Wall Area Research Articles

Denticles: dental pulp calculi

Denticles (pulp stones) are round to oval hard substance formations of various sizes that occur in the dental pulp or in the area of the pulpal dentin wall. They can occur free, without connection to the pulp wall (free denticles), fused to the pulp wall (adherent denticles) or embedded in the pulp wall (interstitial denticles).

Numerical simulation of autoclaved aerated concrete masonry wall subjected to close-in explosion and the structural damage assessment

In this study, we investigated the destructive effect of autoclaved aerated concrete (AAC) masonry walls subjected to close-in explosions. First, full-size refined finite-element models of the AAC masonry wall were established, and the accuracy of the models was verified by comparison with the test results. The destruction pattern and damage characteristics of the AAC wall were studied, and the effects of block size, wall thickness, mortar compressive strength, and explosion distance on the destruction degree of the AAC masonry walls were analyzed. The results showed that the destruction pattern of the AAC masonry wall subjected to close-in explosion manifested as punching damage in the middle of the wall. When the scaled distance remained unchanged, the punching damage area of the AAC masonry wall was positively correlated with the block size and negatively correlated with the wall thickness and mortar compressive strength. When the explosive equivalent remained unchanged and the explosion distance increased, the punching damage area first increased and then decreased. According to the damage mechanism of the AAC masonry wall, a calculation method for predicting the punching damage area of the AAC masonry wall was established, and the accuracy of this method was verified by comparing it with the numerical results. In addition, the damage criterion based on the punching damage area was established to determine the destruction levels of AAC masonry walls.

Analyzing the effectiveness of building integrated Photovoltaics (BIPV) to reduce the energy consumption in Dubai

In Dubai, 38.9 % of the total energy consumption is related to buildings, and the high-rise building sector is key to energy efficiency. BIPV (Building Integrated Photovoltaic) can be a very efficient alternative in Dubai because of building load reduction and power generation. This paper aims to investigate energy efficiency according to the number of floors with BIPV application. As a methodology, an analysis model for office use was used with the curtain wall with a floor height of 3.6 m, floor area of 400 m2, and a window area ratio to wall area ratio of 80 %. Energy Plus Version 9.0 and TRNSYS were used as evaluation tools. The physical properties of windows and doors in the analysis model were assumed to be low-E double-glazed glass with a Solar Radiation Gain Coefficient (SHGC) of 0.564, a visible light transmittance of 47.2 %, and a thermal transmittance of 1.760 W/m2K. The result showed that when the alternatives of the window replacement type, exterior wall finishing type, and hybrid type BIPV system are applied, heating and cooling energy consumption is reduced by 13.2 % to 32.8 %. It was proven that applying BIPV was effective in high-rise office buildings. It is practical to replace windows and apply light-transmitting amorphous thin film Photovoltaic (PV) double-layered, double-layered Low-E, or triple Low-E windows, replace exterior wall finishing materials with crystalline PV, or use a mixture of both. The simulation results show that applying a roof-top BAPV (Building-Applied Photovoltaic) system is only practical for low-rise buildings.

Study on the Wind-induced Interference Effect of a Large-span Roof Structure Building Group

The wind-induced interference effects existing during the construction of a building group were studied in the context of the Zhangjiakou Olympic Sports Center project. Based on CFD numerical simulations, 120 and 96 different working conditions during construction of a swimming pool and speed skating hall were simulated and analyzed respectively, and the numerical simulation results were found to be in high agreement with the wind tunnel test results, which verified the accuracy and feasibility of the numerical simulation. By comparing the wind-induced interference effects of the surrounding buildings on the swimming pool and the speed skating hall during different construction periods, it was found that the swimming pool was more affected by the interference of the surrounding buildings than the speed skating hall, and the wall area was more affected by the interference than the roof area. The wind-induced response of the swimming pool structure during different construction periods was analyzed, and it was found that the interference effect under some working conditions had a greater impact on the structural stress, and it was suggested that the wind interference effect brought about by the construction of the building should not be ignored in such projects.

Enhancement of Radiative Power Using a Divergent Splitter Plate Design in H2–Air Non-Premixed Micro-Combustor

Abstract Micro-combustion based power generation devices can be considered as future alternatives to batteries in miniature electronic devices. Micro-combustors operating in non-premixed mode are free from flashback but face the challenge of properly mixing fuel and air within a small volume. In this work, the effect of a divergent fuel–air splitter design on the mixing performance and combustion characteristics of H2–air fueled diffusion micro-combustor is studied. The laminar reacting flow is simulated using the finite volume method and a detailed hydrogen kinetic mechanism. Three divergent splitter designs are compared with the commonly used rectangular splitter to study the effect on radiation power, an essential parameter for thermophotovoltaic power generation. The best-performing divergent and base rectangular splitter designs are investigated in detail. The study shows that the micro-combustor with divergent splitter design reduces mixing distance (Lmix) by 5–23% depending on inlet velocity and channel height. With the divergent splitter, the peak value of the heat release rate also increases slightly, implying enhanced combustion. The divergent splitter increases the high-temperature surface area of the outer wall as compared to the rectangular splitter. This leads to the micro-combustor with divergent splitter producing significantly higher radiation power (>10%) than the rectangular splitter for larger channel heights and higher inlet velocities.

ANALYSIS OF MAN-HOUR REQUIREMENTS AND SCHEDULING FOR FLOATING DOCK REPAIRS

A floating dock (FD) is a platform for ship construction and repair. Structural damages to a FD can significantly reduce ship docking productivity, leading to substantial losses for shipyard companies. In order to restore its operational capabilities, repairing the damaged FD becomes essential. This research aims to plan and analyze the schedule to ensure the efficiency and effectiveness of FD repair activities. The process begins with the establishment of a Work Breakdown Structure (WBS), followed by determining the required man hours (MH) and scheduling using the Precedence Diagram Method (PDM). Finally, the S-curve is made for monitoring the progress of the FD repairment. The findings of this study, based on a case study involving a 6700 TLC FD, reveal a WBS comprising 66 repair tasks including two tasks for FD testing and finishing in addition to four areas of hull, walls, deck and tanks, piping systems, and machinery. The MH requirement for these tasks is 4048 MH. From the scheduling results, it was found that the duration was 12 days, with a total of 53 critical activities and 25 critical paths in the floating dock repair work using the precedence diagram method.

Abstract WP116: Plaque Features and Infarct Pattern in Ischemic Stroke With Bilateral Carotid Artery Atherosclerosis

Objective: to compare the carotid artery plaque characteristics between ipsilateral and contralateral infarct in ischemic stroke with bilateral carotid artery atherosclerosis, and explore the association between plaque characteristics and infarct pattern. Methods: a total of 186 ischemic stroke patients with bilateral carotid artery atherosclerosis were included, carotid artery plaque burden (the degree of stenosis, maximum wall thickness, lumen area, wall area, normalized wall index (NWI=wall area/[lumen area+ wall area]), and eccentricity index), and vulnerability (intraplaque hemorrhage [IPH], calcification, irregular surface, thin or ruptured fibrous cap[TRFC], and lipid-rich necrotic core[LRNC]) were obtained by MR vessel wall imaging, infarct pattern was divided as single and multiple/recurrent infarcts in infarct ipsilateral carotid artery. Ipsilateral and contralateral carotid artery plaque features were compared, then the carotid artery plaque characteristics on the infarct side were correlated with the infarct pattern. Results: the mean age of subjects included was 68 years old, 79.6% of them were male. Compared with contralateral carotid artery plaque, plaque burden at the ipsilateral carotid artery was much heavy, presented with a higher degree of stenosis, smaller lumen area (0.22±0.15 vs. 0.28±0.15), larger wall area (0.50±0.19 vs.0.42±0.17), and higher eccentricity index (0.67±0.13 vs. 0.58±0.23), all p values<0.05. The vulnerable plaques were also more prevalent at ipsilateral infarct, with a high percentage of IPH (47.8% vs. 19.8%), irregular surface (36.3% vs. 17.5%), TRFC (38.5% vs.12.3%), and LRNC (38.1% vs. 15.9%), all p values were <0.05. After adjusting for covariates, the degree of stenosis (OR=1.590, 95% CI 1.048-2.410) and LRNC (OR=0.259, 95% CI 0.087-0.769) were associated with multiple or recurrent infarcts independently. Conclusion: in ischemic stroke with bilateral carotid atherosclerosis, the atherosclerotic plaque burden at ipsilateral infarct was much heavier and more vulnerable. Both lumen stenosis and plaque components were correlated with multiple or recurrent infarcts in this population.

Research on cavitation characteristics of water-jet pumps with different blade tip clearances based on entropy production theory

Water-jet pumps are widely used in ship and other power fields. An axial-flow water-jet pump is studied with different size of tip clearance, and the cavitation characteristics are studied based on the theory of entropy production. Modified SST with curvature correction and modified Zwart cavitation model based on vortex identification are adopted, and the numerical calculation method is verified by reference experiments of a model pump. Under normal operating conditions, the results show that when the size of the tip clearance varies from 1.6‰ to 7.9‰ of the impeller diameter, efficiency takes a linear decrease accordingly, and the total entropy production increases linearly. At the same time, the main energy dissipation mode changes from wall dissipation to turbulent dissipation. Under severe cavitation conditions the total entropy production adds 30%. The water-jet pump shows that the entropy production in the impeller section is the highest, which accounts for 40%-50% and is closely related to the vortex and cavitation flow field in the tip clearance of the impeller. The tip leakage vortex region causes cavitation, but significant energy dissipation occurs at the outer edge of leakage vortex and on the nearby wall area, while the attached cavitation on the blade surface is the main source of turbulent dissipation.

Mechanical advantage of subsidiary cells depends on the stomatal complex structure

Structural features of stomatal complexes influencing the mechanical advantage of subsidiary cells were studied. Light, scanning and transmission electron microscopy were used to research the morphology of Fagraea ceilanica stomatal complexes. Their guard cells are located on subsidiary cells. The walls of the subsidiary cells are thickened unevenly. The inner tangential walls are thin and most extensive as compared to other walls of these cells. The data obtained allowed a 3D model of F. ceilanica stomatal complex to be constructed. To elucidate the interaction between the guard and subsidiary cells during stomatal movements, we have applied modelling using the finite-element method. According to the modelling results, the mechanical advantage of the subsidiary cells depends on mutual location of the guard and subsidiary cells, uneven thickening, area and rigidity of the subsidiary cell walls and presence of substomatal chambers, into which the inner tangential walls of the subsidiary cells can bulge when turgor pressure in these cells increases. The modelling results were confirmed by the observed deformations in actual stomatal complex cells of F. ceilanica. The decrease in mechanical advantage of the subsidiary cells ensures stoma opening in the conditions of excessive saturation of the epidermis with water, for example, in the conditions of tropical rainforests.

Synergistic Effects of Heating Platens’ Temperature and Compression Ratio on the Periodic Hot-Press Drying of Chinese Fir Lumber

The effects of periodic hot-press drying on drying behavior and mechanical damage to Chinese fir lumber were investigated by taking the heating platens’ temperature (TP) and compression ratio (Rc) as experimental factors. The temperature and pressure inside lumber were analyzed during drying process. The results were as follows. The drying rate of lumber was significantly increased with increasing TP and Rc. Scanning electron microscope (SEM) micrographs showed that bordered pit membranes, cross-field pits, middle lamella between adjacent cells, and tracheid walls were damaged after drying, and the damage became more severe with higher TP and Rc. Detachments between ray parenchyma cells and tracheids were observed at 170 °C. Nitrogen-adsorption measurement results demonstrated that more cell wall pores in the 2.5~6.2 nm pore diameter range were generated at higher TP, resulting in an enlarged specific surface area and pore volume of cell walls. These structural changes contributed to accelerating moisture migration and decreasing the drying time. Furthermore, fluctuating pressure inside lumber was the main driving force leading to moisture migration and cell tissue damage in lumber during drying. The influence of TP on internal temperature (TM) and pressure (PM) was greater than Rc. With the increase in TP from 130 to 170 °C at the Rc of 10%, the maximum TM and PM were increased by 30.90% and 39.84%, respectively. However, TP should not be too high to prevent the formation of macro-cracks caused by high pressure, which may significantly affect wood’s mechanical properties. These results provide theoretical support for periodic hot-press drying processes’ improvement and high-value utilization of Chinese fir.

Effect of silver diamine fluoride on the microleakage of flowable resin composite and glass ionomer cement restorations to carious primary dentin: an-in vitro study

BackgroundThis study aimed to evaluate the effect of Silver Diamine Fluoride (SDF) on the microleakage of flowable resin composite (FRC) and resin-modified glass ionomer cement (GIC) restorations bound to carious primary dentin.MethodsForty-four extracted carious primary molars were allocated into four groups as follows (n = 11 teeth/group): Group I, Flowable resin composite (FRCa): SDF38% treatment + FRC, Group II, Flowable resin composite (FRCb): FRC without SDF treatment, Group III, Resin-modified glass ionomer cement (GICa): SDF38% treatment + GIC, Group IV, Resin-modified glass ionomer cement (GICb): GIC without SDF treatment. Specimens were subjected to thermo cycling at 500 cycles between 5 to 55 °C (dwell time of 60 seconds) in baths before being immersed for 24 h in a 1% toluidine blue solution. Microleakage testing was conducted for each specimen in two areas; occlusal and gingival. Specimens were evaluated under stereomicroscope at 4x magnification. Results were analyzed using Kruskal-Wallis test followed by pairwise comparisons utilizing Dunn’s post hoc test at p ≤ 0.05.ResultsInsignificant differences between different groups (p = 0.49) were observed at the gingival walls area readings. The highest value was found in GICb (2.33 ± 0.52), while the lowest value was found in FRCa (1.71 ± 0.76). Insignificant differences between different groups (p = 0.982) were observed at the occlusal walls area readings. The highest value was found in FRCa (1.43 ± 0.98), while the lowest value was found in GICb (1.17 ± 1.33).ConclusionSDF does not adversely affect the microleakage of FRC and GIC restorations bound to carious primary dentin.

Is Primary Open-Angle Glaucoma a Vascular Disease? Assessment of the Relationship between Retinal Arteriolar Morphology and Glaucoma Severity Using Adaptive Optics.

Retinal vascular abnormalities may be associated with glaucomatous damage. Adaptive optics (AO) is a new technology that enables the analysis of retinal vasculature at the cellular level in vivo. The purpose of this study was to evaluate retinal arteriolar parameters using the rtx1 adaptive optics fundus camera (AO-FC) in patients with primary open-angle glaucoma (POAG) at different stages and to investigate the relationship between these parameters and changes in spectral-domain optical coherence tomography (SD-OCT) and perimetry. Parameters of the retinal supratemporal and infratemporal arterioles (wall thickness (WT), lumen diameter (LD), total diameter (TD), wall-to-lumen ratio (WLR), and cross-sectional area of the vascular wall (WCSA)) were analysed with the rtx1 in 111 POAG eyes, which were divided into three groups according to the severity of the disease, and 70 healthy eyes. The associations between RTX1 values and the cup-to-disk ratio, SD-OCT parameters, and visual field parameters were assessed. Compared with the control group, the POAG groups showed significantly smaller TD and LD values (p < 0.05) and significantly higher WLR and WT values (p < 0.05) for the supratemporal and infratemporal arterioles. TD was significantly positively correlated with the retinal nerve fibre layer (RNFL) and ganglion cell complex (GCC) (p < 0.05). LD was significantly positively correlated with the RNFL, GCC, and rim area (p < 0.05). The WLR was significantly negatively correlated with the RNFL, GCC, rim area, and MD (p < 0.05), while it was significantly positively correlated with the cup-to-disc ratio and PSD (p < 0.05). The results suggest that vascular dysfunction is present in POAG, even at a very early stage of glaucoma, and increases with the severity of the disease.

Computational Fluid Dynamics and Its Potential Applications for the ENT Clinician.

This article is an examination of computational fluid dynamics in the field of otolaryngology, specifically rhinology. The historical development and subsequent application of computational fluid dynamics continues to enhance our understanding of various sinonasal conditions and surgical planning in the field today. This article aims to provide a description of computational fluid dynamics, the methods for its application, and the clinical relevance of its results. Consideration of recent research and data in computational fluid dynamics demonstrates its use in nonhistological disease pathology exploration, accompanied by a large potential for surgical guidance applications. Additionally, this article defines in lay terms the variables analyzed in the computational fluid dynamic process, including velocity, wall shear stress, area, resistance, and heat flux.

Quantitative evaluation of the damage to RC buildings caused by the 2023 southeast Turkey earthquake sequence

Data from 15 earthquakes that occurred in 12 different countries are presented showing that, without better drift control, structures built with building codes allowing large seismic drifts are likely to keep leaving a wide wake of damage ranging from cracked partitions to building overturning. Following the earthquake sequence affecting southeast Turkey in 2023, a team led by Committee 133 of the American Concrete Institute surveyed nearly 250 reinforced concrete buildings in the area extending from Antakya to Malatya. Buildings ranging from 2 to 16 stories were surveyed to assess their damage and evaluate the robustness of their structures in relation to overall stiffness, as measured by the relative cross-sectional areas of structural walls and columns. The majority of the buildings were estimated to have been built in the past 10 years. Yet, the structures surveyed were observed to have amounts of structural walls and columns comparable with amounts reported after the Erzincan (1992), Duzce (1999), and Bingol (2003) Earthquakes in Turkey. These amounts are, on average, much smaller than the wall and column amounts used in Chile and Japan. Because of that lack of robustness and given the intensities of the motions reported from Antakya to Malatya (with 10 stations with peak ground velocity (PGV) of 100 cm/s or more), it is concluded that structures in this region experienced large drifts. Excessive drift (1) exposed a myriad of construction and detailing problems leading to severe structural damage and collapse, (2) induced overturning caused by p-delta for some buildings, and (3) caused widespread damage to brittle masonry partitions. The main lesson is simple: ductility is necessary but not sufficient. It is urgent that seismic drift limits are tightened in high-seismicity regions worldwide.

Prediction of energy performance of residential buildings using regularised neural models

Human habitats are one of the major consumers of energy. Therefore, in the current age of increasing carbon dioxide footprints, analysing energy efficiency of a building is important and is the subject of the current study. Machine-learning-based artificial neural network (ANN) approaches are used in the current study to investigate building energy performance. Eight parameters – relative compactness, surface area, wall area, roof area, overall height and orientation of the building, as well as the glazing area and its distribution – are selected as the input parameters and heating and cooling loads (CLs) as the output parameters. The network prediction capability was checked by comparing the predictions of the ANN architecture with the benchmark test case. A well-trained and validated ANN is used to predict 96 conditions by varying glazing area and glazing area distribution. The ANN is found to capture the physics efficiently. This study revealed that there is a significant potential to improve the energy efficiency of a building and the maximum saving in the CL can be as high as 20.67% for a fraction of the glazing areas equal to 0.15 if the glazing area distribution is 32.5% in the north and 22.5% each in the east, south and west.

Energy Performance Analysis and Study of an Office Building in an Extremely Hot and Cold Region

China is committed to reaching peak carbon by 2030 and carbon neutrality by 2060. The goals of reducing energy consumption and building a “beautiful China” are being urgently pursued in China. The building studied in this paper is located in the city of Turpan, where the problem of excessive energy use among buildings is significant due to the region’s hot summers and cold winters. Additionally, the fact that the office building studied in this paper has an east–west orientation is significant: the building’s main façade is oriented to the west, comprising a large area of single-layer glass curtain wall. Based on this, this paper proposes optimization strategies from two perspectives of renovation and new construction. Four design options are proposed at the retrofit level: glazed circular curtain wall; glazed enclosed curtain wall; west-facing double-glazed curtain wall circulation combined with south-facing light from the east; recycling of windows on the inside of the exterior glass curtain wall. These suggestions focus on retrofitting the glass curtain wall on the west elevation of the building. Two design options are proposed at the new-build level: west-facing south-oriented light and west-facing north-oriented light. These suggestions were primarily built around the idea of changing the orientation of the windows on the west elevation. The results show that the optimal solution is to implement the west-facing double-glazed curtain wall circulation combined with south-facing light from the east. This program shows a 64.14% reduction in heating energy consumption, a 77.12% reduction in cooling energy consumption, and a 69.67% reduction in total energy consumption. The above research has improved the deficiencies in the performance-based energy efficiency retrofit of office buildings in the region and provided new ideas and suggestions for policymakers and designers to build energy-efficiency retrofits in the early stages.

Glucuronidase Gene

Gluconacetobacter diazotrophicus lives inside plant tissue cells in the form of colonies and excretes about half of the fixed nitrogen, which offers potential power that improves plant growth. The aim of this study is to find the interaction of glucuronidase (GUS)-labeled G. diazotrophicus with spinach seedlings and the detection of GUS genes using X-gluc dye (5-bromo-4-chloro-3-indolyl-β-D- glucuronic acid). The GUS protocol is used to detect GUS-labeled G. diazotrophicus in spinach seedling tissues by chemical detection using X-gluc dye. The results show that the spinach seedlings are successfully infected with GUS-labeled G. diazotrophicus , with the survival of the seedlings throughout their growth period and an improvement in the growth of pollinated seedlings. The outcomes of the microscopic inspection of the root slices reveal the presence of bacterial cells at the root tips and their concentration in the area of the cell walls of the peripheral cells. Furthermore, the findings of microscopic examinations of longitudinal sections for cotyledons show the presence of a number of bacteria within epidermal cell walls. This indicates that the determinants of the interaction between these bacteria and spinach seedlings are suitable for the expression of the gene responsible for the formation of the nitrogenase enzyme.

Long-term efficacy of house dust mite sublingual immunotherapy on clinical and pulmonary function in patients with asthma and allergic rhinitis

BackgroundA previous study reported that house dust mite (HDM) sublingual immunotherapy (SLIT) for 48 weeks was effective as add on treatment for allergic asthma; however, data regarding its long-term efficacy is scarce. ObjectiveThis open-label extension study aimed to evaluate the effect of HDM SLIT on asthma control, pulmonary function, airway inflammation and remodeling throughout the 5-year treatment period. MethodsA total of 140 patients with asthma and allergic rhinitis sensitized to HDM were randomized to receive either drugs alone or drugs plus SLIT for 5 years. Asthma Control Questionnaire (ACQ)-5, Asthma Quality of Life Questionnaire (AQLQ), Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), spirometry, quantitative computed tomography, and type 2 biomarkers were assessed. ResultsAn improvement in the ACQ-5, AQLQ, and RQLQ scores was observed in the SLIT group compared with the control group. HDM SLIT increased lung function and reduced the percentage of airway wall area (WA/Ao). The levels of fractional exhaled nitric oxide (FeNO), blood eosinophil, serum specific IgE (s-IgE) for HDM, and total IgE decreased and were sustained during the 5 years. The change in type 2 biomarkers correlated with change in AQLQ score. Based on receiver operating characteristic (ROC) analysis for predicting responders, the area under the ROC curve in FEV1% predicted, WA/Ao, FeNO, and s-IgE was high. Multivariate regression analysis showed that the strongest predictor of responders was FeNO. ConclusionsHDM SLIT continued to provide sustained efficacy, improve lung function, and prevent progression of airway inflammation and remodeling in asthma through to year 5.

Bird diversity in a Sahelian ecosystem under restoration: A study in the great Grenn wall extension area of Senegal

In this study, we survey the avian biodiversity in Koyli Alpha, Senegal, located in the extension area of the Great Green Wall (GGW) project in Senegal to restore the degraded ecosystems by the long years of drought during the 1970s in addition to anthropogenic pressures. Data are collected during a period of 52 days between July 2019 and Jun 2021 in Koyli Alpha and their surroundings, we identified the presence of avian species through daytime focal observations using transects, fixed points and trapping cameras. Thus, we recorded the presence of 198 total bird species. Species composed of 143 landbirds and 55 waterbirds distributed in 22 orders and 59 families. The most common were granivorous birds such as the Golgen sparrow (Passer luteus) and the Red-billed quelea (Quelea quelea). Among these inventoried species, three are categorized as critically endangered species (CR) (IUCN Redlist). They are the Rüppell's vulture (Gyps rueppelli), the White-backed vulture (Gyps africanus) and the hooded vulture (Necrosyrtes monachus). Additionally, the Martial eagle (Polemaetus bellicosus) is categorized as endangered (EN), and the Great grey shrike (Lanius meridionalis), the Abyssinian ground hornbill (Bucorvus abyssinicus) and the European turtle dove (Streptopelia turtur) are categorized as vulnerable species (VN). Furthermore, 37% of observed birds are palearctic migratory species.

Fine particulate matter contributes to COPD-like pathophysiology: experimental evidence from rats exposed to diesel exhaust particles

BackgroundAmbient fine particulate matter (PM2.5) is considered a plausible contributor to the onset of chronic obstructive pulmonary disease (COPD). Mechanistic studies are needed to augment the causality of epidemiologic findings. In this study, we aimed to test the hypothesis that repeated exposure to diesel exhaust particles (DEP), a model PM2.5, causes COPD-like pathophysiologic alterations, consequently leading to the development of specific disease phenotypes. Sprague Dawley rats, representing healthy lungs, were randomly assigned to inhale filtered clean air or DEP at a steady-state concentration of 1.03 mg/m3 (mass concentration), 4 h per day, consecutively for 2, 4, and 8 weeks, respectively. Pulmonary inflammation, morphologies and function were examined.ResultsBlack carbon (a component of DEP) loading in bronchoalveolar lavage macrophages demonstrated a dose-dependent increase in rats following DEP exposures of different durations, indicating that DEP deposited and accumulated in the peripheral lung. Total wall areas (WAt) of small airways, but not of large airways, were significantly increased following DEP exposures, compared to those following filtered air exposures. Consistently, the expression of α-smooth muscle actin (α-SMA) in peripheral lung was elevated following DEP exposures. Fibrosis areas surrounding the small airways and content of hydroxyproline in lung tissue increased significantly following 4-week and 8-week DEP exposure as compared to the filtered air controls. In addition, goblet cell hyperplasia and mucus hypersecretions were evident in small airways following 4-week and 8-week DEP exposures. Lung resistance and total lung capacity were significantly increased following DEP exposures. Serum levels of two oxidative stress biomarkers (MDA and 8-OHdG) were significantly increased. A dramatical recruitment of eosinophils (14.0-fold increase over the control) and macrophages (3.2-fold increase) to the submucosa area of small airways was observed following DEP exposures.ConclusionsDEP exposures over the courses of 2 to 8 weeks induced COPD-like pathophysiology in rats, with characteristic small airway remodeling, mucus hypersecretion, and eosinophilic inflammation. The results provide insights on the pathophysiologic mechanisms by which PM2.5 exposures cause COPD especially the eosinophilic phenotype.