The associations between gut microbiota and fecal metabolites with intelligence quotient in preschoolers.

BACKGROUND: The awareness of the association between the gut microbiota and human intelligence levels is increasing, but the findings are inconsistent. Furthermore, few research have explored the potential role of gut microbial metabolites in this association. This study aimed to investigate the associations of the gut microbiota and fecal metabolome with intelligence quotient (IQ) in preschoolers. METHODS: The 16 S rRNA sequencing and widely targeted metabolomics were applied to analyze the gut microbiota and fecal metabolites of 150 children aged 3-6 years. The Wechsler Preschool and Primary Scale of Intelligence, Fourth Edition (WPPSI-IV) was used to assess the cognitive competence. RESULTS: The observed species index, gut microbiome health index, and microbial dysbiosis index presented significant differences between children with full-scale IQ (FSIQ) below the borderline (G1) and those with average or above-average (all P < 0.05). The abundance of Acinetobacter, Blautia, Faecalibacterium, Prevotella_9, Subdoligranulum, Collinsella, Dialister, Holdemanella, and Methanobrevibacter was significantly associated with preschooler's WPPSI-IV scores (P < 0.05). In all, 87 differential metabolites were identified, mainly including amino acid and its metabolites, fatty acyl, and benzene and substituted derivatives. The differential fecal metabolites carnitine C20:1-OH, 4-hydroxydebrisoquine, pantothenol, creatine, N,N-bis(2-hydroxyethyl) dodecanamide, FFA(20:5), zerumbone, (R)-(-)-2-phenylpropionic acid, M-toluene acetic acid, trans-cinnamaldehyde, isonicotinic acid, val-arg, traumatin, and 3-methyl-4-hydroxybenzaldehyde were significantly associated with the preschooler's WPPSI-IV scores (P < 0.05). The combination of Acinetobacter, Isonicotinic acid, and 3-methyl-4-hydroxybenzaldehydenine may demonstrate increased discriminatory power for preschoolers in G1. CONCLUSION: This study reveals a potential association between gut microbiome and metabolites with IQ in preschoolers, providing new directions for future research and practical applications. However, due to limitations such as the small sample size, unclear causality, and the complexity of metabolites, more validation studies are still needed to further elucidate the mechanisms and stability of these associations.

Association between maternal metal exposure during early pregnancy and intelligence in children aged 3-6 years: Results from a Chinese birth cohort.

OBJECTIVE: Maternal environmental metal exposure is common, but long-term prospective epidemiological evidence of its impact on children's intellectual development is still insufficient. METHODS: Data on maternal plasma metal levels and child intelligence were obtained for 211 3-6-year-old children from Guangxi Zhuang Birth Cohort. ICP-MS was employed to detect 17 metals, including 7 essential metals (Mn, Fe, Co, Ni, Cu, Zn, Mo) and 10 non-essential metals (As, Rb, Sr, Cd, Sb, Cs, Ba, W, Pb, U), in maternal plasma samples obtained before 13 weeks of gestation during the initial maternity checkup. Child intelligence was assessed using the Wechsler Intelligence Scale for Children-Fourth Edition. The GLM, RCS and mixture models were used to assess the associations of maternal plasma metal levels with child intelligence quotient (IQ) scores. RESULTS: The GLM analysis revealed that U had a significant adverse effect on child IQ scores in high-dose exposure groups (-9.236 [-18.644, -4.936], p = 0.006) after adjusting for covariates, while Sb showed a linear adverse effect on children's intelligence in the adjusted model (-4.028 [-7.432, -0.626], p = 0.021). BKMR modeling indicated that overall IQ scores decreased as concentrations of non-essential metals mixtures increased after adjusting for essential metal mixtures, consistent with findings from the WQS (ß [95% CI], -8.463 [-14.449, -2.476], p = 0.007) and Qgcomp models (-7.003 [-12.928, -1.078], p = 0.022). Among the non-essential metals, U had the highest negative weight at 37.96%, followed by Pb (23.35%) and Sb (16.91%). Furthermore, potential interactions were observed between metals (Pb and U) and Sb in the study findings. CONCLUSION: Reducing exposure to non-essential metal mixtures, especially U, Sb and Pb, during early pregnancy and ensuring adequate intake of specific essential metal elements could be a critical intervention in addressing childhood intellectual impairment.

Association between prenatal exposure to alkylphenols and intelligence quotient among preschool children: sex-specific effects.

BACKGROUND: While prenatal exposure to alkylphenols (APs) has been demonstrated to be associated with neurodevelopmental impairments in animals, the evidence from epidemiological studies remains limited and inconclusive. This study aimed to explore the link between AP exposure during pregnancy and the intelligence quotient (IQ) of preschool children. METHODS: A total of 221 mother-child pairs from the Guangxi Zhuang Birth Cohort were recruited. Nonylphenol (NP), 4-tert-octylphenol (4-T-OP), 4-n-nonylphenol (4-N-NP), and 4-n-octylphenol were measured in maternal serum in early pregnancy. Childhood IQ was evaluated by the Fourth Edition of Wechsler Preschool and Primary Scale of the Intelligence at 3 to 6 years of age. The impact of APs on childhood IQ were evaluated by generalized linear models (GLMs), restricted cubic spline (RCS), and Bayesian kernel machine regression (BKMR). RESULTS: In GLMs, prenatal exposure to NP and the second tertile of 4-T-OP exhibited an inverse association with full-scale IQ (FSIQ) (ß = -2.38; 95% CI: -4.59, -0.16) and working memory index (WMI) (ß = -5.24; 95% CI: -9.58, -0.89), respectively. Prenatal exposure to the third tertile of 4-N-NP showed a positive association with the fluid reasoning index (ß = 4.95; 95% CI: 1.14, 8.77) in total children, as well as in girls when stratified by sex. A U-shaped relationship between maternal 4-T-OP and WMI was noted in total children and girls by RCS (all P nonlinear < 0.05). The combined effect primarily driven by NP, of maternal AP mixtures at concentrations above the 50th percentile exhibited an inverse trend on FSIQ in total children and girls in BKMR. CONCLUSIONS: Prenatal exposure to various APs affects IQ in preschool children, and there may be nonmonotonic and sex-specific effects. Further investigation across the population is required to elucidate the potential neurotoxic effects of APs.

Associations of prenatal exposure to per- and polyfluoroalkyl substances and fetal sex hormones in the Guangxi Zhuang Birth Cohort Study: Greater effect of long-chain PFAS.

Fetal sex hormone homeostasis disruption could lead to reproductive and developmental abnormalities. However, previous studies have reported inconsistent findings regarding the association of maternal per- and polyfluoroalkyl substances (PFAS) exposure with fetal sex hormone levels. A total of 277 mother-infant pairs from the Guangxi Zhuang Birth Cohort Study between 2015 and 2019 were selected. We quantified nine PFAS in maternal serum in early pregnancy, and detected three sex hormones, namely, estradiol (E2), progesterone (P4) and testosterone (TT), in cord blood. The generalized linear model (GLM) and Bayesian kernel machine regression (BKMR) model were used for single- and multiple-exposure analyses, respectively. In the GLM, there was no significant association between an individual PFAS and any hormone level or the E2/TT ratio, but a negative association between perfluorododecanoic acid (PFDoA) exposure and P4 levels in female infants was observed after stratification by sex. In the BKMR, a mixture of nine PFAS was positively associated with E2 levels and the E2/TT ratio, with the same main contributors, i.e., perfluoroundecanoic acid (PFUnA). And PFAS mixtures were not associated with P4 or TT levels. After stratification by infant sex, positive associations of PFAS mixtures with E2 levels and the E2/TT ratio were observed only in male infants, with the same main contributors, i.e., PFUnA. There was a positive association between PFAS mixtures and P4 levels in male infants, in which PFUnA was the main contributor; but a reverse association between PFAS mixtures and P4 levels in female infants, in which PFDoA was the main contributor. This study suggested that prenatal exposure to PFAS mixtures is associated with fetal sex hormones, and long-chain PFAS may play an important role in this association. Furthermore, sex differences in the association of maternal PFAS exposure with E2 and P4 levels need additional attention.

Exposure to alkylphenols during early pregnancy and the risk of gestational diabetes mellitus: Fetal sex-specific effects.

Alkylphenols (APs) may cause gestational diabetes mellitus (GDM) in pregnant women by impairing glucose metabolism through endocrine disruption. However, the current literature has limited epidemiological evidence on the association between APs exposure and the risk of GDM, especially the lack of evidence on joint exposure. Thus, we evaluated the effect of exposure to APs during early pregnancy on the risk of GDM. The study involved 2035 pregnant women from Guangxi Zhuang Birth Cohort (GZBC) in China. Poisson regression model, restricted cubic spline (RCS), Bayesian kernel machine regression (BKMR), and quantile g-computation (Qgcomp) were conducted to evaluate the effects of serum APs levels on the risk of GDM in pregnant women. For each Ln-unit increase in the serum nonylphenol (NP) of pregnant women, the adjusted relative risk (RR) for GDM risk was 1.12 (95 % CI: 1.00, 1.24). After sex stratification, the effect was more pronounced among pregnant women carrying female fetuses（RR=1.22; 95 % CI: 1.09, 1.38). The serum 4-t-octylphenol (4-T-OP) of the medium-exposure (adjusted RR = 3.25: 95 % CI: 1.30, 8.12) and high-exposure groups (adjusted RR = 2.90: 95 % CI: 1.15, 7.31) were related to a significantly increased risk of GDM in pregnant women carrying female fetuses only when compared to the low-exposure group. A reverse U-shaped nonlinear association was found between 4-n-octylphenol (4-N-OP) and 4-n-nonylphenol (4-N-NP) concentrations and GDM risk, and it was more susceptible in pregnant women carrying female fetuses. The Qgcomp and BKMR models showed that exposure to APs mixtures was correlated with an elevated risk of GDM in pregnant women carrying female fetuses (adjusted OR = 1.90: 95 % CI: 1.07, 3.38). Exposure to APs during early pregnancy may have potential fetal sex-specific effects on the risk of GDM, with pregnant women carrying female fetuses being more susceptible.

Effects of prenatal single and mixed bisphenol exposure on bone mineral density in preschool children: A population-based prospective cohort study.

Exposure to bisphenols can affect bone mineral density (BMD) in animals and humans. However, the effects of maternal exposure to bisphenols during pregnancy on bone health in preschool children remain unknown. We aimed to assess the effects of prenatal exposure to single and multiple bisphenols on bone health in preschool children. A total of 230 mother-child pairs were included in this study. Generalized linear regression, restricted cubic spline (RCS), principal component analysis (PCA), and Bayesian kernel machine regression (BKMR) were utilized to assess the relationship between bisphenol levels and bone health in preschool children. Each natural log (Ln) unit increase in tetrabromobisphenol A was related to a 0.007 m/s (95 % CI: -0.015, 0.000) decrease in Ln-transformed speed of sound (SOS) among girls. Decreased BMD Z scores in preschool children were found only in the high bisphenol S exposure group (ß = -0.568; 95 % CI: -1.087, -0.050) in boys. The risk of low BMD (BMDL) was significantly higher in the middle-exposure group (OR = 4.695; 95 % CI: 1.143, 24.381) and high-exposure group of BPS (OR = 6.165, 95 % CI: 1.445, 33.789) compared with the low-exposure group in boys. In girls, the risk of BMDL decreased with increasing bisphenol A concentration (OR = 0.413, 95 % CI: 0.215, 0.721). RCS analysis revealed a U-shaped nonlinear correlation between BPB concentration and BMDL in girls (P-overall = 0.011, P-nonlinear = 0.009). In PCA, a U-shaped dose-response relationship was found between PC2 and the risk of BMDL (P-overall = 0.048, P-nonlinear = 0.032), and a significant association was only noted in girls when stratified by sex. The BKMR model revealed a horizontal S-shaped curve relationship between bisphenol mixtures and BMDL in girls. The results indicated that prenatal exposure to single and mixed bisphenols can affect BMD in preschool children, exerting nonmonotonic and child sex-specific effects.

Single and mixed effects of prenatal exposure to multiple bisphenols on hemoglobin levels and the risk of anemia in pregnant women.

INTRODUCTION: Bisphenols have endocrine-disrupting effects, which may disrupt hemoglobin (Hb) homeostasis and lead to anemia. However, the effects of bisphenols on anemia remain unknown. Therefore, we assessed the effects of single- and multiple-exposure to bisphenols on Hb levels and anemia of pregnant women. METHODS: The study involved 2035 pregnant women from Guangxi Zhuang Birth Cohort in China. Generalized linear regression, principal component analysis (PCA), quantile g-computation (Qgcomp), and Bayesian kernel machine regression (BKMR) were performed to examine the effects of serum bisphenols on Hb levels and the risk of anemia. RESULTS: After adjustment, elevated bisphenol A (BPA) levels were correlated with decreased Hb concentrations (ß = -0.51; 95%CI: -0.92, -0.10) in the first trimester, and these correlations were more sensitive in mothers of males. Compared with the low-exposure group, bisphenol B (BPB) levels in the high-exposure group led to a 1.52 g/L (95%CI: -3.01, -0.03) decrease in Hb levels in the second trimester; tetrabromobisphenol A (TBBPA) levels in the high-exposure group led to a higher the risk of anemia in the third trimester (OR = 1.46; 95%CI: 1.07, 1.99); bisphenol F (BPF) in the high-exposure group led to lower Hb levels (ß = -2.42; 95%CI:-4.69, -0.14) in mothers of male fetuses in the third trimester. Qgcomp showed that elevated levels of bisphenol mixture was correlated with (ß = -1.42; 95%CI: -2.61, -0.24) decrease in Hb levels in the second trimester. PCA revealed a negative association between PC2 and Hb levels in the first trimester (ß = -0.89; 95%CI: -1.61, -0.17). Similarly, a negative relationship was observed between PC1 and Hb levels in the third trimester among mothers with male fetuses (ß = -1.00; 95%CI: -1.94, -0.06). CONCLUSIONS: Prenatal exposure to single and mixed bisphenols may decrease Hb levels and increase the risk of anemia during pregnancy, the associations may be greater in mothers with male fetuses than those with female fetuses.

Population Study Confirms Serum Proteins' Change and Reveals Diagnostic Values in Congenital Ventricular Septal Defect.

This study was designed to validate thrombospondin 1 (TSP-1), vascular endothelial-cadherin complex (VE-cad), insulin-like growth factor 2 (IGF-2), and amyloid precursor protein (APP) and assess their diagnostic value in ventricular septal defect (VSD). We investigated the serum levels of TSP-1, VE-cad, IGF-2, and APP by enzyme-linked immunosorbent assay in a hospital-based case-control study that included 40 VSD children and 40 healthy controls. Logistic regression analysis was applied to evaluate the relationship of the proteins and VSD, and receiver operating characteristic (ROC) curve was used to assess the diagnostic value of the significant proteins. The serum levels of TSP-1, VE-cad, and IGF-2 were significantly higher in VSD patients than those in healthy controls (p < 0.05). Multivariate logistic regression analysis demonstrated that high levels of TSP-1, VE-cad, and IGF-2 were significantly associated with an increased risk of VSD [TSP-1 (OR 26.91, 95% CI 6.60-72.66, p < 0.001), VE-cad (OR 11.91, 95% CI 3.90-36.36, p < 0.001), IGF-2 (OR 3.25, 95% CI 1.25-8.43, p = 0.015)]. Areas under the ROC curve for TSP-1, VE-cad, and IGF-2 were 0.985, 0.838, and 0.658, respectively. These data demonstrated that TSP-1, VE-cad, and IGF-2 were significantly associated with risk of VSD and manifested diagnostic values, which may provide new evidence for understanding the etiology and promote the early diagnosis and prevention of VSD.

Associations between maternal exposure to multiple metals and metalloids and blood pressure in preschool children: A mixture-based approach.

BACKGROUND: Exposure to metals during pregnancy can potentially influence blood pressure (BP) in children, but few studies have examined the mixed effects of prenatal metal exposure on childhood BP. We aimed to assess the individual and combined effects of prenatal metal and metalloid exposure on BP in preschool children. METHODS: A total of 217 mother-child pairs were selected from the Zhuang Birth Cohort in Guangxi, China. The maternal plasma concentrations of 20 metals [e.g. lead (Pb), rubidium (Rb), cesium (Cs), and zinc (Zn)] in early pregnancy were measured by inductively coupled plasmamass spectrometry. Childhood BP was measured in August 2021. The effects of prenatal metal exposure on childhood BP were explored by generalized linear models, restricted cubic spline and Bayesian kernel machine regression (BKMR) models. RESULTS: In total children, each unit increase in the log10-transformed maternal Rb concentration was associated with a 10.82-mmHg decrease (95% CI: -19.40, -2.24) in childhood diastolic BP (DBP), and each unit increase in the log10-transformed maternal Cs and Zn concentrations was associated with a 9.67-mmHg (95% CI: -16.72, -2.61) and 4.37-mmHg (95% CI: -8.68, -0.062) decrease in childhood pulse pressure (PP), respectively. The log10-transformed Rb and Cs concentrations were linearly related to DBP (P nonlinear=0.603) and PP (P nonlinear=0.962), respectively. Furthermore, an inverse association was observed between the log10-transformed Cs concentration and PP (ß =-12.18; 95% CI: -22.82, -1.54) in girls, and between the log10-transformed Rb concentration and DBP (ß =-12.54; 95% CI: -23.87, -1.21) in boys, while there was an increasing association between the log10-transformed Pb concentration and DBP there was an increasing in boys (ß =6.06; 95% CI: 0.36, 11.77). Additionally, a U-shaped relationship was observed between the log10-transformed Pb concentration and SBP (P nonlinear=0.015) and DBP (P nonlinear=0.041) in boys. Although there was no statistically signiffcant difference, there was an inverse trend in the combined effect of maternal metal mixture exposure on childhood BP among both the total children and girls in BKMR. CONCLUSIONS: Prenatal exposure to both individual and mixtures of metals and metalloids influences BP in preschool children, potentially leading to nonlinear and sex-specific effects.

Association between maternal exposure to per- and polyfluoroalkyl substances and serum markers of liver function during pregnancy in China: A mixture-based approach.

Previous studies have shown that per- and polyfluoroalkyl substances (PFAS) may have hepatotoxic effects in animals. However, epidemiological evidence in humans, especially pregnant women, is limited. This study aimed to assess the association of single and multiple PFAS exposure with serum markers of liver function in pregnant women. A total of 420 pregnant women from the Guangxi Zhuang Birth Cohort were enrolled from June 2015 to April 2019. Nine PFAS were measured in the maternal serum in early pregnancy. Data for liver function biomarkers, namely, alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyltransferase (GGT), total bilirubin (TBIL), direct bilirubin (DBIL), and indirect bilirubin (IBIL), were obtained from medical records. In generalized linear model (GLM), there was a positive association of perfluorooctane sulfonate (PFOS) with ALT, perfluorodecanoic acid (PFDA) and perfluorobutanesulfonic acid (PFBS) with GGT, and perfluorohexane sulfonate (PFHxS) with TBIL and IBIL. In contrast, there was a negative association of perfluoroheptanoic acid (PFHpA) with TBIL. There were inverse U-shaped relationships of PFUnA with ALT and AST and PFDA with ALT by restricted cubic spline. The weighted quantile sum (WQS) regression model revealed the positive effects of the PFAS mixture on GGT, TBIL, DBIL, and IBIL. Bayesian kernel machine regression (BKMR) analysis confirmed that the PFAS mixture was positively associated with GGT, and PFBS was the main contributor. In addition, the BKMR model showed a positive association of individual PFBS with GGT, individual PFHxS with TBIL and IBIL, and a negative association of individual PFHpA with TBIL. Our findings provide evidence of an association between individual PFAS, PFAS mixture and maternal serum markers of liver function during pregnancy. Additionally, these findings also enhance concerns over PFAS exposure on maternal liver function and PFAS monitoring in pregnancy, reducing the effect of maternal liver dysfunction on maternal and infant health.

Confirmation of three inflammatory bowel disease susceptibility loci in a Chinese cohort.

PURPOSE: Recent genome-wide association studies have identified a number of inflammatory bowel diseases (IBD) susceptibility loci in White populations. The aim of our study was to evaluate whether these susceptibility loci also existed in a Chinese Han IBD population. METHODS: Peripheral blood DNA samples from groups of patients with Crohn's disease (CD) (n = 48), ulcerative colitis (UC) (n = 49), and healthy controls (n = 50) were genotyped for eight genes. Then, an extended analysis of the relationship between genotype and phenotype was performed. RESULTS: NOD2-P268S (P = 0.025) was found to contribute susceptibility to CD in the Chinese population. IL23R-rs11805303 was detected to confer a strong protective effect against UC (P = 0.010), whereas PTPN2-rs2542151 was significantly associated with an increased risk of UC (P = 0.001). Further phenotype-genotype analysis revealed that P268S was associated with early age of onset (P = 0.028), ileal disease (P = 0.003), and enteric cavity narrowing (P = 0.007). CONCLUSIONS: The study indicates that IL23R-rs11805303 and PTPN2-rs2542151 might contribute to the development of UC and NOD2-P268S might be involved in the etiology of CD in the Chinese Han population.

Associations of bisphenol exposure with thyroid hormones in pregnant women: a prospective birth cohort study in China.

Bisphenols are endocrine disruptor chemicals that disrupt thyroid hormone homeostasis. However, evidence on the effects of bisphenol mixtures on thyroid hormones are insufficient. Therefore, the present study aimed to explore the effects of bisphenol substitutes and bisphenol mixtures on thyroid hormones during pregnancy. The study was conducted among 446 pregnant women in the Guangxi Zhuang Birth Cohort (GZBC), China. In multiple linear regressions, compared with the low-exposure group, bisphenol S (BPS) concentrations in the middle-exposure group led to a 10.90% (95% CI: - 18.16%, - 2.99%) decrease in triiodothyronine (T3) levels in the first trimester; tetrabromobisphenol A (TBBPA) levels in the middle-exposure group led to an 8.26% (95% CI: - 15.82%, - 0.01%) decrease in T3 levels in the first trimester; bisphenol B (BPB) levels in the middle-exposure group led to higher free thyroxine (FT4) levels (9.84%; 95% CI: 1.73%, 18.60%) in the second trimester; bisphenol F (BPF) in the middle-exposure group led to higher FT4 levels (8.59%, 95% CI: 0.53%, 17.31%) in the second trimester; and TBBPA levels in the high-exposure group led to a 9.39% (95% CI: 1.46%, 17.93%) increase in FT4 levels in the second trimester. The Bayesian kernel machine regression (BKMR) and restricted cubic spline (RCS) models showed a U-shaped dose-response relationship between bisphenol A (BPA) and free triiodothyronine (FT3) (p < 0.01) as well as BPS and FT4 (p < 0.05). Nonlinear relationships were also observed between the bisphenol mixture and FT3. Overall, maternal bisphenol exposure affected thyroid hormone levels during pregnancy. This study provides evidence that BPB, BPF, BPS, and TBBPA are unsafe substitutes for BPA, as well as the overall effect of bisphenols on adverse health in human beings.

Pollution and Ecological Risk Evaluation of Heavy Metals in the Soil and Sediment around the HTM Tailings Pond, Northeastern China.

Tailings ponds are a main heavy metal pollution source in mining areas. In this study, the geo-accumulation index (Igeo) and the potential ecological risk index (RI) are used to evaluate the environmental impact of Hongtou Mountain (HTM) tailings pond on the surrounding area. Farmland soil, surface water, and sediment samples in the Hun River around the HTM tailings pond were collected. Heavy metal contents in the samples were analyzed by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results show that Cu, Zn, and Cd content in the farmland soil and sediment around the lower reaches of the Hun River (HTM tailings pond section) are obviously higher than the upper reaches. The Igeo values show that the farmland soil near the outlet of the tailings pond is the most polluted area. Cu was classified as moderate-strongly pollution, Zn was moderately pollution, and Cd was strongly pollution. Cd is the major pollutant in farmland soil, the monomial ecological risk (Eri) for Cd is a very high potential ecological risk. The potential ecological risk of sediment in the dry season is more serious than in the raining season. In the dry season, the Igeo index shows strong pollution for Cu and Cd at the confluence of the Hun River and the tributary from the HTM tailings pond, and a moderate-strongly pollution for Zn. Whereas, the Eri index shows that the monomial ecological risk for Zn at H3 is low, and Cu is moderate. The potential ecological risk at H3 is high, and Cd is the main source of the ecological risk around the HTM tailings pond.

Impact of Titanium Dioxide Nanoparticles on Cd Phytotoxicity and Bioaccumulation in Rice (Oryza sativa L.).

The impact of engineered nanoparticles (ENPs) on the migration and toxicity of coexisting pollutants is still unclear, especially in soil media. This study aims to evaluate the impact of titanium dioxide nanoparticles (TiO2 NPs) on the phytotoxicity of cadmium (Cd) to Oryza sativa L., and the migration of cadmium (Cd) in the soil-rice system. Three different Cd stress groups (C1 group: 1.0 mg kg-1, C2 group: 2.5 mg kg-1 and C3 group: 5.0 mg kg-1) were set in the pot experiment, and the target concentration of TiO2 NPs in each group were 0 mg kg-1 (T0), 50 mg kg-1 (T1), 100 mg kg-1 (T2) and 500 mg kg-1 (T3). Plant height and biomass decreased with the increasing of Cd content in paddy soil. TiO2 NPs could lower the phytotoxicity of Cd in terms of the changes in the morphological and biochemical characteristics, especially in the tillering and booting stage. In the tillering stage, TiO2 NPs addition caused a significant increase in plant height, biomass and the total chlorophyll content in the leaves of Oryza saliva L. In the booting stage, TiO2 NPs addition caused a 15% to 32% and 24% to 48% reduction of malondialdehyde (MDA) content for the C2 and C3 group, respectively, compared to that of the respective control treatment (T0). TiO2-NPs addition reduced the activity of peroxidase (POD) in the leaves in the booting and heading stage, and the activity of catalase (CAT) in the tillering stage. In the C1 and C2 group, the grain Cd content in the 100 and 500 mg kg-1 TiO2 NPs treatments reached 0.47-0.84 mg kg-1, obviously higher than that of the treatment without TiO2 NPs (0.27-0.32 mg kg-1), suggesting that TiO2-NPs could promote Cd migration in the soil-rice system.

Effect of Metal Oxide Nanoparticles on the Chemical Speciation of Heavy Metals and Micronutrient Bioavailability in Paddy Soil.

The effects of engineered nanoparticles (ENPs) on heavy metal fate and biotoxicity in farmland soil are mostly unknown. A flooding-drying simulation experiment was conducted to study the effects of three typical metal oxide nanoparticles (TiO2-NPs, ZnO-NPs and CuO-NPs) on the chemical speciation of heavy metals and micronutrient bioavailability in paddy soil. The results showed that the addition of ZnO-NPs and CuO-NPs caused significant increases in soil pH, Eh and EC after a 90-d flooding-drying process. ZnO-NPs and CuO-NPs addition caused clearly increase in the Zn and Cu concentrations in the acid-soluble fraction, Fe/Mn oxides-bound fraction and organic-bound fraction, leading to higher bioavailability in the soil. DTPA-extractable Zn and Cu increased to 184.6 mg kg-1 and 145.3 mg kg-1 in the maximum ZnO-NPs and CuO-NPs concentration treatments (500 mg kg-1). TiO2-NPs promoted the transformation of Mn from a Fe/Mn oxides-bound fraction to an acid-soluble fraction. Soil Cd bioavailability obviously decreased in the TiO2-NPs treatment but increased in the ZnO-NPs and CuO-NPs treatments.

Impact of ZnO nanoparticles on Cd toxicity and bioaccumulation in rice (Oryza sativa L.).

With the widespread use of metal oxide nanoparticles (MNPs), agricultural soil is gradually becoming a primary sink for MNPs. The effect of these nanoparticles on the fate and the toxicity of co-existing heavy metals is largely unknown. In this paper, pot experiments were conducted to evaluate the impact of ZnO nanoparticles (ZnO-NPs) on Cd toxicity and bioaccumulation in a soil-rice system. Different amounts of ZnO-NPs were added to three different levels of Cd-contaminated paddy soil (L-Cd, 1.0 mg kg-1; M-Cd, 2.5 mg kg-1; H-Cd, 5.0 mg kg-1). The results showed that the addition of ZnO-NPs significantly increased the soil pH value, and the soil pH value increased with the increase in ZnO-NP concentration. Reductions in plant height and biomass under Cd stress were recovered and increased after the addition of ZnO-NPs; the addition of ZnO-NP promoted rice biomass increased by 13~22% and 25~43% in the M-Cd and H-Cd groups, respectively, compared with that of the respective control treatment. A high concentration of ZnO-NPs could increase the concentration of bioavailable Cd in rhizosphere soil. In the L-Cd group, the Cd concentration of the rice in the L-Z500 treatment increased to 0.51 mg kg-1, exceeding the limit for acceptable Cd concentrations in rice of China (0.2 mg kg-1). This work revealed that ZnO-NPs could improve plant growth, especially in the early-growth stage, and alleviate the toxic effects of Cd. However, the addition of high-concentration (500 mg kg-1) ZnO-NPs in the lower Cd pollution soil could significantly facilitate the accumulation of Cd by Oryza sativa L.

Application of a fast electrical pulse in gated multichannel plate camera.

An eight-frame gated microchannel plate (MCP) camera and a gating electrical pulse are described in this article. The gating electrical pulse is obtained by first generating a high voltage fast step pulse using avalanche transistors in Marx bank configuration, and then shaping it using avalanche diodes. The high voltage fast step pulse is about 200 ps in fall time and 4 kV in amplitude. The gating pulse wave form with width of 160 ps and amplitude of 2.5 kV is achieved. Each frame photocathode coated with gold on the MCP is part of a 12 Omega transmission line with open circuit end driven by the gating electrical pulse. The camera is tested by illuminating its photocathode with ultraviolet laser pulses, 266 nm in wavelength, which shows exposure time as short as 120 ps.

Observation of electron beam moiré fringes in an image conversion tube.

An image conversion tube with a magnetic lens was designed to observe electron beam moiré fringes. Electron beam moiré fringes result from the interference between the photocathode and the anode meshes. The photocathode had a strip line structure with a spatial frequency of 10L/mm. The anode mesh had a fixed spatial frequency of 10L/mm, and could be rotated around the axis of the image tube. The changes to the fringe direction and the spacing as a function of the rotation angle between the photocathode and the anode mesh were examined. The experimental results agreed with the theoretical analysis. Moiré fringes with a modulation of ~20% were obtained using a 3keV electron beam.

Note: Non-gain microchannel plate gated framing camera.

An x-ray framing camera using a non-gain microchannel plate (MCP) is reported in this article. The advantage of the non-gain MCP is the less transit time spread. The non-gain MCP gated framing camera has four microstrip line cathodes with 6 mm in width. The time domain reflectometry curves of the four microstrip lines are measured, which show that the characteristic impedance of each microstrip line is about 17 Ω. While the photocathode is driven by the gating electrical pulse with width of 125 ps and amplitude of -1.48 kV with -400 V bias, the measured exposure time of this camera is about 72 ps.