Frequency Responses of Molar Electrochemical Peltier Heat and Entropy Changes Analyzed as Thermometric Transfer Functions

This work proposes a theoretical framework to obtain the frequency response of molar electrochemical Peltier heat and entropy changes induced by a modulated electrical signal. This is based on an internal energy balance developed for a working electrode thermistor in ac regime. Then, from an analysis that correlates the electrochemical impedance and the interfacial temperature variation, two new transfer functions that depend on the frequency ω, named as entropy changes ∆S(ω), and molar electrochemical Peltier heat, Π(ω) are obtained. This strategy is tested in two electrochemical systems: the ferrocyanide/ferricyanide couple and the copper ions in an acid sulphate-chloride medium. Both systems are analyzed by dc thermometric measurements, electrochemical impedance spectroscopy and ac-thermometric experiments namely variation of interfacial temperature. As a result, ∆S(ω) and Π(ω), are obtained and their values are correlated to the relaxation processes involved in the electrochemical reaction. Additionally, a brief discussion is included concerning the differences between the classical dc thermoelectrochemical methodology and the proposed approach here.

Profiling and Characterization of Environmental Quality of Leachates from Selected Dumpsites in Owerri, Imo State, Nigeria

This study profiled and characterized environmental quality of selected dumpsite leachates in Imo State with emphasis on Nekede, Worldbank, Irete and Orji areas of the state. Leachates were collected under stringent sample collection protocols from the selected dumpsites and analyzed. Samples were collected from three different sampling points of the dumpsite and bulked to form representative sample for each sampling site. The samples were analyzed for a number of standard physical and chemical parameters using standard analytical protocols and compared with the Federal Ministry of Environment (FMENV) benchmark. The result of the analysis showed that the values of electrical conductivity, total dissolved solid, temperature, BOD, COD, CO, salinity, sulphate, chloride, turbidity, nickel, chromium, lead, and cadmium were above FMENV limit; while nitrate, sulphate and zinc (from Worldbank, Irete and Orji), were below FMENV detectable limit. The outcome of the study is a pointer to the fact that the assayed leachates have high pollution potentials. There is possibility of gradual buildup of contaminants in the study area’s dumpsites, which could pose a serious threat, including the inhabitants around the vicinity. The study underscores the need for continual monitoring of the dumpsite leachates, and possibly an upgrade to a sustainable engineered landfill, to forestall possible pollution problems of other components of the environment such as aquatic bodies in future.

Pathogenicity of Philippine and Indonesian Trypanosoma evansi Isolates in Mice and Their Responses to Trypanocides

Pathogenicity of 10 isolates of <em>T. evansi</em> collected from Mindanao, Philippines, and one isolate from East Java, Indonesia was determined and compared. The susceptibility of these isolates against diminazene aceturate, melarsomine dihydrochloride, suramin and quinapyramine sulphate/chloride was also tested. Twenty-five mice were infected intraperitoneally with each isolate and 20 were treated with the 4 drugs (5 mice/drug) while 5 infected and 7 uninfected mice served as infected-untreated and uninfected controls, respectively. Treatment was carried out 24 hours post-infection and parasitemia was monitored for 35 days. Mice infected with Philippine isolates significantly died earlier (5-11 days) than those infected with the Indonesian isolate (14-16 days). The prepatent period for Philippine isolates (3-8 days) was significantly shorter than the Indonesian strain (11-13 days). Trypanosomes were not observed in the blood of mice infected with any of the Philippine isolates when treated with quinapyramine sulphate/chloride, melarsomine dihydrochloride or suramin. Two of 10 mice infected with either C4 or A9 Philippine isolates and treated with diminazene aceturate had parasitemia on days 29 and 31, respectively. It is concluded that isolates of <em>T. evansi</em> from Mindanao, Philippines, are more pathogenic than the isolate from East Java, Indonesia. This study also indicated that quinapyramine sulphate/chloride, melarsomine dihydrochloride and suramin are effective against these <em>T. evansi</em> isolates from Mindanao, Philippines and East Java, Indonesia, while two of the Mindanao isolates are resistant to diminazene. This information is valuable in the enhancement of the control strategy against surra in the Philippines and Indonesia.

Strength and Durability Properties of Concrete Containing Pumice and Scoria as Supplementary Cementitious Material

Concrete structures suffer serious deterioration under a corrosive environment. Consequently, the service life of these concrete structures is decreased and deteriorates under combined attack of sulphate and chlorides. Most studies confined on single deteriorating factor such as sulphate attack only or chloride attack only but the current study focused on the influence of natural pumice (NP) and natural scoria (NS) on the strength performance of concrete exposed to the combined attack of sulphate and chloride. Portland cement (PLC) was replaced with NP or NS at a substitution level of 10%. Concrete samples were cured in water for the curing period of 28 days. Afterwards, the specimens were immersed in 5% sodium sulphate (Na2SO4), 5% sodium chloride (NaCl), and combined sodium sulphate and chloride solutions for additional curing of 28, 56, and 90 days. The results were compared between concrete mixes with NP or NS and control mix (CT) with PLC. The effects of sulphate, chloride, and combined sulphate and chloride were evaluated in terms of change in weight, variation in compressive strength, and degree of damage. Conclusively, the application of NP and NS has extraordinary potential to be utilized as a cementitious material in concrete to increase the resistance against aggressive salts.

Assessment of Groundwater Quality in Close Proximity to Septic Tanks and Potential Impact on Health

A field study was conducted to assess groundwater samples collected in close proximity to septic tanks and its potential impact on health. pH, Total Alkalinity, Total Hardness. TDS, BOD, Turbidity, EC, Magnesium, Phosphate, Sulphate, Chloride, Nitrate, Cu, Fe, Pb and Cd were determined using standard methods. The human health risk assessment was performed by determining the hazard quotient of physicochemical and heavy metals through human oral consumption. The results indicate that the hazard quotient for pH, Total Alkalinity, Total Hardness, TDS, BOD, Turbidity, EC, Magnesium, Phosphate, Sulphate, Chloride, Nitrate, Cu, Fe, Pb and Cd were less than 1 while Temperature (1.1, 1.1 and 1,1), Dissolved Oxygen [CE1(3.3), CE2(3.8) and CE3(3.7)] and Calcium [CE1 (0.0), CE2 (2.6), and CE3 (1.2)] except for CE1 were greater than 1. This indicates that the borehole water poses risk for human consumption. Regulatory agencies should be proactive in monitoring borehole water quality, agencies in charge of approving building plan should ensure a safe distance between borehole water and septic tank is maintained and enforced.

ESTIMATION OF MASS TRANSFER OF PRINCIPLE IONS, IRON, AND METHANE DURING THE DISCHARGE OF UNDERGROUND WATER OF THE QUATERNARY AQUIFER COMPLEX TO THE SEA OF AZOV

The specificity of the chemical composition of underground waters of the Quaternary aquifer complex of the Azov sea catchment basin, which dominates the flow volume, is considered. Using deterministic models, the volumes of runoff of the main ions, common iron, and methane are calculated. The predominant ones are sulphate, chloride-sulphate or sulphate-chloride, less often bicarbonate and chloride waters, usually of a sodium or calcium cationic composition. The average annual volume of underground water flow in the Quaternary complex is about 0.024 km3/year (66,300 m3/day). The average annual value of underground ion runoff is ~387,000 t/year, with 47.2% of this value being accounted for by sulfate ions. The average annual underground runoff of total iron and methane is ~0.968 t/year and ~0.037 t/year, respectively. The dominant contribution (over 98%) to the volume of underground runoff of the main ions, common iron and methane is made by their runoff from the Northern sections of the sea catchment basin, which is mainly due to the distribution of the module of underground water flow.

Anion Effect on the Electropolymerization Reaction of Metanil Yellow in Aqueous Media and Characterization of Polymer Films

The electropolymerization of Metanil Yellow was investigated in aqueous solutions containing inorganic acids (sulphuric, hydrochloric, nitric, phosphoric and perchloric acid) as well as sulphonic acids (5-sulpho salicylic acid, sulphanilic acid, dodecylbenzene sulphonic acid, 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid) and lauryl sulphate in its acidic solution. By the inorganic ions the conductivity increased in the sulphate, chloride, nitrate, perchlorate serie. Of the organic sulphonic compounds 5-sulpho-salicylic acid was found to be a very efficient dopant in increasing polymer conductivity being obviously better than the other sulphonate anions. The formed conducting polymer was not suitable for detection of the corresponding anion. Nitrite ions completely diminished the electric properties of the polymer due to the reaction resulting nitrosamine.