An investigative study of Diffusion of Commercial Aspirin (Acetylsalicylic acid) in Sodium Hydroxide Solution at 25oC

Diffusion is a macroscopic motion of components of a system that arises from concentration difference. Reaction diffusion is widely used to model developmental process. This project considers effective mechanism leading to effective diffusion coefficient. A mathematical formalism for transforming local transport law into diffusive terms is developed. The diffusion coefficient of drug aspirin was studied in basic NaOH of concentration range 0.01 to 0.1M at 25oC. The rate of diffusion was monitored by observing the boundary conditions of the indicator between the drug and solution. In the study five (5) aspirin tablets collected from a local pharmacy in Eldoret town were used for the study. From the profile it was observed that as the time progressed the boundary increased fast for non-coated tablets compared to the coated ones. All the aspirin were found to give values according to underlying mechanism. For the drug A (600mg) of aspirin the best value of diffusion coefficient of 1.69 x 10-4 cm2 sec-1 was observed while the values for coated drug E with 75 mg aspirin was found to be slightly lower. Fickian mechanism is believed to be the consequence of drug molecule small size.  First of all fractional drug uptake is linear and independent of the sample of thickness when In [NaOH] is plotted against square distance. A graph of x2 against In [NaOH] was plotted which was used to calculate the diffusion coefficient. The experimental values of diffusion coefficient D were within the experimental error to those of (4Dt)-1. The study also adopted a descriptive case study; it was conducted at Kimumu municipality, Eldoret town. The target population consisted of 25 respondents. Data was collected using self-administered questionnaires and interview schedules, coded and analysed using SPSS version 16.0. Systematic quantitative review data was analysed using means and frequency tables and percentages while qualitative data was analyzed using inferential statistics chi-square. Data was presented using table, pie charts and graphs.  The study found that most of the individuals preferred drug B. Keywords:  Diffusion, Aspirin, Acetylsalicylic acid, Diffusion Coefficient, Sodium Hydroxide, Fickian Mechanism, Systematic Revie

Variation of Pollutant Levels in Vegetables: A Case Study of

There is growing public concern over the illegal cultivation of vegetables on soils amended with sewage sludge or irrigated with mixtures of sewage and sewage sludge. Effluents and wastewater from Bidii in Kitale treatment plant are used by vegetable farmers for the irrigation of their vegetables during dry season. These effluents may contain some toxic pollutants which bioaccumulate along the food chain. Moreover the uptake of such toxic metals by vegetables is governed by their availability and concentration in the soil. Therefore such vegetables may accumulate pollutants in excessive amount in their various parts. This may ultimately, adversely affect humans and other species that depend on such crops for food, hence the need to evaluate the variation of pollutant levels in vegetables samples in these areas. Samples of spinach and kales and top soils (0-20) cm were collected from the vegetable farms of Bidii and Taito area as control point. Random sample collections were made five (5) times during the period from the two plots between October to December 2012. The vegetables samples were dried in an oven at 80°C for 72 h. The dry samples were crushed in a mortar  and pestle and the resulting powder digested by weighing 1.0 g of oven-dried ground and sieved (<1 mm) into an acid-washed porcelain crucible and placed in furnace for 4 hours at 500°C. The crucibles were removed and cooled. The weighed vegetable samples were transferred to 300 ml digesting flasks and then 27 ml of a mixture of HNO3 and concentrated H2SO4 were added to the sample. The mixture was heated on a hot plate for about half an hour until brown fumes disappeared. The mixture was cooled, and 3 ml of percloric acid were carefully added and then heating continued until white fumes disappeared. The digested sample was filtered into a 100 ml volumetric flask and made up to volume with de-ionized water. Soil samples were digested using aqua regia and 1.0 g of the soil sample was placed in a flask and 6 ml of concentrated nitric acid (HNO3) was added first before adding 18 ml of concentrated HCl. The mixture was then heated until a clear digest was obtained. The digest was then cooled and a few drops of water were added before filtering. The filtrate was then diluted with de-ionized water to 100 ml. The concentrations of heavy metals which include, Cu, Zn, Cr, and Pb, were determined using atomic absorption spectrophotometer (AAS). Levels of some anions (nitrate and phosphate were determined using Spectroscan 30 UV-Vis spectrophotometer. The results revealed that Cr and Pb had the highest concentrations, while Cu had the lowest in the leafy vegetables studied. The order of heavy metals was found to be Zn>Pb>Cr>Cu in soils while Pb>Zn>Cr>Cu in vegetables. The concentration of NO3- ranged between 2.176 mg/kg to 3.202 mg/kg while PO43- 2.897 mg/kg to 3.342 mg/kg in vegetables. Levels of NO3- in soils were 1.88 mg/kg to 2.06 mg/kg while PO43- had 4.66 mg/kg to 4.99 mg/kg. The vegetables from Bidii area contained much higher concentrations than those from Taito area. The levels of Cr and Pb in vegetables exceeded WHO Maximum Limit (0.05 mg/kg for Cr and 0.3 mg/kg for Pb). The variation in the parameters determined were found to be statistically significant (p<0.05) as determined by one way ANOVA. Key words: copper, lead, chromium, zinc, nitrates, phosphates, polluted soils, vegetables

Variation of Pollutant Levels in Vegetables: A Case Study of

There is growing public concern over the illegal cultivation of vegetables on soils amended with sewage sludge or irrigated with mixtures of sewage and sewage sludge. Effluents and wastewater from Bidii in Kitale treatment plant are used by vegetable farmers for the irrigation of their vegetables during dry season. These effluents may contain some toxic pollutants which bioaccumulate along the food chain. Moreover the uptake of such toxic metals by vegetables is governed by their availability and concentration in the soil. Therefore such vegetables may accumulate pollutants in excessive amount in their various parts. This may ultimately, adversely affect humans and other species that depend on such crops for food, hence the need to evaluate the variation of pollutant levels in vegetables samples in these areas. Samples of spinach and kales and top soils (0-20) cm were collected from the vegetable farms of Bidii and Taito area as control point. Random sample collections were made five (5) times during the period from the two plots between October to December 2012. The vegetables samples were dried in an oven at 80°C for 72 h. The dry samples were crushed in a mortar  and pestle and the resulting powder digested by weighing 1.0 g of oven-dried ground and sieved (<1 mm) into an acid-washed porcelain crucible and placed in furnace for 4 hours at 500°C. The crucibles were removed and cooled. The weighed vegetable samples were transferred to 300 ml digesting flasks and then 27 ml of a mixture of HNO3 and concentrated H2SO4 were added to the sample. The mixture was heated on a hot plate for about half an hour until brown fumes disappeared. The mixture was cooled, and 3 ml of percloric acid were carefully added and then heating continued until white fumes disappeared. The digested sample was filtered into a 100 ml volumetric flask and made up to volume with de-ionized water. Soil samples were digested using aqua regia and 1.0 g of the soil sample was placed in a flask and 6 ml of concentrated nitric acid (HNO3) was added first before adding 18 ml of concentrated HCl. The mixture was then heated until a clear digest was obtained. The digest was then cooled and a few drops of water were added before filtering. The filtrate was then diluted with de-ionized water to 100 ml. The concentrations of heavy metals which include, Cu, Zn, Cr, and Pb, were determined using atomic absorption spectrophotometer (AAS). Levels of some anions (nitrate and phosphate were determined using Spectroscan 30 UV-Vis spectrophotometer. The results revealed that Cr and Pb had the highest concentrations, while Cu had the lowest in the leafy vegetables studied. The order of heavy metals was found to be Zn>Pb>Cr>Cu in soils while Pb>Zn>Cr>Cu in vegetables. The concentration of NO3- ranged between 2.176 mg/kg to 3.202 mg/kg while PO43- 2.897 mg/kg to 3.342 mg/kg in vegetables. Levels of NO3- in soils were 1.88 mg/kg to 2.06 mg/kg while PO43- had 4.66 mg/kg to 4.99 mg/kg. The vegetables from Bidii area contained much higher concentrations than those from Taito area. The levels of Cr and Pb in vegetables exceeded WHO Maximum Limit (0.05 mg/kg for Cr and 0.3 mg/kg for Pb). The variation in the parameters determined were found to be statistically significant (p<0.05) as determined by one way ANOVA. Key words: copper, lead, chromium, zinc, nitrates, phosphates, polluted soils, vegetables

Diffusion of Aspirin (ASA) Based Drugs in Sodium Hydroxide Solution at Ambient Temperature.

Diffusion is a macroscopic motion of components of a system that arises from concentration difference and plays a vital role in drug migration in the body governed by Fickian diffusion laws. This project considers effective mechanism leading to effective diffusion coefficient. The diffusion coefficient of aspirin based drugs was studied in basic NaOH of concentration range 0.01M to 0.1M and a relatively more concentrated set ranging from 0.1M to 1.0M were studied at 25oC. The study looks into the rate of diffusion of coated and non-coated aspirin drugs in aqueous NaOH solution designated different letter heads A, B, C, D, and E. The objective of this work was to determine the diffusion coefficients of aspirin drugs at different concentrations range at 25oC and to compare with those calculated from limiting ionic conductance at infinite dilution. The rate of diffusion was monitored by observing the boundary conditions of the indicator between the drug and solution. The problem statement is that there are various aspirin based drugs in the market and all have different amount of aspirin in them. The research sought to find out the rate of diffusion of the drugs and conclude if at all their values relate to their masses as per the diffusion law. In the study five (5) aspirin tablets collected from a local pharmacy in Eldoret town were used for the study. From the profile it was observed that as the time progressed the boundary increased fast for noncoated tablets compared to the coated ones. The boundary heights (x) at a time t and concentration are also recorded. The moving boundary method coefficients ranged from 2.780 x 10-6 cm2 sec-1 to 6.995 x 10-6 cm2 sec- 1, 2.196 x 10-6 cm2 sec-1 to 6.092 x 10-6 cm2 sec-1, 2.138 x 10-7 cm2 sec-1 to 6.576 x 10-7 cm2 sec-1 , 3.241 x 10-10 cm2 sec-1 to 1.617 x 10-10 cm2 sec-1 and 1.378 x 10-10 cm2 sec-1 to 2.172x 10-10 cm2 sec-1 for drugs aspirin A , B, C. D and E respectively. All the aspirin were found to give values according to Fickian mechanism. For the drug A (600mg) of aspirin the best value of diffusion coefficient of 6.995 x 10-6 cm2 sec-1 at concentrated solution and 2.780 x 10-6 cm2 sec-1 was observed at dilute range solutions while the values for coated drug E with 75 mg aspirin was found to be slightly lower. The fractional drug uptake is linear and independent of the sample of thickness when distance is plotted against time. A graph of x2 against time was plotted which was used to calculate the diffusion coefficient. The experimental values of diffusion coefficient Do were in close agreement with the expected value from infinite dilution which was a general estimation of diffusion coefficients. Quantitative data was analysed using analysis of variance and chi-square statistical. Data was presented using table and graphs. The study found that the aspirin drug with the highest diffusion coefficient is drug A. In addition, conductometric technique was recommended to give more accurate results and similar method should be constituted with the use of other techniques such as TLC and spectrophotometric method for comparison purposes with the free diffusion and it is important for manufacturers to revalidate steps in the production process, for any critical control point in the production process leads to hydrolysis of aspirin. Key words: Diffusion, Aspirin, Acetylsalicylic acid, Diffusion Coefficient, Sodium Hydroxide, Fickia

Mediating household energy transitions through co-design in urban Kenya, Uganda and South Africa

Approaches to providing sustainable energy in cities have generated considerable interest in academic and policy circles. The development of this body of work, however, has not shed much light on the modes of intermediation that are needed to reconfigure urban energy systems towards sustainability in energy-poor countries. This paper focuses on the role of academics as knowledge intermediaries who can trigger cross-sector collaborations around innovations for a sustainable energy transition in African cities. The research presented here was generated by an interdisciplinary research team made up of partners in Kenya, Uganda and South Africa. The research partners set out to better understand how sustainable energy transitions can be achieved through collaborative efforts between community members, experts and policy actors in the three countries. This paper provides evidence-based reflections on how the research partners used participatory methods to facilitate solution co-design and knowledge co-production over a period of two years under the Leading Integrated Research for Agenda 2030 in Africa (LIRA 2030) program. A key knowledge outcome of the research partnership is an improved understanding of how transdisciplinary research across the sub-region can be used to unearth the socio-spatial, cultural and political dimensions of energy in relation to other urban services such as health and housing. Based on this understanding, the paper proposes transdisciplinary co-design as a promising approach to providing sustainable energy in urban informal settlements in Sub-Saharan Africa

Interrogating differences: A comparative analysis of Africa's informal settlements

Urban development in Africa is a very diverse and ambivalent phenomenon with aspects that do not fall neatly into global standards. Informal settlements therefore challenge governance by standards. We argue that quantifying and interrogating differences offers a better basis for governance. By drawing on a comparative analysis of three different informal settlements in Sub-Saharan Africa, this paper explores what differences reveal about the governance of informal settlements. The paper uses an urban societal metabolism approach, focussed on gender, energy and health, based on questionnaires and focus group discussions in Enkanini (Stellenbosch, South Africa), Mathare (Nairobi, Kenya), and Kasubi-Kawaala (Kampala, Uganda). The contribution of the paper is both empirical and theoretical. Empirically, we provide new evidence about the metabolism of urban informality at multiple levels of analysis: the individual, the household and the settlement. Findings show the gender asymmetries in urban poverty and the intricate links between energy choices, health and economic status. Theoretically, we argue that different levels of analysis produce different understandings of urban informality, and that analyzing informal settlements only by population aggregates means missing information. We conclude by arguing that understanding differences leads to the formulation of modest and localised goals, which are better able to take into account the complexity of urban informality