Pub Date : 2013-04-01DOI: 10.5251/AJSIR.2013.4.2.253.256
A. Elagib, Hiba Mirgani
Sickle cell anemia is a haemoglobinpathy due to a single point mutation in the -chain of human haemoglobin. A hospital based case control study was done on the paediatric section in Khartoum Teaching hospital to investigate the role of haptoglobin phenotypes among sickle cell disease patients. A total number of 127 sickle disease patients and 34 healthy controls were screened for Hb phenotypes. Out of 88 homozygous sickle cell anaemia patients (HbSS), 77.3% patients had the Hp 1-1 phenotype, 22.7% had the Hp 2-1 phenotype, and none of them had Hp 2-2 type. Out of the 39 sickle cell trait (HbAS) individuals, 41% individuals had Hp1-1 phenotype, 59% had Hp21 phenotype and none of them had the Hp 2-2 phenotypes. Out of the 34 healthy controls (HbAA), 44% had Hp 1-1 phenotype, 38% had Hp 2-1 phenotype and 18% had Hp2-2 phenotype. There was a highly significant difference in the distribution of haptoglobin phenotypes among the three groups (P = 0.0001). The sickle cell trait (AS) had high frequency of Hp2-1. The sickle cell disease individuals (SS) had higher frequencies of Hp1-1. In conclusion, Malaria infection among the sickle cell homozygous (SS) individuals may be related to the high frequency of Hp1-1 and the protection of sickle cell trait (AS) against malaria infection may be due to the high frequency of haptoglobin phenotype 2-1.
{"title":"Is resistance to P. falciparum infection in sickle cell trait (AS) individuals is related to presence of high frequencies of haptoglobin Hp2-1?","authors":"A. Elagib, Hiba Mirgani","doi":"10.5251/AJSIR.2013.4.2.253.256","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.2.253.256","url":null,"abstract":"Sickle cell anemia is a haemoglobinpathy due to a single point mutation in the -chain of human haemoglobin. A hospital based case control study was done on the paediatric section in Khartoum Teaching hospital to investigate the role of haptoglobin phenotypes among sickle cell disease patients. A total number of 127 sickle disease patients and 34 healthy controls were screened for Hb phenotypes. Out of 88 homozygous sickle cell anaemia patients (HbSS), 77.3% patients had the Hp 1-1 phenotype, 22.7% had the Hp 2-1 phenotype, and none of them had Hp 2-2 type. Out of the 39 sickle cell trait (HbAS) individuals, 41% individuals had Hp1-1 phenotype, 59% had Hp21 phenotype and none of them had the Hp 2-2 phenotypes. Out of the 34 healthy controls (HbAA), 44% had Hp 1-1 phenotype, 38% had Hp 2-1 phenotype and 18% had Hp2-2 phenotype. There was a highly significant difference in the distribution of haptoglobin phenotypes among the three groups (P = 0.0001). The sickle cell trait (AS) had high frequency of Hp2-1. The sickle cell disease individuals (SS) had higher frequencies of Hp1-1. In conclusion, Malaria infection among the sickle cell homozygous (SS) individuals may be related to the high frequency of Hp1-1 and the protection of sickle cell trait (AS) against malaria infection may be due to the high frequency of haptoglobin phenotype 2-1.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"100 1","pages":"253-256"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88366186","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 : 2013-04-01DOI: 10.5251/AJSIR.2013.4.2.246.252
E. Ubani, I. Onyejekwe
Gas flaringis the burning of natural gas and petroleum hydrocarbons in flare stacks by upstream oil companies in oil fields during operations. Gas flaring is the singular and most common source of global warming and contributes to emissions of carbon monoxide, nitrogen (II) oxide and methane which have the propensity of causing environmental pollution and ecological disturbances or destruction. This research explore and presents a method of analysing the environmental impact of gas flaring in the Niger Delta so to provide the data required for the complete analysis and evaluation of the various observed and noted health and environmental effects of gas flaring in Niger Delta. The major environmental impacts considered in the study are environmental pollution, and ecological disturbance or destruction. Several visitations to the neighbouring communities adjacent to most gas flare locations were carried out to ascertain any existence of common environmental hazards. Data was gathered through a well designed and articulating oral and written questionnaires, direct and first-hand observation of their environment, and comprehensive interview sessions with community heads (royal authorities where possible), patients and youth. Different samples at various proximities from the gas flare locations were taken and measurements and experimentations were meticulously carried out. The result obtained in this research shows a marked trend as all the parameters considered showed a gradient away from the flare point in all the flow stations such as soil pH changing from acidic (4.0-4.2) to near neutral (6.4-6.6) away from the flare points and the average low soil moisture content of (17% - 23%) as against 40% for the (10m and 20m) and control distance. The quantity of carbon emitted by these flare is about 2525000.00 tonnes of carbon per day. These values portray a bad omen for the affected communities. This study recommends that gas flaring should be seen as violet action against the people and that the flared gas should be channelled to meeting the ever increasing demand for energy in the industrial sector of the economy.
{"title":"Environmental impact analyses of gas flaring in the Niger delta region of Nigeria","authors":"E. Ubani, I. Onyejekwe","doi":"10.5251/AJSIR.2013.4.2.246.252","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.2.246.252","url":null,"abstract":"Gas flaringis the burning of natural gas and petroleum hydrocarbons in flare stacks by upstream oil companies in oil fields during operations. Gas flaring is the singular and most common source of global warming and contributes to emissions of carbon monoxide, nitrogen (II) oxide and methane which have the propensity of causing environmental pollution and ecological disturbances or destruction. This research explore and presents a method of analysing the environmental impact of gas flaring in the Niger Delta so to provide the data required for the complete analysis and evaluation of the various observed and noted health and environmental effects of gas flaring in Niger Delta. The major environmental impacts considered in the study are environmental pollution, and ecological disturbance or destruction. Several visitations to the neighbouring communities adjacent to most gas flare locations were carried out to ascertain any existence of common environmental hazards. Data was gathered through a well designed and articulating oral and written questionnaires, direct and first-hand observation of their environment, and comprehensive interview sessions with community heads (royal authorities where possible), patients and youth. Different samples at various proximities from the gas flare locations were taken and measurements and experimentations were meticulously carried out. The result obtained in this research shows a marked trend as all the parameters considered showed a gradient away from the flare point in all the flow stations such as soil pH changing from acidic (4.0-4.2) to near neutral (6.4-6.6) away from the flare points and the average low soil moisture content of (17% - 23%) as against 40% for the (10m and 20m) and control distance. The quantity of carbon emitted by these flare is about 2525000.00 tonnes of carbon per day. These values portray a bad omen for the affected communities. This study recommends that gas flaring should be seen as violet action against the people and that the flared gas should be channelled to meeting the ever increasing demand for energy in the industrial sector of the economy.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"7 I 1","pages":"246-252"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86869917","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 : 2013-04-01DOI: 10.5251/AJSIR.2013.4.2.161.166
A. Ladu, Usman A. Abjah
Sickle cell anaemia (SCA) is a genetic disorder which can be complicated by haemolytic, vasoocclusive and thrombotic processes. Antithrombin III (ATIII) is a naturally occurring anticoagulant with anti inflammatory properties. The objective of this study was to determine the level of ATIII in individuals with SCA and to assess its role in vaso-occlusive crisis. This was an observational cross sectional study in which 60 adult HbSS (34 in steady state and 26 in vaso-occlusive crisis) subjects and 60 apparently healthy adults matched for sex and age served as controls. Haemoglobin (Hb) electrophoresis of subjects and controls was determined using Hb electrophoresis. Nine and a half (9.5) milliliters of blood, divided into two aliquots of 4.5mls (in 0.5mls of tri sodium citrate for coagulation studies) and 5mls (in EDTA containing bottle for full blood count) was obtained. Quantitative assessment of antithrombin III by chromogenic assay with Factor Xa was carried out using Diachrom ATIII test kit. Prothrombin time(PT), activated partial thromboplastin time(APTT), haematocrit, total white blood cells (WBC) and platelets count were assessed using standard protocol. SPSS (version 13 for windows) was used for data analysis. A p value of <0.05 was considered significant. The subjects were made up of 33(55%) males and 27(45%) females, with a mean age of 22.52(5.21) years whilst the controls consisted of 34(56.7%) males and 26(43.3%) females with a mean age of 22.85 (4.20). HbS subjects had a significantly lower ATIII levels compared with controls (p=0.009). Levels of ATIII that was found in SCA patients in steady state and in vaso-occlusive crisis did not differ significantly (p=0.468). Haematocrit was significantly lower in HbS than controls (p=0.000), whereas total WBC count (p=0.000), absolute platelet count (p=0.003), and Prothrombin time (0.008) were significantly higher in the HbS subjects. ATIII levels did not differ significantly between steady state and vasoocclusive crisis, suggesting that ATIII does not play an active role in pathogenesis of vasoocclusive crisis.
镰状细胞性贫血(SCA)是一种遗传性疾病，可并发溶血、血管闭塞和血栓形成过程。抗凝血酶III (ATIII)是一种天然存在的抗凝血剂，具有抗炎特性。本研究的目的是确定SCA患者的ATIII水平，并评估其在血管闭塞危机中的作用。这是一项观察性横断面研究，其中60名成人HbSS(34名处于稳定状态，26名处于血管闭塞危象)受试者和60名性别和年龄相匹配的明显健康成人作为对照。受试者和对照组的血红蛋白(Hb)电泳采用Hb电泳测定。9.5毫升血液，分为两份，4.5毫升(在0.5毫升三柠檬酸钠中进行凝血研究)和5毫升(在含有EDTA的瓶子中进行全血细胞计数)。采用Diachrom ATIII检测试剂盒，用Xa因子显色法定量评价抗凝血酶III。使用标准方案评估凝血酶原时间(PT)，活化部分凝血活素时间(APTT)，红细胞压积，总白细胞(WBC)和血小板计数。使用SPSS (version 13 for windows)进行数据分析。p值<0.05为显著性。其中男性33人(55%)，女性27人(45%)，平均年龄22.52岁(5.21岁);对照组男性34人(56.7%)，女性26人(43.3%)，平均年龄22.85岁(4.20岁)。与对照组相比，HbS受试者的ATIII水平显著降低(p=0.009)。SCA患者在稳定状态和血管闭塞危像时的ATIII水平无显著差异(p=0.468)。HbS患者的红细胞压积显著低于对照组(p=0.000)，而白细胞总数(p=0.000)、绝对血小板计数(p=0.003)和凝血酶原时间(0.008)显著高于对照组。在稳定状态和血管闭塞性危象之间，ATIII水平没有显著差异，提示ATIII在血管闭塞性危象的发病机制中没有积极作用。
{"title":"A study of antithrombin 111 in sickle cell anaemia patients in steady state and during vaso-0cclusive crisis in North-Eastern Nigeria.","authors":"A. Ladu, Usman A. Abjah","doi":"10.5251/AJSIR.2013.4.2.161.166","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.2.161.166","url":null,"abstract":"Sickle cell anaemia (SCA) is a genetic disorder which can be complicated by haemolytic, vasoocclusive and thrombotic processes. Antithrombin III (ATIII) is a naturally occurring anticoagulant with anti inflammatory properties. The objective of this study was to determine the level of ATIII in individuals with SCA and to assess its role in vaso-occlusive crisis. This was an observational cross sectional study in which 60 adult HbSS (34 in steady state and 26 in vaso-occlusive crisis) subjects and 60 apparently healthy adults matched for sex and age served as controls. Haemoglobin (Hb) electrophoresis of subjects and controls was determined using Hb electrophoresis. Nine and a half (9.5) milliliters of blood, divided into two aliquots of 4.5mls (in 0.5mls of tri sodium citrate for coagulation studies) and 5mls (in EDTA containing bottle for full blood count) was obtained. Quantitative assessment of antithrombin III by chromogenic assay with Factor Xa was carried out using Diachrom ATIII test kit. Prothrombin time(PT), activated partial thromboplastin time(APTT), haematocrit, total white blood cells (WBC) and platelets count were assessed using standard protocol. SPSS (version 13 for windows) was used for data analysis. A p value of <0.05 was considered significant. The subjects were made up of 33(55%) males and 27(45%) females, with a mean age of 22.52(5.21) years whilst the controls consisted of 34(56.7%) males and 26(43.3%) females with a mean age of 22.85 (4.20). HbS subjects had a significantly lower ATIII levels compared with controls (p=0.009). Levels of ATIII that was found in SCA patients in steady state and in vaso-occlusive crisis did not differ significantly (p=0.468). Haematocrit was significantly lower in HbS than controls (p=0.000), whereas total WBC count (p=0.000), absolute platelet count (p=0.003), and Prothrombin time (0.008) were significantly higher in the HbS subjects. ATIII levels did not differ significantly between steady state and vasoocclusive crisis, suggesting that ATIII does not play an active role in pathogenesis of vasoocclusive crisis.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"24 1","pages":"161-166"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73646280","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 : 2013-04-01DOI: 10.5251/AJSIR.2013.4.2.173.182
A. Afolabi, E. Adagunodo
The Bell-LaPadula Model was developed by David Elliott Bell and Len LaPadula in 1973,it focuses on data confidentiality and access to classified information,the model is built on the concept of a state machine with a set of allowable ststes in a system. The model is found to be limited due to the fact that it only deal with confidentiality not integrity, also it does not address management of access control and contains covert channels. With this background another model called AFOADAG is developed as an improvement on Bell –Lapadula model ,by an
{"title":"Application of Afoadag model (an improvement on bell –lapadula model) to security in e-learning","authors":"A. Afolabi, E. Adagunodo","doi":"10.5251/AJSIR.2013.4.2.173.182","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.2.173.182","url":null,"abstract":"The Bell-LaPadula Model was developed by David Elliott Bell and Len LaPadula in 1973,it focuses on data confidentiality and access to classified information,the model is built on the concept of a state machine with a set of allowable ststes in a system. The model is found to be limited due to the fact that it only deal with confidentiality not integrity, also it does not address management of access control and contains covert channels. With this background another model called AFOADAG is developed as an improvement on Bell –Lapadula model ,by an","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"115 1","pages":"173-182"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80823888","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 : 2013-04-01DOI: 10.5251/AJSIR.2013.4.2.167.172
Arif Ahmed, Md Sariful Islam Howlader
In Bangladesh, the herb Operculina turpethum is used for otitis media, suppurative sores, burns, conjunctivitis and skin diseases (eczema, abscesses, acne, scabies and warts) although the compounds responsible for the medicinal properties have not been identified. The present study has been undertaken for antibacterial activity of the ethanol, ether and chloroform extract of O. turpethum root and leaf. Antibacterial activity has been investigated against Shigella boydii, Shigella flese, Shigella dysenteriae, Escherichia coli, Proteus vulgaris, Salmonella typhi, Hafnia alvei, Staphylococcus epidermidis, Streptococcus pyogenes, Staphylococcus aureus, Enterococcus faecalis by disc diffusion and broth macro-dilution assay. The zone of inhibition has been observed with almost all bacteria with some exceptions. Minimum inhibitory concentrations (MIC) of the extracts were found to be significant.
{"title":"Phytochemical screening and antibacterial activity of different fractions of Operculina turpethum root and leaf","authors":"Arif Ahmed, Md Sariful Islam Howlader","doi":"10.5251/AJSIR.2013.4.2.167.172","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.2.167.172","url":null,"abstract":"In Bangladesh, the herb Operculina turpethum is used for otitis media, suppurative sores, burns, conjunctivitis and skin diseases (eczema, abscesses, acne, scabies and warts) although the compounds responsible for the medicinal properties have not been identified. The present study has been undertaken for antibacterial activity of the ethanol, ether and chloroform extract of O. turpethum root and leaf. Antibacterial activity has been investigated against Shigella boydii, Shigella flese, Shigella dysenteriae, Escherichia coli, Proteus vulgaris, Salmonella typhi, Hafnia alvei, Staphylococcus epidermidis, Streptococcus pyogenes, Staphylococcus aureus, Enterococcus faecalis by disc diffusion and broth macro-dilution assay. The zone of inhibition has been observed with almost all bacteria with some exceptions. Minimum inhibitory concentrations (MIC) of the extracts were found to be significant.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"29 1","pages":"167-172"},"PeriodicalIF":0.0,"publicationDate":"2013-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79217678","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 : 2013-02-01DOI: 10.5251/AJSIR.2013.4.1.22.30
R. Alani, K. Drouillard, K. Olayinka, B. Alo
The rate at which organochlorine pesticides (OCs) are being used in Nigeria is becoming a matter of concern considering the heavy negative health effects associated with these chemicals. OCs are very persistent, bioaccumulative and toxic, and they can easily find their way into an adjacent water course such as the Lagos Lagoon via soil run-off and leaching. The levels of OCs were therefore assessed in water, sediment, invertebrates (crayfish shrimps and crabs) and twelve species of fish, including commercially important fish sold to local markets. Samples were collected and analyzed using Gas chromatography/ Mass selective Detector (GC/MSD). The most bioaccumulated OCs in the fish were beta-HCH (22.72-0.90ng/g d. w.) and p,p’DDE (16.040.44ng/g d. w.). The most bioaccumulative OCs in the invertebrates were still beta-HCH (24.5016.10ng/g d. w.) and p,p’DDE (22.20-1.85ng/g d. w.). The sum OCs of 55.22 ng/g d. w. in crab eggs, 63.90ng/g d. w. in agaza (Caranx hippos), and 69.40ng/g d. w. in young blue crabs (Callinectus amnicola) revealed these biota as the most contaminated. Spatial patterns of contaminant accumulation were contrasted between environmental media and biological samples and a risk model for human exposures of organochlorine pesticides due to consumption of contaminated fish and invertebrates is presented.
考虑到与有机氯农药相关的严重负面健康影响，尼日利亚有机氯农药的使用率正成为一个令人关切的问题。OCs具有很强的持久性、生物蓄积性和毒性，它们可以很容易地通过土壤径流和淋滤进入邻近的水道，如拉各斯泻湖。因此，在水、沉积物、无脊椎动物(小龙虾、虾和螃蟹)和12种鱼类(包括销往当地市场的具有重要商业价值的鱼类)中评估了OCs的水平。采用气相色谱/质量选择检测器(GC/MSD)对样品进行分析。鱼体内生物积累最多的OCs是- hch (22.72 ~ 0.90ng/g d. w)和p,p 'DDE (16.040.44ng/g d. w)。无脊椎动物体内生物蓄积量最大的OCs仍然是- hch (24.5016.10ng/g d. w)和p,p’dde (22.20-1.85ng/g d. w)。蟹卵的总OCs为55.22 ng/g d. w，海蟹(Caranx hippos)为63.90ng/g d. w，青蟹(calinectus amnicola)为69.40ng/g d. w。对比了环境介质和生物样本之间污染物积累的空间格局，并提出了食用受污染的鱼类和无脊椎动物对人体有机氯农药暴露的风险模型。
{"title":"Bioaccumulation of organochlorine pesticide residues in fish and invertebrates of Lagos Lagoon, Nigeria","authors":"R. Alani, K. Drouillard, K. Olayinka, B. Alo","doi":"10.5251/AJSIR.2013.4.1.22.30","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.1.22.30","url":null,"abstract":"The rate at which organochlorine pesticides (OCs) are being used in Nigeria is becoming a matter of concern considering the heavy negative health effects associated with these chemicals. OCs are very persistent, bioaccumulative and toxic, and they can easily find their way into an adjacent water course such as the Lagos Lagoon via soil run-off and leaching. The levels of OCs were therefore assessed in water, sediment, invertebrates (crayfish shrimps and crabs) and twelve species of fish, including commercially important fish sold to local markets. Samples were collected and analyzed using Gas chromatography/ Mass selective Detector (GC/MSD). The most bioaccumulated OCs in the fish were beta-HCH (22.72-0.90ng/g d. w.) and p,p’DDE (16.040.44ng/g d. w.). The most bioaccumulative OCs in the invertebrates were still beta-HCH (24.5016.10ng/g d. w.) and p,p’DDE (22.20-1.85ng/g d. w.). The sum OCs of 55.22 ng/g d. w. in crab eggs, 63.90ng/g d. w. in agaza (Caranx hippos), and 69.40ng/g d. w. in young blue crabs (Callinectus amnicola) revealed these biota as the most contaminated. Spatial patterns of contaminant accumulation were contrasted between environmental media and biological samples and a risk model for human exposures of organochlorine pesticides due to consumption of contaminated fish and invertebrates is presented.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"10 1","pages":"22-30"},"PeriodicalIF":0.0,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78795942","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 : 2013-02-01DOI: 10.5251/AJSIR.2013.4.1.59.74
Hani Aziz Ameen, Rahman Hussain
Rolling play an increasingly significant role in forming process, very few studies have been devoted to the case of rolling superplastic alloy. This paper presents an investigation of symmetrical and unsymmetrical rolling process, which is of fundamental interest for forming processes. The prediction of the strain rate in the unsymmetrical rolling process is thus a challenging task. This paper has a novel discussion of symmetrical and unsymmetrical rolling of superplastic (lead-tin) eutectic alloy and with different range of rolling speed ratios and percentage reduction in thickness. It was found that the strain rate calculated experimentally was always greater than that calculated from theoretical considerations. Curling of the specimen as it leaves the rolls in the unsymmetrical rolling depends on the percentage reduction in thickness and on roll speed ratio.
{"title":"Theoretical and experimental investigation of superplastic rolling process","authors":"Hani Aziz Ameen, Rahman Hussain","doi":"10.5251/AJSIR.2013.4.1.59.74","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.1.59.74","url":null,"abstract":"Rolling play an increasingly significant role in forming process, very few studies have been devoted to the case of rolling superplastic alloy. This paper presents an investigation of symmetrical and unsymmetrical rolling process, which is of fundamental interest for forming processes. The prediction of the strain rate in the unsymmetrical rolling process is thus a challenging task. This paper has a novel discussion of symmetrical and unsymmetrical rolling of superplastic (lead-tin) eutectic alloy and with different range of rolling speed ratios and percentage reduction in thickness. It was found that the strain rate calculated experimentally was always greater than that calculated from theoretical considerations. Curling of the specimen as it leaves the rolls in the unsymmetrical rolling depends on the percentage reduction in thickness and on roll speed ratio.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"14 1","pages":"59-74"},"PeriodicalIF":0.0,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73799977","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 : 2013-02-01DOI: 10.5251/AJSIR.2013.4.1.36.43
Lekaa Ali Mohamed
This paper deals with introducing four estimators of parameters ( ), for linear hazard (risk) function { }. Two consist of the proposed which are mixed estimators, and the proposed estimator depend on order record data. While the two other methods, include maximum likelihood method which are solved numerically, using Newton Raphson method, and last method is white estimators depend on principle of least square's method. The comparison between ( ), has been done through simulation experiment for different sample size chosen and replicate is ( ). The statistical measure mean square error (MSE) is used for comparison. All results are explained through tables, for different sets of chosen parameters. Keyword: Hazard rate { }, maximum likelihood, OLS, proposed method, mean square error (MSE).
{"title":"Introducing a New Estimators of Parameters of Linear Hazard Rate Function","authors":"Lekaa Ali Mohamed","doi":"10.5251/AJSIR.2013.4.1.36.43","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.1.36.43","url":null,"abstract":"This paper deals with introducing four estimators of parameters ( ), for linear hazard (risk) function { }. Two consist of the proposed which are mixed estimators, and the proposed estimator depend on order record data. While the two other methods, include maximum likelihood method which are solved numerically, using Newton Raphson method, and last method is white estimators depend on principle of least square's method. The comparison between ( ), has been done through simulation experiment for different sample size chosen and replicate is ( ). The statistical measure mean square error (MSE) is used for comparison. All results are explained through tables, for different sets of chosen parameters. Keyword: Hazard rate { }, maximum likelihood, OLS, proposed method, mean square error (MSE).","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"35 1","pages":"36-43"},"PeriodicalIF":0.0,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81033655","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 : 2013-02-01DOI: 10.5251/AJSIR.2013.4.1.95.110
S. Twum, E. Aspinwall
This paper presents a state of the art review of the vibrant and fast growing field of reliability optimisation in design as it was in the early 1980s, when the field had started to gain attention, to date; in terms of research and development of theories and applications. The field is classified into the pertinent existing reliability optimisation strategies and the types of optimisation models employed. The solution methods used are also discussed. The models are critically reviewed and gaps needing attention noted. Particularly noted was the dominance of redundancy allocation optimisation over other strategies such as reliability allocation optimisation which virtues have not been fully explored. Attention is drawn also to the scarcity of multi-objective optimisation models in the literature, even though typically real life reliability optimisation problems are of that nature. The discussions are concluded by drawing attention to potential model formulations of the multiobjective type.
{"title":"Models in design for reliability optimisation","authors":"S. Twum, E. Aspinwall","doi":"10.5251/AJSIR.2013.4.1.95.110","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.1.95.110","url":null,"abstract":"This paper presents a state of the art review of the vibrant and fast growing field of reliability optimisation in design as it was in the early 1980s, when the field had started to gain attention, to date; in terms of research and development of theories and applications. The field is classified into the pertinent existing reliability optimisation strategies and the types of optimisation models employed. The solution methods used are also discussed. The models are critically reviewed and gaps needing attention noted. Particularly noted was the dominance of redundancy allocation optimisation over other strategies such as reliability allocation optimisation which virtues have not been fully explored. Attention is drawn also to the scarcity of multi-objective optimisation models in the literature, even though typically real life reliability optimisation problems are of that nature. The discussions are concluded by drawing attention to potential model formulations of the multiobjective type.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"51 1","pages":"95-110"},"PeriodicalIF":0.0,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90767486","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 : 2013-02-01DOI: 10.5251/AJSIR.2013.4.1.111.122
I. Adejoro, O. Oyeneyin
A novel polymeric zinc (II) complex of quinine, [chlorosulphato (2-ethenyl)-4-azabicyclo [2.2.2]oct5-ylium-(6-methoxyquinolin-4-yl) methanol zinc (II)] has been synthesized and characterized. However, theoretical studies on the geometries, thermodynamic parameters, vibrational frequencies, geometric parameters, dipole moments, and band gaps of the complex were carried out. All these properties were obtained using the AM1, PM3 and DFT methods. Comparisons were made on the calculated bond distances, bond angles, dihedral and vibrational frequencies with the experimental data and it compared favourably well.
{"title":"Characterization of a novel polymeric Zinc (II) complex containing the anti- malarial Quinine as ligand: A Theoretical Approach (Semi-empirical and DFT methods).","authors":"I. Adejoro, O. Oyeneyin","doi":"10.5251/AJSIR.2013.4.1.111.122","DOIUrl":"https://doi.org/10.5251/AJSIR.2013.4.1.111.122","url":null,"abstract":"A novel polymeric zinc (II) complex of quinine, [chlorosulphato (2-ethenyl)-4-azabicyclo [2.2.2]oct5-ylium-(6-methoxyquinolin-4-yl) methanol zinc (II)] has been synthesized and characterized. However, theoretical studies on the geometries, thermodynamic parameters, vibrational frequencies, geometric parameters, dipole moments, and band gaps of the complex were carried out. All these properties were obtained using the AM1, PM3 and DFT methods. Comparisons were made on the calculated bond distances, bond angles, dihedral and vibrational frequencies with the experimental data and it compared favourably well.","PeriodicalId":7661,"journal":{"name":"American Journal of Scientific and Industrial Research","volume":"57 1","pages":"111-122"},"PeriodicalIF":0.0,"publicationDate":"2013-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90455371","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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