Generation, properties, and order packing of monodispersed spherical colloid particles of yttrium hydroxy-carbonate: A colloidal route to minimizing voids in ceramics

Monosized spherical colloid particles of yttrium hydroxy-carbonate were prepared by in situ decomposition of urea at elevated temperatures in yttrium nitrate solutions. The nucleation and growth phenomena generating these particles were studied through measurement of induction periods, particle sizes and growth rates in silica seeded and unseeded systems. It was found that precipitation took place only under neutral conditions. In unseeded systems, homogeneous nucleation yielded about 3 x 10[superscript]10 nuclei/cm[superscript]3 while in seeded precipitation enough nuclei were produced to bring the total number of particles to 4 x 10[superscript]10 seeds/cm[superscript]3. Systems containing at least 4 x 10[superscript]10 seeds/cm[superscript]3 underwent pure heterogeneous precipitation on to the existing seeds. Two diffusion-controlled growth models and the diffusion chronomal analysis were applied to the data of growth rate. These analyses and the narrowing of particle size distribution with growth time confirmed the diffusion-controlled particle growth mechanism;Electron diffraction analysis showed the particles to be crystalline. The surface charge on the particles was characterized by electrophoretic studies. There is a charge reversal from positive to negative as the pH is increased, with an isoelectric point (IEP) of about 7.4. The chemical composition of the powders was determined by thermal, x-ray photoelectron spectroscopic, and chemical analyses to be Y(OH)CO[subscript]3·H[subscript]2O;The stability of aqueous suspensions of particles with a radius of 0.21[mu] was studied as a function of pH (in the range of 7-12.3) using a turbidimetric method. The suspensions are stable in the pH range 8.4 through 11.6, with maximum stability being achieved at pH 10.8. Maximum flocculation appears around the isoelectric point. Ordered particles were prepared from suspensions with particle volume fractions of 0.2. Particle ordering was attributed to flocculation in the secondary minimum in some cases and to ordering of the Kirkwood-Alder character in others. Particles ordered in the secondary minimum were arranged in a close-packed structure of high coordination number. The IEP was exploited, in the former case to rapidly freeze the ordered structure into the primary minimum. ftn*DOE Report IS-T-1302. This work was performed under contract No. W-7405-Eng-82 with the U.S. Department of Energy

The determinants of health related quality of life of patients on maintenance haemodialysis at Kenyatta National Hospital, Kenya

Background: Health related quality of life (HRQOL) is increasingly being recognised as a primary outcome measure in the treatment of end stage renal disease. In addition to being an important surrogate marker of quality of care in patients on maintenance haemodialysis, HRQOL measures have being shown to be robust predictors of mortality and morbidity.Objective: To determine the health related quality of life and its determinants in patients on maintenance haemodialysis at the Kenyatta National Hospital.Design: A cross-sectional descriptive study.Setting: Renal unit, Kenyatta National HospitalSubjects: Adult patients with end stage renal disease on maintenance haemodialysis.Results: The mean physical composite summary and mental composite summary scores were 39.09±9.49 and 41.87±10.56 respectively. The burden of kidney disease sub-scale, symptom and problems sub-scale and effect of kidney disease on daily life sub-scale scores were 16.15±21.83, 73.46±18.06 and 67.63±23.45 respectively. No significant correlations were found between the health-related quality of life scores, socio-demographic and clinical factors assessed.Conclusion: The health-related quality of life of patients on maintenance haemodialysis is reduced. The physical quality of life is more affected than the mental quality of life. No independent determinants of health-related quality of life were identified

Effect of grazing systems and age on enteric methane production and performance plus grazing system effect on ruminal fermentation parameters of Nguni and Bonsmara beef cows

Beef breeds of cattle are predominantly raised through extensive grazing and produce the highest levels of enteric methane (CH4) through ruminal fermentation. The objective of this study was to evaluate the effect of breed, grazing, and age on enteric methane production and performance of beef cows as well as effect of breed and grazing system on ruminal fermentation parameters. Two separate studies were conducted; the first study evaluated the effect of grazing system, breed, and age on ruminal enteric methane production and performance of selected beef breeds. The second study evaluated the effect of the grazing system and breed on ruminal fermentation. In the first study, two breeds (Nguni and Bonsmara) raised under two grazing systems (communal and commercial) in a random complete block design were grouped into 3 age categories. Eighty-four cows aged between 24-120 months were randomly selected and grouped by age: group A (young adult cow, n = 7, 24-48 months old), group B (adult, n = 7, 60-80 months old), and group C (old adult, n = 7, 90-120 months) in either grazing system. Data were collected on methane production per day, body condition, and weight used to estimate dry matter intake (DMI), methane per DMI, and methane per body weight. In the second study, 40 cows of the same age group, parity, and physiological status were used. Ten cows per breed (Bonsmara and Nguni) in either grazing system (communal and commercial) were used in a random complete block design. Rumen fluid collection was done by the stomach tube method. Data were collected on ruminal ammonia-nitrogen (NH3-N), pH, Temperature, volatile fatty acids (VFAs). Older animals produced higher methane per head in the order of C > B > A; (P0.05). Body condition, BW, and DMI were higher (P0.05) among breeds and grazing systems. However, total VFAs were slightly lower in communal grazing (78.87 mmol/L) than commercial grazing (89.80 mmol/L). Acetate, propionate, butyrate proportions, and acetate to propionate ratio did not differ (P>0.05) among breeds but differed (P<0.05) between grazing systems. Acetate (P<0.05) and acetate to propionate ratio (P<0.05) were higher in the communal grazing system, while the reverse was true for propionate (P<0.05) and butyrate (P<0.05). Bonsmara produced more methane than Nguni under similar conditions, with Nguni uniquely producing more methane per BW, indicating host genetics influence. Communal animals and older animals produced more CH4 than commercial and younger cows regardless of the breed, indicating ruminal inefficiencies in very old cows. These results emphasize the idea that host genetics or breed, grazing system, and age influence methane output and performance. Hence, breeding strategies for hard-to-measure traits like methane production need to put all these factors into consideration.Thesis (MSc) (Animal Science) -- University of Fort Hare, 202

Effect of grazing systems and age on enteric methane production and performance plus grazing system effect on ruminal fermentation parameters of Nguni and Bonsmara beef cows

Beef breeds of cattle are predominantly raised through extensive grazing and produce the highest levels of enteric methane (CH4) through ruminal fermentation. The objective of this study was to evaluate the effect of breed, grazing, and age on enteric methane production and performance of beef cows as well as effect of breed and grazing system on ruminal fermentation parameters. Two separate studies were conducted; the first study evaluated the effect of grazing system, breed, and age on ruminal enteric methane production and performance of selected beef breeds. The second study evaluated the effect of the grazing system and breed on ruminal fermentation. In the first study, two breeds (Nguni and Bonsmara) raised under two grazing systems (communal and commercial) in a random complete block design were grouped into 3 age categories. Eighty-four cows aged between 24-120 months were randomly selected and grouped by age: group A (young adult cow, n = 7, 24-48 months old), group B (adult, n = 7, 60-80 months old), and group C (old adult, n = 7, 90-120 months) in either grazing system. Data were collected on methane production per day, body condition, and weight used to estimate dry matter intake (DMI), methane per DMI, and methane per body weight. In the second study, 40 cows of the same age group, parity, and physiological status were used. Ten cows per breed (Bonsmara and Nguni) in either grazing system (communal and commercial) were used in a random complete block design. Rumen fluid collection was done by the stomach tube method. Data were collected on ruminal ammonia-nitrogen (NH3-N), pH, Temperature, volatile fatty acids (VFAs). Older animals produced higher methane per head in the order of C > B > A; (P0.05). Body condition, BW, and DMI were higher (P0.05) among breeds and grazing systems. However, total VFAs were slightly lower in communal grazing (78.87 mmol/L) than commercial grazing (89.80 mmol/L). Acetate, propionate, butyrate proportions, and acetate to propionate ratio did not differ (P>0.05) among breeds but differed (P<0.05) between grazing systems. Acetate (P<0.05) and acetate to propionate ratio (P<0.05) were higher in the communal grazing system, while the reverse was true for propionate (P<0.05) and butyrate (P<0.05). Bonsmara produced more methane than Nguni under similar conditions, with Nguni uniquely producing more methane per BW, indicating host genetics influence. Communal animals and older animals produced more CH4 than commercial and younger cows regardless of the breed, indicating ruminal inefficiencies in very old cows. These results emphasize the idea that host genetics or breed, grazing system, and age influence methane output and performance. Hence, breeding strategies for hard-to-measure traits like methane production need to put all these factors into consideration.Thesis (MSc) (Animal Science) -- University of Fort Hare, 202

Seroprevalence of hepatitis B and C in maintenance dialysis in a public hospital in a developing country

Background. Patients with end-stage renal disease (ESRD) on maintenance dialysis are predisposed to hepatitis B virus (HBV) infection for a number of reasons. In a similar way, the prevalence of anti-hepatitis C virus (HCV) antibodies among patients on chronic haemodialysis and peritoneal dialysis is consistently higher than in healthy populations. There are few published data on these diseases in patients undergoing maintenance dialysis in sub-Saharan Africa.Objective. To determine the seroprevalence of HBV and HCV in patients on maintenance dialysis.Setting. Renal Unit, Kenyatta National Hospital, the largest public referral and teaching hospital in Kenya.Design. Cross-sectional descriptive study.Study population. All 100 patients on maintenance dialysis during the 9-month study period were evaluated.Method. The following information was obtained from all the patients: socio-demographic data, date of diagnosis of ESRD and commencement of dialysis and number of blood transfusions. Additionally, a history suggestive of hepatitis in spouses was looked for and physical examination for tattoos and other scars was carried out. Laboratory investigations included urea, electrolytes and serum creatinine liver enzymes, hepatitis B surface antigen (HBsAg), immunoglobulin M anti-hepatitis B core antibody (IgM anti-HBc), hepatitis Be antigen (HBeAg) and anti-HCV antibodies. Student's t-test was used to assess the significance of the data collected.Results. The results were expressed as mean (±SD). Fifty-seven males and 43 females were studied. Mean age was 44.3 ± 14.6 years. Ten patients (10%) had elevated aspartate aminotransferase (AST) and alanine aminotransferase (ALT) (&gt; 40 U/l for both). HBsAg was found in 8 patients (8%) IgM anti-HBc in 2%, and HBeAg in none. Anti-HCV antibody was found in 5%. Six of the HBsAg-positive patients were on haemodialysis, the other 2 on continuous ambulatory peritoneal dialysis (CAPD). There was no coexistence of HBV and HCV markers. Longer duration of dialysis and the number of blood transfusions were associated with an increased seroprevalence of HBV and HCV.Conclusion. There is a low seroprevalence of HBV and HCV in our dialysis population. This should not lead to complaisance in screening for these potentially lethal complications

Peripheral arterial disease in rheumatoid arthritis patients at the Kenyatta National Hospital, Kenya

Objective: To determine the magnitude of the rosclerotic arterial disease in Rheumatoid Arthritis(RA) patients at Kenyatta National Hospital.Design: hospital based cross-sectional study.Setting: Kenyatta National Hospital Rheumatology outpatient clinic.Subjects: Rheumatoid Arthritis patients.Results: We obtained ABI measurements in 90 RA patients, among them 23(25.5% 95% CI 17.2-36.1) had obstructed lower limb arteries. Among the 23, 21(91.3%) had mild PAD, two (8.7%) had moderate PAD; none had severe PAD nor incompressible vessels. The obstruction of vessels was independent of diabetes, hypertension, dyslipidemia and cigarette smoking though these factors increased the likelihood of having PAD. Risk age( ≥45 males, ≥55 females), Established RA(&gt; 5 year duration) and severe RA were found to be significantly associated with the likelihood of having PAD. These trends remained significant after multivariable adjustment for potential confounders. twenty five (27.7%) of the study subjects exhibited symptoms of intermittent claudication, 13(52%) of them had PAD on ABI measurements, The Edinburgh claudication questionnaire was found to have 56.5% sensitivity and 82% specificity in detectionof PAD in RA patients. Conclusion: There seems to be an association between PAD in RA with chronicity and severity of the RA. This association may support the pathogenic role of accumulated systemic inflammation in atherosclerosis. Clinicians should be alert to the possibility of impared arterial function and thus subsequent cardiovascular morbidity and mortality in this group of patients

Prognostic factors in patients hospitalised with diabetic ketoacidosis at Kenyatta National Hospital, Nairobi

Background: In spite of many advances in the management of diabetes in the last 25 years, the mortality associated with diabetic ketoacidosis (DKA) remains high, especially in the developing countries. The mortality appears greatest in the first 24 - 48 hours of their treatment. Most of the previous studies on DKA focused on children and the precipitating factors thereof but not particularly on clinical predictors of outcomes. Objective: To determine the clinico-laboratory predictors of outcomes of patients hospitalised with diabetic ketoacidosis who were undergoing treatment.Design: Cross-sectional descriptive study.Setting: The accident and emergency department and medical wards of the Kenyatta National Hospital.Subjects: Fifty one patients hospitalised with diabetic ketoacidosis over a nine month period were evaluated clinically and by laboratory tests. They were managed in the standard way with insulin, intravenous fluids and appropriate supportive care. Main outcome measures: Serial assays of serum electrolytes, glucose and blood pH, HbA1c and clinical outcome of either discharge home or death.Results: Of the 51 patients enrolled, 47 were included in the final analysis. Fourteen (29.8%) patients died, and the deaths occurred within less than 48 hours of hospitalisation and treatment. Of the patients who died, all (100%) had altered level of consciousness at hospitalisation, 71.4% had abnormal renal functions, 64.3% were newly diagnosed and an equal proportion of 64.3% were females. The alteration in the level of consciousness was significantly associated systolic hypotension and severe metabolic acidosis, (

Nephrotoxicity of amphotericin B in the treatment of cryptococcal meningitis in acquired immunodeficiency syndrome patients

Objectives: To describe the incidence of renal dysfunction, hypokalaemia and hypomagnesaemia in AIDS patients with cryptococcal meningitis and on amphotericin B treatment. Secondary objective was to determine all-cause mortality in the same group.Design: Prospective, observational study.Setting: Kenyatta National Hospital (KNH), Nairobi, Kenya.Subjects: Seventy consecutive patients with AIDS and cryptococcal meningitis on amphotericin B.Results: About 58.6% of the patients had at least 100% rise in the creatinine level. Thirty eight point six per cent of patients experienced a rise in serum creatinine of at least 50%. Ninty three per cent of the patients developed hypokalaemia and 80% had hypomagnesaemia at trough magnesium level. Only 54.3% of patients completed the intended 14-day treatment. Thirty point five per cent of patients died within the two week follow-up period.Conclussion: The incidences of amphotericin B associated nephrotoxicity, hypokalemia and hypomagnesaemia were high in this studied populatio

Health related quality of life of patients on maintenance haemodialysis at Kenyatta National Hospital

Background: Health related quality of life is increasingly being recognised as a primary outcome measure in treatment of end-stage renal disease. The health related quality of life of patients on maintenance haemodialysis is reduced. Several interventions directed at modifiable risk factors have been shown to improve quality of life of patients on haemodialysis.Objective: To assess the health-related quality of life of patients on maintenance haemodialysis at the Kenyatta National Hospital.Design: Cross sectional descriptive study.Setting: Kenyatta National Hospital, Renal Unit.Subjects: The study was conducted on 96 patients with end-stage renal disease on maintenance haemodialysis. Socio-demographic and clinical factors were recorded for all patients. Health-related quality of life was assessed using the Kidney Disease Quality of Life-36 questionnaire. Two summary scores and three subscale scores were calculated.Results: The mean physical composite summary and mental composite summary scores were 39.09±9.49 and 41.87±10.56 respectively. The burden of kidney disease subscale, symptom and problems subscale and effect of kidney disease on daily life subscale scores were 16.15±21.83, 73.46±18.061 and 67.63±23.45 respectively.Conclusion: Health-related quality of life of patients on maintenance haemodialysis is reduced. The physical quality of life is more affected than the mental quality of life. The burden of kidney disease subscale is the most affected subscale score

The Fate of Nitrogen and Faecal Coliform in the Lubigi Wetland in Uganda

The capacity of the Lubigi wetland to reduce nitrogen and faecal coliform pollution entering Lake Kyoga in Uganda was investigated. Three transects with 5 sampling points in each, were established in the wetland. Wetland plants samples were collected from the specific locations along the transects, and laboratory tests and analyses were carried out for plants biomass and nitrogen contents determination. Samples of wetland sediments were also collected, and laboratory tests and analyses were done for determination of nitrogen content in the sediments. Wetland water samples were taken from the main wetland inlet and the main outlet from the wetland main study area. At the same time, wetland water pH, dissolved oxygen and temperatures were measured in-situ. Laboratory tests and analyses for ammonia-nitrogen, nitrate-nitrogen, total Kjeldahl nitrogen, total nitrogen and faecal coliforms were carried out on the wetland water samples. The results indicate that the Lubigi wetland received about 16 to 173 mg/l of total nitrogen, largely in form of organic- nitrogen (64.7%) and ammonia-nitrogen (35.2%). Nitrate-nitrogen and Nitrite-nitrite accounted for only 0.1% of the total nitrogen in the inlet. The wetland removed about 24.9% of this nitrogen, which is equivalent to removal of about 1,672 tons of nitrogen annually. About 67.5 gN/m2 and 0.30 gN/kg of dry sediments were sequestered in the wetland plants biomass and the benthic layer respectively. The Lubigi wetland main study area also receives faecal coliform concentrations with the wetland inlet mean value of 653,509 CFU/100ml and its outlet mean value is 218,676 CFU/100ml. These values give a faecal coliform (FC) overall removal efficiency of approximately 66.5%. It was thus concluded that the Lubigi wetland has considerable capacity to buffer and protect Lake Kyoga, by reducing nitrogen and faecal coliform pollution entering the lake