A comparative analysis of thermophysical properties correlations for n-paraffins to be used in wax precipitation modeling

The performance of a thermodynamic wax precipitation model strongly depends upon the n-paraffin thermophysical properties used. In order to estimate them, several correlations have been proposed, and their values have a great impact on both calculated wax disappearance temperature (WDT) and amount of wax precipitated at each temperature (WPC). The main goal of this work is to evaluate the correlations available for the relevant thermophysical properties aiming at achieving a reliable wax precipitation modeling. The methodology used involves the direct comparison of the correlations with the values of pure n-paraffin properties, and indirect evaluation by their use in the estimation of wax disappearance temperatures, the amount of wax precipitated at each temperature, and DSC experimental curves. This study contemplates two thermodynamic approaches for paraffin precipitation: the solid solution (SS), which considers the formation of one solid solution; and the multisolid phase model (MS), that assumes that each solid phase consists of a pure component.publishe

Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.

Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants

An analysis of palliative care development in Africa: a ranking based on region-specific macro-indicators

CONTEXT: To date, there is no study comparing palliative care (PC) development among African countries. OBJECTIVE: To analyze comparatively PC development in African countries based on region-specific indicators. METHODS: Data were obtained from the APCA Atlas of PC in Africa and a comparative analysis conducted. Nineteen indicators were developed and defined through qualitative interviews with African PC experts and a two-round modified Delphi consensus process with international experts on global PC indicators. Indicators were grouped by the WHO public health strategy for PC dimensions. These indicators were then sent as a survey to key informants in 52/54 African countries. Through an expert weighting process and ratings from the modified Delphi, weights were assigned to each indicator. RESULTS: Surveys were received from 89% (48/54) of African countries. The top three countries in overall PC development were, in order, Uganda, South Africa, and Kenya. Variability existed by dimension. The top three countries in specialized services were Uganda, South Africa, and Nigeria; in policies, it was Botswana followed by parity among Ethiopia, Rwanda, and Swaziland; in medicines, it was Swaziland, South Africa, then Malawi; in education, it was equivalent between Uganda and Kenya, then Ghana and Zambia. CONCLUSION: Uganda, South Africa, and Kenya are the highest performing countries and were the only ones with composite scores greater than 0.5 (50%). However, not one country universally supersedes all others across all four PC dimensions. The breakdown of rankings by dimension highlights where even high-performing African countries can focus their efforts to further PC development

APCA Atlas of Palliative Care in Africa

BACKGROUND Since Wright & Clark’s book on palliative care in Africa in 2006, there has not been a comprehensive overview describing the state of palliative care development in African countries. AIMS To describe the current state of palliative care (PC) development in Africa according to the WHO’s Public Health Strategy for integrating PC: policies, availability and access to medicines, education, and service provision. METHODS Qualitative interviews were conducted with 16 Country Experts (March-August 2016). From those interviews, 367 indicators were derived, 130 after exclusion criteria and content analysis were performed. The Country Experts rated the indicators for validity & feasibility, a 14-member international committee of experts participated in a two-round modified UCLA-RAND Delphi consensus, and the co-authors (November-December 2016) ranked the indicators. The final 19 indicators were further defined and sent to 66 Key Country Informants from 51 African countries (January-March 2017). RESULTS Surveys were received from 89% (48/54) of African countries. Uganda, South Africa, and Kenya have the highest number of specialised hospice and PC services (71% of identified PC services); 19% (9/48) have no identified hospice and PC services. 22% (12/48) indicated having stand-alone PC policies, and 42% (20/48) reported having a dedicated person for PC in the Ministry. Zambia, Uganda, South Africa, Kenya, Ghana, and Egypt reported some official form of physician accreditation. Opioid consumption per capita was low (75% countries had <1 mg consumption/capita/year) compared to the global average (43mg/capita/year), with highest consumption in Mauritius, South Africa, Namibia, and Morocco. 54% (26/48) reported having a national PC association. CONCLUSIONS This study shows that there is limited PC development in Africa, but there is also a significant improvement in the number of countries with hospice and PC services, compared to previous reports. Improvements in advocacy were identified, with more than half of countries reporting a national PC association. Governments need to take the steps to improve education, increase the number of services, and ensure safe access to opioids

Secreted Human Amyloid Precursor Protein Binds Semaphorin 3a and Prevents Semaphorin-Induced Growth Cone Collapse

The amyloid precursor protein (APP) is well known for giving rise to the amyloid-β peptide and for its role in Alzheimer's disease. Much less is known, however, on the physiological roles of APP in the development and plasticity of the central nervous system. We have used phage display of a peptide library to identify high-affinity ligands of purified recombinant human sAPPα695 (the soluble, secreted ectodomain from the main neuronal APP isoform). Two peptides thus selected exhibited significant homologies with the conserved extracellular domain of several members of the semaphorin (Sema) family of axon guidance proteins. We show that sAPPα695 binds both purified recombinant Sema3A and Sema3A secreted by transfected HEK293 cells. Interestingly, sAPPα695 inhibited the collapse of embryonic chicken (Gallus gallus domesticus) dorsal root ganglia growth cones promoted by Sema3A (Kd≤8·10−9 M). Two Sema3A-derived peptides homologous to the peptides isolated by phage display blocked sAPPα binding and its inhibitory action on Sema3A function. These two peptides are comprised within a domain previously shown to be involved in binding of Sema3A to its cellular receptor, suggesting a competitive mechanism by which sAPPα modulates the biological action of semaphorins