Pub Date : 2014-03-06DOI: 10.14416/J.IJAST.2014.01.008
B. Lamsal, V. Jindal
Measurements and modeling of electrical conductivity (EC) of selected fruit juices were done during continuous ohmic heating. Ten-cm long acrylic heating cell with 3.8 cm internal diameter was utilized to measure the juice electrical conductivity. The variation in electrical conductivity of lab-squeezed juice of orange, pineapple and tomato fruits purchased from different retail markets were measured and modeled in terms of juice properties, such as total soluble solids and pH. EC of all juices had a linear variation with temperature as they were heated continuously to 80°C. EC of juice was affected by fruit maturity: 9-months old oranges had lower EC value of 0.392 S/m at 25°C, whereas 12 months old oranges had 0.475 S/m. The electrical conductivity of lab-squeezed orange juice from fresh fruits from different locations showed a 10% variation in the mean value of 0.343 S/m at 25°C and 0.971 S/m at 80°C. Mean electrical conductivity values for pineapple and tomato juice at 25°C, were 0.295 S/m and 0.504 S/m with maximum variations due to location at about 20% and 18.3%, respectively. These variations in EC of juices studied were observed to be higher at higher temperatures. The observed electrical conductivities for three juices were modeled in terms of temperature and total soluble solids with very high goodness-of-fit values.
{"title":"Variation in Electrical Conductivity of Selected Fruit Juices During Continuous Ohmic Heating","authors":"B. Lamsal, V. Jindal","doi":"10.14416/J.IJAST.2014.01.008","DOIUrl":"https://doi.org/10.14416/J.IJAST.2014.01.008","url":null,"abstract":"Measurements and modeling of electrical conductivity (EC) of selected fruit juices were done during continuous ohmic heating. Ten-cm long acrylic heating cell with 3.8 cm internal diameter was utilized to measure the juice electrical conductivity. The variation in electrical conductivity of lab-squeezed juice of orange, pineapple and tomato fruits purchased from different retail markets were measured and modeled in terms of juice properties, such as total soluble solids and pH. EC of all juices had a linear variation with temperature as they were heated continuously to 80°C. EC of juice was affected by fruit maturity: 9-months old oranges had lower EC value of 0.392 S/m at 25°C, whereas 12 months old oranges had 0.475 S/m. The electrical conductivity of lab-squeezed orange juice from fresh fruits from different locations showed a 10% variation in the mean value of 0.343 S/m at 25°C and 0.971 S/m at 80°C. Mean electrical conductivity values for pineapple and tomato juice at 25°C, were 0.295 S/m and 0.504 S/m with maximum variations due to location at about 20% and 18.3%, respectively. These variations in EC of juices studied were observed to be higher at higher temperatures. The observed electrical conductivities for three juices were modeled in terms of temperature and total soluble solids with very high goodness-of-fit values.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"9 1","pages":"47-56"},"PeriodicalIF":0.0,"publicationDate":"2014-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89728019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2014-02-20DOI: 10.14416/J.IJAST.2014.01.007
M. Shamsinejad, B. Nahid-Mobarakeh, S. Pierfederici, F. Meibody-Tabar
A series architecture providing a fault tolerant drive is proposed. The architecture includes one or two DC sources, two voltage source inverters and a PMSM. Three different operating modes are considered: normal mode, open-circuit degraded mode and short-circuit degraded mode. For each case, an adapted torque control strategy is proposed and tested. For the open phase mode, different operating criteria are considered. For short-circuit faults, two solutions are proposed. The proposed strategies are tested on an 8-pole 1 kW PM drive. They allow operating under fault conditions in real-time and their implementation is easy. The experimental results show the effectiveness of the proposed methods.
{"title":"Fault Tolerant Permanent Magnet Drives: Operating Under Open-circuit and Short-circuit Switch Faults","authors":"M. Shamsinejad, B. Nahid-Mobarakeh, S. Pierfederici, F. Meibody-Tabar","doi":"10.14416/J.IJAST.2014.01.007","DOIUrl":"https://doi.org/10.14416/J.IJAST.2014.01.007","url":null,"abstract":"A series architecture providing a fault tolerant drive is proposed. The architecture includes one or two DC sources, two voltage source inverters and a PMSM. Three different operating modes are considered: normal mode, open-circuit degraded mode and short-circuit degraded mode. For each case, an adapted torque control strategy is proposed and tested. For the open phase mode, different operating criteria are considered. For short-circuit faults, two solutions are proposed. The proposed strategies are tested on an 8-pole 1 kW PM drive. They allow operating under fault conditions in real-time and their implementation is easy. The experimental results show the effectiveness of the proposed methods.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"127 1","pages":"57-64"},"PeriodicalIF":0.0,"publicationDate":"2014-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89622345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Experiments were conducted on rheological behavior of pseudoplastic non-Newtonian tylose-alginate (solid-liquid) suspensions in isothermal laminar flow in a horizontal conduit with variable geometry. The complex flow of loaded spherical and large-sized particles of 4.4 mm diameter, and dependence of hydrodynamics of organoleptic quality of the loaded fluids governed by Ostwald power law were investigated. The geometry of the horizontal pipe of variable cross-section provided turbulence promoters for fluid flow which generated back-flow zones for homogenizing the suspensions by improved mixing quality. The consistency index (K) increased with the volume fraction of solid particles, but decreased with temperature; and for a net change in viscosity of 0.75 % tylose concentrated solution, K increased with temperature of the carrier fluid. The structure index, n, varied with the concentration of the hard spheres, but did not vary substantially with temperature.
{"title":"Experiments on rheology of non-Newtonian flow of tylose-alginate suspension through a horizontal complex conduit","authors":"Benoît Fagla, M. Gradeck, M. Lebouché","doi":"10.4314/JAST.V18I1-2","DOIUrl":"https://doi.org/10.4314/JAST.V18I1-2","url":null,"abstract":"Experiments were conducted on rheological behavior of pseudoplastic non-Newtonian tylose-alginate (solid-liquid) suspensions in isothermal laminar flow in a horizontal conduit with variable geometry. The complex flow of loaded spherical and large-sized particles of 4.4 mm diameter, and dependence of hydrodynamics of organoleptic quality of the loaded fluids governed by Ostwald power law were investigated. The geometry of the horizontal pipe of variable cross-section provided turbulence promoters for fluid flow which generated back-flow zones for homogenizing the suspensions by improved mixing quality. The consistency index (K) increased with the volume fraction of solid particles, but decreased with temperature; and for a net change in viscosity of 0.75 % tylose concentrated solution, K increased with temperature of the carrier fluid. The structure index, n, varied with the concentration of the hard spheres, but did not vary substantially with temperature.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"57 1","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2013-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75903426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-15DOI: 10.5987/UJ-NJSE.17.112.1
C. Ishiekwene, B. A. Afere
The bootstrap boosting algorithm is a bias reduction scheme. The adoption of higher-order Gaussian kernel in a bootstrap boosting algorithm in kernel density estimation was investigated. The algorithm used the higher-order Gaussian kernel instead of the regular fixed kernels. A comparison of the scheme with existing fixed kernel methods indicated the results were better.
{"title":"Higher-order Gaussian kernel in bootstrap boosting algorithm","authors":"C. Ishiekwene, B. A. Afere","doi":"10.5987/UJ-NJSE.17.112.1","DOIUrl":"https://doi.org/10.5987/UJ-NJSE.17.112.1","url":null,"abstract":"The bootstrap boosting algorithm is a bias reduction scheme. The adoption of higher-order Gaussian kernel in a bootstrap boosting algorithm in kernel density estimation was investigated. The algorithm used the higher-order Gaussian kernel instead of the regular fixed kernels. A comparison of the scheme with existing fixed kernel methods indicated the results were better.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"54 1","pages":"95-99"},"PeriodicalIF":0.0,"publicationDate":"2013-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74503976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The occurrences of vehicle-pedestrian crashes at signalized intersections were investigated using a 3 year (2004-2006) crash records of 82 signalized intersections in Accra, Kumasi, Tema, Sekondi-Takoradi and Tamale. The data were analyzed using Micro-computer Accident Analysis Package. Traffic flow characteristics, intersection features and socio- economic activities at the intersections were used as inputs to develop mathematical model for predicting pedestrian crashes. On the assumption that negative binomial errors control over dispersion characteristic of the crash data, a Generalized Linear Model was applied to estimate parameters of the predicting equations. Accra accounted for more than 57.6 % of the pedestrian crashes with highest casualty rate of 34 injuries per annum (including deaths). Crossing was the dominant pedestrian action leading to about 70 % of the injuries. Vehicular traffic flow, crossing pedestrian flow and mean vehicle approach speed were the key predictor variables that had positive correlations with the crash rates, while approach number of lanes and presence of median on the road minimized occurrence of pedestrian crashes. Road designers and planners could apply the pedestrian crash model to predict the effects of traffic growth, vehicular speeds, intersection geometric characte-ristics and dynamics of socio- economic activities on crash frequencies at signalized intersections in Ghana.
{"title":"Prediction equation for vehicle-pedestrian crash and safety analysis at signalled intersections in Ghana","authors":"Ek Debrah","doi":"10.4314/JAST.V17I1-2","DOIUrl":"https://doi.org/10.4314/JAST.V17I1-2","url":null,"abstract":"The occurrences of vehicle-pedestrian crashes at signalized intersections were investigated using a 3 year (2004-2006) crash records of 82 signalized intersections in Accra, Kumasi, Tema, Sekondi-Takoradi and Tamale. The data were analyzed using Micro-computer Accident Analysis Package. Traffic flow characteristics, intersection features and socio- economic activities at the intersections were used as inputs to develop mathematical model for predicting pedestrian crashes. On the assumption that negative binomial errors control over dispersion characteristic of the crash data, a Generalized Linear Model was applied to estimate parameters of the predicting equations. Accra accounted for more than 57.6 % of the pedestrian crashes with highest casualty rate of 34 injuries per annum (including deaths). Crossing was the dominant pedestrian action leading to about 70 % of the injuries. Vehicular traffic flow, crossing pedestrian flow and mean vehicle approach speed were the key predictor variables that had positive correlations with the crash rates, while approach number of lanes and presence of median on the road minimized occurrence of pedestrian crashes. Road designers and planners could apply the pedestrian crash model to predict the effects of traffic growth, vehicular speeds, intersection geometric characte-ristics and dynamics of socio- economic activities on crash frequencies at signalized intersections in Ghana.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"164 1","pages":"16-27"},"PeriodicalIF":0.0,"publicationDate":"2012-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74212452","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-03-25DOI: 10.4314/JAST.V16I1-2.64787
A. A. Baba, F. A. Adekola, O. Opaleye, R. B. Bale
Dissolution kinetics of pyrite ore (sourced from Nigeria) by hydrochloric acid were investigated. The elemental composition was determined by Inductively Coupled Plasma-Mass Spectrometry, while the mineral phase was characterized by powder X-ray diffractometry. The major elements in the ore were Fe (42.76 %), S (31.89 %), Si (7.35 %) and Zn (4.76 %). The minor elements consisted of Pb (2.63 %), Ag (1.39 %), and Mn (0.03 %), whi-le traces of Ca, Mg, V, Sb, Ni and Ra were also found. The major compounds in the ore were FeS2 and Fe2 (SO4)3, with associated mineral phases of ¥a-SiO2, Mn3O5, PbS and ZnS. The effects of HCl concentration, tem-perature and particle size on the dissolution rate indicated that about 76.4 % of the ore of < 0.1 mm particle size was dissolved at 80 ¢aC and stirring rate of 360 rpm. The dissolution rate was also dependence on hydrogen ion concentration of the reaction system. Activation energy of 38.8 kJ mol-1 and Arrhenius constant of 3.00 s-1 were obtained for the dissolution, confirming the rate controlling mechanism to be diffusion controlled surface chemi-cal reaction
{"title":"DISSOLUTION KINETICS OF PYRITE ORE BY HYDROCHLORIC ACID","authors":"A. A. Baba, F. A. Adekola, O. Opaleye, R. B. Bale","doi":"10.4314/JAST.V16I1-2.64787","DOIUrl":"https://doi.org/10.4314/JAST.V16I1-2.64787","url":null,"abstract":"Dissolution kinetics of pyrite ore (sourced from Nigeria) by hydrochloric acid were investigated. The elemental composition was determined by Inductively Coupled Plasma-Mass Spectrometry, while the mineral phase was characterized by powder X-ray diffractometry. The major elements in the ore were Fe (42.76 %), S (31.89 %), Si (7.35 %) and Zn (4.76 %). The minor elements consisted of Pb (2.63 %), Ag (1.39 %), and Mn (0.03 %), whi-le traces of Ca, Mg, V, Sb, Ni and Ra were also found. The major compounds in the ore were FeS2 and Fe2 (SO4)3, with associated mineral phases of ¥a-SiO2, Mn3O5, PbS and ZnS. The effects of HCl concentration, tem-perature and particle size on the dissolution rate indicated that about 76.4 % of the ore of < 0.1 mm particle size was dissolved at 80 ¢aC and stirring rate of 360 rpm. The dissolution rate was also dependence on hydrogen ion concentration of the reaction system. Activation energy of 38.8 kJ mol-1 and Arrhenius constant of 3.00 s-1 were obtained for the dissolution, confirming the rate controlling mechanism to be diffusion controlled surface chemi-cal reaction","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"41 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2011-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77747998","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-03-25DOI: 10.4314/JAST.V16I1-2.64773
K. Ayensu, E. Jensen
With high demand for concrete material in the building market, the goal of Portland Cement Association has be-en to increase the market share of concrete usage by promoting lateral force resisting (LFR) framing systems (moment-resisting and shearwall) in concrete structures. The selection criteria of LFR framing should be based on the importance factors and cost estimation, as cost-effectiveness has become a benchmark in the design indu-stry. In the review, the parameters (column dimensions, slab thickness, floor systems, live loads, bay sizes and aspect ratio) for developing cost-effective LFR framing model are discussed. In addition, the variables, constra-ints, properties of structural members, designs and cost estimations of the framing systems associated with apar-tment buildings are also analyzed. The preferred LFR framing system should meet drift requirements at lower cost. Moment resisting frames are commonly used for low-to mid- rise buildings, while shearwalls are best suit-ed for high-rise structures.
{"title":"Cost effective lateral force resisting concrete frame designs for low, mid and high rise buildings","authors":"K. Ayensu, E. Jensen","doi":"10.4314/JAST.V16I1-2.64773","DOIUrl":"https://doi.org/10.4314/JAST.V16I1-2.64773","url":null,"abstract":"With high demand for concrete material in the building market, the goal of Portland Cement Association has be-en to increase the market share of concrete usage by promoting lateral force resisting (LFR) framing systems (moment-resisting and shearwall) in concrete structures. The selection criteria of LFR framing should be based on the importance factors and cost estimation, as cost-effectiveness has become a benchmark in the design indu-stry. In the review, the parameters (column dimensions, slab thickness, floor systems, live loads, bay sizes and aspect ratio) for developing cost-effective LFR framing model are discussed. In addition, the variables, constra-ints, properties of structural members, designs and cost estimations of the framing systems associated with apar-tment buildings are also analyzed. The preferred LFR framing system should meet drift requirements at lower cost. Moment resisting frames are commonly used for low-to mid- rise buildings, while shearwalls are best suit-ed for high-rise structures.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2011-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79493586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-03-25DOI: 10.4314/JAST.V16I1-2.64774
C. Fokunang, B. Ngameni
Higher plants are capable of synthesizing complex and advanced chemical substances. Many of the unique gene sources may be lost through extinction, but as plants have great potential for producing new drugs, some remed-ial actions are required to preserve medicinal potential of plants. In cancer treatment, the percentage of non-synthetic small molecules of new chemical entities has averaged about 62 %. In other therapeutic areas, such as cardiovascular, antimicrobials, sexual dysfunction, and metabolic diseases, there has been extensive developme-nt of new chemical entities. In anti-hypertensive treatment, out of 74 synthetic drugs, about 48 have been traced to natural products. Active pharmaceutical ingredients, as lead compounds from plant sources have been devel-oped for many cancer antibiotics and anti-parasitic drugs. Other challenges of medicinal plant research are link-ed to the loss of biodiversity and conservation within the framework of sustainable management. The advances in sourcing plant products for new chemical entities as lead compounds in pharmaceuticals are reviewed in this paper. Major aspects of therapeutics, such as anticancer, antibacterial, antitumour, antimicrobials, and the use of NAPRALERT Natural Product Database are also presented. Bulk packaging and labelling of pharmaceutical plant products, and loss of biodiversity are highlighted as key factors in sustainable drug development from plants.
{"title":"Development of antimalaria, antibacterial, anticancer and antitumour drugs from new chemical entities from plant sources","authors":"C. Fokunang, B. Ngameni","doi":"10.4314/JAST.V16I1-2.64774","DOIUrl":"https://doi.org/10.4314/JAST.V16I1-2.64774","url":null,"abstract":"Higher plants are capable of synthesizing complex and advanced chemical substances. Many of the unique gene sources may be lost through extinction, but as plants have great potential for producing new drugs, some remed-ial actions are required to preserve medicinal potential of plants. In cancer treatment, the percentage of non-synthetic small molecules of new chemical entities has averaged about 62 %. In other therapeutic areas, such as cardiovascular, antimicrobials, sexual dysfunction, and metabolic diseases, there has been extensive developme-nt of new chemical entities. In anti-hypertensive treatment, out of 74 synthetic drugs, about 48 have been traced to natural products. Active pharmaceutical ingredients, as lead compounds from plant sources have been devel-oped for many cancer antibiotics and anti-parasitic drugs. Other challenges of medicinal plant research are link-ed to the loss of biodiversity and conservation within the framework of sustainable management. The advances in sourcing plant products for new chemical entities as lead compounds in pharmaceuticals are reviewed in this paper. Major aspects of therapeutics, such as anticancer, antibacterial, antitumour, antimicrobials, and the use of NAPRALERT Natural Product Database are also presented. Bulk packaging and labelling of pharmaceutical plant products, and loss of biodiversity are highlighted as key factors in sustainable drug development from plants.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"104 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2011-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87488003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-03-25DOI: 10.4314/JAST.V16I1-2.64786
B. Samlafo, P. Yeboah, Y. Serfor-Armah
Human hair and nail samples collected from the subjects of Wassa West District were analysed for the levels of selenium using atomic absorption spectrophotometric technique. Selenium levels in hair ranged from (0.50- 1.53) ig/g with a mean of 0.94 ± 0.21 ig/g. Levels in control subjects ranged from (0.74 - 0.8) ig/g with a me-an of 0.82 ± 0.03 ig/g. Significant differences existed between the levels of Se in the field subjects and control subjects (p = 0.003 0.05). The measurement precis-ion specified by the relative standard deviation was within ± 4 %, while the accuracy of determination evaluated by analysing certified standard human hair reference material GBW 09101 was within ± 5 % of the certified value.
{"title":"Atomic absorption spectrophotometric determination of selenium concentrations in hair and nails of residents in Wassa West District of Ghana","authors":"B. Samlafo, P. Yeboah, Y. Serfor-Armah","doi":"10.4314/JAST.V16I1-2.64786","DOIUrl":"https://doi.org/10.4314/JAST.V16I1-2.64786","url":null,"abstract":"Human hair and nail samples collected from the subjects of Wassa West District were analysed for the levels of selenium using atomic absorption spectrophotometric technique. Selenium levels in hair ranged from (0.50- 1.53) ig/g with a mean of 0.94 ± 0.21 ig/g. Levels in control subjects ranged from (0.74 - 0.8) ig/g with a me-an of 0.82 ± 0.03 ig/g. Significant differences existed between the levels of Se in the field subjects and control subjects (p = 0.003 0.05). The measurement precis-ion specified by the relative standard deviation was within ± 4 %, while the accuracy of determination evaluated by analysing certified standard human hair reference material GBW 09101 was within ± 5 % of the certified value.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2011-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82928620","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-03-25DOI: 10.4314/JAST.V16I1-2.64790
S. Tagoe, E. Nani, E. Addison, A. Andam
Measuring the wedge factor (WF) for radiation field of 10 x 10 cm2 at a specified depth and Source to Surface Distance (SSD), and applying the value to all treatment depths and technique could introduce errors > ± 5 % of threshold stipulated for patient radiation dose delivery. Therefore, some Treatment Planning Systems (TPSs) provide for inputs of separate Percentage Depth Dose (PDD) and Tissue Phantom Ratio (TPR) data for wedged fields to account for WF dependence of treatment depths and techniques. Hence, relatively more measurements than usual are taken per wedge filter and photon energy to establish a TPS and obtain dosimetric data for estima-ting treatment time for wedged fields, which required sophisticated equipment and procedures. While many On-cology Centres rely on International PDD and Tissue Maximum Ratio (TMR) data, benchmark data for wedged beams are not readily available. To provide radiotherapy dosimetry of high accuracy and expediency, two emp-irical equations were developed for a GWGP 80 Cobalt-60 teletherapy machine at the Oncology Department, Korle Bu Teaching Hospital (Ghana). The equations were validated via linear interpolations by measuring WFs at various treatment depths using Source Axial distance (SAD) and SSD treatment techniques. The approach required only measurements of WF for a 10 x 10 cm2 field at depth of 5 cm employing SSD treatment technique per wedge filter. Using the empirical equations, WFs were determined to within ± 0.50 % of the measured valu-es over the entire treatment depth range of 1.5 to 15.5 cm for SAD and SSD treatment techniques respectively; and WFs could be obtained for any treatment depth and technique.
在指定深度和源表面距离(SSD)下测量10 x 10 cm2辐射场的楔形因子(WF)，并将该值应用于所有治疗深度和技术，可能会引入误差>患者辐射剂量传递规定阈值的±5%。因此，一些治疗计划系统(tps)为楔形场提供单独的百分比深度剂量(PDD)和组织幻像比(TPR)数据输入，以说明治疗深度和技术对WF的依赖。因此，相对而言，每个楔形滤波器和光子能量需要比通常更多的测量来建立TPS并获得剂量学数据以估计楔形场的处理时间，这需要复杂的设备和程序。虽然许多生态中心依赖国际PDD和组织最大比(TMR)数据，但楔形光束的基准数据并不容易获得。为了提供高精度和方便的放射剂量测定，为加纳科尔布教学医院肿瘤科的GWGP 80钴-60远程治疗机开发了两个经验方程。通过使用源轴向距离(SAD)和SSD处理技术测量不同处理深度的wf，通过线性插值验证了方程。该方法只需要在深度为5厘米的10 × 10平方厘米的场中测量WF，每个楔形滤波器采用SSD处理技术。利用经验方程，确定了SAD和SSD处理技术在1.5 ~ 15.5 cm的整个处理深度范围内的wf值与实测值的±0.50%;在任何处理深度和处理技术下均可获得WFs。
{"title":"Dependence of wedge transmission factor on co-60 teletherapy treatment depths and techniques","authors":"S. Tagoe, E. Nani, E. Addison, A. Andam","doi":"10.4314/JAST.V16I1-2.64790","DOIUrl":"https://doi.org/10.4314/JAST.V16I1-2.64790","url":null,"abstract":"Measuring the wedge factor (WF) for radiation field of 10 x 10 cm2 at a specified depth and Source to Surface Distance (SSD), and applying the value to all treatment depths and technique could introduce errors > ± 5 % of threshold stipulated for patient radiation dose delivery. Therefore, some Treatment Planning Systems (TPSs) provide for inputs of separate Percentage Depth Dose (PDD) and Tissue Phantom Ratio (TPR) data for wedged fields to account for WF dependence of treatment depths and techniques. Hence, relatively more measurements than usual are taken per wedge filter and photon energy to establish a TPS and obtain dosimetric data for estima-ting treatment time for wedged fields, which required sophisticated equipment and procedures. While many On-cology Centres rely on International PDD and Tissue Maximum Ratio (TMR) data, benchmark data for wedged beams are not readily available. To provide radiotherapy dosimetry of high accuracy and expediency, two emp-irical equations were developed for a GWGP 80 Cobalt-60 teletherapy machine at the Oncology Department, Korle Bu Teaching Hospital (Ghana). The equations were validated via linear interpolations by measuring WFs at various treatment depths using Source Axial distance (SAD) and SSD treatment techniques. The approach required only measurements of WF for a 10 x 10 cm2 field at depth of 5 cm employing SSD treatment technique per wedge filter. Using the empirical equations, WFs were determined to within ± 0.50 % of the measured valu-es over the entire treatment depth range of 1.5 to 15.5 cm for SAD and SSD treatment techniques respectively; and WFs could be obtained for any treatment depth and technique.","PeriodicalId":9207,"journal":{"name":"British Journal of Applied Science and Technology","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2011-03-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91554160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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