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Search Results: 1 - 10 of 5112 matches for " Umar Ibrahim Gaya "
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Comparative analysis of ZnO-catalyzed photo-oxidation of p-chlorophenols
Umar Ibrahim Gaya
European Journal of Chemistry , 2011, DOI: 10.5155/eurjchem.2.2.163-167.369
Abstract: The present study compares for the first time the photocatalytic oxidation of three p-chlorophenols (4-chlorophenol, 2,4-dichlorophenol and 2,4,6-trichlorophenol) in irradiated ZnO suspensions. The effect of operating parameters such as catalyst and concentration doses on the decomposition rate of these p-chlorinated compounds has been studied and optimized. The optimal feed concentration for each of the chlorinated phenolic compounds is 50 mg/L whereas the ZnO doses decreased as the number of chlorine substituent is increased. Kinetic profiles on the decomposition of chlorophenols over ZnO agreed with the pseudo-zeroeth order rate scheme with rate constants following the order 2,4,6-trichlorophenol > 2,4-dichlorophenol > 4-chlorophenol. The validity of the pseudo zero order model could be linked to the initial doses of the chlorophenols used vis-à-vis the catalyst. The study revealed stable intermediates of photocatalytic chlorophenol transformation by high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) technique. A combined mechanism is given to account for the photocatalytic destruction of the chlorophenols.
Photocatalytic Degradation of 2,4-dichlorophenol in Irradiated Aqueous ZnO Suspension
Umar Ibrahim Gaya,Abdul Halim Abdullah,Zulkarnain Zainal,Mohd Zobir Hussein
International Journal of Chemistry , 2010, DOI: 10.5539/ijc.v2n1p180
Abstract: This paper focuses on the destruction of aqueous 2,4-dichorophenol in ZnO suspension irradiated by low wattage UV light at 299 K. The operating variables studied include initial 2,4-dichlorophenol concentration, photocatalyst doses and pH. At 1.5 g l-1 feed concentration of ZnO and 50 mg l-1 initial 2,4-dichlorophenol level, a complete degradation was achieved in 180 min. The decomposition kinetics with respect to 2,4-dichlorophenol approximates pseudo zero-order with rate constant peaking at 0.38 mg l-1 min-1. High performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS) detected benzoquinone, 2-chlorohydroquinone, 4-chlorophenol, 3,5-dichlorocatechol, hydroquinone, 4-hydroxybenzaldehyde and phenol during the ZnO-assisted photodegradation of 2,4-dichlorophenol among which some pathway products are disclosed for the first time. The reaction mechanism accounting for the degradation pathway intermediates is proposed. Inorganic anion additives such as S2O8 2-, SO4 2-, Cland HPO4 2- manifested inhibition against 2,4-dichlorophenol removal.
An Appraisal of Spatial Distribution of Solid Waste Disposal Sites in Kano Metropolis, Nigeria  [PDF]
Ali Ibrahim Naibbi, Umar Musa Umar
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.511003
Abstract: This paper describes a research project that has been conducted as part of the Kano Municipal waste management strategy. The aim is to quantify and to identify the existing locations of waste disposal sites by mapping their spatial distribution within the metropolitan Kano. QUICKBIRD satellite imageries; locations of existing waste disposal sites collected using Global Positioning System (GPS); and topographical map (1:5000 scale) of Kano metropolis were used to generate data for the study. The data were prepared and analysed using ArcMap 10.2.1 and Erdas Imagine 11 software to produce the spatial distribution maps for solid waste disposal sites within the metropolis. The result shows that out of the 300 existing waste disposal sites assessed, the city has fairly well-distributed waste disposal sites. Conversely, the disposal sites are more clustered in the centre of the metropolis than the outskirts. However, about 80 percent of the sites are either located very close to roads, settlements or water bodies. Also, while about 92 percent of the existing waste disposal locations are open space, only about 7 percent are containers (closed dumping sites). Correspondingly, about 89 percent are authorised dumping sites and only about 11 percent are unauthorised illegal. The study recommends that policymakers should intervene and relocate the existing unauthorized dump sites to more suitable areas.
Energy use and gross margin analysis for sesame production in organic and inorganic fertiliser user farms in Nigeria
HS Umar, HY Ibrahim
African Crop Science Journal , 2012,
Abstract: As the negative impacts of energy by-products affect the climate, the knowledge and efficient use of energy in crop production will minimise environmental problems and promote sustainable agriculture as an economic production system in Nigeria and else where. The aim of the study was to evaluate energy use and gross margin estimate between sesame (Sesamum indicum) production using organic and inorganic fertilisers in North-central Nigeria. A sample of 120 sesame farmers comprising of 60 organic and 60 inorganic fertilisers user-farmers was used. A structured questionnaire was used in data collection. The results show that the total energy input expended in the production of sesame using organic and inorganic fertilisers were 2,377 and 2,960 MJ ha-1 respectively. Diesel and labour energy inputs dominated the total energy inputs for the two systems. The energy outputs obtained were 13,900 and 15,000 MJ, respectively. Renewable energy input utilisation was higher (50%) in organic than in inorganic fertilised farms (24%). Energy efficiency and productivity was higher in organic than inorganic sesame farms by 14 and 13%, respectively. The gross margin earned per hectare by organic fertiliser user- farmers was lower by only 5% than that of inorganic fertiliser farmers; but returns on investments were equal at (US$0.02). Hence, since organic farms were more energy efficient and productive, and returns on investment was equal, it is recommended that sesame production using organic fertiliser should be encouraged across Nasarawa State in Nigeria, for environmental and income sustainability.
Hypermucoviscosity in Clinical Isolates of Klebsiella pneumoniae Correlates with High Multiple Antibiotic Resistance (MAR) Index  [PDF]
Uzal Umar, Sandra Anagor, Abdullahi Aliyu, Abdulmumini Ibrahim Suleiman
Open Journal of Medical Microbiology (OJMM) , 2016, DOI: 10.4236/ojmm.2016.63013
Abstract: Klebsiella pneumoniae is an opportunistic pathogen of medical importance and the capsule and mucoid phenotype in this organism are considered as requisite virulence determinants. A total of 62 clinical samples from ATBUTH were collected and screened for K. pneumoniae. The isolates were identified using standard tests for this organism. The string test was used to detect the mucoid (hypermucoviscous) phenotype and the antimicrobial susceptibility test to 10 antibiotics was carried out with the disk diffusion technique after standardizing inoculum. A K. pneumoniae prevalence of 24% (15/62) was obtained of which 47% (7/15) were mucoid (hypermucoviscous) and 53% (8/15) were non-mucoid. Colonial sizes of the two strains do not reveal any significant differences in growth fitness of the strains. On blood agar, the mucoid and non-mucoid strains had a mean colonial size ± standard deviations of 4.41 ± 0.58 mm and 4.27 ± 0.42 mm respectively. The antibiotic susceptibility rate showed that the mucoid strains compared to the non-mucoid were more resistant to nine out of 10 antibiotics. The mucoid strains were outrightly resistant to augmentin, amoxicillin, septrin, sparfloxacin and perfloxacin. The non-mucoid strains showed no complete resistant to any antibiotic tested but had a higher resistant rate to chloramphenicol only. The Multiple Antibiotic Resistance (MAR) index shows the themucoid strains with a high MAR index range of 0.7 - 1.0 with a median MAR index of 0.8, while the non-mucoid strains had a MAR index of 0.2 - 0.8 with a median MAR index of 0.35. The data suggest that the mucoid phenotype could be associated with extrachromsomal element(s) carrying resistance genes to antibiotics and that these extrachromosomal elements may not harbour resistance determinants to chloramphenicol. Furthermore, the extrachromosomal elements bearing the mucoid phenotype and the resistance elements in the mucoid strains do not significantly impact on the fitness of the cognate strain. Whether these phenotype and resistances that had no fitness cost to the bacterium could significantly affect the virulence of the bacteria in vivo remains to be investigated.
MCNP Simulation of Physics Parameters of Dispersion Fuels for Conversion of NIRR-1 to LEU  [PDF]
Kola Ibikunle, Umar Sadiq, Yakubu Viva Ibrahim, Sunday Adesunloye Jonah
World Journal of Nuclear Science and Technology (WJNST) , 2018, DOI: 10.4236/wjnst.2018.82003
Abstract: The Nigeria Research Reactor-1 (NIRR-1) is one of the Commercial Miniature Neutron Source Reactors (MNSRs) sited outside China and scheduled for conversion under the auspices of Reduced Enrichment for Research and Test Reactors (RERTR) program. Since 2006, the reduction in the fuel enrichment of MSNR facilities from greater than 90% HEU cores to less than 20% LEU cores has been embarked upon. Consequently in this work, the physics parameters of three dispersion LEU fuels, which include U3Si, U3Si2, and U9Mo enriched to 19.75% were determined by the MCNP code to investigate their suitability for the conversion of NIRR-1 to LEU. The following reactor core physics parameters were computed for the LEU fuel options: clean cold core excess reactivity (ρex), control rod (CR) worth, shut down margin (SDM), neutron flux distributions in the irradiation channels and kinetics data (i.e. effective delayed neutron fraction, βeff?and prompt neutron lifetime, lf). Results are compared with experimental and calculated data of the current HEU core and indicate that it would be feasible to use any of the LEU options for the conversion of commercial MNSR in general and NIRR-1 in particular from HEU to LEU.
Effect of Hyperglycemia on Erythrocyte Carbonic Anhydrase and Lactic Acid in Type II Diabetic Subjects  [PDF]
Salihu Ismail Ibrahim, Ameh Danladi Amodu, Atawodi Sunday Ene-Ojo, Umar Alhaji Ismaila, Mohammed Fakhruddeen
Journal of Diabetes Mellitus (JDM) , 2016, DOI: 10.4236/jdm.2016.62017
Abstract: Background: Carbonic anhydrase (CA) is a ubiquitous enzyme catalyzing the reversible hydration of CO2 to ?and H+. CA plays a crucial role in CO2 transport, acid-base balance, and in linking local acidosis to O2 unloading from hemoglobin and also facilitates lactate shuttling across the monocarboxylate transporters (MCT). The study aimed to investigate the influence of hyperglycemia on erythrocyte carbonic anhydrase activity and lactic acid in type II diabetic patients. Method: Red blood cell carbonic anhydrase activity was determined in washed lysed-hemolysate by the action of the enzyme on the substrate p-nitrophenyl acetate. The absorbance of released p-nitrophenol was recorded at 345 nm. Glycated Hemoglobin was determined by ion exchange method (Spectrum Diagnostic Kit). Blood glucose, lactate, cholesterol and triglyceride were determined using Accutrend GCT meter (Roche, Germany) with cobias®?test strips. Results: The present study showed that hyperglycemia significantly (p < 0.05) increased both erythrocyte carbonic anhydrase activity and blood lactate level in type II diabetic patients. Conclusion: We may conclude that hyperglycemia may be responsible for the increased activity of carbonic anhydrase activity and blood lactate concentration.
The effects of lactose infusion on the pathological manifestations of Trypanosoma vivax infection in cattle
NDG Ibrahim, KAN Esievo, LA Umar
Nigerian Veterinary Journal , 2005,
Abstract: Except for 4 control calves, 8 calves were experimentally infected using 11 x 106 T. vivax Trypanosomes, intravenously, as a source of neuraminidase. At the peak of parasitaemia, lactose was intravenously infused at the rate of 0.5g kg-1 body weight into 4 of the infected calves, to inhibit the binding of desialylated erythrocytes to kupffer cells (macrophages), and therefore, subsequent erythrophagocytosis. This resulted in amelioration of the anaemia in the 4 infected, lactose infused calves which showed no gross lesions except for mild anaemia and emaciation. In contrast, the other 4 infected, non-lactose infused calves had marked anaemia. The mean PCV values were higher in the infected infused calves and the mean PCV values were lower in the infected uninfused calves, with a statistically significant difference (P<0.05). The 4 infected, lactose infused calves showed no gross lesions except for mild anaemia and emaciation. The major gross lesions observed in the infected non-lactose infused calves included rough hair coat, emaciated carcases, serous atrophy of coronary fat, enlarged oedematous lymph nodes, and hepato-splenomegaly. Two calves each from the infected lactose infused and non-lactose infused groups and one of the control calves were sacrificed for pathological examinations. Histopathological lesions in the infected-lactose-infused calves were narrow hepatic sinusoidal spaces, enlarged Bowman's spaces, hypercellular renal glomeruli, and a less dense lymphoid hyperplasia (proliferation of lymphocytes) in the spleen and lymph nodes compared to the infected-non-lactose infused calves. No significant histopathological changes occurred in the heart, lung, and intestine of the infected-lactose infused calves. In the infected-non-lactose-infused calves there were diffuse hepatic necrosis and erythrophagia by Kupffer cells, dense lymphoid hyperplasia (active lymphoid follicles with plasma cells), and haemosiderosis. There were haemosiderin laden macrophages in the spleen, liver, kidney, and lymph node. Hypercellular glomeruli, necrosis of the proximal, distal and collecting tubules of the kidney with periglomerular and inter-tubular mononuclear cellular infiltration. There was minimal myocarditis, while the brain, lung and the intestine of the calves had no significant histopathological lesions. No significant microscopic lesions were observed in the liver, kidney, lung, heart, spleen, lymph node, brain, and the intestine of the control calf examined. The results of this study have shown that lactose plays a vital role in the prevention or amelioration of tissue injury and cellular reactions in various organs of the body during the course of bovine trypanosomiasis. The finding further supports the safety use of lactose without causing any damage to body organs. As such, its incoporation with other chemotherapeutic agents for treatment of trypanosomiasis is, therefore strongly recommended.
IS ROUTINE ANTENATAL SCREENINGTEST FOR SYPHYLIS USING VDRL STILL RELEVANT?
Yakasai IA, Umar U, Ibrahim SA, Abubakar IS
Academic Research International , 2012,
Abstract: Antenatal clinics perform routine serological tests for syphilis as a screening procedure. Syphilis is still a serious but treatable disease with maternal and fetal complications. There are two categories of serological tests for syphilis, the cardiolopin; venereal disease research laboratory (VDRL) test and the specific tests treponema Pallidum haemagglutination (TPHA) test. Pregnancy is a recognised cause of false-positive VDRL test result. The aim of the study was todetermine the seroprevalence and cost-effectiveness of antenatal syphilis screening at Aminu Kano Teaching Hospital (AKTH), Kano, Nigeria. The method includes a retrospective analysis of venereal disease research laboratory (VDRL) test results among pregnant women in AKTH during a 4 year period (January 2007-December 2010) was undertaken. The resulst include: a) fourteen –thousand, eight hundred and seventy-one pregnant women were screened for syphilis, using VDRL test; 95women were positive. Only eighty- two (82) folders were retrieved and analyzed given a seroprevalence rate of 0.55%.The peak age specific incidence was in the 20-24 years age group, b) the median gestational age at booking was 22 weeks, c) the cost of VDRL testper patient in AKTH is $2.5. To detect the 95 seropositive cases the sum of $38,106 was spent. It was concluded that the seroprevalence rate of syphilis in this study was low (0.55%). Initial screening using VDRL alone is neither justified nor cost effective. Selective screening base on risk factors and confirmatory test with FTA-AB is recommended.
DeltaTree: A Practical Locality-aware Concurrent Search Tree
Ibrahim Umar,Otto Anshus,Phuong Ha
Computer Science , 2013,
Abstract: As other fundamental programming abstractions in energy-efficient computing, search trees are expected to support both high parallelism and data locality. However, existing highly-concurrent search trees such as red-black trees and AVL trees do not consider data locality while existing locality-aware search trees such as those based on the van Emde Boas layout (vEB-based trees), poorly support concurrent (update) operations. This paper presents DeltaTree, a practical locality-aware concurrent search tree that combines both locality-optimisation techniques from vEB-based trees and concurrency-optimisation techniques from non-blocking highly-concurrent search trees. DeltaTree is a $k$-ary leaf-oriented tree of DeltaNodes in which each DeltaNode is a size-fixed tree-container with the van Emde Boas layout. The expected memory transfer costs of DeltaTree's Search, Insert, and Delete operations are $O(\log_B N)$, where $N, B$ are the tree size and the unknown memory block size in the ideal cache model, respectively. DeltaTree's Search operation is wait-free, providing prioritised lanes for Search operations, the dominant operation in search trees. Its Insert and {\em Delete} operations are non-blocking to other Search, Insert, and Delete operations, but they may be occasionally blocked by maintenance operations that are sometimes triggered to keep DeltaTree in good shape. Our experimental evaluation using the latest implementation of AVL, red-black, and speculation friendly trees from the Synchrobench benchmark has shown that DeltaTree is up to 5 times faster than all of the three concurrent search trees for searching operations and up to 1.6 times faster for update operations when the update contention is not too high.
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