Photocatalytic degradation of 4-chlorophenol by titanium dioxide: role of annealing temperature and morphology

This work investigates the degradation rate of 4-cholorophenol using Titanium dioxide photocatalysts. Chlorophenols and their compounds are a nuisance as they are recalcitrant to degradation in the environment. Three morphologically different Titanium dioxide catalysts, A, B and C, were immobilized on microscopic glass at a layer of 0.5 mg/cm2 and annealed between 500-700°C. The three different TiO2 powders were characterized using Scanning Electron Microscopy, X-Ray Diffraction and Brunauer Emmett Teller to determine their specific surface area, crystalline and particle sizes. A four–position photocatalytic reactor illuminated by two Ultra violet lamps of wavelength range 320-400 nm and intensity I = 27.87 mW/m2 was used to degrade the 4-Chlorophenol in 2 hrs. Aliquots of the degraded 4- chlorophenol were drawn every 30 minutes and analyzed using UV-Vis spectroscopy at λ=226 nm. The optimum annealing temperature of all TiO2 was found to be 650°C, with type B of hexagonal morphological structure and particle size of 28±2nm having the highest 4-chlorophenol degradation rate, of 71.21%.Keywords: Photocatalytic, 4-chlorophenol, annealing, morpholog

Characterization of Kenyan ceramics for production of medium duty alumina firebrick incinerator linings

The aim of this study was to evaluate locally available ceramic raw materials for the manufacture of Medium Duty Alumina Refractory Firebrick for incinerator lining.The clays were collected from two sites, Eburru in Nakuru County and Mukurwe-ini in Nyeri County in Kenya. Atomic Absorption Spectrophotometer and X-Ray Diffraction analytical methods were used to determine the chemical composition of the respective clays before and after firing at 1000OC for two hours.Atomic Absorption Spectrophotometer results revealed that Eburru Kaolin contained the highest amount of silica at 72.64% SiO2 but had the lowest of all other oxides. All the three raw materials were found to increase their oxide percentages after firing due to the loss in moisture and organic matter and reflected on their aluminasilica ratio. The X-Ray Diffraction results showed that the refractory formulated using the clays at a ratio of 2:2:1 Eburru Kaolin : Eburru Fireclay: Mukuruweini Ballclay attained good structural properties after firing at 1000OC for two hours and was comparable to commercial products in the market in addition to meeting the standards of a Medium Duty Refractory Firebrick.This is suitable for manufacture of incinerator linings.Keywords: Incinerator linings, Kaolin, Firebrick, Refractor

Composition and particle size of mineral trioxide aggregate, portland cement and synthetic geopolymers

Objective: To describe the composition and particle size of Portland cement (PC) and geopolymers in comparison to mineral trioxide aggregate (MTA).Design: A quantitative, laboratory-based exploratory study.Setting: Schools of Dental Sciences and Physical Sciences, University of Nairobi; World Agroforestry Centre (ICRAF); Ministry of Mining, all in Nairobi, Kenya.Study population: Grey PC clinker, Kaolin, Fly ash (FA) and blast furnace (BF) slag, together with alkaline-activated aluminosilicates (AS) or geopolymers derived from them, were evaluated in comparison to two brands of MTA (MTA Cem and ProRoot MTA).Methods: The materials were characterized by x-ray diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), graphite furnace atomic absorption spectroscopy (GFAAS) and fluoride ion selective electrode (FISE) for compositional analysis, and laser diffraction for particle size distribution analysis. Continuous data was subjected to analysis of variance (ANOVA) and Tukey’s post hoc test for hypothesis testing at α level of 0.05.Results: While MTA and PC comprised mainly of dicalcium and tricalcium silicate phases, geopolymers contained aluminosilicate phases such as quartz and mullite. Only FA contained fluoride (43.33μg/g, sd 5.77). There was no statistically significant difference in the composition of MTA and PC as determined by EDXRF except in the Bi (F-statistic=44.29, df=2, adjusted p<0.0001, difference=2.47, 95% CI 16.30, 33.14%wt) and Pb content (F-statistic=164.40, df=2, adjusted p=0.000, difference=1.74, 95% CI 1.43, 2.05%wt). There was no statistically significant difference in the mean particle size distribution of MTA, PC and geopolymers (D50 for PC = 12.46μm, sd 3.18, MTA = 7.23μm, sd 3.43, aluminosilicates = 12.74μm, sd 3.79, p>0.05).Conclusion: Composition of PC was similar to MTA while particle size of PC and geopolymers was similar to MTA

EVALUATION OF EARLY CALVES\u2019 WEANING DIET AS MILK REPLACER FOR SMALLHOLDER DAIRY PRODUCTION SYSTEMS IN KENYA

Small-scale dairy farmers in Kenya are interested more in selling milk to earn income, especially during dry seasons when milk prices hike. This results in depressed calves\u2019 growth rates, high calf mortality rates, late maturity and general economic losses in the smallholder dairy production systems. Innovative development of early calves weaning formulae, as milk replacers, would offer a solution in the calves\u2019 nutrition and household income in the long run. A study was conducted to determine the effectiveness and economic returns to replacing milk with formulated early calf weaning diets (EWDs) on the survival and general performance of dairy calves in Kenya. Treatments included milk feeding up to 105 days (Control) and with milk (28 days) + EWD, fortified or not fortified with effective microorganisms (EM), diamond-V or Diatomite (DT), up to 105 days. There was no (P>0.05) differences in average daily weight gain of the calves as a result of the treatments. However, the EM-treatment had significantly (P<0.01) higher calve dry matter (DM) intake (g kg-1 day) than in the other treatment groups. Due to feeding with EWD, total milk saved for the farmer was 9 kg-1cow-1day-1; equal to 945 kg for the 105 period, valued at US$614. For the conventional milk feeding (control), total milk saved was 5 kg-1 cow-1 day-1; equal to 525 for the 105 period, valued at US$ 341. Significant incidences of diarrhea were observed in the control (milk) and the Diamond-V fortified treatments. Signs of hair loss and discolorations were observed in DT-fortified EWDs. EM- fortification reduced disease incidences, thus, EWD fortified with this microbial feed additive can be an effective milk- replacer in smallholder dairy production systems to wean dairy calves at 28-35 days with good economic and performance results.Les petits fermiers agricoles au Kenya s\u2019int\ue9ressent plus \ue0 la vente du lait pour g\ue9n\ue9rer des revenues, sp\ue9cialement durant les saisons s\ue8ches lorsque le prix du lait est \ue9lev\ue9. Ceci r\ue9sulte en une inhibition du taux de croissance des veaux, des taux de mortalit\ue9s \ue9lev\ue9s, retard de maturit\ue9 et pertes \ue9conomiques dans les syst\ue8mes de production laitier des petits fermiers agricoles. Le d\ue9veloppement des formules innov\ue9es de sevrage pr\ue9coce des veaux en remplacement au lait pourrait offrir une solution dans la nutrition des veaux et \ue0 la longue am\ue9liorer le revenu des m\ue9nages. Une \ue9tude \ue9tait faite pour d\ue9terminer l\u2019efficacit\ue9 et le b\ue9n\ue9fice du remplacement du lait par une alimentation formul\ue9e de sevrage pr\ue9coce des veaux (EWDs) pour la survie et la performance des veaux au Kenya. Les traitements comportaient l\u2019alimentation par le lait jusqu\u2019\ue0 105 jours (t\ue9moin) et le lait (28 jours) + EWD, fortifi\ue9 ou non par des microorganismes efficaces (EM) , le diamant-V ou le Diatomite (DT), jusqu\u2019 \ue0 105 jours. Il n\u2019y avait pas de diff\ue9rences significatives (P>0.05) des traitements sur la moyenne du gain quotidien de poids des veaux. Par ailleurs, le traitement de fortification avec EM avait significativement (P<0.01) induit une ingestion de la mati\ue8re s\ue8che la plus \ue9lev\ue9e (DM) (g kg-1 day) par rapport autres traitements. Par l\u2019alimentation \ue0 l\u2019EWD, les fermiers ont pu gagner 9 kg vache-1jour-1 \ue9quivalant \ue0 945 kg pour toute la p\ue9riode de 105 jours et \ue9valu\ue9s \ue0 US614. Pour l\u2019alimentation conventionnelle en lait (t\ue9moin), le total \ue9pargn\ue9 \ue9tait de 5 kg par vache jour-1 \ue9quivalent \ue0 525 kg d\u2019une valeur d\u2019US 341. Des incidences de diarrh\ue9e \ue9taient observ\ue9es dans le control (lait) et le traitement EWD fortifi\ue9 avec Diamond-V tandis que les signes de perte et d\ue9coloration des poils \ue9taient observ\ue9s dans l\u2019EWD fortifi\ue9 de DT. La fortification avec les microorganismes EM a r\ue9duit les incidences de maladies. D\ue8s lors EWD fortifi\ue9 avec les microorganismes EM peut constituer un remplacement efficace du lait dans les syst\ue8mes de production laiti\ue8res pour sevrer les veaux de 28-35 jours avec des r\ue9sultats \ue9conomiques et des performances satisfaisants

The ASOS Surgical Risk Calculator: development and validation of a tool for identifying African surgical patients at risk of severe postoperative complications

Background: The African Surgical Outcomes Study (ASOS) showed that surgical patients in Africa have a mortality twice the global average. Existing risk assessment tools are not valid for use in this population because the pattern of risk for poor outcomes differs from high-income countries. The objective of this study was to derive and validate a simple, preoperative risk stratification tool to identify African surgical patients at risk for in-hospital postoperative mortality and severe complications. Methods: ASOS was a 7-day prospective cohort study of adult patients undergoing surgery in Africa. The ASOS Surgical Risk Calculator was constructed with a multivariable logistic regression model for the outcome of in-hospital mortality and severe postoperative complications. The following preoperative risk factors were entered into the model; age, sex, smoking status, ASA physical status, preoperative chronic comorbid conditions, indication for surgery, urgency, severity, and type of surgery. Results: The model was derived from 8799 patients from 168 African hospitals. The composite outcome of severe postoperative complications and death occurred in 423/8799 (4.8%) patients. The ASOS Surgical Risk Calculator includes the following risk factors: age, ASA physical status, indication for surgery, urgency, severity, and type of surgery. The model showed good discrimination with an area under the receiver operating characteristic curve of 0.805 and good calibration with c-statistic corrected for optimism of 0.784. Conclusions: This simple preoperative risk calculator could be used to identify high-risk surgical patients in African hospitals and facilitate increased postoperative surveillance. © 2018 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.Medical Research Council of South Africa gran

Search for Higgs-like bosons decaying into long-lived exotic particles

A search is presented for massive long-lived particles, in the 20–60 GeV/c2 mass range with lifetimes between 5 and 100 ps. The dataset used corresponds to 0.62fb-1 of proton-proton collision data collected by the LHCb detector at s=7TeV. The particles are assumed to be pair-produced by the decay of a Higgs-like boson with mass between 80 and 140 GeV/c2. No excess above the background expectation is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime and of the Higgs-like boson mass

First study of the CP-violating phase and decay-width difference in Bs 0→ψ(2S)ϕ decays

A time-dependent angular analysis of Bs 0→ψ(2S)ϕ decays is performed using data recorded by the LHCb experiment. The data set corresponds to an integrated luminosity of 3.0fb−1 collected during Run 1 of the LHC. The CP-violating phase and decay-width difference of the Bs 0 system are measured to be ϕs=0.23−0.28 +0.29±0.02rad and ΔΓs=0.066−0.044 +0.041±0.007ps−1, respectively, where the first uncertainty is statistical and the second systematic. This is the first time that ϕs and ΔΓs have been measured in a decay containing the ψ(2S) resonance