Aqueous Hydrogen Sulphide in Slit-Shaped Silica Nano-Pores: Confinement Effects on Solubility, Structural and Dynamical Properties

Confinement in nm-size pores affects structural and transport properties of water and co-existing volatile species. It has for example been reported that confinement can enhance the solubility of gases in water. We report here equilibrium molecular dynamics simulations for aqueous H2S confined in slit-shaped silica pores at 313K. We investigated the effect of pore width on the H2S solubility in water. We quantified the molecular distribution of the fluid molecules within the pores, the hydration structure for solvated H2S molecules, and the dynamical properties of the confined fluids. The results show that confinement reduces the H2S solubility in water, and that the solubility increases with pore size. Our analysis suggests that these results are due to perturbations on the coordination of water molecules around H2S due to confinement. Confinement is found to dampen the dynamical properties of aqueous H2S as well. Comparing the results obtained for aqueous H2S to those, reported elsewhere, for aqueous CH4 we conclude that H2S permeates hydrated slit-shaped silica nano-pores faster than CH4. These observations contribute to understand fluids in the subsurface, and could have important implications for applications in catalysis and perhaps for developing new natural gas sweetening technologies

Factors Governing the Enhancement of Hydrocarbon Recovery via H2S and/or CO2 Injection: Insights from a Molecular Dynamics Study in Dry Nanopores

Although enhanced oil recovery (EOR) is often achieved by CO2 injection, the use of acid gases has also been attempted, for example, in oil fields in west Canada. To design EOR technologies effectively, it would be beneficial to quantify the molecular mechanisms responsible for enhanced recovery under various conditions. We report here the molecular dynamics simulation results that probe the potential of recovering n-butane confined in silica, muscovite, and magnesium oxide nanopores, all proxies for subsurface materials. The three model solid substrates allow us to identify different molecular mechanisms that control confined fluid behavior and to identify the conditions at which different acid gas formulations are promising. The acid gases considered are CO2, H2S, and their mixtures. For comparison, in some cases, we consider the presence of inert gases such as N2. In all cases, the nanopores are dry. The recovery is quantified in terms of the amount of n-butane displaced from the pore surface as a function of the amount of gases present in the pores. The results show that the gas performance depends on the chemistry of the confining substrate. Whereas CO2 is more effective at displacing n-butane from the protonated silica pore surface, H2S is more effective in muscovite, and both gases show similar performance in MgO. Analysis of the interaction energies between the confined fluid molecules and the surface demonstrates that the performance depends on the gas interaction with the surface, which suggests experimental approaches that could be used to formulate the gas mixtures for EOR applications. The structure of the gas films in contact with the solid substrates is also quantified as well as the self-diffusion coefficient of the fluid species in confinement. The results could contribute to designing strategies for achieving both improved hydrocarbon production and acid gas sequestration

Competitive adsorption and reduced mobility: N-octane, CO₂ and H₂S in alumina and graphite pores

Because gas injection into geological formations is a common technology deployed for enhanced oil recovery (EOR), it is important to understand at the molecular level the relations between competitive adsorption and fluid mobility at the single-pore level. To achieve such an understanding, we report here molecular dynamics simulation results to document structural and dynamical properties of n-octane confined in slit-shaped alumina and graphite pores in the presence of CO₂ and H₂S. The substrates are chosen as proxy models for natural hydrophilic and hydrophobic substrates, respectively. It was found that CO₂ and H₂S could displace n-octane from alumina but not from graphite surfaces. Analysis of the results demonstrates that more attractive n-octane – surface and weaker CO₂/H₂S - surface interactions in graphite compared to alumina are responsible for this observation. Regardless of pore type, the results suggest that adding CO₂ or H₂S suppresses the diffusion of n-octane due to pore crowding. However, the mechanisms responsible for this observation are different, wherein preferential adsorption sites are available on the alumina surface for both CO₂ or H₂S, but not on graphite. To contribute to designing advanced EOR technologies, possible molecular mechanisms are proposed to interpret the results

Heterosis and Reciprocal Effect For Body Weight and Leather Properties in Hybrid Goats

Identification and evaluation of economically important traits in livestock is central to genetic improvement. The objective of this study was to evaluate heterosis and reciprocal effects for bodyweight and leather properties among progenies of pure and reciprocal crossing of West African Dwarf (WAD) and Red Sokoto (RS) goats. Bodyweights of 96 kids were recorded at birth, weaning and yearling. Skins collected from slaughtered goats at yearling were processed to leather using vegetable tanning approach. The leathers were subjected to physical analysis to determine Thickness, Percentage Elongation (PE), Surface Area, weight and grain properties comprising Load at Crack, Load at Tear, Distension at Crack and Distension at Tear.  Heterotic effect for bodyweight was negative at birth (-8.99%) and weaning (-11.15%) but positive at yearling (6.64%). Specific heterosis for bodyweight at yearling was higher for progenies of WAD does serviced with RS bucks. General and specific heterosis were positive for all the leather traits except PE. Specific heterosis was higher when RS does were serviced with WAD bucks. Reciprocal effects for bodyweight reduces with increase in goats’ age (Birth Weaning Yearling: 9.88 6.28 5.62).Reciprocal effects for grain properties were generally higher than other leather traits. This study concluded that WAD and RS goats are dissimilar in leather traits and bodyweight at different ages, and that choice of sire or dam for successful crossbreeding programme is trait dependen

Exploring Measures for Improving Small and Medium Construction Enterprises’ (SMCEs) Participation in the Nigerian Public Procurement

Despite the roles which small and medium construction enterprises (SMCEs) play in the Nigeria construction industry and the economy at large, extant research revealed that their participation in public procurement is poor as large firms have dominated the public procurement market. Previous studies have identified barriers responsible for their low participation and also suggested improvement measures. However, improvement measures best suited to dismantle/mitigate each barrier is not known. This study thus, assessed measures for improving SMCEs’ participation in Nigeria public procurement. The study collected data from 100 SMCEs in Nigeria, via a questionnaire survey. Mean/relative importance index was used for ranking the measures and ANOVA for checking difference between the studied measures. The result of the study revealed that E-procurement is the best measure for improving SMCEs’ participation in public procurement as it is best in dismantling barriers related to “problematic procurement procedure”, “lack of awareness of public procurement” and “legal issues/corruption”. Training which is suitable for eliminating barriers related to “lack of skilled employees and partners”, emerged as the second best followed by Division of Contract into lots that is best suitable for tackling barriers related to “lack of resources” which is contrary to previous researchers’ belief that it is the best measure. The study concludes that E-procurement, training and division of contract into lots are all suitable measures for improving SMCEs’ participation in Nigeria public procurement in their other of priority. The study’s findings show that it is desirous that the measures are applied together as none of these measures is singularly sufficient in dismantling all barriers to SMCEs’ participation in public procurement

Exploring Measures for Improving Small and Medium Construction Enterprises’ (SMCEs) Participation in the Nigerian Public Procurement

Despite the roles which small and medium construction enterprises (SMCEs) play in the Nigeria construction industry and the economy at large, extant research revealed that their participation in public procurement is poor as large firms have dominated the public procurement market. Previous studies have identified barriers responsible for their low participation and also suggested improvement measures. However, improvement measures best suited to dismantle/mitigate each barrier is not known. This study thus, assessed measures for improving SMCEs’ participation in Nigeria public procurement. The study collected data from 100 SMCEs in Nigeria, via a questionnaire survey. Mean/relative importance index was used for ranking the measures and ANOVA for checking difference between the studied measures. The result of the study revealed that E-procurement is the best measure for improving SMCEs’ participation in public procurement as it is best in dismantling barriers related to “problematic procurement procedure”, “lack of awareness of public procurement” and “legal issues/corruption”. Training which is suitable for eliminating barriers related to “lack of skilled employees and partners”, emerged as the second best followed by Division of Contract into lots that is best suitable for tackling barriers related to “lack of resources” which is contrary to previous researchers’ belief that it is the best measure. The study concludes that E-procurement, training and division of contract into lots are all suitable measures for improving SMCEs’ participation in Nigeria public procurement in their other of priority. The study’s findings show that it is desirous that the measures are applied together as none of these measures is singularly sufficient in dismantling all barriers to SMCEs’ participation in public procurement

Renal cell carcinoma in a semi-urban population of south-western Nigeria

Objective: To describe the demographic features, treatment challenges and  prognosis of renal cell carcinoma (RCC) in a semi-urban population of south-western NigeriaDesign: A retrospective review of RCC managed between January 2007 and  December 2014Setting: Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife,  southwestern NigeriaSubjects: Fifty-one patients with histologically confirmed RCC Interventions: Radical nephrectomy, ImmunotherapyMain outcome measures: Surgical outcomesResults: A total of 51 cases were reviewed, representing 46.8/100,000 of all new  patients. Age range was 21 to 83 years, with peak in third decade and male to female ratio of 1:1.5. Identified risk factors were systemic hypertension (15.7%), smoking  (11.8%) and obesity (3.9%). Triad of haematuria, loin pain and loin mass was found in 13.7% while 5.9% were discovered  incidentally. The right and left kidneys were involved in 41.2% and 58.8% respectively. Radical nephrectomy was the most  common procedure done (78.4%). Surgical complications included  excessive primary haemorrhage (8.5%), surgical site  infection (6.4%) and duodenal injury (2.1%) while mortality was (2.1%). Adjuvant immunotherapy with  sunitinib/sorafenib was given in 7.8% of patients. The histologic types were clear cell (60.8%), chromophobe (17.6%), papillary (13.7%), sarcomatoid (3.9%), mixed (1.9%) and multilocular cystic RCC (1.9%). Clear cell variant were low grade with good prognosis. Poor prognostic factors were sarcomatoid histology and late presentationConclusion: RCC is more common in females mainly of the younger age group in our environment. Radical nephrectomy remains the mainstay of management, including in advanced cases

High-sensitivity refractive index sensor based on large-angle tilted fiber grating with carbon nanotube deposition

This paper presents a highly sensitive ambient refractive index (RI) sensor based on 81° tilted fiber grating (81°-TFG) structure UV-inscribed in standard telecom fiber (62.5μm cladding radius) with carbon nanotube (CNT) overlay deposition. The sensing mechanism is based on the ability of CNT to induce change in transmitted optical power and the high sensitivity of 81°-TFG to ambient refractive index. The thin CNT film with high refractive index enhances the cladding modes of the TFG, resulting in the significant interaction between the propagating light and the surrounding medium. Consequently, the surrounding RI change will induce not only the resonant wavelength shift but also the power intensity change of the attenuation band in the transmission spectrum. Result shows that the change in transmitted optical power produces a corresponding linear reduction in intensity with increment in RI values. The sample shows high sensitivities of ∼207.38nm/RIU, ∼241.79nm/RIU at RI range 1.344-1.374 and ∼113.09nm/RIU, ∼144.40nm/RIU at RI range 1.374-1.392 (for X-pol and Y-pol respectively). It also shows power intensity sensitivity of ∼ 65.728dBm/RIU and ∼ 45.898 (for X-pol and Y-pol respectively). The low thermal sensitivity property of the 81°-TFG offers reduction in thermal cross-sensitivity and enhances specificity of the sensor