Effects of Quebracho Tannin on Recovery of Colloidal Gold from Bioleached Wash Liquor

Gold occurs in some concessions as submicron particles in pyrite and arsenopyrite, which is processed in a flotation concentration to obtain gold enriched sulphide concentrate. The concentrate is then treated in a biological oxidation step to oxidize the sulphides, liberate the occluded gold and make them amenable for cyanidation. The oxidized sulphide concentrate with high acidic content is washed in Counter-Current Decantation (CCD) thickeners to obtain thickened slurry, from which gold is recovered by cyanidation and wash liquor which is considered as tailings. The wash liquor from the CCD thickeners of a typical BIOX plant in Ghana, Golden Star Resources Limited, carries away 0.57 g/L of gold to tailings. This paper considered effects of Quebracho Tannin (QT) on recovery of gold from the oxidized flotation concentrate wash liquor. The effect of Quebracho Tannin on Total Suspended Solids (TSS) was also established. This research established that the gold lost to tailings was not soluble in the effluent but was mainly in the form of colloidal particles. Application of Quebracho Tannin to CCD effluent showed a substantial decrease in the loss of gold to tailings. About 0.13 g of gold was recovered from the CCD effluent per tonne of ore treated. An optimum QT dose of 0.05 g/l was determined from laboratory test giving a 21.25 % reduction in the Total Suspended Solids (TSS) and a 45.79 % reduction in the gold loss to tailings. When the 0.05 g/l dose was applied on the plant the TSS reduced by 53.51 %.Keywords: Quebracho Tannin, Pyrite, Arsenopyrite, Gold processing, Colloidal particles

Role of seminal plasma in the anti-HIV-1 activity of candidate microbicides

BACKGROUND: Evaluation of microbicides for prevention of HIV-1 infection in macaque models for vaginal infection has indicated that the concentrations of active compounds needed for protection by far exceed levels sufficient for complete inhibition of infection in vitro. These experiments were done in the absence of seminal plasma (SP), a vehicle for sexual transmission of the virus. To gain insight into the possible effect of SP on the performance of selected microbicides, their anti-HIV-1 activity in the presence, and absence of SP, was determined. METHODS: The inhibitory activity of compounds against the X4 virus, HIV-1 IIIB, and the R5 virus, HIV-1 BaL was determined using TZM-bl indicator cells and quantitated by measuring β-galactosidase induced by infection. The virucidal properties of cellulose acetate 1,2-benzene-dicarboxylate (CAP), the only microbicide provided in water insoluble, micronized form, in the presence of SP was measured. RESULTS: The HIV-1 inhibitory activity of the polymeric microbicides, poly(naphthalene sulfonate), cellulose sulfate, carrageenan, CAP (in soluble form) and polystyrene sulfonate, respectively, was considerably (range ≈ 4 to ≈ 73-fold) diminished in the presence of SP (33.3%). Formulations of micronized CAP, providing an acidic buffering system even in the presence of an SP volume excess, effectively inactivated HIV-1 infectivity. CONCLUSION: The data presented here suggest that the in vivo efficacy of polymeric microbicides, acting as HIV-1 entry inhibitors, might become at least partly compromised by the inevitable presence of SP. These possible disadvantages could be overcome by combining the respective polymers with acidic pH buffering systems (built-in for formulations of micronized CAP) or with other anti-HIV-1 compounds, the activity of which is not affected by SP, e.g. reverse transcriptase and zinc finger inhibitors

Doing Business and Inclusive Human Development in Sub-Saharan Africa

Purpose- This study examines how doing business affects inclusive human development in 48 sub-Saharan Africa for the period 2000-2012. Design/methodology/approach- The measurement of inclusive human development encompasses both absolute pro-poor and relative pro-poor concepts of inclusive development. Three doing business variables are used, namely: the number of start-up procedures required to register a business; time required to start a business; and time to prepare and pay taxes. The empirical evidence is based on Fixed Effects and Generalised Method of Moments regressions. Findings- The findings show that increasing constraints to the doing of business have a negative effect on inclusive human development. Originality/value- The study is timely and very relevant to the post-2015 Sustainable Development agenda for two fundamental reasons: (i) Exclusive development is a critical policy syndrome in Africa because about 50% of countries in the continent did not attain the MDG extreme poverty target despite enjoying more than two decades of growth resurgence. (ii) Growth in Africa is primarily driven by large extractive industries and with the population of the continent expected to double in about 30 years, scholarship on entrepreneurship for inclusive development is very welcome. This is essentially because studies have shown that the increase in unemployment (resulting from the underlying demographic change) would be accommodated by the private sector, not the public sector

Ten-step minimally invasive slalom unilateral laminotomy for bilateral decompression (sULBD) with navigation

Abstract Background Unilateral laminotomy for bilateral decompression (ULBD) is a MIS surgical technique that offers safe and effective decompression of lumbar spinal stenosis (LSS) with a long-term resolution of symptoms. Advantages over conventional open laminectomy include reduced expected blood loss, muscle damage, mechanical instability, and less postoperative pain. The slalom technique combined with navigation is used in multi-segmental LSS to improve the workflow and effectiveness of the procedure. Methods We outline ten technical steps to achieve a slalom unilateral laminotomy for bilateral decompression (sULBD) with navigation. In a retrospective case series, we included patients with multi-segmental LSS operated in our institution using the sULBD between 2020 and 2022. The primary outcome was a reduction in pain measured by Visual Analogue Scale (VAS) for back pain and leg pain and Oswestry Disability Index (ODI). Results In our case series (N = 7), all patients reported resolution of initial symptoms on an average follow-up of 20.71 ± 9 months. The average operative time and length of hospital stay were 196.14 min and 1.67 days, respectively. On average, VAS (back pain) was 4.71 pre-operatively and 1.50 on long-term follow-up of an average of 19.05 months. VAS (leg pain) decreased from 4.33 to 1.21. ODI was reported as 33% pre-operatively and 12% on long-term follow-up. Conclusion The sULBD with navigation is a safe and effective MIS surgical procedure and achieves the resolution of symptoms in patients presenting with multi-segmental LSS. Herein, we demonstrate the ten key steps required to perform the sULBD technique. Compared to the standard sULBD technique, the incorporation of navigation provides anatomic localization without exposure to radiation to staff for a higher safety profile along with a fast and efficient workflow

A new highly sensitive enzyme-linked immunosorbent assay for the detection of Plasmodium falciparum histidine-rich protein 2 in whole blood

Background The detection of submicroscopic infections in low prevalence settings has become an increasingly important challenge for malaria elimination strategies. The current field rapid diagnostic tests (RDTs) for Plasmodium falciparum malaria are inadequate to detect low-density infections. Therefore, there is a need to develop more sensitive field diagnostic tools. In parallel, a highly sensitive laboratory reference assay will be essential to evaluate new diagnostic tools. Recently, the highly sensitive Alere™ Malaria Ag P.f ELISA (HS ELISA) was developed to detect P. falciparum histidine-rich protein 2 (HRP2) in clinical whole blood specimens. In this study, the analytical and clinical performance of the HS ELISA was determined using recombinant P. falciparum HRP2, P. falciparum native culture parasites, and archived highly pedigreed clinical whole blood specimens from Karen village, Myanmar and Nagongera, Uganda. Results The HS ELISA has an analytical sensitivity of less than 25 pg/mL and shows strong specificity for P. falciparum HRP2 when tested against P. falciparum native culture strains with pfhrp2 and pfhrp3 gene deletions. Additionally, the Z′-factor statistic of 0.862 indicates the HS ELISA as an excellent, reproducible assay, and the coefficients of variation for inter- and intra-plate testing, 11.76% and 2.51%, were acceptable. Against clinical whole blood specimens with concordant microscopic and PCR results, the HS ELISA showed 100% (95% CI 96.4–100) diagnostic sensitivity and 97.9% (95% CI 94.8–99.4) diagnostic specificity. For P. falciparum positive specimens with HRP2 concentrations below 400 pg/mL, the sensitivity and specificity were 100% (95% CI 88.4–100) and 88.9% (95% CI 70.8–97.6), respectively. The overall sensitivity and specificity for all 352 samples were 100% (CI 95% 96–100%) and 97.3% (CI 95% 94–99%). Conclusions The HS ELISA is a robust and reproducible assay. The findings suggest that the HS ELISA may be a useful tool as an affordable reference assay for new ultra-sensitive HRP2-based RDTs.</p