Spatiotemporal Sediment Nutrient Dynamics of Kware Lake, Nigeria

Kware Lake provides life to various forms of aqua flora and fauna, livelihood for fishermen community and food for the local populace. The study was conducted to evaluate nutrient dynamics of the lake’s sediment for a period of 12 months (June 2014 to May 2015). Results reveal that some of the variables studied did not show any variation due to space and time but electrical conductivity (EC), phosphate (PO43-), potassium, sodium and clay texture were able to vary according to months, seasons and stations. They recorded range of 101.3-113 µs/cm, 0.97-1.24 g/Kg, 0.29-0.37 g/kg, 0.62-0.77 g/kg, and 13-14 g/kg respectively. Results therefore suggest and confirmed that sediment has a high accumulation of phosphate, due to decomposition on the sediment bed and low nitrate level in sediment than in surface water

Assessment of Productivity Status Using Carlson’s TSI and Fish Diversity of Goronyo Dam, Sokoto State, Nigeria

Goronyo Dam is the largest lentic waterbody in Sokoto, it was constructed to serve as flood control and used for irrigation activities. The study was conducted to evaluate productivity status and fish diversity of Goronyo Dam in 2016. Water samples were collected monthly from the Dam at two sampling sites (Upstream and Downstream). Water samples were collected using sterilized sampling bottles and analyzed in the Laboratory for physicochemical variables and the diversity of fish was evaluated through the use of a structured questionnaire. Depth and transparency were the only variables that did not show any statistically significant difference between the months. Productivity status of the dam was evaluated using Carlson’s Trophic State Index. The downstream has high TSI value of 16.54 compared to upstream with 13.00. A diversity of fishes from the shows that 3 species were more abundant in the dam, these were; Mormyrops species, Alestes species and Clupeid species. Factors contributed to the survival of fish species were an abundance of water and plankton in the dam. While factors affecting the distribution of fish species were pollution and predation

Construction of Association Scheme Using Some (123)-avoiding Class of Aunu Patterns

This paper presents some backgrounds research on association scheme using a class of (123)-avoiding pattern of Aunu numbers as an application area. It also attempts to highlight some further applications in other set structures. The finding in this research has shown that there is some interrelationship between the succession scheme used in generating Aunu numbers and the concept of association scheme. This research also shows us that the Aunu patterns can be used in design theory

Raft approach to the copolymerisation of methyl methacrylate based polymeric micelles

In this study, copolymer micelles were synthesised via free radical RAFT bulk polymerisation and RAFT dispersion polymerisation of methyl methacrylate. 4-CPDB-PDMS was used as the macro- RAFT agent, leading to the formation of the micellar nanostructures. Copolymer micelles obtained from the bulk polymerisation were used as macro RAFT agents in the dispersion polymerisation of methyl methacrylate in hexane, at 70oC. Characterisation of the various polymeric products was carried out using gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy(NMR), fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and dynamic light scattering (DLS) analyses. The results show that the molecular weights of the copolymers in the bulk are controlled. The block copolymers in the dispersion have broad polydispersity indices (PDI) and the kinetic study indicates a deviation from ‘pseudo first order’ kinetics at higher conversions.Keywords: RAF; polymerisation; methyl methacrylate; micelle

Evaluation of Physico-Chemical and Fungal Species Associated with Oil Contaminated Soil from Selected Automobile Garage in Sokoto Metropolis

This study was conducted with a view to evaluating the physicochemical and mycological properties of different oil contaminated soils collected from three different automobile garages in Sokoto Metropolis, and uncontaminated soil from the temporary site, Usmanu Danfodiyo University, Sokoto (UDUS) was used as the control. The pH was determined using pH meter model Hanna (H1991301), quantity of mineral elements was evaluated in accordance with Murphy and Fungi were isolated from the three oil contaminated samples (A, B. and C) and the uncontaminated (sample D) as control, this was done by standard procedure using the method of P. Ren, T. Jankun & B. Leaderer. The physical, chemical, and mineral elements from the oil-contaminated soils of the three automobile garages and control. The results of particle soil analysis revealed the high content of sandy soil (96.2 to 87.3) and silt is the lowest with (2.5–0.6). Magnesium had the highest concentration of studied minerals, ranging from 193 to 649.2 mg/kg. while PH result revealed that the soil samples were pH value ranged from (16.85–16.20) in oil Contaminated samples, while the control had 15.90, and electrical conductivity ranged from 12.8–13.8 % and 28 % in control, four fungal isolates Aspergillus sp., Penicillum sp., Mucor sp. and Sporobolomyces sp. were identified based on colonial, sexual and morphological characteristics. These fungal strains can be used in bioremediation process and oil pollution reduction in aquatic ecosystems

Physicochemical Flux and Phytoplankton diversity in Shagari Reservoir,Sokoto, Nigeria

Nutrients availabilty is one of the major contributors to distribution and growth of phytoplankton species. Physicochemical properties and phytoplankton species and their distribution in Shagari Reservoir were evaluated. Standard methods of UNEP were used to determine monthly physicochemical flux properties, diversity and distribution of phytoplankton species were also determined. Phytoplankton classes identified included Bacillariophyceae, Chlorophyceae, Cynophyceae and Dinophyceae. Class Chlorophyceae had the highest annual percentage distribution (37.55%) with four species identified. The least monthly percentage (7.64%) was recorded in November by Dinophyceae. Anabaena wisconsineae (Dinophyceae) had the highest frequency of occurence (96.6%). August, September and October were the most turbid months using Secchi disc measurement with 8.30, 9.0 and 9.8cm respectively. The monthly variation in the physicochemical parameters may be due to seasonal changes and human activities. The levels of nitrogen and phosphorus ranged from 0.30-7.30 Mg/l and 0.1-0.8Mg/l respectively. The reservoir has low species of phytoplankton, which may be due to low levels of nutrients and age of the reservoir.Keywords: Phytoplankton, Physicochemical, Reservoir, Chlorophyceae, Shagari, Sokoto, Nigeria

Melamino migrants as breakdown products of applied amino resin cross-linked can coatings.

This thesis consists of seven chapters. These are: (1) General introduction; (2) Preparation of reagents, characterisation of raw materials and calibration of the curing oven; (3) Formulation procedures, coating applications and curing procedures; (4) Analyses of liquid coatings, analyses of cured coatings and migration studies; (5) Epoxy-based coatings— study of the migration of melamine, the migration of benzoguanamine and the migration of formaldehyde; (6) Poly(ester)-based coatings— study of the release and migration of melamine, of benzoguanamine and of formaldehyde; (7) General discussion/summary. In the work that was carried out, an investigation of the phenomena of migration of melamine, of benzoguanamine and of formaldehyde, primarily during the retorting of the coatings, was undertaken. Five coating systems were investigated; these were unpigmented epoxy-anhydride coatings, TiO2 pigmented-epoxy anhydride coatings, epoxy-phenolic coatings, poly(ester)-urea coatings and poly(ester)-acrylic coatings. The coatings were applied through controlled repeatable procedures that were designed to represent industrial practices. The coatings were cured under controlled conditions relating to the temperature of curing and to the time over which the curing was performed. The curing oven was repeatedly calibrated to ensure that it was in a consistent and accurate working condition. This involved the need for a peak metal temperature (PMT), of 195 oC, maintained for 12 minutes and a PMT of 200 oC, held for 10 minutes, to be consistently achieved. The raw material samples that comprised the samples and the coatings themselves were characterised/analysed for their compositional integrity. Several analytical techniques were used including NMR spectroscopy, FT-IR spectroscopy, mass spectrometry, scanning electron microscopy, UV-visible spectroscopy, fluorescence spectroscopy, liquid chromatography (UV detection) and gas chromatography (MS detection). Relevant application-based techniques that were used include rheometry, particle size analysis, surface wetting studies and hardness testing, each used as appropriate. For the analyses of migrant species (melamine, benzoguanamine and formaldehyde) from the coatings, aqueous solutions of specified agents were used as food simulants (a simplified model food). These were used as food mimics, according to established European Commission standards. Elevated temperature treatments of cured coatings that were contained in the food simulants, in sealed containers, were carried out according to standard methods, to represent the effects of pressure cooking and the consequences of sterilisation of the canned foodstuffs during manufacture. The effects of the cross-linker chemistry, the amount of cross-linker in the coatings, the curing conditions, the coating application procedures and the kinetics of the release processes were investigated as was the stability of the migrant species in retorted food stimulants and their potential for further reaction, after release. Melamine, benzoguanamine and formaldehyde were not released from the coatings, at room temperature, after the cured coatings had come into contact with food simulants or with selected organic solvents, after a 24 hour exposure period. However, the migrant compounds were released from cured coatings that were retorted in the aqueous food simulants. The release was shown to be via the hydrolysis of the cross-linker components of the coatings. Such release was influenced by the 131 oC retorting temperature and the aqueous conditions. In all cases, the amounts of melamine, benzoguanamine and formaldehyde that were released and subsequently migrated into the food simulants were well within current limits, set by the European regulatory organisations. The results show that increasing the amounts of the cross-linker compounds in the total coating formulations, up to 2% for epoxy coatings and up to 10% for poly(ester) coatings, does not always affect the hydrolysis of the cross-linking agents, although it leads to an increase in melamine release. Excluding the cross-linkers from formulation does not significantly affect thermal properties and the hardness of the coatings. As a consequence of this exclusion, melamine and benzoguanamine release and their subsequent migration should not occur. The results show that a substantial proportion (up to 90%, in unpigmented epoxy coatings) of the cross-linker suffers hydrolysis to give melamine and yet the coatings still clearly perform their function when used commercially. The influence of varying the curing time and the curing temperature were factors that affected the amount of melamine that was released from the various coatings. This influence was more severe with the selected epoxy coatings than with selected poly(ester) coatings. For the epoxy coatings, in certain instances, increasing the curing temperature, in stages, from 160 oC to 240 oC, reduced the extent of cross-linker hydrolysis by up to 60 %. The presence of the TiO2 pigment particles in the epoxy anhydride coatings assisted in lowering the extent of melamine generation that would otherwise have occurred via hydrolysis. Also, the three grades of the TiO2 pigments gave similar contributions with respect to the reduced melamine release from the epoxy coatings. The results also indicate that melamine and formaldehyde are released during the curing of the coatings in the oven. Using various pigmented coating formulations that were allowed to stand under stated laboratory conditions, for specified time periods, resulted in wet ageing occurring. Such wet ageing significantly affected the amount of melamine that was released under hydrolytic conditions, leading to 20% more melamine being released after storage for 30 weeks

Pupil Dilation and Microsaccades Provide Complementary Insights into the Dynamics of Arousal and Instantaneous Attention during Effortful Listening

Listening in noisy environments requires effort- the active engagement of attention and other cognitive abilities- as well as increased arousal. The ability to separately quantify the contribution of these components is key to understanding the dynamics of effort and how it may change across listening situations and in certain populations. We concurrently measured two types of ocular data in young participants (both sexes): pupil dilation (PD; thought to index arousal aspects of effort) and microsaccades (MS; hypothesized to reflect automatic visual exploratory sampling), while they performed a speech-in-noise task under high- (HL) and low- (LL) listening load conditions. Sentences were manipulated so that the behaviorally relevant information (keywords) appeared at the end (Experiment 1) or beginning (Experiment 2) of the sentence, resulting in different temporal demands on focused attention. In line with previous reports, PD effects were associated with increased dilation under load. We observed a sustained difference between HL and LL conditions, consistent with increased phasic and tonic arousal. Importantly we show that MS rate was also modulated by listening load. This was manifested as a reduced MS rate in HL relative to LL. Critically, in contrast to the sustained difference seen for PD, MS effects were localized in time, specifically during periods when demands on auditory attention were greatest. These results demonstrate that auditory selective attention interfaces with the mechanisms controlling MS generation, establishing MS as an informative measure, complementary to PD, with which to quantify the temporal dynamics of auditory attentional processing under effortful listening conditions.SIGNIFICANCE STATEMENT Listening effort, reflecting the "cognitive bandwidth" deployed to effectively process sound in adverse environments, contributes critically to listening success. Understanding listening effort and the processes involved in its allocation is a major challenge in auditory neuroscience. Here, we demonstrate that microsaccade rate can be used to index a specific subcomponent of listening effort, the allocation of instantaneous auditory attention, that is distinct from the modulation of arousal indexed by pupil dilation (currently the dominant measure of listening effort). These results reveal the push-pull process through which auditory attention interfaces with the (visual) attention network that controls microsaccades, establishing microsaccades as a powerful tool for measuring auditory attention and its deficits

Numerical Investigation Of Heat And Mass Transfer In Porous Medium Fixed With Various Geometries

Usaha untuk memahami aliran haba dan jisim dalam bahanantara berliang telah meningkat berlipat ganda penydidikam dalam bahanantara berliang telah mengenalpasti beberapa aspek behantara berliang yang menghasilkan banyak penulisan jurnal. Walau bagaimanapun, terdapat banyak ruang yang tidak dapat dijawab berkaitan aliran haba dan jisim dalam bahanantara berliang. Kajian ini telah dejalankan untuk menyiasat pemindahan haba dan jisim dalam bahantara berliang dan meninjau ruang yang masih tidak dapat dijawab. Pelbagai fenomena seperiti pemindahan haba, pemindahan haba dan jisim, kesan disipasi likat, ketidakseimbangan keadaan terma antara fasa cecair dan pepejal bahantara berliang dikaji dengan mangambil kira tiga geometri iaitu bahantara berliang di sepanjang plat menegak, bahantara berliang di dalam ruang dan bahantara berliang dalam silinder menegak. Selian itu, kesan perolakan semulajadi dan sinaran juga diambil kira. The effort to understand the heat and fluid flow behavior inside the porous medium has increased to many folds in the recent few decades. The intensified research in porous medium has generally addressed many aspects of porous medium resulting into enormous number of publications. In spite of the endeavoring effort, there are many gaps left unanswered related to the heat and fluid flow behavior inside the porous medium. The present study is undertaken to investigate the heat and mass transfer in a porous medium and thus explore some of those unanswered areas. The different phenomenon such as, heat transfer, heat and mass transfer, viscous dissipation effect, the thermal non-equilibrium condition between fluid and solid phases of the porous medium are investigated with respect to three basic geometries i.e. porous medium adjacent to a vertical plate, porous medium enclosed in a cavity and porous medium filled in vertical ann~lar cylinder. The combined effect of natural convection and the radiation is investigated in all above mentioned phenomenon

Maternal Body Mass Index, Dietary Intake and Socioeconomic Status: Differential Effects on Breast Milk Zinc, Copper and Iron Content

Background: As breast milk micronutrients content are essential for health and growth of the infants, this study was conducted to determine the breast milk zinc, copper and iron concen-trations and their possible correlations with maternal nutritional status, dietary intakes as well as socioeconomic status.Methods: Breast milk samples and information on maternal anthropometric characteristics and dietary intake were collected from 90 Iranian lactating women with 3 different socioeco-nomic status who exclusively breastfed their infants. Concentrations of trace elements were analyzed using atomic absorption spectrophotometry. Nutritionist III program, Multiple Re-gression and ANOVA test were used for data analyses.Results: The mean milk zinc, copper, and iron concentrations were 1.93 ± 0.71, 0.58 ± 0.32, and 0.81 ± 0.2 mg/l, respectively. In all three SES groups only zinc mean level was lower than the recommended range. A significant difference was observed in breast milk zinc, copper and iron concentration between high and low SES groups (Zn (P<0.001), Cu (P<0.001) and Fe (P<0.044)) and also moderate and low SES groups (Zn (P<0.03), Cu (P<0.001) and Fe (P<0.049)). After adjusting for maternal body mass index (BMI), socioeconomic status, mean dietary energy, zinc, copper, and iron intakes, there was a negative and significant association between maternal age and breast milk zinc (β=-0.28, P<0.034), copper (β=-0.18, P<0.048), and iron (β=-0.22, P<0.04) concentrations.Conclusion: In low socioeconomic group with lower mean age, breast milk mineral levels were higher than others and there was no significant correlation between mineral levels and dietary intake. Hence it is supposed that maternal age may be better predictor of breast milk mineral levels