Aims: The design of the ultrasonic power supply based on HPWM was researched and developed to reduce the switching loss of high frequency switch and its harmonic distortion in this paper, which the performance of whole system is highly improved. Study Design: An improved control scheme named hybrid pulse width modulation (HPWM) is proposed, in which TMS320F2812 is used as the main control chip, the HPWM control signal is generated by using a voltage and current double closed-loop PI controlling method. Place and Duration of Study: Jiang Nan University, Key Laboratory of Advanced Process Control for Light Industry, in Wuxi, Jiang Su Province between June 2012 and July 2013. Methodology: Two set of experiment about our research including hybrid pulse width modulation (HPWM) and traditional sinusoidal pulse width modulation (SPWM) are carried out. Device parameters of all parts were calculated precisely and the device numbers were chosen after several experiments. A ultrasonic power supply System based on HPWM was designed finally. Results: According to the theoretical analysis, a 3KW Ultrasonic power supply is developed and the resonant frequency is 25KHz, using the hybrid PWM and double closed-loop control strategy proposed in this article. The power is tested successfully. The power experiment shows the system works well and gets high stability. Conclusion: The experiment result shows that the system works well and the switching loss of high frequency MOSFET and its harmonic distortion are effectively reduced. The design of the ultrasonic power supply based on HPWM has high value of application.
Aims: The paper analyzes the impacts of coal mining activities on West Virginia’s environment using GIS. Study Design: Adopted a mixscale appoach. Methodology: The aproach is applied to GIS and primary data connected to descriptive statistics by analyzing the impacts of mining with data collected at the state, county and watershed level. Place and Duration of Study: The coal producing counties of West Virginia May 2010-December 2012. Results: The study shows changes in coal production, and widespread degradation resulting in land loss and open space, impacts on mountain ecosystem and water quality decline in the head waters and human casualities.The spatial analysis revealed the dispersion of mining activities onto senstive environments comprising of streams and mountain ecosystems. Conclusions: The assessment of these trends and the capability of GIS in pinpointing them enhanced our research and understanding of ecosystem vulnerability in the face of recurrent degradation induced by mining. GIS also provided a framework for assessing ecosystem decline. To remedy the problems, the paper offered suggestions ranging from corporate code of ethics to improved data infrastructure and more use of GIS in environmental decision making.
Aims: To investigate the levels, variability and degree of heavy metal pollution in in-situ municipal solid waste dumpsite soil (WDS) compared to adjoining area (CS) at 100 – 120m from dumpsite as a contribution to global knowledge of pattern of pollution and data base at dumpsite. Study Design: Field-scale investigation of nine heavy metals (HM) at source pollution site and surrounding soil. Place and Duration of Study: Uyo municipal solid waste dumpsite in 2010. Methodology: Core sampling of soil at solid waste dumpsite and at 100 – 120m away, taken at 0-10cm and 10-20cm profile depths at 4 spatially different points. Acid digestion of HM in soil samples and determination of elemental HM concentration by flame AAS. HM pollution level was assessed using contamination factor, metal pollution index; ANOVA, and covariance for spatial variability. Results: Mean concentrations of nine heavy metals at municipal waste dumpsite soil were significantly (P < .01) higher than the un-dumped surrounding soil, and gave high mean metal pollution index of 5.21 for the overall soil profile. Toxicity was indicated for Fe, Ni, Pb, and B. Correlation between mean HMs at WDS and CS was very low (R = .488) but difference was significant (P = .05), indicating no lateral transfer to fringe area at 100 – 120m away. Conclusion: Heavy metal pollution in municipal solid waste dumpsite soil was higher at all profile depths than in control soil with contamination factors of 3-22 times the control soil values. Pollution was site-specific / anthropogenic (from waste deposition and leachate) rather than terrigenous. Fringe fields at 100-120m from dumpsite, except downslope, were buffered from dumpsite pollution. More research on deeper profile and minimum pollution - free buffer distance are recommended.
Aims: The influence of brine pretreatment and blanching on drying kinetics, area shrinkage and rehydration of oven-dried chayote slices was investigated. Study Design: Completely Randomized Block Design. Place and Duration of Study: Food Processing and Engineering Division of the Food Research Institute between January 2012 and February 2013. Methodology: Chayote slices (4±1 mm thick) were blanched in hot water at 80ºC or osmo-dehydrated in 10% brine for 3 min, or left untreated as control and subsequently dried at 65ºC. Shrinkage of dried samples, rehydration ratio and effective diffusivity of samples were determined. Experimental drying data was fitted by non-linear regression to 10 selected thin layer drying models. Results: Modified Henderson and Pabis model gave the best fit for untreated chayote (R2= 0.9993) and brine-treated (R2= 0.9991) chayote while Midilli et al. model best described the blanched chayote (R2= 0.9970). Effective moisture diffusivities ranged from 1.09 x 10-8 m2s-1 and 1.30 x 10-8m2s-1, rehydration ratios over a period of 270 min decreased from blanched > control > brine-treated while shrinkage was highest in blanched samples and lowest in brine-treated samples. Conclusion: Blanching and osmo-dehydration in brine pre-treatment prior to oven-drying affect the drying kinetics, shrinkage and rehydration parameters of chayote slices.
Background and Objective: Healthy body weight is an important indicator towards prevention of diseases. In the north western part of Nigeria, there is dearth of data on the prevalence of HBV infection among female adolescents. This study was therefore, carried out to determine the effect of body mass index on the sero-positivity of hepatitis B surface antigen amongst boarding school female adolescent students from a north western geopolitical zone. Methods: Hepatitis B surface antigen was tested in 192 apparently healthy female adolescent students in boarding secondary schools across the metropolitan area of Kano State, Nigeria by parallel diagnostic methods using a Micropoint and EGENS rapid diagnostic test kits (Lot: HBsAg 1301; 1125 USA). Result: The HBsAg sero-positivity of 41.70% was recorded for the 12-14 and 15-17 years and 16.70% for 18-20 year age groups respectively. Sero-positivity does not significantly (p=0.05) increase with age of the participants. The study revealed that HBV sero-positivity is higher (58.33%) among the underweight (BMI: <18.5) female students, followed by 33.33% in their normal (BMI: 18.5-24.9) and 8.33% in overweight (BMI: 25-30) counterparts. However, no association (r = 0.00) was found between low BMI and HBsAg infection. Conclusion: This study indicated no association between the incidence of HBsAg infection and the low BMI (underweight) among female adolescents. We recommend a fervent need from government and Non-governmental organisation for mass enlightenment campaign, screening and immunization focusing mainly adolescents to arrest this public health problem.
The crucial problem of Arabic recognition systems is the availability of several dialects in Arabic language, particularly those with sound variations. Therefore, low recognition rate is encountered as a result of such an environment. In this research paper the authors presented dialect-independent via an enormously effectual wavelet transform (WT) based Arabic digits classier. The proposed system may be divided into two main blocks the features extraction method by combining wavelet transform with the linear prediction coding (LPC) and the classiï¬cation by probabilistic neural network (PNN). The proposed classier provided a high recognition rate reaching up to 100%, in some cases, and an average rate of about 93% based on speaker-independent system. 450 Arabic spoken digit tested signals were used. The performance of the system in the noisy environment was investigated. The obtained results are very promising; however, the larger testing database may provide more credible results.
Quality of irrigation water is one of the key factors which have either direct or indirect impact on plant growth, soil and water management practices and plant yield. This work aims at the assessment of groundwater quality for irrigation, impact of different chemical parameters on plant yield and agriculture and water management practices needed in adverse irrigation water conditions. This study was conducted in semi-arid area where salinity and alkalinity are considered the main threats to the sustainable irrigation agriculture. Various sources of groundwater, within an area of 36 km2, lying in the north-east of the Lakki Marwat district Pakistan, were surveyed and thirty representative samples were collected for the chemical analyses. The data from the chemical analyses of these water samples was compared with the standard values suggested by WAPDA, FAO and USDA Handbook 60. The electrical conductivity values indicate that the groundwater existing in the project area is slightly saline and the pH values find it slightly alkaline. The overall study reveals that none of the water samples has an adverse impact on the yield of barley, sorghum and wheat while 7% and 17% of this water respectively reduce the yield of corn and onion by 50%. Besides, 7% of this water reduces the yield of alfalfa by 25%. The study concludes that the management practices such as deep ploughing, provision of adequate drainage and crop rotation can improve the use of such water.
Aims: The objective of this study was to study the antibacterial activity and the compressive strength of a modified dental resin composite, with a new furan one derivative. Materials and Methods: A novel antibacterial derivative was synthesized and used to formulate a resin composite, with addition of 5 to 70 wt%. Compressive strength (CS) and Streptococcus mutans (S. mutans) viability were used to evaluate the mechanical strength and antibacterial activity of the modified composites. Results: The modified resin composites showed a significant antibacterial activity without substantially decreasing the mechanical strengths. With 5 to 30% addition of the antibacterial derivative, the composite kept its original CS unchanged but showed a significant antibacterial activity with up to 68% reduction in the S. mutans viability. The modified composite also showed a similar antibacterial function in both minimum inhibitory concentration and cell viability percentage to lactobacillus. The bromine-containing derivative-modified composite was lower in CS than its chlorine counterpart but showed a similar antibacterial function. Furthermore, the antibacterial function of the modified composite was not affected by human saliva. The aging study indicates that the composite may have a long-lasting antibacterial function. Conclusion: Within the limitations of this study, it appears that this experimental antibacterial resin composite may potentially be developed into a clinically attractive dental restorative because it has a strength that is similar to the unaltered composite in addition to the antibacterial function.
This work investigates the speciation of phosphorus in four selected streams within Abakaliki, Nigeria using phytase hydrolysis of phytic acid as an indicator. Phytic acid is an important organophosphorus compound that can be hydrolysed by phytases occurring in soil and water. It is the main form in which phosphorus is stored in seeds hence its availability in natural environment like water and soil. Different species of phosphorus exist in nature as a result of the interconversion, hydrolysis and oxidation occurring between organic phosphate molecules. Investigation of these species of phosphorus (PHP, FRP, TDP and DOP) is crucial to the understanding of the biogeochemical processes prevalent in any aquatic ecosystem. Water samples were collected from four streams (Presco campus, Ama, Udele and Iyi-okwu streams) in Abakaliki, Nigeria within a period of 5 days in October, 2012. The samples were digested with 0.04M peroxydisulphate and 0.01M H2SO4 at 121ºC for 45 minutes in an autoclave. After digestion, the presence of PHP, FRP, TDP and DOP were investigated in the water samples using a spectrophotometer at wavelength of 820 nm. Results obtained showed varying concentrations of PHP, FRP, TDP and DOP ranging from ±0.0093-0.069 mgL-1P, 0.205-0.233 mgL-1P, 0.297-0.520 mgL-1P and 0.081-0.127 mgL-1P respectively. Recovery studies using Adenosine-triphosphate (ATP) and the calcium salt of phytic acid (PTA) as model organic phosphorus compounds gave quantitative recoveries ranging from 92-96%. One-way ANOVA showed that sampling location significantly influenced the mean concentration of TDP, FRP and DOP in the affected streams. This technique was effective in digesting both the model compounds and the real water samples. Also, the soluble phytase was effective in hydrolyzing phytic acid and phytase hydrolysable phosphorus (PHP) present in the water samples.
Background: Disability and health-related quality of life are becoming increasingly important issues associated with chronic illnesses including HIV disease. Aims: This study was designed to assess the health related quality of life [HRQoL] among a sample of HIV patients and to identify the clinical and psychological variables that affect quality of life among HIV patients using the functioning and the impact of illness approach in a tertiary health care centre in Western Nigeria. Place and Period of Study: The study was conducted in Olabisi Onabanjo University Teaching Hospital, Sagamu, South-west Nigeria. Data were collected over 4 weeks period between 12th January 2012 to 6thFebruary 2012. Methods: This was an analytical cross-sectional study. All consenting PLWHAs who attended the ART clinic during the study period were recruited into the study. A structured interviewer-administered questionnaire was used to collect relevant information. Result: A total of 205 PLWHAs were interviewed, the mean age of the PLWHAs studied was 31.26±5.38. The overall point prevalence of poor HRQoL among the PLWHAs in this study was 8.3%. A quarter25.9% of the respondents reported reduction in work performance since diagnosis of HIV,51.2%did not have any associated illness, 2.5% were too ill to work and participate in the daily activities while 82.9% of the respondents claimed that their HIV status did not affect their interaction with people. Malaria accounted for 43.9% of opportunistic illnesses, diarrhoea 5.4% and tuberculosis 2.9%. Poor HRQoL was statistically significantly associated with poor mental health status [X2=5.88, p=0.015], non utilization of psychosocial services [X2=5.67, p=0.017] and education [X2=0.65, p=0.022]. There was no statistically significant difference in the HRQoL among the respondents due to sex [X2=1.94, p=0.16], religion [X2=2.05, p=0.36] tribe [X2=0.66, p=0.72] disclosure of HIV/AIDS status [X2=1.15, p=0.28], adherence to antiretroviral drugs [X2=3.31, p=0.69] length of use of ART [X2=, 0.31, p=0.58] and occupation [X2=7.13, p=0.21]. The only predictor of poor HRQoL was poor mental health status among the PLHAs in Sagamu, Nigeria [OR=3.41, CI=1.02-11.48]. Conclusion: The study concludes that understanding the complex relationship between education, psychosocial support, mental health and quality of life might help to identify effective approaches to intervention to promote HIV care giving and its potential positive effects on the well-being of PLWHs thus eliminating the feelings of discrimination and inequalities among PLWHs.