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Widespread 2013-2020 decreases and reduction challenges of organic aerosol in China. Nat Commun 2024; 15:4465. [PMID: 38796477 DOI: 10.1038/s41467-024-48902-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 05/17/2024] [Indexed: 05/28/2024] Open
Abstract
High concentrations of organic aerosol (OA) occur in Asian countries, leading to great health burdens. Clean air actions have resulted in significant emission reductions of air pollutants in China. However, long-term nation-wide trends in OA and their causes remain unknown. Here, we present both observational and model evidence demonstrating widespread decreases with a greater reduction in primary OA than in secondary OA (SOA) in China during the period of 2013 to 2020. Most of the decline is attributed to reduced residential fuel burning while the interannual variability in SOA may have been driven by meteorological variations. We find contrasting effects of reducing NOx and SO2 on SOA production which may have led to slight overall increases in SOA. Our findings highlight the importance of clean energy replacements in multiple sectors on achieving air-quality targets because of high OA precursor emissions and fluctuating chemical and meteorological conditions.
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Seasonal variations of imidazoles in urban areas of Beijing and Guangzhou, China by single particle mass spectrometry. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 844:156995. [PMID: 35777561 DOI: 10.1016/j.scitotenv.2022.156995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 06/15/2023]
Abstract
Imidazoles (IMs) are potential contributors to brown carbon; they may notably contribute to climate radiative forcing. However, only a few studies have assessed the mixing state, seasonal and spatial distributions of IMs, and influencing factors for IM formation in urban aerosols. In this study, two single-particle aerosol mass spectrometers were employed to investigate the IM-containing particles in the urban areas of Beijing and Guangzhou, China. IM-containing particles were identified in the size range (dva) of 0.2-2.0 μm, accounting for 0.7-21.7 % of all the detected particles. The number fractions of IM-containing particles in both cities were the lowest in winter and the highest in spring, probably owing to the difference in the abundance of precursors and the particle acidity. Majority of (60-80 % by number) the IM-containing particles were mixed with organic carbon (OC), with the lowest fractions found in summer. Although the number fractions of IM-containing particles in Beijing were generally higher (~1.5-3 times) than those in Guangzhou, the mixing states of the IM-containing particles at these two sites were only slightly different. Potassium-rich (K-rich) and potassium-sodium (KNa) particles were rarely found in Guangzhou; they accounted for ~15 % of the IM-containing particles in Beijing. Additionally, our results indicate that particles with higher acidity are favorable for IM formation. These findings help improving our knowledge of the mixing state, seasonal variation, and spatial distribution of IMs in urban aerosols, and the insights in influencing factors into IM formation provide valuable information for future studies of the atmospheric chemical processes associated with IMs.
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Significant reduction in atmospheric organic and elemental carbon in PM 2.5 in 2+26 cities in northern China. ENVIRONMENTAL RESEARCH 2022; 211:113055. [PMID: 35257685 DOI: 10.1016/j.envres.2022.113055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 02/22/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
To better understand the change characteristics and reduction in organic carbon (OC) and elemental carbon (EC) in particulate matter (PM) with a diameter of ≤2.5 μm (PM2.5) driven by the most stringent clean air policies and pandemic-related lockdown measures in China, a comprehensive field campaign was performed to measure the carbonaceous components in PM2.5 on an hourly basis via harmonized analytical methods in the Beijing-Tianjin-Hebei and its surrounding region (including 2 + 26 cities) from January 1 to December 31, 2020. The results indicated that the annual average concentrations of OC and EC reached as low as 6.6 ± 5.7 and 1.8 ± 1.9 μg/m3, respectively, lower than those obtained in previous studies, which could be attributed to the effectiveness of the Clean Air Action Plan and the impact of the COVID-19-related lockdown measures implemented in China. Marked seasonal and diurnal variations in OC and EC were observed in the 2 + 26 cities. Significant correlations (p < 0.001) between OC and EC were found. The annual average secondary OC levels level ranged from 1.8-5.4 μg/m3, accounting for 37.7-73.0% of the OC concentration in the 2 + 26 cities estimated with the minimum R squared method. Based on Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithms, the light extinction contribution of carbonaceous PM to the total amount reached 21.1% and 26.0% on average, suggesting that carbonaceous PM played a less important role in visibility impairment than did the other chemical components in PM2.5. This study is expected to provide an important real-time dataset and in-depth analysis of the significant reduction in OC and EC in PM2.5 driven by both the Clean Air Action Plan and COVID-19-related lockdown policies over the past few years, which could represent an insightful comparative case study for other developing countries/regions facing similar carbonaceous PM pollution.
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Historically understanding the spatial distributions of particle surface area concentrations over China estimated using a non-parametric machine learning method. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 824:153849. [PMID: 35176389 DOI: 10.1016/j.scitotenv.2022.153849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
A non-parametric ensemble model was proposed to estimate the long-term (2015-2019) particle surface area concentrations (SA) over China for the first time on basis of a vilification dataset of measured particle number size distribution. This ensemble model showed excellent cross-validation R2 value (CV R2 = 0.83) as well as a relatively low root-mean-square error (RMSE = 195.0 μm2/cm3). No matter in which year, considerable spatial heterogeneity of SA was found over China with higher SA in Beijing-Tianjin-Hebei (BTH), Yangtze River Delta (YRD), and Middle Lower Reaches of Yangtze River (MLYR). From 2015 to 2019, SA significantly decreased in representative city clusters. The reduction rates were 140.1 μm2·cm-3·a-1 in BTH, 110.7 μm2·cm-3·a-1 in Pearl River Delta (PRD), 105.2 μm2·cm-3·a-1 in YRD, and 92.4 μm2·cm-3·a-1 in Sichuan Basin (SCB), respectively. Even though such quick reduction, high SA (ranged from ~800 μm2/cm3 to ~1750 μm2/cm3) during the heavy pollution period (PM2.5 > 75 μg/m3) still existed in the above-mentioned city clusters and may provide rich reaction vessels for multiphase chemistry. A dichotomy of enhanced annual 4th maximum daily 8-h average O3 concentrations (4MDA8 O3) and decreased SA during summertime was found in Shanghai, a representative city of YRD. In Chengdu (SCB), increased 4MDA8 O3 concentration was associated with a synchronous increase of SA from 2017 to 2019. Differently, 4MDA8 O3 concentrations enhanced in Beijing (BTH) and Guangzhou (PRD), while not significant for SA before 2018. This work will greatly deepen our understanding of the historical variation and spatial distributions of SA over China.
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Heavy haze pollution during the COVID-19 lockdown in the Beijing-Tianjin-Hebei region, China. J Environ Sci (China) 2022; 114:170-178. [PMID: 35459482 PMCID: PMC8748337 DOI: 10.1016/j.jes.2021.08.030] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Revised: 08/11/2021] [Accepted: 08/16/2021] [Indexed: 06/02/2023]
Abstract
To investigate the characteristics of particulate matter with an aerodynamic diameter less than 2.5 μm (PM2.5) and its chemical compositions in the Beijing-Tianjin-Hebei (BTH) region of China during the novel coronavirus disease (COVID-19) lockdown, the ground-based data of PM2.5, trace gases, water-soluble inorganic ions, and organic and elemental carbon were analyzed in three typical cities (Beijing, Tianjin, and Baoding) in the BTH region of China from 5-15 February 2020. The PM2.5 source apportionment was established by combining the weather research and forecasting model and comprehensive air quality model with extensions (WRF-CAMx). The results showed that the maximum daily PM2.5 concentration reached the heavy pollution level (>150 μg/m3) in the above three cities. The sum concentration of SO42-, NO3- and NH4+ played a dominant position in PM2.5 chemical compositions of Beijing, Tianjin, and Baoding; secondary transformation of gaseous pollutants contributed significantly to PM2.5 generation, and the secondary transformation was enhanced as the increased PM2.5 concentrations. The results of WRF-CAMx showed obviously inter-transport of PM2.5 in the BTH region; the contribution of transportation source decreased significantly than previous reports in Beijing, Tianjin, and Baoding during the COVID-19 lockdown; but the contribution of industrial and residential emission sources increased significantly with the increase of PM2.5 concentration, and industry emission sources contributed the most to PM2.5 concentrations. Therefore, control policies should be devoted to reducing industrial emissions and regional joint control strategies to mitigate haze pollution.
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[Analysis of Pollution Characteristics, Meteorological Impact, and Forecast Retrospective During the Spring Festival and the Lantern Festival in "2+26" Cities]. HUAN JING KE XUE= HUANJING KEXUE 2022; 43:1212-1225. [PMID: 35258185 DOI: 10.13227/j.hjkx.202104329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The PM2.5concentration characteristics of "2+26" cities in Beijing-Tianjin-Hebei and the surrounding region during the Spring Festival and the Lantern Festival in 2021 were analyzed. The average daily concentration and hourly concentration of PM2.5 in the three days before and after the Spring Festival and the Lantern Festival from 2016 to 2021 and the characteristics of the PM2.5 chemical components during the Spring Festival and the Lantern Festival from 2019 to 2021 were comparatively analyzed. In addition, the impact of meteorological factors on PM2.5 concentration from 2016 to 2021 and the key factors affecting the forecast result of Beijing during the Spring Festival in 2021 were discussed. The results showed that the combination of fireworks and firecrackers and adverse weather conditions resulted in a moderate to heavy pollution process during the Spring Festival in 2021 and a light to moderate pollution process during the Lantern Festival in "2+26" cities. The average ρ(PM2.5) was 111 μg·m-3. The hourly peak ρ(PM2.5) was 156 μg·m-3, which was the lowest in 2016 to 2021. The three days before and after the Lantern Festival in 2021, the average ρ(PM2.5) of "2+26" cities was 85 μg·m-3, and the hourly peak ρ(PM2.5) was 125 μg·m-3. During this period, the hour number of heavy and severe pollution was the lowest in 2016 to 2021. Component observation results showed that the impact of fireworks and firecrackers during the Spring Festival and the Lantern Festival in 2021 was gradually reduced, and the effect of bans and restrictions for fireworks and firecrackers was significant. The regional pollution was dominated by conventional pollution accumulation and nitrate. The concentration of organic matter in some cities during the Spring Festival was relatively high, which may be related to local industrial emissions and the impact of blasting fireworks and firecrackers. The comparative analysis of meteorological factors and PM2.5 concentration showed that the factors such as wind speed and direction, ground pressure, and relative humidity all affected PM2.5 concentration and the duration of the regional pollution process. The influence of oscillation of the boundary layer transport sink on diffusion conditions in the North China Plain, the location and intensity of the small high pressure in North China and the intensity of its high-altitude moving airflow, and the uncertainty of fireworks displays, as well as the low accuracy of weather forecasts caused by frequent weather changes during the alternate period of winter and spring, could affect the accuracy of air quality forecast results in the northern Beijing-Tianjin-Hebei region. In summary, although the impact of fireworks and firecrackers has been reduced in recent years, in order to improve the air quality, it is recommended to further strengthen the control of fireworks and firecrackers, especially outside the Beijing Fifth Ring Road and Beijing's surrounding cities.
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Composition and sources of particulate matter in the Beijing-Tianjin-Hebei region and its surrounding areas during the heating season. CHEMOSPHERE 2022; 291:132779. [PMID: 34742769 DOI: 10.1016/j.chemosphere.2021.132779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 10/25/2021] [Accepted: 11/02/2021] [Indexed: 06/13/2023]
Abstract
This paper aimed to analyze the composition and pollution sources of particulate matter (PM) in the Beijing-Tianjin-Hebei region and its surrounding areas (henceforth the BTH region) during the heating season to support the mitigation and control of regional air pollution. Manual monitoring data from the China National Environmental Monitoring Network for Atmospheric PM in the BTH region were collected and analyzed during the 2016 and 2018 heating seasons. The positive definite matrix factor analysis (PMF) model was used to analyze the PM sources in BTH cities during the heating season. The main PM components were organic matter (OM), nitrate (NO3-), sulfate (SO42-) and ammonium salt (NH4+). Direct emission sources have decreased since 2016, indicating the effectiveness of governmental controls on these sources; however, secondary pollution showed an increasing trend, suggesting control measures should be strengthened. Daily regional average concentrations of OM, SO42-, NH4+, elemental carbon (EC), chloride (Cl-) and trace elements all showed similar trends. When air quality worsened, the concentrations of the main PM components increased, but trends of change varied among components. In 2018, concentrations of OM and chloride were highest in the Taihang Mountains, and NO3 concentrations were highest in Anyang, Hebi, Jiaozuo and Xinxiang. The SO42- concentration was highest in the southern section of the Taihang Mountains. The NH4+ and EC concentrations were generally highest in the central and southern regions. The concentration of crustal substances was highest in some cities in the north and central parts of the BTH region. In the 2018 heating season, the pollution level of five transmission channels showed an increasing trend in the Northwest, Southeast, Yanshan, South and Taihang Mountain channels. These findings provide a scientific basis for the continued management of atmospheric PM pollution.
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Comparative observation of aerosol vertical profiles in urban and suburban areas: Impacts of local and regional transport. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 805:150363. [PMID: 34818754 DOI: 10.1016/j.scitotenv.2021.150363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 09/09/2021] [Accepted: 09/11/2021] [Indexed: 06/13/2023]
Abstract
Ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) instruments were used to carry out observation of aerosol in the urban and suburban areas of Shanghai from October 17 to November 21, 2019. Fudan University (FDU) site is a typical urban environment, surrounded by residential areas, commercial areas and arterial roads, while Dianshan Lake (DSL) site is a suburban environment with high vegetation coverage and no pollutant emission sources. The aerosol retrieved by MAX-DOAS was in good correlation with the observation of sun photometer and the PM2.5 concentration of the corresponding site, which demonstrates that the aerosol retrieved by MAX-DOAS is reliable and feasible. Comparing the mean aerosol extinction coefficient (AEC) profiles during the observation period between urban and suburban areas, it was found that the occurrence of high aerosol concentration at FDU was nearly 3 h later than that of DSL at suburban site. And the aerosol at DSL was concentrated at an altitude of 0.3- 0.5 km, with a mean peak value of 0.486 km-1, which was slightly higher than the peak AEC of 0.453 km-1 at FDU of 0.2- 0.4 km. The difference in aerosol characteristics between the two sites may be due to the fact that the influences of aerosol transport and boundary layer dynamics are different between the two sites. The backward trajectories analysis also presents that there were mutual transports of aerosol between urban and suburban areas, which affect the optical properties of the aerosol in these two sites. In a case of aerosol pollution, we visualized the transport pathway of aerosol from the western part of the North China Plain to Shanghai using AEC profiles and backward trajectories, providing the evidence that the local aerosol pollution in Shanghai was affected by long-distance transport.
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The temporal and spatial distribution of the correlation between PM<sub>2.5</sub> and O<sub>3</sub> contractions in the urban atmosphere of China. CHINESE SCIENCE BULLETIN-CHINESE 2021. [DOI: 10.1360/tb-2021-0765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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The evolution trend and typical process characteristics of atmospheric PM<sub>2.5</sub> and O<sub>3</sub> pollution in Beijing from 2013 to 2020. CHINESE SCIENCE BULLETIN-CHINESE 2021. [DOI: 10.1360/tb-2021-0753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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[Determination of 104 volatile organic compounds in air by double column gas chromatography-mass spectrometry/flame ionization detector coupled with electronically controlled cryo-focusing unit]. Se Pu 2019; 37:418-425. [PMID: 30977345 DOI: 10.3724/sp.j.1123.2018.12022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
A method for the determination of 104 volatile organic compounds (VOCs) in ambient air based on double column multi dean switching gas chromatography-mass spectrometry/flame ionization detector (GC-MS/FID) coupled with sorbent assisted electronically controlled cryo-focusing unit was developed and evaluated. The sorbent assisted electronically controlled cryo-focusing unit was used for trapping, dehydration and focusing of VOCs sampled in summa canisters. The VOCs were split into two parts by the multi dean switching unit in GC-MS/FID. The C2-C3 components were determined in a PLOT capillary column with an FID detector, while the C4-C12 components were determined in an Intercap-624 capillary column with a MS detector. The C2-C3 components were qualitatively confirmed from the retention time and quantified by the calibration curves, while the C4-C12 components were qualitatively confirmed from the retention time and the relative abundance ratio of characteristic ions, and quantified by the internal standard calibration curves. The major factors influencing the cryo-focusing performance including the type of sorbent tube, the pressure employed in assisted pressure control unit (APC), and the split point in multi dean switching unit were investigated. The chromatographic and MS parameters were optimized. Under optimum conditions, a linear relationship was observed with the content of VOCs ranging from 0.0446 to 0.892 μmol/m3, and correlation coefficients (r) no less than 0.9984. The average spiked recoveries of the six VOCs at two levels of 0.0446 μmol/m3 and 0.223 μmol/m3 were 86.4%-116.1%, with relative standard deviations in the range of 0.9%-11.3% The method detection limits (MDLs) and the limits of quantification (LOQs) were 0.145-1.90 μg/m3 and 0.435-5.70 μg/m3, respectively. The method is accurate, sensitive and simple, and is suitable for the determination of the 104 VOCs in ambient air.
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Analysis of spatial and temporal water pollution patterns in Lake Dianchi using multivariate statistical methods. ENVIRONMENTAL MONITORING AND ASSESSMENT 2010; 170:407-416. [PMID: 19936953 DOI: 10.1007/s10661-009-1242-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2009] [Accepted: 10/29/2009] [Indexed: 05/28/2023]
Abstract
Various multivariate statistical methods including cluster analysis (CA), discriminant analysis (DA), factor analysis (FA), and principal component analysis (PCA) were used to explain the spatial and temporal patterns of surface water pollution in Lake Dianchi. The dataset, obtained during the period 2003-2007 from the Kunming Environmental Monitoring Center, consisted of 12 variables surveyed monthly at eight sites. The CA grouped the 12 months into two groups, August-September and the remainder, and divided the lake into two regions based on their different physicochemical properties and pollution levels. The DA showed the best results for data reduction and pattern recognition in both temporal and spatial analysis. It calculated four parameters (TEMP, pH, CODMn, and Chl-a) to 85.4% correct assignment in the temporal analysis and three parameters (BOD, NH₄+-N, and TN) to almost 71.7% correct assignment in spatial analysis of the two clusters. The FA/PCA applied to datasets of two special clusters of the lake calculated four factors for each region, capturing 72.5% and 62.5% of the total variance, respectively. Strong loadings included DO, BOD, TN, CODCr, CODMn, NH₄+-N, TP, and EC. In addition, box-whisker plots and GIS further facilitated and supported the multivariate analysis results.
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The porcine and lagomorph septal cartilages: models for tissue engineering and morphologic cartilage research. AMERICAN JOURNAL OF RHINOLOGY 2001; 15:109-16. [PMID: 11345149 DOI: 10.2500/105065801781543790] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Interest in reconstruction and modification of the facial cartilaginous frameworks using advanced technology and instrumentation is growing rapidly. Despite this maturing interest, no animal model has been established to provide morphologic cartilage tissue with similar characteristics to human septum in suitable quantities. The objective of this study was to characterize porcine and lagomorph (rabbit) nasal septal cartilage tissue. Both models share great similarity with their human counterpart and provide a low-cost, high-volume, and easily obtained source of bulk cartilage tissue. We present a technique for harvesting intact septal cartilages from these species, and characterize select cellular, metabolic, and physical properties using pulse-chase radiolabeling, flow cytometry, and mechanical analysis. Our selective evaluation of key tissue properties establishes these species as appropriate animal models for nasal septal cartilaginous surgery.
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Abstract
OBJECTIVE To demonstrate feedback-controlled laser-mediated cartilage reshaping using dynamic measurements of tissue optical properties and radiometric surface temperatures. DESIGN Flat cartilage specimens were reshaped into curved configurations using a feedback-controlled laser device. MATERIALS Fresh porcine nasal septum, stripped of perichondrium and cut into uniform strips (25 x 10 x 1.5-2.1 mm) with a custom guillotine microtome. INTERVENTIONS Cartilage specimens secured in a cylindrical reshaping jig (2.5 cm in diameter) and irradiated with an Nd:YAG laser (lambda = 1.32 microns, 25 W/cm2, 50-Hz pulse repetition rate). During laser irradiation, radiometric surface temperature was measured along with changes in forward-scattered light from a diode probe laser (lambda = 650 nm, 5 mW), using a lock-in detection technique. Sequential irradiation of the specimen outer surface was made (3 laser passes). Characteristic changes in tissue temperature and light-scattering signals were used to terminate laser irradiation. RESULTS Effective reshaping was accomplished for both thin (1.5-mm) and thick (2.1-mm) specimens. Following reshaping, specimens were stored in saline solution at 4 degrees C for 21 days. No return to the original flat configuration was noted during this period. CONCLUSIONS The prototype device effectively reshapes flat native porcine cartilage into curve configurations. The use of optical and thermal signals provides effective feedback control for optimizing the reshaping process.
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