Mechanochemical Formation of Poly(melamine-formaldehyde) Microplastic Fibers During Abrasion of Cleaning Sponges.

The abrasion of synthetic textile fibers is a significant factor in the generation of environmental microplastic fibers (MPFs). The extent to which polymer sponges designed specifically for surface cleaning have a tendency to release MPFs during normal use remains unknown. Here, the tribological behaviors of melamine cleaning sponges (also known as "magic erasers") with different strut densities against metal surfaces of different roughness were investigated using a reciprocating abrader. The MPFs formed by sponge wear under various conditions were characterized in terms of their morphology, composition, and quantity. They were mainly composed of poly(melamine-formaldehyde) polymer with linear or branched fiber morphologies (10-405 µm in length), which were formed through deformation and fracture of the struts within open cells of the sponges, facilitated by friction-induced polymer decomposition. The rate and capability of MPF production generally increased with increasing roughness of the metal surface and density of the struts, respectively. The sponge wear could release 6.5 million MPFs/g, which could suggest a global overall emission of 4.9 trillion MPFs due to sponge consumption. Our study reveals a hitherto unrecognized source of the environmental MPF contamination and highlights the need to evaluate exposure risks associated with these new forms of MPFs.

Maize (Zea mays L.) Plants Alter the Fate and Accumulate Nonextractable Residues of Sulfamethoxazole in Farmland Soil.

The fate of sulfonamide antibiotics in farmlands is crucial for food and ecological safety, yet it remains unclear. We used [phenyl-U-14C]-labeled sulfamethoxazole (14C-SMX) to quantitatively investigate the fate of SMX in a soil-maize system for 60 days, based on a six-pool fate model. Formation of nonextractable residues (NERs) was the predominant fate for SMX in unplanted soil, accompanied by minor mineralization. Notably, maize plants significantly increased SMX dissipation (kinetic constant kd = 0.30 day-1 vs 0.17 day-1), while substantially reducing the NER formation (92% vs 58% of initially applied SMX) and accumulating SMX (40%, mostly bound to roots). Significant NERs (maximal 29-42%) were formed via physicochemical entrapment (determined using silylation), which could partially be released and taken up by maize plants. The NERs consisted of a considerable amount of SMX formed via entrapment (1-8%) and alkali-hydrolyzable covalent bonds (2-12%, possibly amide linkage). Six and 10 transformation products were quantified in soil extracts and NERs, respectively, including products of hydroxyl substitution, deamination, and N-acylation, among which N-lactylated SMX was found for the first time. Our findings reveal the composition and instability of SMX-derived NERs in the soil-plant system and underscore the need to study the long-term impacts of reversible NERs.

Long-Term Field Study on Fate, Transformation, and Vertical Transport of Tetrabromobisphenol A in Soil-Plant Systems.

Soil contamination with tetrabromobisphenol A (TBBPA) has been an environmental concern for many years, but in situ studies of the fate and potential risk of TBBPA are lacking. In this study, we investigated the dissipation, metabolism, strong alkali-hydrolytic (SAH-TBBPA), and vertical movement of TBBPA in the field with and without rice-wheat rotation and reed growth for 1225 days. After 342 days of incubation, 21.3% of the TBBPA remained in the surface soil accompanied by obvious leaching to deeper soil layers in the first 92 days. By day 1225, TBBPA was nearly absent from the surface soil layer. A very low amount of SAH-TBBPA (2.31-3.43 mg/kg) was detected during the first 342 days of incubation. In the surface soil, five metabolites were identified that represented four interconnected pathways: oxidative skeletal cleavage, O-methylation, type II ipso-substitution, and reductive debromination. Both rice-wheat rotation and monocultural reed growth accelerated TBBPA removal in the field by stimulating the anaerobic debromination and aerobic O-methylation, especially the oxidative skeletal cleavage of TBBPA in the rhizosphere soil. Though far from comprehensive, our study investigated the natural attenuation and metabolism of TBBPA in situ and the influence by crops to estimate the environmental risk of TBBPA in a field scale.

Fungal endophytes promote the accumulation of Amaryllidaceae alkaloids in Lycoris radiata.

Lycoris radiata is a main source of Amaryllidaceae alkaloids; however, the low content of these alkaloids in planta remains a limit to their pharmaceutical development and utilization. The accumulation of secondary metabolites can be enhanced in plants inoculated with fungal endophytes. In this study, we analysed the diversity of culturable fungal endophytes in different organs of L. radiata. Then, by analysing the correlation between the detectable rate of each fungal species and the content of each tested alkaloid, we proposed several fungal candidates implicated in the increase of alkaloid accumulation. This was verified by inoculating these candidates to L. radiata plants. Based on the results of two independent experiments conducted in May 2018 and October 2019, the individual inoculation of nine fungal endophytes significantly increased the total content of the tested alkaloids in the entire L. radiata plants. This is the first study in L. radiata to show that fungal endophytes are able to improve the accumulation of various alkaloids. Therefore, our results provide insights into a better understanding of interactions between plants and fungal endophytes and suggest an effective strategy for enhancing the alkaloid content in the cultivation of L. radiata.

Linkage mapping and genome-wide association reveal candidate genes conferring thermotolerance of seed-set in maize.

It is predicted that high-temperature stress will increasingly affect crop yields worldwide as a result of climate change. In order to determine the genetic basis of thermotolerance of seed-set in maize under field conditions, we performed mapping of quantitative trait loci (QTLs) in a recombinant inbred line (RIL) population using a collection of 8329 specifically developed high-density single-nucleotide polymorphism (SNP) markers, combined with a genome-wide association study (GWAS) of 261 diverse maize lines using 259 973 SNPs. In total, four QTLs and 17 genes associated with 42 SNPs related to thermotolerance of seed-set were identified. Among them, four candidate genes were found in both linkage mapping and GWAS. Thermotolerance of seed-set was increased significantly in near-isogenic lines (NILs) that incorporated the four candidate genes in a susceptible parent background. The expression profiles of two of the four genes showed that they were induced by high temperatures in the maize tassel in a tolerant parent background. Our results indicate that thermotolerance of maize seed-set is regulated by multiple genes each of which has minor effects, with calcium signaling playing a central role. The genes identified may be exploited in breeding programs to improve seed-set and yield of maize under heat stress.

Prevalence and Risk Factors of Infertility for Han, Uygur, and Kazakh Ethnicities in Xinjiang Rural Residents.

OBJECTIVE: To estimate the prevalence and associated factors of current infertility for Han, Uygur, and Kazakh ethnicities in Xinjiang rural residents. Chinese Uygur, Kazakh, and Han populations represent > 90% of the total population of the Xinjiang Uygur Autonomous Region, and their customs, culture, and food consumption are different. The effect of ethnic differences on infertility risk factors is rarely studied. STUDY DESIGN: A cross-sectional study of 5,086 married and common-law couples, with a female partner aged 18-49, living in Hami, Kuche, or Xinyuan counties in Xinjiang, China. General information for the study subjects, including demographic characteristics, life customs, sexual history, history of contraception use, and history of disease, was collected by questionnaire. General health, gynecologic examinations, and sociodemographic characteristics were also carried out. RESULTS: A total of 5,086 females from Xinjiang Province were surveyed, including 493 with infertility. The standardized prevalence rate of infertility was 9.7% (95% CI 8.9-10.5), and the prevalence of infertility in Han, Uygur, and Kazakh ethnicities was 6.8% (95% CI 5.7-7.9), 10.9% (95% CI 8.0-13.8), and 10.1% (95% CI 7.4-12.8), respectively. CONCLUSION: The present study suggests that the prevalence of infertility was lower in the Han as compared to the Kazakh and Uygur ethnicities.

Water management affects arsenic and cadmium accumulation in different rice cultivars.

Paddy rice (Oryza sativa L.) is a staple food and one of the major sources of dietary arsenic (As) and cadmium (Cd) in Asia. A field experiment was conducted to investigate the effects of four water management regimes (aerobic, intermittent irrigation, conventional irrigation and flooding) on As and Cd accumulation in seven major rice cultivars grown in Zhejiang province, east China. With increasing irrigation from aerobic to flooded conditions, the soil HCl-extractable As concentrations increased significantly and the HCl-extractable Cd concentrations decreased significantly. These trends were consistent with the As and Cd concentrations in the straw, husk and brown rice. Water management both before and after the full tillering stage affected As and Cd accumulation in the grains. The intermittent and conventional treatments produced higher grain yields than the aerobic and flooded treatments. Cd concentrations in brown rice varied 13.1-40.8 times and As varied 1.75-8.80 times among the four water management regimes. Cd and As accumulation in brown rice varied among the rice cultivars, with Guodao 6 (GD6) was a low Cd but high-As-accumulating cultivar while Indonesia (IR) and Yongyou 9 (YY9) were low As but high-Cd-accumulating cultivars. Brown rice Cd and As concentrations in the 7 cultivars were significantly negatively correlated. The results indicate that As and Cd accumulated in rice grains with opposite trends that were influenced by both water management and rice cultivar. Production of 'safe' rice with respect to As and Cd might be possible by balancing water management and rice cultivar according to the severity of soil pollution.

Fate of bisphenol A (BPA) in a flooded soil-rice system.

In this study, 14C-tracers were used to investigate the fate of BPA in flooded soil with or without rice plants during a complete growing period. In flooded soil, the dissipation of BPA (half-life 14.8 d) was accompanied by its mineralization (8.4% of the initially applied radioactivity) and the formation of non-extractable residues (NERs) in amounts (79.5%) similar to that formed under oxic conditions. The growth of rice significantly accelerated the dissipation of BPA in flooded soil, resulting in a reduction in both the half-life (5.6 d) and the amount of NERs (35.8%). Two non-polar metabolites were detected both in unplanted and in rice-planted soil. At rice harvest, 57.1% of the radioactivity had accumulated in rice plants, mainly as NERs (54.2%) rather than as extractable radioactivity (2.7%), and mainly in roots (34.5 ± 1.4%), stems (9.4 ± 1.1%), and leaves (8.8 ± 0.6%), with trace amounts in seeds (3.6 ± 0.3%) and seed shells (0.7 ± 0.05%). Our study thus demonstrates that the oxic-anoxic interface stimulates the dissipation of BPA in flooded soil. The link between the releasing of NERs in flooded soil and the uptake of BPA metabolites by rice should be considered in environmental risk assessments of agroecosystems.

Sample size calculation for the proportional hazards cure model.

In clinical trials with time-to-event endpoints, it is not uncommon to see a significant proportion of patients being cured (or long-term survivors), such as trials for the non-Hodgkins lymphoma disease. The popularly used sample size formula derived under the proportional hazards (PH) model may not be proper to design a survival trial with a cure fraction, because the PH model assumption may be violated. To account for a cure fraction, the PH cure model is widely used in practice, where a PH model is used for survival times of uncured patients and a logistic distribution is used for the probability of patients being cured. In this paper, we develop a sample size formula on the basis of the PH cure model by investigating the asymptotic distributions of the standard weighted log-rank statistics under the null and local alternative hypotheses. The derived sample size formula under the PH cure model is more flexible because it can be used to test the differences in the short-term survival and/or cure fraction. Furthermore, we also investigate as numerical examples the impacts of accrual methods and durations of accrual and follow-up periods on sample size calculation. The results show that ignoring the cure rate in sample size calculation can lead to either underpowered or overpowered studies. We evaluate the performance of the proposed formula by simulation studies and provide an example to illustrate its application with the use of data from a melanoma trial.

[A cross-sectional study on the current status of female infertility in three counties of Xinjiang Uygur Autonomous Region].

OBJECTIVE: To explore the distribution and factors associated with female infertility in 3 areas in Xinjiang Uygur Autonomous Region so as to provide rationales for the prevention, diagnosis and treatment of infertility. METHODS: A total of 1895 women of reproductive age were enrolled with a cluster random stratified sampling method. A questionnaire survey and pelvic examinations were conducted. The collected data were statistically analyzed. RESULTS: The prevalence of infertility in these three areas ranged from 7.5% (76/1014) to 26.2% (144/550) with an average of 15.2% (279/1835). The prevalence of infertility was the highest in Shan shan and it was related with its unique geographical environment and life style. The lower levels of education and income, the higher prevalence of infertility. The occurrence of infertility was also correlated with their residence, premarital sex, body mass index and some concurrent diseases. CONCLUSION: It is necessary to carry out further studies on healthful life styles and those factors associated with the morbidity of infertility. The prevalence of infertility may be reduced and local reproductive health improved by avoiding or reducing the adolescent premarital sex and unmarried abortion.

Peanut Rotation and Flooding Induce Rhizobacteriome Variation With Opposing Influences on the Growth and Medicinal Yield of Corydalis yanhusuo.

Corydalis yanhusuo, a precious herb of the Papaveraceae family, is widely used in multiple traditional Chinese medicines for the treatment of many painful conditions, and its medicinal part is the dried tuber. Yet how to improve this plant's medicinal yield as well as its economic efficiency remains a key problem in its cultivation. The planting of C. yanhusuo in rotation with peanut (Arachis hypogaea L.) aims to improve land utilization efficiency, but the total production of tubers is severely reduced relative to fields without rotation. However, an increased yield was observed in C. yanhusuo plants grown in previously flooded fields (HR field) compared to the ones grown in the fields that had been used to cultivate peanut (PL field) or in fields without rotation or flooding (N field). Based on these phenomena, in this study, we explored the potential factors responsible for the altered growth/yield of C. yanhusuo under different field conditions. Soil physicochemical properties and the diversity and community of rhizobacteriome of C. yanhusuo were both analyzed. By testing several soil physicochemical properties, we found that the cation exchange capacity (CEC), soil organic matter (SOM), total nitrogen (TN), and pH value differed significantly among these three types of fields. 16S rRNA amplicon sequencing revealed stark differences in the composition, diversity, and potential functions of the bacterial community in the rhizosphere of C. yanhusuo plants grown in field with the peanut rotation or flooding. Notably, the Acidobacteria were enriched in the HR field, while Actinobacteria were enriched in the PL field. More importantly, further analysis showed that changed soil physicochemical properties could be one reason for why the rhizospheric bacterial community has changed; hence, soil physicochemical properties might also be affecting plant performance indirectly by regulating the rhizospheric bacterial community. The RDA analysis distinguished CEC as the most important soil physicochemical property influencing the structure and composition of the C. yanhusuo rhizobacteriome. In summary, our results suggest peanut rotation- and flooding-induced soil physicochemical properties changes would further impact the rhizobacteriome of C. yanhusuo albeit differentially, culminating in opposite effects upon the plant growth and medicinal yield of C. yanhusuo.

Fate of bisphenol S (BPS) and characterization of non-extractable residues in soil: Insights into persistence of BPS.

The environmental fate and persistence of bisphenol S (BPS), a substitute for bisphenol A (BPA), are unclear. This study used 14C-labeled BPS to examine the fate, biodegradation, and residue properties of BPS incubated in an oxic soil for 28 days. BPS dissipated quickly, with a half-life of 2.8 days. Most of the BPS was mineralized (53.6 ± 0.2% of initial amount by day 28) or transformed into non-extractable residues (NERs) (45.1 ± 0.3%), with generation of minor extractable residues (3.7 ± 0.2%) containing two metabolites. NERs were formed mainly via physico-chemical entrapment (51.1 ± 2.4% of the total NERs, consisting almost exclusively of BPS) and ester-linkages (31.5 ± 3.0% of the total NERs, consisting of both BPS and polar metabolites). When mixed with fresh soil, BPS-derived NERs became unstable and bioavailable. Subsequent mineralization was determined for 19.5 ± 1.1% of the total NERs and 35.5 ± 2.6% of the physico-chemically entrapped BPS. A fate model was used to describe the kinetics of NER formation, which indicated that microbial activity in soil could have strongly reduced the kinetic rate of the release of physico-chemically entrapped NERs into free form and therefore increased the stability of this type of NERs in soil. Our results provide unique insights into the fate of BPS in soil and suggest that while BPS is biodegradable, it includes the formation of large amounts of reversibly physico-chemically entrapped and covalently bound ester-linked NERs. The instability of these NERs should be considered in assessments on environmental persistence and risks of BPS. Our study also points out the environmental importance of NERs of agrochemicals.

Insight into the interaction between Fe-based nanomaterials and maize (Zea mays) plants at metabolic level.

Properly understanding the fundamental interactions between engineered nanoparticles (NPs) and plants is crucial for nano-enabled agriculture. In this study, Fe and Fe3O4 (magnetite), which are naturally occurred nanosized crystals and minerals, were foliar applied to 4-week-old maize plants for 10 days to evaluate their impact on plant photosynthesis and growth. Hill reaction of isolated maize leaf chloroplasts was carried out to determine the performance of two Fe-based NPs on photosynthetic activities at cell level. Meanwhile, gas chromatography-mass spectrometry (GC-MS) based metabolomics was used to explore the deep insight into the interaction between Fe-based NPs and maize plants. Results showed that maize leaf net photosynthesis rate and chlorophyll content were significantly increased by Fe NPs for 19.9% and 19.3%; and Fe3O4 NPs for 27.5% and 26.1%, respectively. Accordingly, plant biomass has been significantly increased by Fe and Fe3O4 NPs by 31.8% and 34.6%, respectively. Metabolomics revealed that both Fe-based NPs induced metabolic reprogramming in maize leaves. The biosynthesis of some compatible solutes and antioxidant compounds were inhibited. In addition, exposure to Fe-based NPs tentatively shut down some energy consuming pathways, such as photorespiration, alanine metabolism, branch chain amino acid biosynthesis. The trade-off of energy consuming pathways might be alternative explanation for the enhanced photosynthesis. The results of this study exhibited the promising potential for Fe-based NPs to be used in nano-enabled agriculture to promote plant growth.

Release of tetrabromobisphenol A (TBBPA)-derived non-extractable residues in oxic soil and the effects of the TBBPA-degrading bacterium Ochrobactrum sp. strain T.

Tetrabromobisphenol A (TBBPA) forms large amount of non-extractable residues (NER) in soil. However, the stability of TBBPA-NER with TBBPA degrader in soil had not been determined. In this study, a 14C-tracer was used to follow the release and alteration of TBBPA-derived NER during 214 days of incubation in oxic soil and in the presence or absence of the TBBPA-degrading bacterium Ochrobatrum sp. strain T. In the absence of strain T, 1.89% of the TBBPA and its metabolites were slowly released from the NER, with TBBPA as the predominant component, accompanied by 2.47% mineralization by day 91 of the incubation. The addition of active cells strongly stimulated the release and mineralization of NER (10.93% and 4.64%, respectively), reduced the amount of the ester-linked fraction, and transformed NER from humin-bound to HA-bound forms. Cells added to the soil in sterilized form had much smaller effects on the stability and internal alterations of NER. Among the ester-linked compounds, 47.4% consisted of TBBPA; two metabolites were so detected. These results provide new information on the stability and internal transformation of TBBPA-NER in soil during its long-term incubation and underlines the importance of microbial TBBPA degraders in determining the composition of NER in soil.

Formation, characterization, and mineralization of bound residues of tetrabromobisphenol A (TBBPA) in silty clay soil under oxic conditions.

The nature and stability of bound residues (BRs) derived from the widely used brominated flame retardant tetrabromobisphenol A (TBBPA) in fine-textured soil is unknown. We incubated 14C-labeled TBBPA in silty clay rice paddy soil for 93days under oxic conditions. TBBPA dissipated with a first-order kinetic constant kd of 0.0474±0.0017day-1 (t1/2 14.6±0.3days) and mineralized with a km of 0.0011±0.00002day-1. At the end of the incubation, four metabolites, including two methylation products (TBBPA monomethyl and dimethyl ether), accounted for 7.9±0.1% of the initial TBBPA. The BRs continuously increased in amount to a maximum of 80.1±3.6%. About 86.3±0.9% of the BRs localized in the humin fraction and 55.9±1.5% was hydrolyzable with strong alkali (SAH-BRs), which represents reversible BRs. Together with results previously reported for coarse-textured soil, these results indicate that the absolute amounts of both BRs and SAH-BRs of TBBPA as well as the relative contribution of SAH-BRs to total BRs in fine-textured soil are markedly higher than in coarse-textured soil. When BRs-containing soil was incubated with fresh soil for 231days, 9.2±0.3% was mineralized (km 0.00047±0.00002day-1) and SAH-BRs decreased to 34.1±1.1%, accompanied by transformation into other BR forms. These indicate that BRs are bioavailable in the soil. Amendment with rice root exudates did not effectively affect the mineralization, release, and distribution of BRs, suggesting that bioavailability of BRs but not microbial activity limits the degradation of BRs in the silty clay soil. This study provides first insights into the nature and stability of TBBPA-derived BRs in fine-textured soil under oxic conditions and indicates the significant role of reversible BRs in the environmental risk of TBBPA.

Mineralisation of 14C-labelled polystyrene plastics by Penicillium variabile after ozonation pre-treatment.

Large amounts of polystyrene (PS), one of the most widely used plastics in the world, end up in the environment through industrial discharge and littering, becoming one of the major components of plastic debris. Such plastics, especially the small-sized microplastics and nanoplastics, have received increasing concerns in terms of their potential environmental risks. Feasible approaches for the degradation of PS in waste materials and in the environment are highly desirable. Physicochemical pretreatments of PS may be applied to enhance biological degradation. In the present study, we synthesized 14C-labelled PS polymers, either uniformly labelled on the ring ([U-ring-14C]-PS) or labelled at the ß-carbon position of the alkyl chain ([ß-14C]-PS), and investigated the mineralisation of the 14C-PS polymers by the fungus Penicillium variabile CCF3219 as well as the effect of ozonation as a physico-chemical pre-treatment on the mineralisation by the fungi. Biodegradation of the 14C-PS polymers was studied in liquid medium (pH 7.5, without additional carbon substrate) with P. variabile for 16 weeks. During the incubation time, 14CO2 was captured to calculate the mineralisation of 14C-PS and the remaining polymers were analysed by means of scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectrometry and gel-permeation chromatography (GPC). The results showed that the fungi mineralised both labelled polymers, and that the [U-ring-14C]-PS with a lower molecular weight led to a higher mineralisation rate. Ozonation pre-treatment strongly enhanced mineralisation of [ß-14C]-PS. SEM analysis showed that the surface of the ozonated [ß-14C]-PS became uneven and rough after the incubation, indicating an attack on the polymer by P. variabile. FT-IR analysis showed that ozonation generated carbonyl groups on the [ß-14C]-PS and the amount of the carbonyl groups decreased after incubation of the [ß-14C]-PS with P. variabile. GPC analysis showed that the molecular weights of the ozonated [ß-14C]-PS decreased after incubation. The present data suggest that ozonation pretreatment could be a potential approach for degradation of PS waste and remediation of PS-contaminated sites.

A Bayesian normal mixture accelerated failure time spatial model and its application to prostate cancer.

In the United States, prostate cancer is the third most common cause of death from cancer in males of all ages, and the most common cause of death from cancer in males over age 75. It has been recognized that the incidence of the prostate cancer is high in African Americans, and its occurrence and progression may be impacted by geographical factors. In order to investigate the spatial effects and racial disparities for prostate cancer in Louisiana, in this article we propose a normal mixture accelerated failure time spatial model, which does not require the proportional hazards assumption and allows the multi-model distribution to be modeled. The proposed model is estimated with a Bayesian approach and it can be easily implemented in WinBUGS. Extensive simulations show that the proposed model provides decent flexibility for a variety of parametric error distributions. The proposed method is applied to 2000-2007 Louisiana prostate cancer data set from the Surveillance, Epidemiology and End Results Program. The results reveal the possible spatial pattern and racial disparities for prostate cancer in Louisiana.

Fate and metabolism of the brominated flame retardant tetrabromobisphenol A (TBBPA) in rice cell suspension culture.

Tetrabromobisphenol A (TBBPA) is the brominated flame retardant with the highest production volume and its bioaccumulation in environment has caused both human health and environmental concerns, however the fate and metabolism of TBBPA in plants is unknown. We studied the fate, metabolites, and transformation of (14)C-labeled TBBPA in rice cell suspension culture. During the incubation for 14 days, TBBPA degradation occurred continuously in the culture, accompanied by formation of one anisolic metabolite [2,6-dibromo-4-(2-(2-hydroxy)-propyl)-anisole] (DBHPA) (50% of the degraded TBBPA) and cellular debris-bound residues (46.4%) as well as mineralization (3.6%). The cells continuously accumulated TBBPA in the cytoplasm, while a small amount of DBHPA (2.1% of the initially applied TBBPA) was detectable inside the cells only at the end of incubation. The majority of the accumulated residues in the cells was attributed to the cellular debris-bound residues, accounting for 70-79% of the accumulation after the first incubation day. About 5.4% of the accumulation was associated with cell organelles, which contributed 7.5% to the cellular debris-bound residues. Based on the fate and metabolism of TBBPA in the rice cell suspension culture, a type II ipso-substitution pathway was proposed to describe the initial step for TBBPA degradation in the culture and balance the fate of TBBPA in the cells. To the best of our knowledge, our study provides for the first time the insights into the fate and metabolism of TBBPA in plants and points out the potential role of type II ipso-hydroxylation substitution in degradation of alkylphenols in plants. Further studies are required to reveal the mechanisms for the bound-residue formation (e.g., binding of residues to specific cell wall components), nature of the binding, and toxicological effects of the bound residues and DBHPA.

NPHMC: an R-package for estimating sample size of proportional hazards mixture cure model.

Due to advances in medical research, more and more diseases can be cured nowadays, which largely increases the need for an easy-to-use software in calculating sample size of clinical trials with cure fractions. Current available sample size software, such as PROC POWER in SAS, Survival Analysis module in PASS, powerSurvEpi package in R are all based on the standard proportional hazards (PH) model which is not appropriate to design a clinical trial with cure fractions. Instead of the standard PH model, the PH mixture cure model is an important tool in handling the survival data with possible cure fractions. However, there are no tools available that can help design a trial with cure fractions. Therefore, we develop an R package NPHMC to determine the sample size needed for such study design.