Numerical examination of concentration-dependent wastewater sludge ejected into a drinking water source.

One of the significant water-related health challenges globally is due to pollutant fate. Contaminants endanger the lives of humans, animals, and even plants. The present mathematical analysis explains reactive wastewater sludge ejected into a drinking water source from wastewater treatment plants. The assumption that wastewater sludge follows a power-law constitutive relation leads to nonlinear momentum and concentration equations. The contaminants are assumed to follow a nonlinear irreversible first-order sorption model. The numerical solution of the coupled problem is solved using the Bivariate Spectral Local Linearization Method and validated with the spectral Chebyshev weighted residual method. Profiles are presented for dimensionless flow velocity and concentration. Comprehensive explanations for the obtained results are provided with relevant applications.

The whitening effect of chlorine dioxide--an in vitro study.

OBJECTIVES: The aim of this study was to investigate the whitening properties and rate of bleaching action of chlorine dioxide and compare them with those of hydrogen peroxide of similar concentration. METHODS: Sixty bovine central incisor crowns were ground and polished until flat surfaces were obtained. The crowns were subjected to extensive staining cycles of artificial saliva, chlorehexidine and tea before being randomly assigned to three groups: chlorine dioxide (ClO2), hydrogen peroxide (H2O2) and deionised water (H2O). The crowns in each group were subjected to seven 2 min exposure cycles in addition to an extra 30 min cycle. CIE LAB spectrophotometric measurements were taken at baseline, after each 2 min, and each extended 30 min bleaching cycle. RESULTS: L* for ClO2 specimens was significantly higher only after the first 2 min cycle (p<0.001) while for H2O2 specimens, L* significantly increased after the first two cycles (p<0.001) and continued to increase, at a slower rate, until the end of the treatment cycles. ΔE was significantly greater within H2O2 than within ClO2 specimens (p<0.001). CONCLUSION: Chlorine dioxide whitens teeth at a faster rate than hydrogen peroxide. Specimens treated with chlorine dioxide were significantly lighter than those treated with hydrogen peroxide at the end of the first 2 min application cycle, however, extended exposures did not enhance color.

The evaluation of a novel method comparing quantitative light-induced fluorescence (QLF) with spectrophotometry to assess staining and bleaching of teeth.

This study reports the development and evaluation of a novel method using quantitative light-induced fluorescence (QLF), which enables its use for quantifying and assessing whole tooth surface staining and tooth whitening. The method was compared with a spectrophotometer to assess reliability. Two experimental phases, intrinsic stain formation and tooth whitening, were conducted in vitro on 16 extracted bovine teeth. Intrinsic stains were developed via access through lingual surfaces and root canals of these teeth using tea solution (2 g/100 ml, Marks and Spencer Extra Strong Tea, Marks and Spencer, London, UK) for 6 days. Stains were removed using 33% hydrogen peroxide (VWR Prolab, Leicestershire, UK) in cycles over 150 min. Stain development/whitening was monitored with QLF (Inspektor Research systems, Amsterdam, Netherlands) and spectrophotometry (Easy shade, Vita Zahnfabrik, Bad Säckingen, Germany). Parameters Delta F for QLF and Delta E for the spectrophotometer were obtained. The progression of stain intensity and removal observed by the methods were tested for correlation using Pearson's correlation coefficient. Intra-examiner reliability for each method was tested. QLF showed a high correlation with spectrophotometry for detecting and monitoring intrinsic tooth stain progression (Pearson coefficient r was -0.987 with correlation significant p < 0.0001). For stain removal, the Pearson coefficient (r) between both methods was -0.906 with no significance p = 0.094. The use of an external reference material in combination with the inner patch QLF analysis technique had the ability to detect and measure whole tooth surface staining and its removal longitudinally. The reliability of the method shows a potential clinical application.

The effect of bleaching, varying the shade or thickness of composite veneers on final colour: an in vitro study.

OBJECTIVE: To investigate whether bleaching prior to placement of a composite veneer had an effect on the final shade of the restoration and whether this was affected by the thickness or shade of the veneer. METHODS: Twenty bovine teeth were collected, sectioned and divided into two groups. One group was the non-bleached control, while the other was the bleached group. A colour reading was recorded using a spectrophotometer. The bleached group then underwent external bleaching with 38% hydrogen peroxide and a colour reading was recorded. Each of these two groups were further sub-divided into four subgroups, on which composite veneers were placed. These subgroups were: 0.5 m thick A1, 1 m thick A1, 0.5 mm thick A4 and 1 mm thick A4 composite veneers. Colour readings were recorded after veneer placement. Statistical significance was assessed using analysis of variance. RESULTS: There was a difference between the colour produced for the same veneer properties, between the bleached and non-bleached groups. For a thin (0.5mm) A4 veneer bleaching produced a statistically significant difference in the amount of colour change (DeltaE) compared to veneering alone. For A1, non-bleached group there is a significant difference in the DeltaE produced by altering the thickness of the veneer. CONCLUSION: Within the limitations of this study, we can conclude that bleaching prior to placement of a thin A4 dark veneer produces a significant difference in colour change. If no bleaching is performed, altering the thickness of an A1 veneer produces a significant colour difference DeltaE. However, if bleaching is carried out there is no significant difference.

Investigation of in vitro anthelmintic activities of Pycnanthus angolensis and Sphenocentrum jollyanum.

Extracts from Pycnanthus angolensis stem bark, and fruits and seeds of Sphenocentrum jollyanum, when tested in vitro, showed potent anthelmintic activity on the earthworm, Eudrilus eugeniae. Methanolic extract of P. angolensis was more active than its chloroform extract (P<0.001), while fruit ethanolic extract of S. jollyanum was also more potent than the seed extract. When compared with other worms, S. jollyanum fruit extract showed the greatest activity on wireworms when tested at 80 mg/ml.

Anthelmintic activities of three medicinal plants from Nigeria.

Aqueous extracts of the leaf, stem bark and root bark from Canna bidentata, Spondias mombin and Commiphora africana were examined for anthelmintic activity against earthworm. All the extracts demonstrated a concentration-dependent activity at tested concentrations of 10-80 mg/ml. Higher activities were observed at the higher concentrations, 40-80 mg/ml for all the plant extracts. C. bidentata with a paralysis time of 3-5 min and death time of 5-18 min at these concentrations for the stem bark, and S. mombin which exhibited comparatively higher efficacy (34-44 min paralysis time and 105 min death time for the leaf) at lower concentrations of 10-20 mg/ml were adjudged the outstanding anthelmintics of plant origin accordingly.

Anti-inflammatory and antimicrobial activities of Hippocratea indica root bark and Poga oleosa fruits.

The methanolic extracts of Hippocratea indica root bark and Poga oleosa fruits were investigated for anti-inflammatory and antimicrobial activities. Both extracts inhibited carrageenan-induced paw oedema significantly in rats in a dose-dependent manner in 4 h. H. indica inhibited oedema significantly at the minimal dose (125 mg/ml, p< 0.05) from 2 h onward, and gave 100% inhibition in 4 h. at 250 mg/kg. It was shown to be a more potent anti-inflammatory agent than P. oleosa. Also, H. indica extract exhibited greater antimicrobial activity against tested bacteria, with Staphylococcus aureus being the most susceptible bacterium (MIC, 16 mg/ml). Both plants were inactive against Candida albicans. These results confirm the anti-inflammatory and antibacterial activities of the two plants.

Comparison of quantitative light-induced fluorescence (QLF) and digital imaging applied for the detection and quantification of staining and stain removal on teeth.

OBJECTIVES: This study compares the use of QLF with digital imaging in the detection and quantification of the development and removal of stain on teeth. METHODS: Two experimental phases, tooth staining and tooth whitening, conducted in vitro on labial 12 mm(2) enamel windows made on ten extracted bovine teeth, developed stains in 6-min cycles (2 min in each solution) using artificial saliva, chlorhexidine and tea solutions and removed them using sodium perborate monohydrate in 2-min cycle monitored at the end of each cycle with QLF (Inspektor Research Systems, NL) and digital photography (Fuji, Japan). The stain values were quantified as DeltaQ derived from QLF and DeltaE from digital imaging. This was observed by the two methods correlated with Pearson correlation coefficient (r). Regression equations (R(2)) were also obtained. RESULTS: For both staining and stain removal there was a statistically significant (p<0.01) reverse correlation between DeltaQ values for QLF (r=-0.924, R(2)=85.4%) and DeltaE values for digital imaging (r=-0.994, R(2)=98.8%), respectively. CONCLUSION: QLF showed a high correlation with digital imaging as a technique for detecting and monitoring tooth stains and tooth whitening in vitro. The potential for QLF with further development as a tool for monitoring staining and whitening of teeth may be possible in vivo in addition to the diagnostic ability for caries detection.

Seasonal accumulation of anthraquinones in leaves of cultivated Cassia podocarpa Guill et Perr.

Seasonal variations and spectrophotometric determination of anthraquinones in cultivated Cassia podocarpa are presented. The study shows that combined anthraquinones are concentrated in the leaves at peak flowering (2.43%) and lowest in the bark (0.21%). Anthraquinone glycosides reached peak levels during the months of October to March (dry season), the maximum being recorded during January to March. There was significant drop in glycosidic content during the period April to September (rainy season). There was slight increase in concentration of aglycones during the rainy season which may be due to inter-conversion of some glycosides to the aglycones. However, the free aglycone content is much lower than the glycosides. This is desirable for optimum laxative activity and reduced toxicity. This study is significant because it provides useful information on the seasonal distribution of anthraquinones and the best period for harvesting leaves of C. podocarpa for drug development. The inclusion of C. podocarpa in the African Pharmacopoeia will, no doubt, enhance its commercialization as laxative and for its antimicrobial effect.

Microscopic evaluation and seasonal variations of anthraquinone glycosides of cultivated Cassia fistula Linn.

In this report, we present the results of the microscopy, seasonal variations and spectrophotometric estimation of hydroxy-anthraquinone glycosides of culitivated Cassia fistula Linn. The total glycoside contents ofthe morphological parts of this species at different stages of growth are also presented. The study shows that anthraquinone glycosides are concentrated in the leaves (1.75%) and flowers (1.58%) at peak flowering. Notable seasonal variations were observed in the cultivated species. Hydroxyanthraquinones reached peak levels druing the months of September (1.08%) and October (2.20%). There was a significant drop (P < 0.05) in glycoside content during most part of the rainy season. It has been established that anthraquinone glycosides, rather than the aglycones, are the active forms and hence an estimation of the total glycoside content of a sample is a reliable indication of biological activity. The advantages of using the natural anthraquinone laxative when the glycoside content is highest are discussed. The study has provided useful information on the best period for harvesting the morphological parts of C. fistula for drug development.

Seasonal variations of hydroxyanthraquinone content of cultivated Cassia spectabilis DC.

Seasonal variations and spectrophotometric estimation of the anthraquinone content of cultivated Cassia spectabilis DC are presented. Concentrations of anthraquinones peaked in the leaves (1.03%) at flowering Significant (P < 0.05) variations in anthraquinone content were observed in the cultivated species. Anthraquinones reached peak levels during the months of September to January (dry season). There was a significant (P < 0.05) drop in anthraquinone content during the rainy season. The diagnostic microscopic features of this little studied species are also described. This study has provided vital information on the best period of harvest and seasonal distribution of anthraquinones in the leaves of the species.