RESUMEN

Background: Survivors of sexual violence are at higher risk of adverse mental health outcomes compared to those exposed to other interpersonal traumas.Objective: To examine the trajectory of both post-traumatic stress disorder (PTSD) and depression as well as the role of early counselling over 24 months among rape survivors.Method: The South African Rape Impact Cohort Evaluation (RICE) study enrolled women aged 16-40 years attending post-rape care services within 20 days of a rape incident (n = 734), and a comparison group (n = 786) was recruited from primary health care. Women were followed for 24 months; the main study outcomes were depression and PTSD. Reports of early supportive counselling by the exposed group were also included. The analysis included an adjusted joint mixed model with linear splines to account for correlated observations between the outcomes.Results: At 24 months, 45.2% of the rape-exposed women met the cut-off for depression and 32.7% for PTSD. This was significantly higher than levels found among the unexposed. Although a decline in depression and PTSD was seen at 3 months among the women who reported a rape, mean scores remained stable thereafter. At 24 months mean depression scores remained above the depression cut-off (17.1) while mean PTSD scores declined below the PTSD cut-off (14.5). Early counselling was not associated with the trajectory of either depression or PTSD scores over the two years in rape-exposed women with both depression and PTSD persisting regardless of early counselling.Conclusion: The study findings highlight the importance to find and provide effective mental health interventions post-rape in South Africa.

Asunto(s)

RESUMEN

Adverse pregnancy outcomes (APOs) are common occurrences that contribute to negative maternal and child health outcomes. Our aim was to test the hypothesis that trauma exposure and depression are drivers of the better-recognised risk factors for miscarriage, abortion and stillbirths. Our comparative cohort study based in Durban, South Africa recruited women who reported a recent rape (n = 852) and those who had never experienced rape (n = 853), with follow-up for 36 months. We explored APOs (miscarriage, abortion or stillbirth) among those having a pregnancy during follow-up (n = 453). Potential mediators were baseline depression, post-traumatic stress symptoms, substance abuse, HbA1C, BMI, hypertension and smoking. A structural equation model (SEM) was used to determine direct and indirect paths to APO. Overall, 26.6% of the women had a pregnancy in the follow-up period and 29.4% ended in an APO, with miscarriage (19.9%) the most common outcome, followed by abortion (6.6%) and stillbirths (2.9%). The SEM showed two direct pathways from exposure to childhood trauma, rape and other trauma, to APO which were ultimately mediated by hypertension and/or BMI, but all paths to BMI were mediated by depression and IPV-mediated pathways from childhood and other trauma to hypertension. Food insecurity mediated a pathway from experiences of trauma in childhood to depression. Our study confirms the important role of trauma exposure, including rape, and depression on APOs, through their impact on hypertension and BMI. It is critical that violence against women and mental health are more systematically addressed in antenatal, pregnancy and postnatal care.

Asunto(s)

RESUMEN

The Pb(II) adsorption characteristics of chemically activated waste activated sewage sludge (WAS) were compared to raw WAS. Adsorption kinetics and equilibrium isotherm parameters were fit using classic adsorption models. HCl and H2SO4 activation terminated any significant sludge-based adsorption. Raw and ZnCl2 activated WAS displayed Langmuir adsorption capacities of 307 mg/g and 274 mg/g, respectively. Surface characterization revealed that chemical activation with ZnCl2 increased the BET surface area for raw WAS from 0.97 m2/g to 1.78 m2/g, but did not significantly change the surface structure. FTIR analyzes and XPS were used to further investigate the nature of lead binding. The relationships between equilibrium ion concentration and Pb(II) adsorption suggest cationic exchange with hydrogen, calcium, and zinc as a significant mechanism of Pb(II) removal alongside electrostatic attraction. The pHPZC was determined as 2.58 and 2.30 for ZnCl2 activated WAS and raw WAS respectively. HNO3 and Ca(NO3)2 demonstrated sufficient elution properties for WAS recovery. For authentic industrial effluent both raw and ZnCl2 activated WAS displayed Pb(II) removal behavior comparable to simulated Pb(II) solutions. In comparison with modified and unmodified sludges from literature, this study demonstrates the auspicious potential of raw WAS as an effective Pb(II) adsorbent independent of pyrolytic or chemical activation.

Asunto(s)

RESUMEN

The performance of photocatalytic oxidation of chemical pollutants is subjected to the presence of anion complexes in natural waters. This study investigated the influence of alkali metal (Na+ (sodium), K+ (potassium)) halides (Cl- (chloride), Br- (bromide), F- (fluoride)) as inorganic ion sources in the photocatalytic degradation of pentachlorophenol (PCP) in batch systems. It was found that the exclusive presence of halides in the absence of an electron acceptor adequately facilitated the photocatalyst process below critical levels of anion populations, where beyond the critical point the process was significantly hindered. Below the determined critical point, the performance in some cases near matches that of the facilitation of the photocatalytic process by exclusive oxygen, acting as an electron scavenger. The coupling of halide ions and oxygenation presented significantly improved photo-oxidation of PCP, this was confirmed by the inclusion of formic acid as a comparative electron donor. The Langmuir-Hinshelwood kinetic expression was used to calculate the performance rate kinetics. The probable impact of the halide anions was discussed with regards to the process of electron hole pair recombination prevention.

RESUMEN

The project investigated the simultaneous degradation of chlorophenols dissolved in aqueous systems. The photocatalysis advanced oxidation process was the technology applied to achieve treatment. Chemical behavioural tracking was performed using the chloride dehalogenation sequence dynamics. The study recorded reductive dehalogenation chemical transformation kinetics of multi-substituted chlorinated phenolics in continuous flow reactor systems. This was performed by manipulation of liquid flow-rates in the photocatalytic oxidations process using suspended and immobilised catalyst applications. A modified Langmuir-Hinshelwood kinetic model was proposed that explained the oxidation transformational behaviour of the dehalogenation process derived intermediates. Complementary photocatalytic performance matrices were established for each flow regime; model parameters were calculated and estimated for behavioural profiles of all compounds under scrutiny.

Asunto(s)

RESUMEN

The purpose of this study was to determine the effect different biofilm carrier filling ratios would have on biofilm morphology and activity and bacterial diversity in a hybrid fixed-film bioreactor treating high strength coal gasification wastewater (CGWW) for the removal of chemical oxygen demand (COD), phenols and ammonia-nitrogen. Results showed that a carrier fill of 70% formed a 'compact' biofilm, a 50% fill formed a 'rippling' biofilm and a 30% fill formed a 'porous' biofilm. The highest microbial activity was obtained with a 50% carrier fill supporting a relatively thin biofilm. The highest level of biofilm bound metals were aluminium, silicon, calcium and iron in the 'compact' biofilm; nitrogen, magnesium, chloride, sodium and potassium in the 'rippling' biofilm, and copper in the 'porous' biofilm. The bioreactor improved the quality of the CGWW by removing 49% and 78% of the COD and phenols, respectively. However, no significant amount of ammonia-nitrogen was removed since nitrification did not take place due to heterotrophic bacteria out-competing autotrophic nitrifying bacteria in the biofilm. The dominant heterotrophic genera identified for all three carrier filling ratios were Thauera, Pseudaminobacter, Pseudomonas and Diaphorobacter.

Asunto(s)

RESUMEN

This study investigated, modelled and simulated the influence of multi-chlorohalogenation in heterogeneous photocatalytic degradation of substituted phenols (pentachlorophenol (PCP), trichlorophenol (TCP), dichlorophenol (DCP), and monochlorophenol (CP)). The Langmuir-Hinshelwood approach was applied to determine oxidation kinetics. Aquasim 2.0 computational software was used to model, simulate and estimate model parameters of the different chlorophenols. Chemical adsorption equilibrium isotherms for the four chlorophenols and phenol were studied and modelled for adsorption onto titanium dioxide (TiO2) semiconductor catalyst. Langmuir adsorption parameters were determined and used to calculate adsorption constant and maximum adsorption capacity. The adsorption of chloride phenolics onto titanium dioxide catalyst increased in the order of 4 - CP < DCP < Ph < TCP < PCP. Photocatalytic studies analysed the efficiency of oxidation and found improved degradation with higher chloride substituted phenolics in the order of PCP > TCP > DCP ≥ 4 - CP. Photocatalytic parameters were calculated and estimated along with sensitivity and uncertainty analyses.

RESUMEN

Thallium (Tl) is a highly volatile and toxic heavy metal regarded to cause pollution even at very low concentrations of several parts per million. Despite the extremely high risk of Tl in the environment, limited information on removal/recovery exists. The study focussed on the use of green algae to determine the sorption potential and recovery of Tl. From the study, removal efficiency was achieved at 100% for lower concentrations of ≥150 mg/L of Tl. At higher concentrations in a range of 250-500 mg/L, the performance of algae was still higher with sorption capacity (qmax) between 830 and 1000 mg/g. Generally, Chlorella vulgaris was the best adsorbent with a high qmax and lower affinity of 1000 mg/g and 1.11 L/g, respectively. When compared to other studies on Tl adsorption, the tested algae showed a better qmax than most adsorbents. The kinetic studies showed better correlation co-efficient of ≤0.99 for Pseudo-second order model than the first order model. Recovery was achieved highest for C. vulgaris using nitric acid at 93.3%. The strongest functional groups responsible for Tl binding on the algal cell wall were carboxyl and phenols. Green algae from freshwater bodies showed significant potential for Tl removal/recovery from industrial wastewater.

Asunto(s)

RESUMEN

OBJECTIVES: To compare growth velocity of two African child cohorts and examine the relationship between postnatal growth velocity in infancy/early childhood and the risk of overweight/stunting in early adolescence. METHODS: The study used data from two child cohorts from urban (Birth to Twenty Cohort, South Africa) and rural (Lungwena Child Survival Study, Malawi) African settings. Mixed effect modelling was used to derive growth and peak growth velocities. T-tests were used to compare growth parameters and velocities between the two cohorts. Linear and logistic regression models were used to determine the relationship between growth velocity and early adolescent (ages 9-11 years) body mass index and odds of being overweight. RESULTS: Children in the BH cohort were significantly taller and heavier than those in the Lungwena cohort, and exhibited faster weight and height growth velocity especially in the first year of life (P < 0.05). No significant association was shown between baseline weight (αw ) and overweight in early adolescence (OR = 1.25, CI = 0.67, 2.34). The weight growth velocity parameter ßw was highly associated with odds of being overweight. Association between overweight in adolescence and weight velocity was stronger in infancy than in early childhood (OR at 3 months = 4.80, CI = 2.49, 9.26; OR at 5 years = 2.39, CI = 1.65, 3.47). CONCLUSION: High weight and height growth velocity in infancy, independent of size at birth, is highly associated with overweight in early adolescence. However, the long term effects of rapid growth in infancy may be dependent on a particular population's socio-economic status and level of urbanization.

Asunto(s)

RESUMEN

In this study, the adsorption and desorption kinetics of lanthanum (La) on micro algal cells was investigated. The internal transcribed spacer (ITS) and 18S ribosomal RNA gene (rRNA) were used for molecular identification of the species. The algal species were found to have 95-98% identities to Desmodesmus multivariabilis, Scenedesmus acuminutus, Chloroidium saccharophilum and Stichococcus bacillaris. The species were cultured and tested independently. D. multivariabilis was found to be the most efficient at adsorbing lanthanum with a maximum sorption capacity (qmax) of 100 mg/g and a high affinity (b) of 4.55 L/g. Desorption of La was also highest in D. multivariabilis with recovery up to 99.63% at initial concentration as high as 100 mg/L. Desorption data fitted best to the modified pseudo second-order with a better correlation coefficient (R(2)) of ⩽0.98 than first order model. The results showed feasibility of lanthanum recovery using algal sorbents, a cost effective method.

Asunto(s)

RESUMEN

BACKGROUND: The rapid scale-up of free antiretroviral therapy has lead to decline in adult mortality at the population level and reduction of vertical transmission. Consequently, some couples living with HIV are maintaining their reproductive decisions; marrying and having children. This paper analyses policies and guidelines on HIV, AIDS and sexual and reproductive health in Malawi for content on marriage and childbearing for couples living with HIV. METHODS: A qualitative study using interpretive policy analysis approach was conducted from July to December 2010 in two phases. First, data on access to HIV, AIDS and sexual and reproductive health services were collected using in-depth interviews with twenty couples purposively sampled in matrilineal Chiradzulu and patrilineal Chikhwawa communities. Secondly, data were collected from Malawi policies and guidelines on HIV, AIDS and sexual and reproductive health. The documents were reviewed for content on marriage and childbearing for couples living with HIV. Data were analysed using framework approach for applied policy analysis. RESULTS: Four categories emerged from each phase. From the study, we extracted health workers attitudes, weak linkage between HIV, AIDS and sexual and reproductive health services, contradictory messages between media and the hospitals and lack of information as factors directly related to guidelines and policies. Analysis of guidelines and policies showed non-prescriptiveness on issues of HIV, AIDS and reproduction: they do not reflect the social cultural experiences of couples living with HIV. In addition, there is; lack of clinical guidelines, external influence on adoption of the policies and guidelines and weak linkages between HIV and AIDS and sexual and reproductive health services. CONCLUSION: This synthesis along with more detailed findings which are reported in other published articles, provide a strong basis for updating the policies and development of easy-to-follow guidelines in order to effectively provide services to couples living with HIV in Malawi.

Asunto(s)

RESUMEN

Nuclear energy is becoming a preferred energy source amidst rising concerns over the impacts of fossil fuel based energy on global warming and climate change. However, the radioactive waste generated during nuclear power generation contains harmful long-lived fission products such as strontium (Sr). In this study, cationic strontium uptake from solution by microbial cultures obtained from mine wastewater is evaluated. A high strontium removal capacity (q(max)) with maximum loading of 444 mg/g biomass was achieved by a mixed sulphate reducing bacteria (SRB) culture. Sr removal in SRB was facilitated by cell surface based electrostatic interactions with the formation of weak ionic bonds, as 68% of the adsorbed Sr(2+) was easily desorbed from the biomass in an ion exchange reaction with MgCl2. To a lesser extent, precipitation reactions were also found to account for the removal of Sr from aqueous solution as about 3% of the sorbed Sr was precipitated due to the presence of chemical ligands while the remainder occurred as an immobile fraction. Further analysis of the Sr-loaded SRB biomass by scanning electron microscopy (SEM) coupled to energy dispersive X-ray (EDX) confirmed extracellular Sr(2+) precipitation as a result of chemical interaction. In summary, the obtained results demonstrate the prospects of using biological technologies for the remediation of industrial wastewaters contaminated by fission products.

Asunto(s)

RESUMEN

Comparison of changes over time of a continuous response variable between treatment groups is often of main interest in clinical trials. When the distributional properties of the continuous response variable are not regular enough, or when the response is discrete, nonparametric techniques have been used. The relative performances of selected repeated measures nonparametric two-sample tests proposed by Wei and Lachin, Koziol, Wei and Johnson, and the adapted Wilcoxon Rank-Sum test are compared through simulations based on quality of life data. The Wilcoxon Rank-Sum test is the most powerful and is not significantly affected by the different patterns of missing data.

Asunto(s)

RESUMEN

A mixed-culture of bacteria collected from a wastewater treatment plant in Brits, North-West Province (South Africa) biocatalytically reduced Cr(VI) at much higher concentrations than previously observed in cultures isolated in North America. Complete Cr(VI) reduction in aerobic cultures was achieved at a high concentration of 200 mg/L after incubation for only 65 hours. Under anaerobic conditions up to 150 mg, Cr(VI)/L was completely removed after incubating for 130 to 155 hours, still higher than the Cr(VI) reduction achieved with previous cultures where complete removal was only observed in cultures with the added Cr(VI) concentration not greater than 30 mg/L. Cr(VI) reduction capability of the cultures was verified in purified cultures. Consortium cultures were characterised using 16S rRNA partial sequence analysis. Results showed that the gram-positive Bacillus genera predominated under aerobic conditions with a small composition of the gram-negative Microbacterium sp. There was more biodiversity observed in the anaerobic cultures with the marked appearance of Enterococcus, Arthrobacter, Paenibacillus and Oceanobacillus species. The results showed that Cr(VI) reduction rate in the new culture was up to eight times higher than that previously observed in other Cr(VI) reducing cultures isolated from Cr(VI) contaminated soil environments in Newark (New Jersey) and other sites in North America.

Asunto(s)

RESUMEN

The Cr(VI) reducing capability of an acclimated indigenous culture cultivated from primary sludge was evaluated in batch and packed-bed bioreactor systems. Performance evaluation was carried out in unmodified cultures, cultures modified by substituting terminal organisms in the consortium by a known Cr(VI)-reducing organism (Escherichia coli ATCC 33456), and pure cultures of Cr(VI)-reducing organisms. A high Cr(VI) reduction rate was observed in modified cultures and in the pure culture of the Cr(VI)-reducing bacteria (Bacillus sp.). Furthermore, the Bacillus sp. pure culture outperformed both the unmodified and modified consortium cultures in reducing Cr(VI). Abiotic Cr(VI) reduction activity was evaluated in heat-killed and azide (N3) inactivated control cultures. No significant Cr(VI) reduction was observed in the controls. This study is part of the continuing research to identify synergistic culture systems for treating toxic compounds from polluted environments.

Asunto(s)

RESUMEN

Simultaneous Cr(VI) reduction and phenol degradation was observed in a fixed-film bioreactor consisting of a coculture of phenol-degrading bacteria, Pseudomonas putida DMP-1, and Cr(VI)-reducing bacteria, Escherichia coli ATCC 33456. Near complete Cr(VI) reduction and phenol degradation was observed during steady-state operation of the reactor under loadings of 5-21 mg Cr(VI) l-1 d-1 and 840-3350 mg phenol l-1 d-1. 2-hydroxymuconic semialdehyde (2HMSA), succinate, and acetate were the detected steady-state organic acid metabolites which accounted for 13-23% of TOC in the effluent. Optimum Cr(VI) reduction rate was observed under a Cr(VI) loading of approximately 26.5 mg Cr(VI) l-1 d-1 just before system overload. System overload was characterized by the increase in effluent Cr(VI) and phenol concentrations. System resilience to Cr(VI) toxicity was demonstrated by rapid recovery of biological activity and reduced effluent Cr(VI) and phenol concentrations after off-loading the system from overloaded conditions.

Asunto(s)

Asunto(s)