Removal of Surfactant Cetyldimethylethyl Ammonium Bromide from Water using Adsorption in Combination with a Membrane Pilot Plant

In this study, a magnetic carbon nanocomposite (MCNC) was prepared using peanut shell biomass as carbon source. The prepared adsorbent was characterised by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric/differential thermal analysis (TGA/DTA) and BET surface analysis. Batch experiments were carried out to determine the adsorption parameters of cetyl dimethylethyl ammonium bromide (CDEAB) on MCNC. Of the isotherm and kinetics models used, the Langmuir model fitted the equilibrium adsorption data best, while the kinetics data were best explained by the second-order kinetic pseudo-equation. The numerical values of enthalpy change (ΔH8 = 38 kJ mol–1) and Gibb free energy (ΔG8 = 70.95 kJ mol–1, 72.19 kJ mol–1 and 73.32 kJ mol–1 corresponding to 20°C, 30°C and 40 °C, respectively) were positive, while the value of entropy change (ΔS8 = –0.11 kJ mol–1 K–1) indicated an endothermic and non-spontaneous process. After determining the optimal adsorption parameters, the adsorbent was used in a hybrid plant with a membrane pilot plant equipped with ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) membranes. In MCNC/membrane operation, an improvement in permeate flux was observed for the three selected membranes. The percentage retention of UF and NF membranes was also improved by MCNC pre-treatments in hybrid mode.

Retention of Pro-Vitamin A Content in Products from New Biofortified Cassava Varieties

Plant breeding efforts in sub-Saharan Africa (SSA) have produced biofortified cassava with high carotenoid content to address vitamin A deficiencies (VAD). Since carotenoids in foods are easily depleted during processing, the retention of β-carotene in some newly released cassava varieties is under query. From four of these new varieties, two commonly consumed products (gari and its dough) were processed according to standard methods. Retention of β-carotene was then probed after applying fermentation periods of a day and three days. The possible contribution of the products to Vitamin A intake in children, adolescents, and women was also assessed. The concentration of β-carotene in fresh Cassava roots ranged from 5.32 to 7.81 µg/g. The percentage retention ranged from 14.4 to 29.3% and 10 to 21.7% in gari fermented for one and three days respectively. The impact of varietal difference and length of fermentation was significant on retention in the intermediate and final products (p < 0.001). When compared with dietary intake data, cooking biofortified gari into its dough reduced Vitamin A intake in most varieties. We conclude that processing Cassava into gari (especially its dough) could hinder the retention of β-carotene however some varieties have retention advantage over others irrespective of the initial concentration in their fresh roots.

EFFECT OF DEVULCANIZATION ON CROSSLINK DENSITY AND CROSSLINK DISTRIBUTION OF CARBON BLACK FILLED NATURAL RUBBER VULCANIZATES

ABSTRACTCarbon black filled natural rubber (NR) vulcanizates were devulcanized at ambient temperature in a two roll mill. The effect of cure system, that is, conventional vulcanization (CV), semiefficient vulcanization (semi EV), and efficient vulcanization (EV) systems, used for vulcanization of the original sample, on the efficiency of devulcanization was studied. The efficiency of devulcanization expressed as percentage devulcanization of the samples calculated from residual crosslink density measurements was correlated with the sol fraction of the devulcanized samples based on Horikx analysis. Using chemical probe analysis, we determined (i) the crosslink distribution pattern of the original sample, (ii) the extent to which the different types of crosslinks—that is, polysulfidic, disulfidic, and monosulfidic crosslinks—have been debonded or broken during the shearing process in the two roll mill, and (iii) the pattern of bond formation during revulcanization. Mechanical shearing predominantly breaks the majority crosslink type (polysulfidic crosslinks in CV and semi EV cure systems and disulfidic crosslinks in EV samples). Irrespective of the significant reduction in total crosslink density in all three sets of samples, chain shortening reactions similar to the post-crosslinking chemical reactions at curing temperatures also occur during mechanical shear at ambient conditions, which increased the absolute value of monosulfidic links in CV and semi EV systems. However, in the devulcanized EV system, the absolute value of polysulfidic crosslinks increased, which might be due to the re-crosslinking of the cleaved bonds. All the devulcanized samples were revulcanized, and the mechanical and morphological properties were analyzed. The percentage retention of the vulcanizate properties after revulcanization of the devulcanized samples correlated very well with efficiency of devulcanization.

Retention efficiencies of halogenated and non-halogenated hydrocarbons in selected wetland ecosystem in Lake Victoria Basin

The determination of retention efficiencies of halogenated and non-halogenated hydrocarbon in selected wetland ecosystems in Lake Victoria basin was carried out. Qualitative and quantitative determination of the presence of residual hydrocarbons in Kigwal/Kimondi, Nyando and Nzoia wetland ecosystems using Gas Chromatography - Mass Spectrometer (GC-MS) instrument indicated the presence of residual organochlorines, organophosphorus, carbamates and synthetic pyrethroid hydrocarbons in water, sediment and plant materials. In order to compare the retention efficiencies of the wetlands, the wetland ecosystems were divided into three different sections, namely: inlet, mid and outlet. Calculations of mass balances of residual halogenated and non-halogenated hydrocarbons at the respective sections was done taking into account the partition of the studied compounds in samples of water, sediments and papyrus reed plant materials and analyzed using validated Gas Chromatography - Mass Spectrometer (GC-MS) method. From the analysis, several residual hydrocarbons namely: bendiocarb, benzene hexachloride (BHC), carbaryl, cypermethrin, decis, deltamethrin, diazinon, dieldrin, DDT, DDD, DDE, malathion, propoxur, sumithion, 5-phenylrhodanine, 1,3,5-trichlorobenzene, 1-(2-phenoxybenzyl)hydrazine were detected and quantified. The levels of the selected residual hydrocarbons in water samples were used to calculate the retention efficiencies of a specific hydrocarbon and the values recorded. Generally, River Nyando wetland recorded mean percentage retention efficiencies of 76 and 94% for dry and rainy seasons respectively; Kigwal/Kimondi wetland had seasonal mean percentage retention efficiencies of 63 to 78%. River Nzoia also had calculated seasonal mean percentage retention efficiencies of between 56 to 88%. Dry season had lower mean percentages retention efficiencies as compared to rainy season in the three wetlands of interest during the period of study. The study observed that retention efficiencies of tropical wetland ecosystems is greatly affected by its concentration within the wetland tank systems, anthropogenic activities, physical properties of the hydrocarbon, and environmental conditions among others. There are several anthropogenic activities which contributed to the presence of hydrocarbons in the wetlands and they included: agricultural, municipal, industrial and public health activities. DOI: http://dx.doi.org/10.3126/ije.v4i2.12623 International Journal of Environment Vol.4(2) 2015: 38-52

Quality and storage stability of provitamin A biofortified amahewu, a non-alcoholic cereal beverage

Vitamin A deficiency (VAD) is a major health problem in sub-Saharan Africa where maize is a staple food. Amahewu, a fermented non-alcoholic,maize-based beverage is a popular drink in southern Africa.The aim of this study is to produce a provitamin A enriched and acceptable amahewu, using provitamin A biofortified maize which can be used to alleviate VAD. The optimal processing parameters for the production of amahewu using provitamin A-biofortified maize were determined. Amahewu samples were prepared with reference to a traditional method by boiling a mixture of maize meal and water (rato:1:7) at 90ᴼC, with occasional stirring, for 15 minutes. The resulting porridge was left to cool to approximately 40ᴼC, before inoculation and fermentation at 37oC. Processing parameters investigated were inoculum types (wheat bran (WB), maize malt (MM) and Lactobacillus mixed starter culture) and inoculum concentration (0.5,1 and 2% (w/w)) and varieties of provitamin A maize (PVAH 62 and PVAH 19). Wheat flour (at 2%) was used as reference inoculum to conform to the traditional practice. White maize amahewu samples processed in the same way as those of provitamin A-biofortified maize were used as references. Provitamin A amahewu samples were produced using the optimized processing parameters and then analysed for nutrient composition, including carotenoids, protein, ash, amino acids, mineral profile and invitro protein digestibility. The consumer acceptability of amahewu samples was evaluated using regular consumers of amahewu (n= 54), who rated the acceptability of the samples on a 9-point hedonic scale (1:disliked extremely, 9:liked extremely). The storage stability of the provitamin A biofortified amahewu samples was assessed by subjecting the samples to different storage conditions: 4ᴼC, 25ᴼC and 37ᴼC. The microbiological quality of the stored samples was monitored by taking samples every day for a period of five days to analyse for the presence of aerobic and anaerobic bacterial spore formers, E.coli and moulds. The provitamin A maize variety did not influence pH and Total titratable acidity (TTA) of amahewu samples during fermentation. As expected, there was a substantial drop in pH with fermentation time. After 24 hours, all the samples of amahewu, including those made with white maize, prepared using malted maize and wheat bran inocula reached a pH of 3.3-3.8 and TTA of 0.3-0.6, which were within acceptable range for amahewu. The addition of a starter culture substantially reduced fermentation time, from 24 to six hours. The inoculum of WB and MM, respectively, at a concentration of 0.5%, with or without starter culture (5%), were found to be suitable for the production of amahewu using provitamin A biofortified maize. The total provitamin A content of amahewu samples, produced using optimised parameters (i.e one variety of provitamin A biofortified maize, 0.5% MM, WB with or without starter culture), ranged from 3.3-3.8 μg/g (DW). The percentage retention of total provitamin A ranged from 79%- 90% (DW). The lowest percentage retention was observed in products fermented with the addition of starter culture. The gross energy of the amahewu samples was approx. 20 MJ/kg. There was a slight increase in the lysine content of amahewu after fermentation. The protein digestibility (approx. 91%) of amahewu samples was slightly higher than that of raw provitamin A maize (86%). Amahewu processed using starter cultures had a slightly higher iron content than those processed without a starter culture. Consumer acceptability data showed that amahewu samples made with provitamin A biofortified maize were slightly more acceptable (average rating for overall acceptability was 7.0 ± 1.2), compared to those made with white maize (average rating for overall acceptability was 6.4 ± 0.8). Principal component analysis (PCA) of Amahewu sensory data showed that 71% of variation was due to maize types and 18% of variation may be due to the inoculum used during fermentation. The use of a starter culture improves the taste and aroma acceptability of amahewu. Segmentation of consumers based on overall linking for amahewu revealed three clusters, named A, B and C. Cluster A consisted of most consumers (43%), who liked amahewu moderately. About 60% of these consumers were females. Cluster B consisted of most of the consumers (31%) who were undecided about their liking for the product. Approximately 52% of the consumers in this cluster were female. Cluster C consisted of consumers (26%) who liked amahewu very much. Sixty-four percent (64%) of these consumers were female. It appeared that gender may have some influence on overall liking for amahewu, as cluster B, consisting of undecided consumers, had more male consumers compared to clusters A and C. Age did not seem to be significantly associated with the liking of amahewu. Provitamin A biofortified amahewu samples stored under refrigerated conditions (4ᴼC) had better microbiological quality compared to those stored at 25ᴼC and 37ᴼC. Refrigeration effectively maintains the microbiological quality of amahewu for about three of days. Provitamin A biofortified maize can be used to produce β-carotene enriched amahewu that is acceptable to consumers following the processing method that is traditionally employed for white amahewu at both domestic and commercial level. Provitamin A biofortified amahewu has the potential to make a significant contribution towards alleviating VAD among rural communities, who are the most vulnerable to VAD.

Effect of Calcium Stearate Concentration on Tensile Properties of Epoxidized Natural Rubber

The tensile strength and elongation at break of epoxidized natural rubber (ENR) was investigated by adding different concentration of calcium stearate. Two grades of epoxidized natural rubber (ENR), namely, ENR 25 and ENR 40 were used as model materials. Semi-efficient vulcanization (semi-EV) was used throughout the study. The tensile property of unaged and aged ENR vulcanizates was determined by using U-CAN electron tensile testing machine. Results indicate that tensile strength and elongation at break of unaged ENR 25 and ENR40 vulcanizates increase gradually with increasing concentration of calcium stearate up to about 1phr of calcium stearate and after which, the tensile strength and elongation at break drop with a further increase in calcium stearate loading. For a similar alcium stearate concentration, the tensile strength and elongation at break of ENR 40 vulcanizates exhibits a consistently higher value than that of ENR 25 vulcanizates, which is due to the higher crosslink density of ENR40 which contains more epoxide groups than ENR 25. For aged samples, the addition of calcium stearate could enhance the tensile strength and elongation at break of aged samples. Percentage retention of tensile strength and elongation at break also gradually increases with calcium stearate loading. That means that the incorporation of calcium stearate is found to improve the aging resistance of ENR vulcanizates. This is because calcium stearate neutralizes sulfur acids which can catalyze ring-opening of expoxide groups via ether crosslinks.

Pattern of memory compromise in chronic geriatric schizophrenia, frontotemporal dementia and normal geriatric controls

Objective:The purpose of this study was to explore whether memory deficits in schizophrenia are attributable to poor organisation/encoding during initial learning vs. memory decay.Methods:Subjects included geriatric schizophrenia/schizoaffective disorders [SSD; n = 37; age = 59.92 (55–74); education = 11.70 (7–18)]; frontotemporal dementia [FTD; n = 41; age = 76.59 (64–83); education = 14.61 (12–20)] and geriatric controls [n = 107; age = 70.97 (55–93); education = 13.76 (6–20)]. Subjects were administered the Wechsler Memory Scale, Third Edition and discrepancy scores between immediate and delayed subtests/indices were used to explore possible differences between groups in pattern of impairment.Results:Significant differences were found between groups on age/education and these variables were related to several outcome measures. Gender was not related to diagnostic group and there were no gender differences on study variables. There were differences between the SSD subjects on several variables, with the schizoaffective subjects performing worse despite equivalence on global cognitive function, living status and chronicity. Seven one-way between-subjects ANCOVAs compared groups on discrepancy scores. Results failed to suggest differences between groups on immediate-delayed memory discrepancy scores (p> 0.05). Subsequent analyses revealed differences in percentage retention scores between SSD and FTD on the faces subtest (p = 0.040), with SSD retaining greater information over time.Conclusion:Results failed to show distinctions between groups on pattern of memory impairment when using discrepancy comparisons. However, an analysis examining percentage retention scores revealed better maintenance of non-contextual visual information over time in SSD. Findings may suggest deficits in immediate encoding rather than memory decay for some types of memory ability among geriatric SSD. Our failure to document group differences when using discrepancy comparisons may be attributable to relative similarity in pattern between groups or the limited sensitivity of this technique.

Evaluation of Eustachian tube function with ventilation scintigraphy by using 133Xe gas

The aim of this study was to evaluate Eustachian tube function by ventilation scintigraphy. In 13 patients with normal tube function and 16 with one-sided tube dysfunction, 50 MBq 133Xe was applied into the nasopharyngeal space through a tube inserted into the nasal cavity. Immediately after the insufflation, the patients were asked to perform three Valsalva manoeuvres.The visualization of the middle ear was possible in 10 of the 13 patients (77 per cent) with normal tube function. Decreased uptake of the middle-ear region in the side of dysfunction was demonstrated in 11 of the 16 patients (68.7 per cent) with one-sided tube dysfunction. Quantitative evaluation by region of interest technique revealed that by using percentage retention of activity and uptake rates, there were significant differences between the sides of dysfunction and sides of normal tube function (p<0.05) and also between sides of dysfunction and both sides of controls (p<0.05). There was no significant differences between normal sides of patients and both sides of controls (p>0.05).As a conclusion, this method is non-invasive, easy-to perform and has a low radiation burden in the evaluation of Eustachian tube function. Although the number of patients is limited, the test seems to be applicable with a success rate of about 74 per cent.

Decomposition of plant material in Australian soils. I. The effect of quantity added on decomposition and on residual microbial biomass

14C and 15N-labelled legume (Medicago littoralis) material was added in amounts ranging from 23.0 to 92.1 kg nitrogen ha-1 to a calcareous, sandy-loam topsoil and allowed to decompose under field conditions for up to four years. Characteristic curves for decomposition were obtained; residual organic 14C accounted for about 65% and 18% of input after four weeks and four years respectively. About one-half of the 15N in the added plant material remained in organic residues after four years. However, the amounts of residual organic 14C and 15N were only approximately proportional to the amounts originally added. The proportions of plant material 14C and 15N mineralized calculated from recovery data differed significantly with the amount of substrate added; the greater the amount of plant material added, the more extensive its decomposition. Carbonate in soil became labelled during plant residue decomposition. Levels of carbonate 14C were low, however, and were directly related to the total residual 14C levels, whether in soils sampled four weeks or four years after substrate addition. Carbonate 14C accounted for only 1.1% of total residual 14C. Biomass 14C and 15N in soil decreased significantly with time within a 2-4 year decomposition period, the percentage decrease being greater than for 14C and 15N in the corresponding non-biomass organic pool. Further, the proportions of substrate 14C and 15N retained as biomass 14C and 15N in soils decreased significantly with increasing amounts of added substrate. From a consideration of the turnover of biomass C and N during plant residue decomposition in soils, we concluded that stabilization of extracellular substrates and metabolites alone does not account for the greater percentage retention of organic residues when lower amounts of substrate are added, but that factors leading to the accumulation of higher proportions of substrate carbon and nitrogen in microbial biomass are important.