Long-term observation of global black carbon,organic carbon and smoke using CALIPSO and MERRA-2 data

Black carbon (BC), organic carbon (OC) and smoke are some of the aerosols that are emitted during combustion reactions. These air pollutants impact human health and the environment negatively, hence it is important to study their sources and distributions. This work concentrates on three global regions; central South America (CSA), central Africa (CA) and east Asia (EA). The study reveals that biomass burning is responsible for the major emissions of BC, OC and smoke aerosols in the CSA and CA regions during the JJA and SON seasons. The EA region is dominated by BC and smoke aerosols emanating from industrial activities during all seasons. However, a high OC aerosol optical depth is only observed in the MAM season indicating biomass burning during this period. High altitude smoke aerosols up to 10 km are observed in CSA and CA regions in the DJF season. The CSA and CA regions further shows the highest planetary boundary layer height at 1400 m in the JJA and SON seasons.     

The induction of bone formation by coral-derived calcium carbonate/hydroxyapatite constructs

The spontaneous induction of bone formation in heterotopic rectus abdominis and orthotopic calvarial sites by coral-derived biomimetic matrices of different chemical compositions was investigated in a long-term study in the non-human primate Papio ursinus. Coral-derived calcium carbonate constructs were converted to hydroxyapatite by hydrothermal exchange. Limited conversion produced hydroxyapatite/calcium carbonate (HA/CC) constructs of 5% and 13% hydroxyapatite. Rods of 20 mm in length and 7 mm in diameter were implanted in heterotopic rectus abdominis sites; discs 25 mm in diameter were implanted in orthotopic calvarial defects of six adult non-human primates P. ursinus. Heterotopic samples also included fully converted hydroxyapatite replicas sintered at 1100 °C. To further enhance spontaneous osteoinductive activity, fully converted hydroxyapatite replicas were coated with the synthetic peptide P15 known to increase the adhesion of fibroblasts to anorganic bovine mineral. Bone induction was assessed at 60, 90 and 365 days by histological examination, alkaline phosphatase and osteocalcin expression, as well as by the expression of BMP-7, GDF-10 and collagen type IV mRNAs. Induction of bone occurred in the concavities of the matrices at all time points. At 365 days, bone marrow was evident in the P15-coated and uncoated implants. Resorption of partially converted calcium carbonate/hydroxyapatite was apparent, as well as remodeling of the newly formed bone. Northern blot analyses of samples from heterotopic specimens showed high levels of expression of BMP-7 and collagen type IV mRNA in all specimen types at 60 days, correlating with the induction of the osteoblastic phenotype in invading fibrovascular cells. Orthotopic specimens showed prominent bone formation across the different implanted constructs. The concavities of the matrices biomimetize the remodeling cycle of the osteonic primate cortico-cancellous bone and promote the ripple-like cascade of the induction of bone formation. This study demonstrates for the first time that partially converted HA/CC constructs also induce spontaneous differentiation of bone, albeit only seen one year post-implantation.     

A Qualitative Assessment of Decisions Affecting Contraceptive Utilization and Fertility Intentions among HIV-Positive Women in Soweto,South Africa

The HIV epidemic in sub-Saharan Africa disproportionately affects women of reproductive age. The increasing provision of Highly Active Anti-Retroviral Therapy (HAART) with improved prognosis and maternal-fetal outcomes calls for an understanding of fertility planning for HIV-positive women. We describe the effect of HIV and HAART on pregnancy desires and contraceptive use among HIV-positive women in Soweto, South Africa. Focus group discussions and in-depth interviews were conducted with 42 HIV-positive women of reproductive age. Analysis was performed using ATLAS-ti (ATLAS-ti Center, Berlin). Emergent themes were impact of HIV diagnosis on pregnancy intentions; factors affecting contraceptive uptake including real and normative side effects, body image, and perceived vaginal wetness; and the mitigating influence of partnership on both pregnancy intentions and contraceptive use. Routine counseling about pregnancy desires and contraception should be offered to HIV-positive women.     

Elucidating the effect of precursor decomposition time on the structural and optical properties of copper(i) nitride nanocubes

To study the effect of time on the colloidal synthesis of Cu₃N nanoparticles, copper(ii) nitrate was thermally decomposed at 260 °C for up to 60 min in octadecylamine as a stabilizing ligand. Thermolysis of the nitrate followed four steps which included; nucleation, growth, ripening and decomposition. At 5 min, partially developed nanocubes were found in a dense population of Cu₃N nuclei. Well-defined Cu₃N nanocubes were obtained at 15 min with no presence of the nuclei. TEM images showed disintegration of the cubes at 20 min and as time progressed, all the Cu₃N decomposed to Cu by 60 min. The formation of the Cu₃N nanocubes was confirmed by XRD and XPS. FTIR suggested the formation of a nitrile (RCN) as a result of the thermal decomposition in octadecylamine (ODA) and this was confirmed using NMR and hence, a reaction mechanism was then proposed. The optical properties of the as-synthesized Cu₃N were studied using UV-vis and photoluminescence spectroscopies. The absorption spectra for particles synthesized from 5 min to 15 min showed a singular exciton peak while from 20 min to 60 min two peaks were observed. The two peaks may both be associated with the two direct transitions observed in Cu₃N or the more red-shifted peak could be a result of localized surface plasmon resonance due to the Cu nanoparticles. Nevertheless, similar to other studies, it is clear that the optical properties of Cu₃N are complex.

To study the effect of time on the colloidal synthesis of Cu₃N nanoparticles, copper(ii) nitrate was thermally decomposed at 260 °C for up to 60 min in octadecylamine as a stabilizing ligand.     

A Qualitative Assessment of Decisions Affecting Contraceptive Utilization and Fertility Intentions among HIV-Positive Women in Soweto, South Africa

The HIV epidemic in sub-Saharan Africa disproportionately affects women of reproductive age. The increasing provision of Highly Active Anti-Retroviral Therapy (HAART) with improved prognosis and maternal-fetal outcomes calls for an understanding of fertility planning for HIV-positive women. We describe the effect of HIV and HAART on pregnancy desires and contraceptive use among HIV-positive women in Soweto, South Africa. Focus group discussions and in-depth interviews were conducted with 42 HIV-positive women of reproductive age. Analysis was performed using ATLAS-ti (ATLAS-ti Center, Berlin). Emergent themes were impact of HIV diagnosis on pregnancy intentions; factors affecting contraceptive uptake including real and normative side effects, body image, and perceived vaginal wetness; and the mitigating influence of partnership on both pregnancy intentions and contraceptive use. Routine counseling about pregnancy desires and contraception should be offered to HIV-positive women.     

The Impact of Highly Active Antiretroviral Therapy on Activities of Daily Living in HIV-Infected Adults in South Africa

This study investigated the relationship between highly active antiretroviral therapy (HAART) and instrumental activities of daily living (IADLs) among two clinical cohorts in South Africa. Between 2003 and 2008 structured questionnaires were administered to HIV-positive patients attending outpatient clinics at an urban hospital (Soweto, n = 3,081) and a rural hospital (Acornhoek, n = 1,247). Among those receiving help, an average of 4.8 and 5.1 h of assistance with IADLs daily was reported (rural and urban participants, respectively), with the patient’s mother and children assisting the most. Participants on HAART were 17 and 41% less likely to receive assistance with IADLs in the rural and urban cohorts, respectively, after adjusting for demographic characteristics, healthcare utilization, and CD4 counts. HAART significantly decreased the IADL assistance among patients in South Africa. Alongside clinical benefits, HAART has the potential to reduce the burden of HIV-related care, potentially extending wider social and economic gains to other family members.