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The aim of this study was to investigate the potential of using multidetector computed tomography (MDCT) to measure the bone mineral density (BMD) in the medial meta-epiphyseal region of clavicle (MERC) for adult age estimation. A total of 1064 chest MDCT scans from individuals aged 21 to 102 years were utilized to determine the MERC BMD. The Mimics software was used for the BMD measurements, and the average BMD of both MERC was also calculated. Regression analysis was conducted with chronological age as a dependent variable and MERC BMD as an independent variable to establish a mathematical model for age estimation. The mean absolute error (MAE) was calculated to evaluate the accuracy of the regression model using an independent validation sample. Among all the models, the cubic regression model showed the highest correlation between MERC BMD and chronological age and also provided the most accurate age prediction for both males and females (MAE = 9.41 for males, MAE = 10.38 for females). Our study suggests that BMD measured by MERC can be utilized for age estimation in adults when more reliable indicators are not available., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

This study aimed to explore and develop data mining models for adult age estimation based on CT reconstruction images from the sternum. Maximum intensity projection (MIP) images of chest CT were retrospectively collected from a modern Chinese population, and data from 2700 patients (1349 males and 1351 females) aged 20 to 70 years were obtained. A staging technique within four indicators was applied. Several data mining models were established, and mean absolute error (MAE) was the primary comparison parameter. The intraobserver and interobserver agreement levels were good. Within internal validation, the optimal data mining model obtained the lowest MAE of 9.08 in males and 10.41 in females. For the external validation (N = 200), MAEs were 7.09 in males and 7.15 in females. In conclusion, the accuracy of our model for adult age estimation was among similar studies. MIP images of the sternum could be a potential age indicator. However, it should be combined with other indicators since the accuracy level is still unsatisfactory., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: Adult age estimation (AAE) is a challenging task. Deep learning (DL) could be a supportive tool. This study aimed to develop DL models for AAE based on CT images and compare their performance to the manual visual scoring method., Methods: Chest CT were reconstructed using volume rendering (VR) and maximum intensity projection (MIP) separately. Retrospective data of 2500 patients aged 20.00-69.99 years were obtained. The cohort was split into training (80%) and validation (20%) sets. Additional independent data from 200 patients were used as the test set and external validation set. Different modality DL models were developed accordingly. Comparisons were hierarchically performed by VR versus MIP, single-modality versus multi-modality, and DL versus manual method. Mean absolute error (MAE) was the primary parameter of comparison., Results: A total of 2700 patients (mean age = 45.24 years ± 14.03 [SD]) were evaluated. Of single-modality models, MAEs yielded by VR were lower than MIP. Multi-modality models generally yielded lower MAEs than the optimal single-modality model. The best-performing multi-modality model obtained the lowest MAEs of 3.78 in males and 3.40 in females. On the test set, DL achieved MAEs of 3.78 in males and 3.92 in females, which were far better than the MAEs of 8.90 and 6.42 respectively, for the manual method. For the external validation, MAEs were 6.05 in males and 6.68 in females for DL, and 6.93 and 8.28 for the manual method., Conclusions: DL demonstrated better performance than the manual method in AAE based on CT reconstruction of the costal cartilage., Clinical Relevance Statement: Aging leads to diseases, functional performance deterioration, and both physical and physiological damage over time. Accurate AAE may aid in diagnosing the personalization of aging processes., Key Points: • VR-based DL models outperformed MIP-based models with lower MAEs and higher R 2 values. • All multi-modality DL models showed better performance than single-modality models in adult age estimation. • DL models achieved a better performance than expert assessments., (© 2023. The Author(s), under exclusive licence to European Society of Radiology.)

Radiology plays a crucial role in forensic anthropology for age estimation. However, most studies rely on morphological methods. This study aims to investigate the feasibility of using pubic bone mineral density (BMD) as a new age estimation method in the Chinese population. 468 pubic bone CT scans from living individuals in a Chinese hospital aged 18 to 87 years old were used to measure pubic BMD. The BMD of the bilateral pubic bone was measured using the Mimics software on cross-sectional CT images and the mean BMD of the bilateral pubic bone was also calculated. Regression analysis was performed to assess the correlation between pubic BMD and chronological age and to develop mathematical models for age estimation. We evaluated the accuracy of the best regression model using an independent validation sample by calculating the mean absolute error (MAE). Among all established models, the cubic regression model had the highest R 2 value in both genders, with R 2  = 0.550 for males and R 2  = 0.634 for females. The results of the best model test showed that the MAE for predicting age using pubic BMD was 8.66 years in males and 7.69 years in females. This study highlights the potential of pubic BMD as a useful objective indicator for adult age estimation and could be used as an alternative in forensic practice when other better indicators are lacking., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objectives: To assess the performance of knee MRI for forensic age prediction and classification for 12-, 14-, 16-, and 18-year thresholds., Methods: The ossification stages of distal femoral epiphyses and proximal tibial epiphyses were assessed using an integrated staging system by Schmeling et al. and Kellinghaus et al. for knee 3.0T MRI with T1-weighted turbo spin-echo (T1-TSE) in sagittal orientation among 852 Chinese Han individuals (483 males and 369 females) aged 7-30 years. Regression models for age prediction were constructed and their performances were evaluated based on mean absolute deviation (MAD) values. In addition, the performances of age classification were assessed using receiver operating characteristic (ROC) analyses., Results: The intra- and inter-observer agreement levels were very good (κ > 0.80). The complete fusion of those two types of epiphyses took place before 18.0 years in our study participants. The minimum MAD values were 2.51 years (distal femur) and 2.69 years (proximal tibia) in males, and 2.75 years (distal femur) and 2.87 years (proximal tibia) in females. The specificity values of constructed prediction models were all above 90% for the 12-, 14-, and 16-year thresholds, compared to the 74.8-84.6% for the 18-year threshold. Better performances of age prediction and classification were observed in males by distal femoral epiphyses., Conclusions: Ossification stages via 3.0T MRI of the knee with T1-TSE sequence using an integrated staging system could be a reliable noninvasive method for age prediction or for age classification for 12-, 14-, and 16-year thresholds, especially in males by distal femoral epiphyses. However, assessments based on the full bony fusion of the distal femoral epiphysis and proximal tibial epiphysis seemed not reliable for age classification for the 18-year threshold in the Chinese Han population., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Age estimation is an important topic of human identification in forensic practice, especially coming to biological samples in crime scene, such as blood, saliva, semen. As rate-limiting enzyme in Nucleotide excision repair (NER) that was associated with aging, Excision repair cross-complementation group 5 (ERCC5) was considered to be a candidate biomarker for individual age estimation. The ERCC5 mRNA and protein expression levels association with age have been demonstrated in our previous study. However, very little is known about relationship DNA-based quantification of ERCC5 with age. In this study, we detected ERCC5 level in peripheral blood from a Chinese Han population by SYBR qPCR assay to gain better insight into the quantitative relationship with age. The results showed ERCC5 level declined with individual age with a negative correlation(r = -0.8, R 2  = 0.63, P < 0.001). The data model for age estimation based on ERCC5 level was Y = -31.352X + 14.436 ± 10.28 (Y: age, year; X: Cq TBP -Cq ERCC5 ; standard error: year). The accuracy about the data model for age estimation was about 73.33%. The mean absolute difference (MAD) values were 8.22, 8.09 and 8.38 in total, male and female, respectively. Furthermore, ERCC5 quantification for age estimation was also applicable for stored blood samples under low temperature up to 6 months. It was suggested that the ERCC5 quantification was expected to be a valuable additional method for individual age estimation, especially in cases where traditional morphologic method is absent or inefficient in forensic practice., (Copyright © 2021 Elsevier B.V. All rights reserved.)

To develop population - specific stature prediction equations from measurements of the lower limb bone in a contemporary Chinese. 303 individuals of Han group in Western China, including 201 females and 102 males were collected. The study sample was randomly divided into two subgroups. A calibration sample, which consisted of 171 females and 87 males, was used to develop the regression formula. A validation sample comprising the remaining 30 female and 15 male individuals was then used to test the predictive accuracy of the established formula. The regression equations were developed from intact bones and fragments of the femur, tibia and fibula, the maximum lengths of femur, tibia, and fibula were highly correlated with the stature. The maximum length of femur provide the most accurate result with the prediction accuracy of 3.84 cm for unknown sex, 4.00 cm in the male group, 3.45 cm in the female group, 3.61 cm in the group with age no more than 45, 3.45 cm in the group with age above 45. Moreover, the multiple regression equations were developed, and they portray a more accurate stature in instances in which the femur, tibia and fibula are available. This paper provides indications that the femur, tibia and fibula are important bones for stature estimation and they could be effectively used in forensic cases., (Copyright © 2019 Elsevier Ltd and Faculty of Forensic and Legal Medicine. All rights reserved.)

Abstract: Objective To explore the feasibility of the CT image reconstruction of laryngeal cartilage and hyoid bone in adult age estimation using data mining methods. Methods The neck thin slice CT scans of 413 individuals aged 18 to <80 years were collected and divided into test set and train set, randomly. According to grading methods such as TURK et al., all samples were graded comprehensively. The process of thyroid cartilage ossification was divided into 6 stages, the process of cricoid cartilage ossification was divided into 5 stages, and the synosteosis between the greater horn of hyoid and hyoid body was divided into 3 stages. Multiple linear regression model, support vector regression model, and Bayesian ridge regression model were developed for adult age estimation by scikit-learn 0.17 machine learning kit （Python language）. Leave-one-out cross-validation and the test set were used to further evaluate performance of the models. Results All indicators were moderately or poorly associated with age. The model with the highest accuracy in male age estimation was the support vector regression model, with a mean absolute error of 8.67 years, much higher than the other two models. The model with the highest accuracy in female adult age estimation was the support vector regression model, with a mean absolute error of 12.69 years, but its accuracy differences with the other two models had no statistical significance. Conclusion Data mining technology can improve the accuracy of adult age estimation, but the accuracy of adult age estimation based on laryngeal cartilage and hyoid bone is still not satisfactory, so it should be combined with other indicators in practice., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine.)

Sex estimation is an important part of creating a biological profile, and ultimately assisting in creating a presumptive identification of unidentified skeletal remains. However, manual methods of anthropometric are time-consuming and prone to observer variability. The present study is an attempt to estimation of sex from automatic measurement of patella by multidetector computed tomography (MDCT) in a contemporary Chinese population. Four measurements for every patella, including maximum height (MAXH), maximum breadth (MAXB), maximum thickness (MAXT) and patellar volume (PV), were automatically provided by the software from CT image of 300 Chinese. The sample is composed of 156 males and 144 females with an average age of 41.44 and 45.68 years, respectively. The statistical analyses showed that all variables were sexually dimorphic. Receiver operating characteristic (ROC) analysis was performed to estimate sex from patella. The univariate analysis of each patellar parameter yielded a sex classification accuracy rate of 73.1% to 85.7%. The classification accuracy rates of sex estimation using the combination of the patellar parameters are 81.9% to 91.6%. This paper provides indications that the patella is important bone for sex estimation and it may be used as an alternative in forensic cases when the skull and pelvis are unavailable., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Abstract: Adult age determination plays an important role in individual identification, criminal investigation and social welfare. The most popular adult age determination indicators are pubic symphysis, iliac auricular surface, costal cartilage, cranial sutures, teeth, laryngeal cartilage, etc. In recent years, with the progress of CT imaging and 3D reconstruction technology, the adult age determination study gradually has transferred from a time-consuming general observation of bones with complex pre-processing in the past to the non-destructive, convenient, time-saving and easy to store image analysis technology. To explore more accurate, rapid and convenient adult age determination methods, multiple imaging methods and artificial intelligence have been applied in adult age determination. This paper reviews the common methods and research progress of adult age determination at home and abroad, infers the development direction of adult age determination, in order to provide reference for the improvement and optimization of forensic adult age determination., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine.)

Abstract: Objective To estimate sex based on patella measurements of Sichuan Han population by computed tomography three-dimensional volume reconstruction technique, and to explore the application value of patella in sex estimation. Methods CT three-dimensional volume reconstruction images of patella of 250 individuals were collected, the four measurement indicators including patellar length, patellar width, patellar thickness, and patellar volume were measured. The t -test was used to determine measurement indicators with sex differences. Fisher discriminant analysis was used to establish the sex discriminant function and the prediction accuracy was calculated by leave-one-out cross validation. Results The sex differences of the four measurement indicators had a statistical significance （ P <0.05）. The accuracy rate of the univariate discriminant function established by the patellar length was the highest （82.0%）. The accuracy rates of the all indicators discriminant function and the stepwise discriminant function were 80.4% and 81.6%, respectively. Conclusion It is feasible and accurate to estimate sex of Sichuan Han population by patella measurements with CT three-dimensional volume reconstruction technique. The method may be used as an alternative for sex estimation of Sichuan Han population when other bones with higher accuracy are not available., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine.)

Objectives: To expand the database on magnetic resonance imaging (MRI) analysis of distal tibial and calcaneal epiphyses as proposed by Saint-Martin et al. and investigate a more elaborate staging technique to establish regression models for age estimation in a modern Chinese Han population., Materials and Methods: T1-weighted ankle MRIs were retrospectively collected from April 2008 to July 2019, and data from 590 individuals (372 males and 218 females; aged from 8 to 25 years old) were obtained. One-sided sagittal images were assessed because data from both sides were considered coincidental, as no significant differences were found (P > 0.05). Three-stage and six-stage staging techniques were applied separately and subsequently compared. A subset was re-assessed a second time and by a different observer. Regression models were established accordingly., Results: Our results showed very good repeatability and consistency of two staging techniques (all Cohen's kappa values were more than 0.8). By comparison, the values of the coefficient of determination (R 2 ) of the six-stage technique were generally higher than those of the three-stage technique. Compared with the distal tibia and two ankle bones combined, the calcaneus decreased the mean absolute deviation (MAD) with the six-stage technique. In males, incorporating only the calcaneus resulted in a MAD of 2.15 years, with correct classification rates of 87.5% adults and 50.0% among minors. In females, the corresponding results were 1.67 years, 100.0%, and 44.4%, respectively., Conclusions: The six-stage technique may outperform the three-stage technique in MRI analysis of ankle bones for age estimation, while age estimation based on the calcaneus may perform better than that based on the distal tibia or both ankle bones in a modern Chinese Han population.

Community-acquired pneumonia (CAP) contributes substantially to morbidity and mortality in children under the age of 5 years. In examining bronchoalveolar lavages (BALs) of children with CAP, we found that interleukin-17 (IL-17) production was significantly increased in severe CAP. Immune profiling showed that mucosal-associated invariant T (MAIT) cells from the BALs, but not blood, of CAP patients actively produced IL-17 (MAIT17). Single-cell RNA-sequencing revealed that MAIT17 resided in a BAL-resident PLZF hi CD103 + MAIT subset with high expression of hypoxia-inducible factor 1α (HIF-1α), reflecting the hypoxic state of the inflamed tissue. CAP BALs also contained a T-bet + MAIT1 subset and a novel DDIT3 + (DNA damage-inducible transcript 3-positive) MAIT subset with low expression of HIF1A. Furthermore, MAIT17 differed from T-helper type 17 (Th17) cells in the expression of genes related to tissue location, innateness, and cytotoxicity. Finally, we showed that BAL monocytes were hyper-inflammatory and elicited differentiation of MAIT17. Thus, tissue-resident MAIT17 cells are induced at the infected respiratory mucosa, likely influenced by inflammatory monocytes, and contribute to IL-17-mediated inflammation during CAP.

Abstract: Objective To explore the value of degree of cranial suture closure in forensic adult age estimation by thin-layer CT scan and establish an adult age estimation model of the Han nationality. Methods Thin-layer CT scan samples of the heads of 220 healthy Sichuan Han adults （110 males, 110 females） aged 20 to 70 were collected, of which 20 samples （10 males, 10 females） were randomly selected as test samples. The sagittal suture, coronal suture （both left and right） and lambdoid suture （both left and right） were respectively and equally divided into 2 segments, and every segment was equally divided into 10 layers and the corresponding multiplanar reformation （MPR） images were selected. The closure of cranial sutures on MPR images was classified into the grades 1-7. The correlations between cranial sutures and age were analyzed to build regression equation for age estimation. Results The degree of closure of sagittal suture, coronal suture （both left and right） and lambdoid suture （both left and right） was positively correlated with age. The coefficient of determination （ R 2 ） of regression equation was 0.419 in males, 0.589 in females, and 0.522 in all samples. The results of the verification test showed that the mean absolute error （MAE） was 6.39 years in males, 6.16 years in females, and 6.29 years in all samples. Conclusion There was a higher accuracy in adult age estimation by thin-layer CT scan of cranial sutures. The age of Han nationality adults can be estimated by the degree of cranial sutures closure., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine.)

Objective: To observe the clinical therapeutic effect of herb-separated moxibustion on dysmenorrhea in ovarian endometriosis., Methods: A total of 54 patients with ovarian endometriosis dysmenorrhea were randomized into a herb-separated moxibustion group and a waiting-list group, 27 cases in each one (3 cases dropped off in the herb-separated moxibustion group, 4 cases dropped off in the waiting-list group). Herb-separated moxibustion was applied at hypogastrium and lumbosacral area for 30 min in the herb-separated moxibustion group, once a week for 3 months, and oral ibuprofen sustained-release capsule was given to relieve pain when necessary. Excepting giving ibuprofen sustained-release capsule when necessary, no more intervention was adopted in the waiting-list group. Before and after treatment and in 3 months follow-up, visual analogue scale (VAS) score, days of dysmenorrhea, total dose of oral painkiller were observed., Results: Compared before treatment, the VAS scores after tratment and in follow-up were decreased in the herb-separated moxibustion group ( P <0.05), and were less than those in the waiting-list group ( P <0.05); the days of dysmenorrhea and the total doses of oral painkiller after tratment and in follow-up were decreased in the herb-separated moxibustion group ( P <0.05), and were less than those in the waiting-list group ( P <0.05)., Conclusion: Herb-separated moxibustion can effectively improve dysmenorrhea symptom and shorten dysmenorrhea days in patients with ovarian endometriosis.

Abstract: Bone age is an important indicator of human growth and development, which can objectively reflect the growth level and maturity of individuals. Traditional manual bone age assessment usually compares the X-ray of the left wrist with the reference standard to obtain the corresponding bone age. This method is time-consuming and its results vary with different observers. In recent years, with the continuous development of computer science, bone age assessment has began to change from traditional manual assessment to automatic assessment. Although there has already been numerous researches on automatic bone age assessment, most of them are still in the experimental stage. This paper reviews related research and progress on automatic bone age assessment at home and abroad in recent years, in order to provide reference and research ideas for relevant researchers., Competing Interests: The authors of this article and the planning committee members and staff have no relevant financial relationships with commercial interests to disclose., (Copyright© by the Editorial Department of Journal of Forensic Medicine.)

The present study is an attempt to estimation of stature and sex from skull measurements by multidetector computed tomography (MDCT) in contemporary Chinese. In the present study, fifteen measurements for every skull were taken from CT image of 382 Chinese. The sample was composed of 200 males and 182 females with an average age of 47 and 46 years, respectively. Discriminant function was used in sex determination and regression analysis was used in stature estimation from skull measurements. The stepwise analysis of all measurements yielded a sex classification accuracy rate of 89.3%. The classification accuracy rates of the univariate discriminant function analyses were from 50.5% to 84.8%. For stature estimation, the standard error of estimate (SEE) ranged from 5.072 to 6.355 cm for male, from 5.090 to 5.829 cm for female, respectively. This study is the first to provide a metric and statistical characterization of the skull in contemporary Chinese, and indicates that it is feasible to sex estimation by skull measurement. Furthermore, the equations presented for stature estimation in this study may be used as alternatives in forensic cases, particularly in cases where better predictors such as the long bones are not available., (Copyright © 2019 Elsevier B.V. All rights reserved.)

The objective of the present study was to generate multiple regression models for stature estimation on the basis the combination of the clavicle, scapula and sternum derived from 3D-VRT images in Chinese population. The study sample comprised 363 individuals from China, including 159 females and 204 males, with documented ages between 19 and 82 years. Separate multiple linear regression equations for estimating stature on the basis of the measurements from the clavicle, scapula and sternum were then devised for males and females. For assessing the correlation between the stature and measurements of the clavicle, scapula and sternum, the Pearson's correlation coefficient was calculated and its significance was tested by Students t test. Finally, the multiple regression equations calculated from the measurements of the clavicle, scapula and sternum in relation to stature for each sex were established in the present study. The accuracy of stature prediction ranged from 4.777 to 5.313 cm for male and from 4.388 to 4.658 cm for female. In conclusion, the present results provide indications that the combination of the clavicle, scapula and sternum should be used as alternatives for stature estimation, and the multiple equations presented for stature estimation seem to be a more accurate than the equations from single bone.

The present study is an attempt to estimation of stature and sex from sacrum and coccyx measurements by multidetector computed tomography (MDCT) in a contemporary Chinese population. Nine measurements for every sacrum and coccyx were taken from CT image of 350 Chinese. The sample is composed of 190 males and 160 females with an average age of 55 and 50 years, respectively. Discriminant function was used in sex estimation and regression analysis was used in stature estimation from these two bones. The stepwise analysis of all measurements yielded a sex classification accuracy rate of 84.9%. The classification accuracy rates of the univariate discriminant function analyses are 58.3%-76.9%. For stature estimation, the accuracy of stature prediction ranged from 4.891 to 6.107 cm for male, from 4.474 to 5.606 cm for female, respectively. This paper provides indications that the sacrum and coccyx are important bones for sex estimation and they could be effectively used as alternatives in forensic cases when the skull and pelvis are unavailable. Furthermore, the regression equations presented in this study may be useful for forensic estimation of the stature of Chinese individuals, particularly in cases where better predictors such as the long bones are not available., (Copyright © 2018 Elsevier B.V. All rights reserved.)

High order harmonics generation from argon gas was comprehensively investigated by using multi-cycle and few-cycle laser pulses. Non-odd order harmonics were observed for sub-5-fs pulses, compare to the normal odd-order harmonics in the multi-cycle case. Theoretic analysis shows that the new spectral structure origins from the asymmetry of laser field in few-cycle pulses. This asymmetry induced both amplitude and phase difference between attosecond pulses from consecutive half-cycle of the laser field, which change the interference property of attosecond pulses and result in complex spectrum.

The aqueous photodegradation of bisphenol A (BPA) in the presence of Fe(III)-oxalate complexes (Fe(III)-Ox), which are common compositions of natural water, was investigated in this study. BPA underwent rapid indirect photolysis in Fe(III)-Ox solution under simulated solar irradiation, proceeding pseudo-first-order kinetics. The photolysis rate increased with decreasing pH or initial BPA level and increasing Fe(III)/oxalate concentration ratio. Hydroxyl radicals (*OH), which were generated from the photochemical processes of Fe(III)-Ox complexes and contributed to the photooxidation of BPA, were determined by molecular probe and electron spin resonance (ESR) methods with the steady-state concentration of 2.56 x 10(-14) mol/L. Superoxide anion radical (O2*-) was considered as the precursor of *OH and qualitatively determined by adding nitro blue tetrazolium as well as ESR experiments. Based on the structural analysis of the intermediate photoproducts of BPA in Fe(III)-Ox complexes solution, the possible degradation pathways of BPA were proposed, involving *OH addition, alkyl scission and alky oxidation. The results indicate that the photochemical reactivity of Fe(III) may affect the environmental fate of BPA in natural water significantly.

Under simulated solar irradiation, the degradation of bisphenol A (BPA) was studied in the presence of Suwannee River Fulvic Acid (SRFA). The results demonstrate that the photodegradation of BPA followed a pseudo-first-order kinetics and the photodegradation rate increased rapidly with increasing initial concentration of SRFA. Hydroxyl radical, singlet oxygen were found in the SRFA solutions of BPA with molecular probes and the technique of electronic spin resonance. The electronic energy transfer of triplet state fulvic acid was also studied with various aerated conditions. The results showed that the photodegradation of BPA was related with triplet state fulvic acid. The photodegradation products of BPA in the presence of SRFA were identified with GC/MS methods. The photodegradation pathways of BPA were also discussed.

The qualitative and quantitative analyses of reactive oxygen species are essential to determine their steady-state concentration and related reaction mechanisms in environmental aquatic systems. In this study, salicylic acid was employed as an innovative molecular probe of hydroxyl radical(OH) generated in aqueous nitrate and nitrite solutions through photochemical reactions. Kinetic studies showed that the steady-state concentrations of OH in aqueous NO3- (10 mmol/L, pH = 5) and NO2- (10 mmol/L, pH = 5) solutions under ultraviolet irradiation were at a same magnitude, 10(-15) mol/L. Apparent quantum yields of OH at 313 nm were measured as 0.011 and 0.07 for NO3- and NO2- respectively, all comparable to the results of previous studies.