdG), interlukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in urine samples as well as blood pressure (BP, including systolic BP [SBP] and diastolic BP [DBP]) and heart rate (HR) among the groups in winter and summer were investigated using statistical analysis. Results: IL-6, 8-OHdG, HR, SBP, and DBP were significantly higher in winter than in summer (P

Abnormal proliferation, migration and foaming of vascular smooth muscle cells (VSMCs) are involved in atherosclerosis (AS) process. Imperatorin (IMP) is a coumarin compound mainly originated from angelica dahurica in natural plants. In this study, effects of IMP on proliferation, migration and foaming of oxidized low-density lipoprotein (ox-LDL)-induced VSMCs were investigated. The results showed that IMP regulated cell cycle in S ~ G2/M phase and down-regulated the proliferating cell nuclear antigen (PCNA), and then exerted anti-proliferation effect. IMP might have a repressive effect on migration in ox-LDL-stimulated VSMCs through inhibiting the metalloproteinase-2 (MMP-2). Oil red O staining showed IMP suppressed lipid accumulation in ox-LDL-induced-VSMCs. This was consistent with the determination of Lectin-like oxidation of lectin-like ox-LDL receptor-1 (LOX-1) and total cholesterol (TC). IMP also reduced the expression of p-PI3K, p-Akt and p-mTOR in ox-LDL-treated VSMCs. These results suggested that IMP might play an anti-lesion role in ox-LDL-stimulated-VSMCs by inhibiting the PI3K/Akt/mTOR pathway.

Solid (biomass and coal) fuels burned for residential heating are major sources of atmospheric volatile organic compounds (VOCs). In this study, VOC samples were collected in-situ from chimneys in 10 typical heating scenarios in rural areas of the Guanzhong Plain. A modified SUMA canister approach was then employed, followed by gas chromatography/mass spectrometry analysis. Emission factors (EFs) (as received basis) of targeted non-methane VOCs (NMVOCs) varied from 90.3 ± 29.3 to 12300 ± 1510 mg kg−1 in descending order of fuel wood > maize straw > bitumite ≫ anthracite (p 95%) were contributed by aromatics. A semi-gasifier and coal briquettes were effective in reducing TVOC emissions, even when used in conjunction with a traditional stove and fuels. It is estimated that over 15,000 ton year−1 emissions can be reduced in Guanzhong Plain by adopting a semi-gasifier and coal briquettes, resulting in a 57,000 and 65,000 ton year−1 reduction of OFP and SOAP emissions, respectively. These results demonstrate that the use of clean heating technologies in Guanzhong Plain has considerable potential in relation to emissions reduction and thus provides a feasible solution to mitigate VOCs and related secondary pollutants emitted by residential solid fuel burning. Keywords: Solid fuel, VOCs, Clean heating technology, Ozone formation potential, Secondary organic aerosol formation potential

The outbreak of the 2019 novel coronavirus (COVID-19) has attracted global attention. During the Chinese New Year holiday, population outflow from Wuhan induced the spread of the epidemic to other cities in China. This study analyzed massive intercity movement data from Baidu and epidemic data to study how intercity population outflows affected the spatiotemporal spread of the epidemic. This study further investigated how urban factors influenced the spatiotemporal spread of COVID-19. The analysis indicates that intercity movement was an important factor in the spread of the epidemic in China, and the impact of intercity movement on the spread was heterogeneous across different classes of cities. The spread of the epidemic also varied among cities and was affected by urban factors including the total population, population density, and gross domestic product (GDP). The findings have implications for public health management. Mega-cities should consider tougher measures to contain the spread of the epidemic compared with other cities. It is of great significance for policymakers in any nation to assess the potential risk of epidemics and make cautious plans ahead of time.

Secondary organic carbon (SOC) formation and its effects on human health require better understanding in Chinese megacities characterized by a severe particulate pollution and robust economic reform. This study investigated organic carbon (OC) and elemental carbon (EC) in PM2.5 and PM0.25 collected 8–20 March 2012. Samples were collected inside and outside a classroom in a middle school at Xi’an. On average, OC and EC accounted for 20%–30% of the particulate matter (PM) mass concentration. By applying the EC-tracer method, SOC’s contribution to OC in both PM size fractions was demonstrated. The observed changes in SOC:OC ratios can be attributed to variations in the primary production processes, the photochemical reactions, the intensity of free radicals, and the meteorological conditions. Total carbon (TC) source apportionment by formula derivation showed that coal combustion, motor vehicle exhaust, and secondary formation were the major sources of carbonaceous aerosol. Coal combustion appeared to be the largest contributor to TC (50%), followed by motor vehicle exhaust (25%) and SOC (18%) in both size fractions.

Copyright of Nuclear Technology & Radiation Protection is the property of Vinca Institute of Nuclear Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)