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RISS 인기검색어
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- 저자 : Abubakar Usman (검색결과 4 건)
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Adamu Usman Abubakar,Abu Bakar Noor Hana Hanif,Zango Zakariyya Uba,Sambudi Nonni Soraya,Iqbal Anwar,Hussin Mohd Hazwan,Hamidon Tuan Sherwyn 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.9
Low-temperature hydrothermal technique was employed for the synthesis of highly porous and crystalline MIL-101(Cr) metal-organic frameworks series. The resulting as-synthesized MOFs were characterized by Fourier transform infrared (FTIR) spectroscopy, powdered X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption-desorption analysis, thermogravimetric analysis (TGA), photoluminescence (PL) spectroscopy, and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy. The photocatalytic activity of the MOFs was evaluated for degradation of phenanthrene (PHE) under visible light irradiation. Among the MOFs, MIL-101@160 has the highest Brunner Emmett-Teller (BET) specific surface area and corresponding pore volume of 2,592.2 m2g−1 and 1.09 cm3g−1, respectively. Furthermore, it has shown higher photocatalytic degradation of the PHE than other samples with 98% degradation efficiency achieved within 150 minutes.
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Skilled Migration, Human Capital and Educated Unemployment
( Abubakar Lawan Ngoma ),( Usman Umaru Bubaram ) 한양대학교 경제연구소 2021 JOURNAL OF ECONOMIC RESEARCH Vol.26 No.3
It is, theoretically, argued that the possibility of migration to where-the-returns to education is higher promotes human capital investment and educated unemployment in the migrants’ source countries. However, empirical studies seeking to support this claim are uncommon in the received literature. This paper examines the effect of skilled migration on human capital formation and unemployment of educated workers in migrants’ source developing countries. The paper uses System Generalised Method of Moments (SGMM) technique on panel dataset from 96 migrant-sending countries over the period of 1980 - 2000. The results reveal that skilled migration exerts positive effect on educational investment in migrants’ source countries. The results further show that the possibility of skilled migration attenuates skilled unemployment in migrants’ source countries. From the policy standpoint, the paper shows that policymakers in migrantsending countries can use the potentials of international migration to boost their countries level of human capital and reduce skilled unemployment.
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Shah Sayyed Haleem,Wang Xiaoyuan,Abubakar Usman,Gao Peng 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.5
Permanent magnet synchronous machines, especially interior permanent magnet (IPM) synchronous machines, are being used widely nowadays in a variety of applications. The (IPM) synchronous machine vibration and noise remain one of the critical factors to consider when some new design prototype of the machine is taken into consideration. In this paper, an effi cient modular type fractional slot concentrated winding (FSCW) interior type permanent magnet synchronous motor (IPMSM) is designed, taking into account the capability of fault tolerance and open circuit fault conditions. The radial force and the associated vibration phenomenon are fi rst investigated for the modular type (IPMSM) under normal operating conditions and then under symmetrical and asymmetrical three-phase units open circuit fault conditions. Two-dimensional (2-D) Fourier Transform has been used to investigate the relationship between the faulty operating conditions and the associated induced harmonics in the radial force density of the machine. Then, a detailed harmonic structural analysis, along with a three-dimensional (3-D) transient structural analysis, is performed on the stator of the proposed machine to investigate and verify the normal healthy design approach and the machine fault operating cases under post-fault conditions. Lastly, the vibration and noise characteristics of the prototype machine under the symmetrical and asymmetrical three-phase units’ faulty conditions are thoroughly investigated for comparison purposes over a wide operating speed range. The fi ndings from this comparative analysis are validated through experiments, which confi rm the validation of the proposed design. Moreover, the associated considerations can be used by machine designers to lower the vibration and noise level in fault-tolerant modular design machines.
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Dengue Virus is Hyperendemic in Nigeria from 2009 to 2020: A Contemporary Systematic Review
Anthony Uchenna Emeribe,Idris Nasir Abdullahi,Idongesit Kokoabasi Isong,Anthony Ogbonna Emeribe,Justin Onyebuchi Nwofe,Buhari Isa Shuaib,Abubakar Muhammad Gwarzo,Yahaya Usman,Madjid Sadi,Chikodi Modes 대한감염학회 2021 Infection and Chemotherapy Vol.53 No.2
Backround: Data on Dengue virus (DENV) infection prevalence, geographic distribution and risk factors are necessary to direct appropriate utilization of existing and emerging control strategies. This study aimed to determine the pooled prevalence, risk factors of DENV infection and the circulating serotypes within Nigeria from January 1, 2009 to December 31, 2020. Materials and methods: Twenty-one studies out of 2,215 available articles were eligible and included for this systematic review. Relevant articles were searched, screened and included in this study according to the Preferred Reporting Items for Systematic reviews and MetaAnalyses (PRISMA) criteria. The risk of bias in primary studies was assessed by Cochrane's method. Heterogeneity of pooled prevalence was calculated using the chi-square test on Cochrane's Q statistic, which was quantified by I-square values. The random-effects analyses of proportions were used to determine the pooled prevalence of DENV antibodies, antigen and RNA from eligible studies. Results: Of these, 3 studies reported co-circulation of all the 4 serotypes, while 2 separately reported co-circulation of DENV-1 &2 and DENV-1 to -3. All the antibody-based studies had significantly high heterogeneity (I2 >90%, P <0.05), while the NS1 and PCR-based studies had low heterogeneity (I2 <25%, P >0.05). The pooled prevalence of DENV IgM, IgG, RNA, NS1 and neutralizing antibodies were 16.8%, 34.7%, 7.7%, 7.7% and 0.7%, respectively. Southeast Nigeria had the highest pooled DENV-IgG seropositivity, 77.1%. Marital status, gender, educational level and occupation status, the proximity of residence to refuse dumpsite, frequent use of trousers and long sleeve shirts were significantly associated with DENV IgG seropositivity (P <0.05). Conclusion: Based on these findings, it can be inferred that Nigeria is hyperendemic for Dengue fever and needs concerted efforts to control its spread within and outside the country.
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