Physico-Chemistry of Elechi Creek in the Upper Bonny Estuary, Rivers State, Nigeria

The physico-chemistry of tidal Elechi Creek in the upper Bonny Estuary was investigated to assess the toxicity of the water body as this could have adverse effects on the native organisms that form part of the ecosystem and to evaluate the extent and magnitude of petroleum hydrocarbon and heavy metal concentration in the water body. Standard field procedures were adopted in sample collection while laboratory analysis was carried out also following standard methods. Parameters measured include pH, temperature, dissolved oxygen (DO), biological oxygen demand (BOD), electrical conductivity, salinity and total dissolved solids (TDS). Heavy metals namely Copper (Cu), Lead (Pb), Zinc (Zn), nitrate (NO3), sulphate (SO4), Ammonia (NH4), and Total Hydrocarbon Concentration (THC) in the surface water body were also determined on samples collected from five (5) sampling stations spread along the creek in both dry and wet seasons. The results showed that the surface water body is oligohaline with low acidity, pH values ranging from 6.2 to 7.6. Temperature varies from 27&#176C to 30&#176C. Dissolved Oxygen (DO) concentration ranges from 2.9 to 7.5 mg/l which is adequate for aquatic organism with Biological Oxygen Demand (BOD) values varying from 0.45 to 7.0 mg/l. The values of total dissolved solids (TDS) vary from 11,700 mg/l to 26,250 mg/l with the highest mean value obtained at the study station located downstream. The mean nutrient concentration showed that the study area is not eutropic. Anthropogenic activities were very high at the sites throughout the period of the study and may have resulted in the stress conditions of the area. Pollution trend along the study stations showed that no one station is unpolluted. The study recommends the introduction of enforceable and stringent waste management plans to highlight and discourage direct discharge of untreated waste and storm water runoff into an aquatic environment.

Multiclass stand-alone and ensemble machine learning algorithms utilised to classify soils based on their physico-chemical characteristics

This study has provided an approach to classify soil using machine learning.Multiclass elements of stand-alone machine learning algorithms(i.e.logistic regression(LR)and artificial neural network(ANN)),decision tree ensembles(i.e.decision forest(DF)and decision jungle(DJ)),and meta-ensemble models(i.e.stacking ensemble(SE)and voting ensemble(VE))were used to classify soils based on their intrinsic physico-chemical properties.Also,the multiclass prediction was carried out across multiple cross-validation(CV)methods,i.e.train validation split(TVS),k-fold cross-validation(KFCV),and Monte Carlo cross-validation(MCCV).Results indicated that the soils’clay fraction(CF)had the most influence on the multiclass prediction of natural soils’plasticity while specific surface and carbonate content(CC)possessed the least within the nature of the dataset used in this study.Stand-alone machine learning models(LR and ANN)produced relatively less accurate predictive performance(accuracy of 0.45,average precision of 0.5,and average recall of 0.44)compared to tree-based models(accuracy of 0.68,average precision of 0.71,and recall rate of 0.68),while the meta-ensembles(SE and VE)outperformed(accuracy of 0.75,average precision of 0.74,and average recall rate of 0.72)all the models utilised for multiclass classification.Sensitivity analysis of the meta-ensembles proved their capacities to discriminate between soil classes across the methods of CV considered.Machine learning training and validation using MCCV and KFCV methods enabled better prediction while also ensuring that the dataset was not overfitted by the machine learning models.Further confirmation of this phenomenon was depicted by the continuous rise of the cumulative lift curve(LC)of the best performing models when using the MCCV technique.Overall,this study demonstrated that soil’s physico-chemical properties do have a direct influence on plastic behaviour and,therefore,can be relied upon to classify soils.

Influence of Some Physico-Chemical Exposure Factors on the Carbocysteine Content of an Opened Pharmaceutical Product

The aim of this study was to investigate the stability of Carbocysteine (CBC) contained in a reference substance (RS) and in a sample of opened RHINATHIOL® 5% syrup (RNTL 5%) under the effect of some physicochemical parameters (temperature, light, time, pH, bile salts). The developed method was linear, precise and accurate according to USP 38. The co-efficient of determination R2 for linearity was 0.9993. The respective RSD of intra-day and inter-day between days (1st, 2nd and 3rd day) were respectively 0.338% and the interval from 0.05% to 0.387%. The average recovery rate ranged from 98.490% to 100.450%. The detection and quantification limits were 0.0001 mg/mL and 0.001 mg/mL respectively. The method was applied to four samples of opened syrup containing CBC and the CBC content in these samples was found to be in accordance with USP 38. The CBC content in the opened sample of RNTL 5% was obtained by UV-visible spectrophotometry at 217 nm and was 4.887 g/100mL. The study of the influence of physico-chemical factors on the content of CBC in RS and RNTL 5% showed that the evolution of CBC contents in each drug matrix remained dependent on pH and temperature. However, these levels remained stable in the presence of light.

EFFECTS OF TECTONIC FORCE ON HYDROSTATIC PRESSURE DURING PETROGENESIS AND METALLOGENESIS

Research on hydrostatic pressure in the crust has been previously conducted from the viewpoint that the hydrostatic pressure is equal to gravity,considering the hydrostatic preessure in the geochemical process of petrogenesis and metallogenesis is mainly derived from the gravity of overlying rocks. This paper suggests that the stress state of any point in the crust is caused by both gravity and tectonic force.The author puts forward a viewpoint that the hydrostatic pressure is a combination or superposition of two isotropic stresses, i. e. tectonic force and gravity, in the stress field. The results obtained by a finite-element simulation indicate that the. additional hydrostatic pressure borne by rocks decreases gradually frotn the compression zone (K), the shear zone to the tensile sone (K) and the difference of the tectonic additional hydrostatic pressure between these deformed zones tends to increase, following the increase in absoIute vaIue and/or difference of external forces in different directions.This study tries to explain the effects of tectonic force on hydrostatic pressure during petrogenesis and metallogenesis,which will lay the foundation for research on tectonic physico-chemistry.

Evaluation of Quality Borehole Water Consumed in Public Schools in N’Djamena City(Chad)

In N’Djamena city,majority of population living there is connected to drinking water supply network.However,given untimely water cuts,some schools have chosen to carry out private drilling.Our objective is therefore to assess the quality of water intended for human consumption in these schools,to do this we have carried out a physico-chemical and bacteriological control on a number of water points.Seventeen(17)water points were collected during July 2015 and the physico-chemical parameters analyzed are as follows:pH,EC(Electrical Conductivity),TH(Total Hardness),turbidity,Ca^(2+),Mg^(2+),K^(+),Na^(+),Cl^(-),NO_(3)^(-),HCO_(3)^(-)and SO_(4)^(2-).In addition to this,we looked for possible undesirable germs,indicators of pollution.The results of physico-chemical analyses carried out show that water from most boreholes has good quality with the exception of drilling F7,which has a high conductivity,and drilling F_(3)whose turbidity is also high.Bacteriological analysis shows that all water points contain total germs,the other germs of faecal origin are mainly present in the F9 borehole.

Bacteriological and Physico-Chemical Characterisation of Liquid Wastes: The Case of the University Hospital Centre (UHC) of Yaoundé-Cameroon

The untreated effluents generated by hospital activities contribute to the dissemination of pathogenic germs and multi-resistant bacteria, thus presenting a great potential danger for health and the environment. The objective of this study was to evaluate the microbiological and physico-chemical quality of the effluents of the Yaoundé University Hospital Centre and their impact on the environment. It was a prospective and analytical study on three sites where hospital effluents from the intensive care unit (Station A), the upstream of the wastewater treatment plant (Station B), and the gynaecology, surgery and hospitalisation departments (Station C) were sampled. Samples were collected in sterile glass bottles for bacteriological analyses and polyethylene bottles for physico-chemical analyses. The bacteriological parameters measured showed that the density of the bacterial species sought was very high at Station B with a predominance of the species Escherichia coli (57.36%). At Station A, total coliforms were very abundant (50.12%) and at Station C, the genus Pseudomonas was predominant (14.69%). Bacteria of the genus Streptococcus were represented by three species, namely: Streptococcus agalactiae, Streptococcus faecalis, and Streptococcus pneumoniae. The Pseudomonas genus was also represented by 3 species, namely Pseudomonas aeruginosa, Pseudomonas maltophilia and Pseudomonas putida. The physico-chemical parameters showed that apart from temperature and conductivity, which were in compliance with the standards, the other had values higher than these standards. This study shows that untreated hospital effluent contains most of the bacteria involved in community, nosocomial infections and would be a potential source of risk to the surrounding population.