Aims: To examine the effectiveness of low-flow high-ozone concentration disinfection of dental impressions, by means of an automated prototype device. Methodology: Disc shaped dental addition-cured silicone was inoculated with Klebsiella pneumoniae and Staphylococcus aureus, 10 mm discs were removed and ozone disinfected for different time intervals, immersion disinfected or served as controls. Disinfection success was examined by using the viable plate count method, while the statistical analysis was conducted via one way-ANOVA (p < 0.05). Results: Significant eradication was observed for selected Gram (+) and Gram (-) bacteria after 3 minutes of ozone exposure, leading to complete disinfection of the samples. Conclusion: While immersion disinfection of dental impressions is currently the most widely accepted method of disinfecting dental impressions, low-flow high-ozone concentration disinfection provides a quick, efficient, fully automated alternative method, limiting liquid waste generation. Possible alterations of the materials’ physical and chemical properties, like those of immersion disinfection, are not included in the present manuscript. A precise automated method for impression disinfection is established, relieving the dental team of possible cross-contamination.
The aim of study is to demonstrate that separation of solvated ions in solution of mix of salts under the action of external periodic electric field happens because of around ions there are formed clusters consisting of molecules of solvent and the sizes of such clusters have dimensions ~ 0.1 µm. In investigations the sizes of clusters theoretically were defined and experimentally value of frequency of external electric field which action excites the effect of separation of the solvated ions was defined. Experiments were done in the Technical Physics Chair of the National Research Tomsk Polytechnic University. At theoretical determination of the dimensions of clusters Poisson's equation was solved and was considered that polar molecules of solvent are oriented under the action of electric field of an ion. The chemical composition of samples of solutions was determined by means of the X-ray excited fluorescent radiation analysis method. Theoretical estimates and results of experiments confirmed the assumption that clusters which are formed around ions in solutions have the dimensions ~ 0.1 µm. Results of investigation testify that placing of volume distributed electric charge of ion in dielectric liquid is accompanied by formation of the supramolecular particles, which we called “clusters”, linear sizes of which is significantly more than first and second radiuses of solvation (~ 1 Angstrom) and reach size ~ 0.1 µm. At such sizes inertial properties of clusters and their natural frequencies give the chance to operate their movement by means of action of external electric field on solution.
This study concerns an area located at central-east of Côte d'Ivoire and constituted by fractured crystalline and metamorphic rocks. In this area, problems of drinking water supply exist because of overpopulation and lack of knowledges about groundwater prospection. This study aims to highlight hydrogeological potentiality areas where drilling can provide a large discharge. Database is constituted by technical data from drillings and satellite images of Landsat ETM+. Remote sensing tools, multi-criteria analysis and geographic information systems (GIS) are used in this study. The results indicate that water resources are available in this area. GIS enabled to elaborate thematic maps of groundwater. Indeed, more than 80% of studied area has good to excellent availability of groundwater. Poor and bad groundwaters potentiality classes respectively cover 14 and 6% of the studied area. These resources are well exploited over 78% of the territory with good and excellent exploitability of groundwater resources. However, these resources are not easy to be reached because 67% of the territory presents difficult accessibility. Results of this study constitute an important element that must be considered for hydrogeological prospection.
Aims: To determine the effect of land cover change and local temperature variation on the thermal comfort of inhabitants of the town while carrying out their outdoor activities. Study Design: Application of satellite imageries, meteorological data and questionnaire for the study. Place and Duration of Study: Department of Geography and Planning, Kofi State University, Antigua, Nigeria between June and October, 2012. Methodology: Computation of 12 months humidor values from temperature and humidity data for the year 1987, 2001 and 2011. Satellite image processing, classification, victimization and interpretation for land use and land cover change for 1987, 2001 and 2012; extraction of NDVI values and map for 2012 using Arc GIS 9.2. Land use and Land cover change rate were calculated. Temporary installation of thermo-hygrometers in 10 identified neighborhoods for a daily humidor values for the months of July, August and September 383 copies of questionnaire was retrieved and analyses using principal component analysis method of SPPS 17 software. Results: The least humidor values of 34.7 in December 1987, 34.4 in January 2001 and 35.8 in December 2011 indicated that discomfort is a common feature. The increasing change in rate in built up (0.95km2/yr) and the corresponding decline in rate of vegetation (1.73km2/yr) is the responsible for the near dryness in the built up area indicated by the NDVI values are attest to the increasing level of discomfort in the area of study. The perception level is significant s the KMO value of 0.602 which suggest a strong positive correlation among the variables. Effect of Land and sea breezes accounted for 22.7% of the variation in discomfort, urbanization 16.4% and Exposure 10%, while improper mitigation processes accounted for 8.8% and 11.4% for health implication. Conclusion: The rapid response to urban green economy will enhance the proper benefits of ecosystem services to Lakota environment. The governmental and non-governmental agencies are sensitize the general public on the role of vegetation in the environment, as this contribute to regulating air temperature.
This study was carried out to determine the concentration and sources of trace elements in top soils, road deposited sediments and filling station dusts in Benin metropolis in order to evaluate the effect of increased urbanization on the environment. Ninety-nine (99) samples were collected from the study area. These samples were air dried, disaggregated and digested using aqua regia. They were subsequently analyzed for metallic ion concentrations using inductively coupled plasma emission spectrometry (ICP-ES). The physico-chemical parameters were determined using appropriate probe to measure the pH, EC and TDS of the soil and dusts samples. GIS and multi variant analyses were used in the interpretation of the data analyzed. The results of the analyzed topsoil in ppm showed that Cu ranged from 4 - 1125, Pb from 9 - 2889, Zn, from 29 - 5022, Ni, from 2 - 52, Co, from 1 - 12, Mn, from 53 - 132, Cd, from below detection limit (BDL) - 27.2, V, from 17 - 108, Cr, from 15 - 90, Ba, from 6 - 530 and As, from BDL - 6. The pH of the topsoil samples ranged from 5.5 to 7.8, Electrical Conductivity from 37. 0 - 860.0 μS/cm, while TDS ranged from 24.0 - 328.25mg/L. The results of the concentrations of these metals in the Road deposited sediment, equally showed varied concentrations at different location. The geochemical results of both media are more than the background concentration for most of the elements.
There is no doubt that in Nigeria, the change to mis-using and counterfeiting of the paper bank notes have given cause for concern by the Central Bank of Nigeria (CBN), prompting the introduction of the polymer bank notes to address some of these problems. This research work investigates the physico-mechanical properties of samples of Nigerian polymer and paper bank notes of N5, N10, N20 and N50 denominations for quality parameters such as sizes, sorption rates, tear and tensile strengths, wet and dry rubfastness testing on standard Grey Scales ratings as well as microbial loads. The results showed that polymer notes have sizes of 131.0 x 72mm/0.7 on the average compared to 150.0 x 72mm/0.8 for paper for all the sample denominations. Tensile strength determinations on a Standard Organization of Nigeria (SON),s Stable Micro-System (SMS) Tensometer 5011 indicates 122.64Nmm-2±2 mean for both polymer and paper while tear strength measurements on Elmendarf 2000 tear testing Machine showed a mean value of 6341.2N±3.0 for polymer as against 3223.8N±5.0 for paper. Rubfastness testings indicate that polymer notes have ratings of 4/5(wet condition) and 5 (dry condition) compared to 1(wet condition) and 2(dry condition) for paper. Sorption rates (% Swelling Indices) in selected polar and non- solvents (liquids) were carried out as well as microbial loads and the results are reported in this paper. Generally, the results showed that polymer notes exhibit far superior physico- mechanical properties with very low coliform count compared to paper notes.
Aims: To determine the level of radioactivity due to naturally occurring radioactive materials (NORM) and also assess the radiological hazards to both workers and the public. Place and Duration of Study: Centre for Energy Research and Development, Obafemi Awolowo University, Ile-Ife, Nigeria between January and April 2012. Methodology: Fifteen samples comprising rocks, soils, water and mine wastes were obtained from three (3) mining sites in Olode, Ibadan and a topsoil sample two kilometers away from the site that served as control were investigated for their natural radioactivity contents using a well-calibrated HPGe gamma-ray spectrometer. Results: For both rock and soil samples, the activity concentrations of the radionuclides range between 86.42-2200.71Bq/kg; 3.00-13.11Bq/kg and 6.09-11.95Bq/kg for 40K, 238U and 232Th respectively, while the Absorbed Dose Rate and the Dose Equivalent were in the range of 10.58–96.71nGy/h and 0.07–0.6mSv/yr. In water, the activity concentration was in the order of 10-2 Bq/L and the Annual Effective Dose was between 0.08–0.12; 3.47–3.78 and 20.65–24.18μSv/yr for 40K, 238U and 232Th respectively. Conclusion: The gemstone-bearing pegmatite rock from mine 1 has the highest dose equivalent value of 0.60mSv/yr which is lower than the threshold limit of 1mSv/yr set by the International Commission on Radiation Protection (ICRP) for the general public. The results obtained thus indicate that the mining activities do not pose any significant radiation hazard so far. However, caution must be exercised in case of prolonged exposure in the mine environment to avoid other unnecessary health hazards.
Bed-form characteristics have been investigated because of the close relation to hydraulic friction. Pool is one of the most important bed forms in coarse-bed rivers. The form friction factor should be considered in determining many river engineering projects including stable channel design, the scour depth along bank protection and at bridges piers. This study was conducted in the coarse-bed, Saymareh river, in western Iran. Two reaches, with Froude number less than 1.0, were selected to investigate the contribution of the double-average method in determining friction factor, one with pool bed form, range of Reynolds numberfrom 1.325×106 to 2×106, and the other, plane bed with range of Reynolds number from 5.75×105 to 6.22×105. In this study, the friction factor of the selected pool was calculated and then to compare the results with the one of the selected plane bed. The average flow velocity, shear velocity, shear stress and friction factor of the selected four cross sections were investigated and determined In each reach. The results revealed that the pool in a gravel-bed river affects considerably friction factor and the double-average method worked well for applying the law of the wall. The form friction, which contributed 82% to total friction factor in the selected pool, showed the necessity of considering bed form effect in river engineering projects.
Background: In medical research, statistical tests have become more important. Several parametric procedures are available but each of them requires normality assumption. As normality violation may affect interpretation and inferences reliability and validity, so importance of normal distribution is undeniable. Although several normality tests available for software users but the power of each test in specified situation is not clear. Methods: The aim of this study is to compare the power of nine normality tests. In this paper power of Jarque-Bera test, D’Agostino and Pearson test, Chi-square test, Kolmogrov-Smirnov test, Lilliefors test, Cramer-Von Mises test, Anderson-Darling test, Shapiro-Wilk test and Shapiro-Francia test compared via Monte Carlo simulation of sample data generated from alternative distributions that follow symmetric, skewed, skewed & heavy tailed, highly skewed and highly skewed & heavy tailed distributions. Results: Simulation study shows that Shapiro-Francia test under symmetric, skewed, skewed& heavy tailed and highly skewed& heavy tailed distributions perform better than others. Also, Shapiro-Wilk performs better when underlying distribution is skewed. Conclusion: Although, Shapiro-Francia and Shapiro-Wilk have greater power than their competitors but their powers are still low for small sample size. So their singly use is not recommended.
The polyurethane foam industry in Nigeria depends largely on imported feedstocks based on fossil sources at exorbitant cost and high foreign exchange. Furthermore, emissions from some of these chemicals during processing have been reported to cause negative environmental impact effects and also carcinogenic to both animal and humans. It is for these reasons that this present research explores and exploits alternative non-conventional or supplement local sources of raw materials such as castor oil (CO) for the commercial manufacture of polyurethane foams in our quest for local content development. Mechanically extracted (CO) was characterized for physico-chemical properties such as refractive index, relative viscosity, pH, specific gravity, boiling point and acid, hydroxyl, saponification and iodine values by conventional and titrimeric methods were found to be within the ASTM D 1639 – 90, 1994 standard specifications. IR spectral analysis of the oil shows characteristic absorption bands of hydroxyl, carbonyl and olefinic groups. These results show that CO properties compare reasonably with those of conventional (CPO) and polymer (PPO) polyols. Foam formulations based on CO and various blend compositions with CPO and PPO were investigated for physico-mechanical properties such as density, tensile stress, tensile strain, elongation at break, compression set, and creep recovery (resilience). The results obtained show a critical blend composition at CPO/CO (90/10, % w/w) and PPO/CO (90/10, % w/w). This blend composition displays a good balance of density, tensile strength, elongation at break and creep recovery compared to other blend compositions. It also shows higher values than those of 100% CPO or PPO, for instance, tensile strength at CPO/CO (90%:10%) displayed a value of 11.06N/cm2 as against 6.81 N/cm2 at CPO/CO (100%:0%), while tensile strength value at PPO/CO (90%:10%) showed 9.49 N/cm2 as against 6.03 N/cm2 at 100% PPO. Similarly, values for elongations at break,indicate 49.99mm at CPO/CO (90%:10%) as against 73.98mm for 100% CPO, while at PPO/CO (90%:10%), the value was 37.05mm compared to 44.75mm for 100%: PPO. However, 100% CO shows a low tensile strength of 2.04 N/cm2 with a high elongation at break of 89.95mm. Furthermore, results of creep recovery indicate a value of 30.21% at CPO/CO (90%:10%) compared to 21.52% at 100% CPO, while the corresponding value for PPO/CO (90%:10%) was 25.49% as against 14.65%. for 100% PPO. Similar trends were observed for mechanical testing of factory trials of Iso-block foams.