Ion energetics in collisionless sheaths of rf process plasmas

S. Hamaguchi, Physics of Fluids B: Plasma Physics 4, 2362 (1992) https://doi.org/10.1063/1.86020

Relationship between firewood usage and urinary Cr Cu and As in informal areas of Cape Town

OBJECTIVES: The study investigated whether wood usage by informal food vendors and household residents in Cape Town results in the absorption of arsenic (As), chromium (Cr) and copper (Cu) owing to release of these metals in the burning of chromated copper arsenate (CCA)-treated wood. METHODS: The participants (N=78) selected included an equal number of food vendors and non-vendors from 2 informal settlements. All participants answered a questionnaire concerning exposure and were tested for urinary Cr, Cu and As, while the urine of 29 participants was also tested for toxic As (As(tox)). RESULTS: Multivariate analysis showed that the time spent in close proximity to the wood, as well as the quantity of wood used for cooking and for household use, was weakly positively associated with urinary levels of As, Cr and the sum of As, Cr and Cu. CONCLUSIONS: The study provides evidence that use of wood likely to contain CCA as a fuel for informal food outlets and household purposes may increase the absorption of inorganic As, Cu and Cr

Ponderomotive force and ion energy distributions in an rf sheath

The incident-ion energy distribution in a collisionless radio-frequency (rf) sheath is derived analytically for a general electric-field configuration in the high-frequency regime. The analysis is based on a two-time-scale asymptotic expansion of the ion equation of motion, where the ratio of the ion transit frequency tr to the rf frequency is assumed to be small. It is shown that the ponderomotive force due to the rf modulation of the electric field exerts a retarding effect on the ion motion, counteracting the dc-bias field. The results obtained here are applicable to rf-discharge-based process tools used in microelectronics fabrication, where the conditions of low collisionality and high rf frequency are usually satisfied. © 1992 The American Physical Society.S. Hamaguchi, R. T. Farouki, and M. Dalvie, Phys. Rev. Lett. 68, 44, 199

Association of activities related to pesticide exposure on headache severity and neurodevelopment of school-children in the rural agricultural farmlands of the Western Cape of South Africa

OBJECTIVE: Children and adolescents living in agricultural areas are likely to be exposed to mixtures of pesticides during their daily activities, which may impair their neurodevelopment. We investigated various such activities in relation to headache severity and neurodevelopment of school-children living in rural agricultural areas in the Western Cape of South Africa. METHOD: We used baseline date from 1001 school-children of the Child Health Agricultural Pesticide Cohort Study in South Africa (CapSA) aged 9-16 from seven schools and three agriculture areas in the Western Cape. Questionnaires were administrated to assess activities related to pesticide exposure and health symptoms addressing four types of activities: 1) child farm activities related to pesticide handling, 2) eating crops directly from the field, 3) contact with surface water around the field, and 4) seen and smelt pesticide spraying activities. Neurocognitive performance across three domains of attention, memory and processing speed were assessed by means of an iPad-based cognitive assessment tool, Cambridge Automated NeuroPsychological Battery (CANTAB). Headache severity was enquired using a standard Headache Impact Test (HIT-6) tool. Cross-sectional regression analysis was performed. RESULTS: About 50% of the cohort report to have ever been engaged in activities related to pesticide exposure including farm activities, eating crops directly from the field and leisure activities. Headache severity score was consistently increased in relation to pesticide-related farm activities (score increase of 1.99; 95% CI: 0.86, 3.12), eating crops (1.52; 0.41, 2.67) and leisure activities of playing, swimming or bathing in nearby water (1.25; 0.18, 2.33). For neurocognitive outcomes, an overall negative trend with pesticide exposure-related activities was observed. Among others, involvement in pesticide-related farm activities was associated with a lower multi-tasking accuracy score (-2.74; -5.19, -0.29), while lower strategy in spatial working memory (-0.29; -0.56; -0.03) and lower paired associated learning (-0.88; -1.60, -0.17) was observed for those who pick crops off the field compared to those who do not pick crops off the field. Eating fruits directly from the vineyard or orchard was associated with a lower motor screening speed (-0.06; -0.11, -0.01) and lower rapid visual processing accuracy score (-0.02; -0.03, 0.00). CONCLUSIONS: Children who indicate activities related to pesticide exposure may be at higher risk for developing headaches and lower cognitive performance in the domains of attention, memory and processing speed. However, self-reported data and cross-sectional design are a limitation. Future research in CapSA will consider pesticide exposure estimations via urinary biomarkers and longitudinal assessment of cognitive functions

Psychosis and relapse in bipolar disorder are related to GRM3 DAOA and GRIN2B genotype

Objective: Dysfunction in glutamate signalling is thought to play a role in the pathophysiology of bipolar disorder (BD). There is evidence of associations between single nucleotide polymorphisms (SNPs) in GRM3, GRIN2B, and DAOA genes and the diagnosis of BD. In this pilot study, we investigated the frequency of SNP variants in these 3 genes within South African population groups, and assessed interactions between genes and phenotypes of BD disease severity. Method: Multiplex SNaPshotTM PCR was used to genotype 191 case and 188 control samples. Cases comprised of 191 individuals in a South African cohort of mixed ancestry and Caucasians, with BD Type 1. Phenotypes of BD disease severity were: age of onset, number of illness episodes, number of hospitalisations for depression or mania and history of psychotic symptoms. Results: There were no significant difference in SNP allele frequencies between cases and controls. In the case-only analysis, the GRM3 rs6465084 heterozygote was associated with a 4-fold increased risk of lifetime history of psychotic symptoms, and the specific variants within the gene pair, DAOA and GRIN2B, had a significant interaction with the number of hospitalisations for mania, with lowest admission rates associated with both pairs of ancestral alleles.Conclusion: In BD, variations in glutamatergic genes may influence phenotypes related to the severity of illness. Speculatively, newly derived genes associated with various evolutionary advantages, may also increase the risk for more severe BD. These preliminary findings deserve validation in a larger cohort

Psychosis and relapse in bipolar disorder are related to GRM3, DAOA, and GRIN2B genotype

Objective:  Key Words: Manic-Depressive Psychosis; Glutamate; GRIN2B receptor; mGluR3; G72 protein; HumanDysfunction in glutamate signalling is thought to play a role in the pathophysiology of bipolar disorder (BD). There is evidence of associations between single nucleotide polymorphisms (SNPs) in GRM3, GRIN2B, and DAOA genes and the diagnosis of BD. In this pilot study, we investigated the frequency of SNP variants in these 3 genes within South African population groups, and assessed interactions between genes and phenotypes of BD disease severity. Method: Multiplex SNaPshotTM PCR was used to genotype 191 case and 188 control samples. Cases comprised of 191 individuals in a South African cohort of mixed ancestry and Caucasians, with BD Type 1. Phenotypes of BD disease severity were: age of onset, number of illness episodes, number of hospitalisations for depression or mania and history of psychotic symptoms. Results: There were no significant difference in SNP allele frequencies between cases and controls. In the case-only analysis, the GRM3 rs6465084 heterozygote was associated with a 4-fold increased risk of lifetime history of psychotic symptoms, and the specific variants within the gene pair, DAOA and GRIN2B, had a significant interaction with the number of hospitalisations for mania, with lowest admission rates associated with both pairs of ancestral alleles. Conclusion: In BD, variations in glutamatergic genes may influence phenotypes related to the severity of illness. Speculatively, newly derived genes associated with various evolutionary advantages, may also increase the risk for more severe BD. These preliminary findings deserve validation in a larger cohort

Genetic variation within GRIN2B in adolescents with alcohol use disorder may be associated with larger left posterior cingulate cortex volume.

OBJECTIVE: Brain structure differences and adolescent alcohol dependence both show substantial heritability. However, exactly which genes are responsible for brain volume variation in adolescents with substance abuse disorders are currently unknown. The aim of this investigation was to determine whether genetic variants previously implicated in psychiatric disorders are associated with variation in brain volume in adolescents with alcohol use disorder (AUD). METHODS: The cohort consisted of 58 adolescents with DSM-IV AUD and 58 age and gender-matched controls of mixed ancestry ethnicity. An Illumina Infinium iSelect custom 6000 bead chip was used to genotype 5348 single nucleotide polymorphisms (SNPs) in 378 candidate genes. Magnetic resonance images were acquired and volumes of global and regional structures were estimated using voxel-based morphometry. To determine whether any of the genetic variants were associated with brain volume, association analysis was conducted using linear regression in Plink. RESULTS: From the exploratory analysis, the GRIN2B SNP rs219927 was associated with brain volume in the left posterior cingulate cortex (p<0.05), whereby having a G-allele was associated with a bigger volume. CONCLUSION: The GRIN2B gene is involved in glutamatergic signalling and may be associated with developmental differences in AUD in brain regions such as the posterior cingulate cortex. Such differences may play a role in risk for AUD, and deserve more detailed investigation

Temporal variation of pesticide mixtures in rivers of three agricultural watersheds during a major drought in the Western Cape, South Africa

South Africa is the leading pesticide user in Sub-Saharan Africa. However, little is known about the occurrence of pesticide mixtures in surface water and potential environmental risks in Africa. This study investigated the occurrence of pesticides mixtures in three watersheds during a drought year in South Africa. The study was conducted in the Krom River, Berg River and Hex River watersheds within larger agriculture systems in the Western Cape. Pesticide spray records were collected from 38 farms. A total of 21 passive water samplers (styrenedivinylbenzene disks (SDB)) were deployed, each for two weeks per month, over seven sampling rounds during the main pesticide application period between July 2017 and January 2018. Samples were analyzed for 248 pesticide compounds using LC-HR-MS/MS. Pesticide occurrence was analyzed for temporal agreement with pesticide spraying events (Cohen's kappa) and correlation with rainfall patterns and river discharge (Pearson correlation (r p )). Pesticide time-weighted average concentrations were estimated and compared to environmental quality standards (EQS). According to the farm spray records, 96 different pesticides were sprayed during the sampling period and differed considerably between the three study areas, seasons and crops grown. In total, 53 compounds were detected in river water. We detected 39% of compounds from the spraying records and demonstrated close temporal correlations of seasonal patterns for 11 pesticide compounds between reported on spraying records and observations in the streams (kappa = 0.90). However, 23 detected pesticides were not found on spray records, many of them being herbicides. Most of the estimated two-week average pesticide concentrations were below 40 ng/L. The insecticides imidacloprid, thiacloprid, chlorpyrifos and acetamiprid and the herbicide terbuthylazine exceeded at least once their EQS 58-fold (EQS 13 ng/L), 12-fold (EQS 10 ng/L), 9-fold (EQS 0.46 ng/L), 5-fold (EQS 24 ng/L) and 3-fold (EQS 220 ng/L), respectively. Our study substantially widens the view on pesticide pollution in surface water compared to previous studies in Sub-Saharan Africa by targeting more than 200 pesticides using passive sampling systems. This broad assessment revealed the presence of 53 compounds, some of them in high concentrations, indicating possible adverse effects on biota and the quality of the ecosystem. Whether the observed concentration levels in the year 2017 were exceptional due to the lowest ever recorded rainfall and river discharge needs to be tested with additional data to better understand how pesticide pollution levels manifest under average rainfall and river discharge conditions

Current use pesticides in soil and air from two agricultural sites in South Africa: implications for environmental fate and human exposure

Concerns about the possible negative impacts of current use pesticides (CUPs) for both the environment and human health have increased worldwide. However, the knowledge on the occurrence of CUPs in soil and air and the related human exposure in Africa is limited. This study investigated the presence of 30 CUPs in soil and air at two distinct agricultural sites in South Africa and estimated the human exposure and related risks to rural residents via soil ingestion and inhalation (using hazard quotients, hazard index and relative potency factors). We collected 12 soil and 14 air samples over seven days during the main pesticide application season in 2018. All samples were extracted, purified and analyzed by high-performance liquid chromatography coupled with tandem mass spectrometry. In soils, nine CUPs were found, with chlorpyrifos, carbaryl and tebuconazole having the highest concentrations (up to 63.6, 1.10 and 0.212 ng g(-1), respectively). In air, 16 CUPs were found, with carbaryl, tebuconazole and terbuthylazine having the highest levels (up to 25.0, 22.2 and 1.94 pg m(-3), respectively). Spatial differences were observed between the two sites for seven CUPs in air and two in soils. A large dominance towards the particulate phase was found for almost all CUPs, which could be related to mass transport kinetics limitations (non-equilibrium) following pesticide application. The estimated daily intake via soil ingestion and inhalation of individual pesticides ranged from 0.126 fg kg(-1) day(-1) (isoproturon) to 14.7 ng kg(-1) day(-1) (chlorpyrifos). Except for chlorpyrifos, soil ingestion generally represented a minor exposure pathway compared to inhalation (i.e. <5%). The pesticide environmental exposure largely differed between the residents of the two distinct agricultural sites in terms of levels and composition. The estimated human health risks due to soil ingestion and inhalation of pesticides were negligible although future studies should explore other relevant pathways

Non-optimal apparent temperature and cardiovascular mortality: the association in Puducherry, India between 2011 and 2020

BACKGROUND: Cardiovascular diseases (CVDs), the leading cause of death worldwide, are sensitive to temperature. In light of the reported climate change trends, it is important to understand the burden of CVDs attributable to temperature, both hot and cold. The association between CVDs and temperature is region-specific, with relatively few studies focusing on low-and middle-income countries. This study investigates this association in Puducherry, a district in southern India lying on the Bay of Bengal, for the first time. METHODS: Using in-hospital CVD mortality data and climate data from the Indian Meteorological Department, we analyzed the association between apparent temperature (T(app)) and in-hospital CVD mortalities in Puducherry between 2011 and 2020. We used a case-crossover model with a binomial likelihood distribution combined with a distributed lag non-linear model to capture the delayed and non-linear trends over a 21-day lag period to identify the optimal temperature range for Puducherry. The results are expressed as the fraction of CVD mortalities attributable to heat and cold, defined relative to the optimal temperature. We also performed stratified analyses to explore the associations between T(app) and age-and-sex, grouped and considered together, and different types of CVDs. Sensitivity analyses were performed, including using a quasi-Poisson time-series approach. RESULTS: We found that the optimal temperature range for Puducherry is between 30 degrees C and 36 degrees C with respect to CVDs. Both cold and hot non-optimal T(app) were associated with an increased risk of overall in-hospital CVD mortalities, resulting in a U-shaped association curve. Cumulatively, up to 17% of the CVD deaths could be attributable to non-optimal temperatures, with a slightly higher burden attributable to heat (9.1%) than cold (8.3%). We also found that males were more vulnerable to colder temperature; females above 60 years were more vulnerable to heat while females below 60 years were affected by both heat and cold. Mortality with cerebrovascular accidents was associated more with heat compared to cold, while ischemic heart diseases did not seem to be affected by temperature. CONCLUSION: Both heat and cold contribute to the burden of CVDs attributable to non-optimal temperatures in the tropical Puducherry. Our study also identified the age-and-sex and CVD type differences in temperature attributable CVD mortalities. Further studies from India could identify regional associations, inform our understanding of the health implications of climate change in India and enhance the development of regional and contextual climate-health action-plans