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        검색결과 1,065

        41.
        2022.09 구독 인증기관·개인회원 무료
        Maize is an important cereal crop widely grown in all of Nigeria’s agroecology based on its economic and food values. This has led to its optimum production with Nigeria ranking top 12th maize producer in the world. Presently, the fall armyworm (FAW), Spodoptera frugiperda is considered a potential threat to food security in Nigeria due to its devastating feeding pattern on maize and its wide host range. Its invasive and high dispersal nature enhances its spread from its first reported state (Oyo) in early 2016 to the entire 36 states of Nigeria by the year 2018. It accounts for averagely an estimated 34% or more yield reduction in Nigeria’s maize field, hence, a need for an efficient management approach. Although most farmers rely on the use of insecticide, it is found ineffective because of the inaccessible location of FAW in maize. This study was carried out to investigate the different management approaches adopted in Nigeria to control FAW and its impact on the insect pest population. Conventional measures such as planting improved seeds, avoidance of late planting, and polyculture to increase the natural enemy’s population have been used but with limited control of FAW. Maize lines with aflatoxin resistance or transgenic Bt-maize are found resistant to FAW. Botanicals such as neem extract lowered the percentage of leaf area damage, incidence of FAW larva infestation, and the number of larvae. It is difficult to curtail the menace of FAW through one control method, hence, the need for an integrated approach
        42.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The ZnO–Na2Ti6O13 composites were synthesized by facile solution combustion method with different molar concentrations of sodium titanate which is prepared by hydrothermal route. The formation of the composites was confirmed by the X-ray diffraction (XRD) analysis. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) results revealed that the synthesized composites exhibit porous morphology, whereas the pristine Na2Ti6O13 nanoparticles have whisker like morphology. Diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) studies were utilized to compute the bandgap and the presence of defects in the composites respectively. The photocatalytic activity of ZnO–Na2Ti6O13 catalyst was investigated through the degradation of 4-nitrophenol under solar light over a period of 180 min and the composite with 0.05 M of Na2Ti6O13 showed higher degradation efficiency (96%) than the other concentrations of Na2Ti6O13 and pristine ZnO. The reduced bandgap, high charge transfer, more oxygen vacancies and the production of high superoxide anion radicals have profound effect on the higher photocatalytic efficiency of the composite with 0.05 of M Na2Ti6O13.
        4,000원
        43.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The central theme of this work is the synthesis of single-walled carbon nanotubes (SWCNTs) through the chemical vapor deposition method (CVD). Single-walled carbon nanotubes are synthesized using catalyst-chemical vapor deposition of acetylene at 750 °C temperature. X-ray diffraction study gives a characteristic peak (002) at 26.55° corresponding to the existence of carbon nanotube confirms that the particles are crystalline in nature and hexagonal phase. An SEM and HRTEM outcome gives surface morphology of SWCNTs. The elemental composition was confirmed by EDAX. The ideal concentration of single-walled carbon nanotubes was used to design a novel electrochemical sensor for determining paracetamol (PA) using cyclic voltammetry. Electrochemical determination of paracetamol is described using a single-walled carbon nanotube modified carbon paste electrode (SWCNT/MCPE). The SWCNT/MCPE was used in this study to detect paracetamol electrochemically at pH 7.2 in a 0.2 M PBS with a scan rate of 50 mV s− 1. A single-walled nanotube modified carbon paste electrode was used to develop a sensitive and selective electrochemical technique for the detection of PA. The SWCNT/MCPE showed excellent electrocatalytic activity towards the oxidation of paracetamol in phosphate buffer solution. Therefore, with increased oxidation currents, the voltammetric responses of paracetamol at the bare carbon paste electrode are organized within cyclic voltammetric peaks.
        4,000원
        44.
        2022.08 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The utilization of carbonaceous reinforcement-based polymer matrix composites in structural applications has become a hot topic in composite research. Although conventional carbon fiber-reinforced polymer composites (CFRPs) have revolutionized the composite industry by offering unparalleled features, they are often plagued with a weak interface and lack of toughness. However, the promising aspects of carbon fiber-based fiber hybrid composites and hierarchical composites can compensate for these setbacks. This review provides a meticulous landscape and recent progress of polymer matrixbased different carbonaceous (carbon fiber, carbon nanotube, graphene, and nanodiamond) fillers reinforced composites’ mechanical properties. First, the mechanical performance of neat CFRP was exhaustively analyzed, attributing parameters were listed down, and CFRPs’ mechanical performance barriers were clearly outlined. Here, short carbon fiber-reinforced thermoplastic composite was distinguished as a prospective material. Second, the strategic advantages of fiber hybrid composites over conventional CFRP were elucidated. Third, the mechanical performance of hierarchical composites based on carbon nanotube (1D), graphene (2D) and nanodiamond (0D) was expounded and evaluated against neat CFRP. Fourth, the review comprehensively discussed different fabrication methods, categorized them according to performance and suggested potential future directions. From here, the review sorted out three-dimensional printing (3DP) as the most futuristic fabrication method and thoroughly delivered its pros and cons in the context of the aforementioned carbonaceous materials. To conclude, the structural applications, current challenges and future prospects pertinent to these carbonaceous fillers reinforced composite materials were elaborated.
        8,000원
        45.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The team has studied the relationship between the ability of the coals to be dissolved in crude anthracene oil and their composition. The coal samples taken from different deposits in Russia and Mongolia were characterized by different stages of metamorphism and tested by the Fourier transform infrared spectroscopy and Carbon-13 nuclear magnetic resonance. The data of a correlation analysis enabled us to find out that an amount of aromatic structures in coal macromolecules provided the main influence on the thermal dissolution of the coals. The middle-rank coals had the highest rates of coal organic matter transfer to liquid products. The data showed that the dissolution process was accompanied by destruction of weak bonds among aliphatic groups. The amount of methylene groups in the aliphatic part of coal macromolecules had a direct impact on conversion of the coal organic matter into soluble products.
        4,000원
        46.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Soybean is an important crop widely grown in the northern region of Nigeria for human and animal consumption. Commercial production of soybean in Nigeria has existed for eight decades. Current malnutrition and nutrient health problems in Nigeria warranted the introduction of high nutritive and affordable food sources such as soybean in the Nigerian diet. The high demand for soybean and its products has led to the rise in the cultivation of soybean in Nigeria. Although an increase in production has been recorded, the region of production has failed to achieve the potential yield per hectare. In improving soybean production in Nigeria, it is paramount to understand the factors that contribute to the process of production. This review paper provides information on factors affecting soybean production across the regions of production in Nigeria. The identified factors responsible for the yield gap include the impact of climate change on the agroecology shift, nutrient depletion and soil fertility, sowing date, the emergence of pests and diseases, and limited improved soybean cultivars. Adoption of improved soybean variety suitable in agroecology and sowing, at the appropriate sowing date by Nigerian farmers, can guarantee optimum soybean production. Further soybean breeding improvement studies are needed to provide more improved varieties with superior performance in Nigeria’s agroecology to achieve yield potential.
        4,000원
        47.
        2022.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The main objective of the research was to deposit thin films of silver on a graphite carbon paste in a phosphate buffer medium using an electrochemical method. To construct a nitrofurazone detection sensor that is highly sensitive. Different manufacturing parameters, such as electrodeposition potential, pH effect, potential scan rate effect, and number of scan cycles, were examined in this section. The parameters were optimized to improve the deposited silver layers various electrocatalytic characteristics. The Nitrofurazone reduction process is diffusion controlled, as seen by the linear variation of Epc with log(v). The constructed Ag-NPs@CPE electrod has excellent electrical characteristics a large active surface area and low background with extremely high electrical conductivity, according to structural and electrochemical characterizations such as Scanning electron microscopy, X-ray diffraction (XRD) and cyclic voltammetry. The constructed sensor has a very remarkable analytical performance for nitrofurazone molecule identification, with a very low detection limit of about 10– 8 M. The detection of nitrofurazone using our Ag-NPs@CPE sensors in real samples contaminated with the antibiotic nitrofurazone, such as tap water and urine. In the selected sample, the electroanalytical findings reveal a very satisfactory recovery rate of more than 94 percent.
        4,600원
        48.
        2022.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        NiMoS2 is a promising material for various functional applications and highly compatible with GO to make hybrid nanocomposites with excellent characteristics for supercapacitor electrode material. Deposition of NiMoS2 was achieved on the rGO(reduced Graphene Oxide) surface to form a NiMoS2− rGO nanocomposite by the method of the facile hydrothermal synthesis process. XRD pattern shows the crystalline nature of composites. Raman and EPMA result interpreting the composites formation and elements compositions, respectively. The sheet-like morphology of rGO was found in the composites by FESEM images. Particles distribution was confirmed by HR-TEM. The electrochemical properties of the pure NiMoS2 and NiMoS2– rGO composites have been studied by cyclic voltammetry analysis. The results revealed that the NiMoS2/ 5% rGO nanocomposites exhibit high specific capacitance compared to pure NiMoS2 due to the synergistic effects of NiMoS2 and rGO in the composite material. The photocatalytic behavior of the prepared nanocomposites for dye degradation was tested. The quantity of rGO has significantly improved the photocatalytic behavior of NiMoS2/ rGO composites. The studies on degradation mechanism, the N2 adsorption/desorption isotherms, pore size distribution behavior and % of removal of MB reveal the enhanced photocatalytic performance of sysnthesised composites.
        4,500원
        49.
        2022.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Rapid development of carbon nanotubes (CNTs) reinforced to polymer composites has been recently noticed in many aspects. In this work, the latest developments on fatigue and fracture enhancement of polymer composites with CNTs reinforcement with diverse methods are thoroughly compiled and systematically reviewed. The existing available researches clearly demonstrate that fatigue fracture resistance of polymer composites can be improved accordingly with the addition of CNTs. However, this work identifies an interesting research gap for the first time in this field. Based on the systematic reviewing approach, it is noticed that all previously performed experiments in this field were mostly focused upon studying one factor only at a time. In addition, it is also addressed that there were no previous studies reported a relationship or effect of one factor upon others during examining the fatigue fracture of carbon nanotubes. Moreover, there was no adequate discussion demonstrating the interaction of parameters or the influence of one parameter upon another when both were examined simultaneously. It is also realized that the scope of the conducted fatigue fracture studies of carbon nanotubes were mainly focused on microscale fatigue analysis but not the macroscale one, which can consider the effect of environment and service condition. In addition, the inadequacy of fatigue life predicting models via analytical and numerical methods for CNT-reinforced polymer composites have also been highlighted. Besides, barriers and challenges for future directions on the application of CNT-reinforced polymer composite materials are also discussed here in details.
        4,600원
        59.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Preparation of advanced functional materials from agricultural waste by eco-friendly processing route is inevitable for sustainable development. This work demonstrates the development of carbon/silica (C/SiO2) and carbon/silicon carbide (C/ SiC) composite foam monoliths of low thermal conductivity, high EMI shielding performance and reasonable compressive strength from rice husk. The C/SiO2 and C/SiC composite foams are obtained by carbonization and subsequent carbothermal reduction, respectively, of rice husk–sucrose composites consolidated by filter-pressing rice husk powder dispersed in sucrose solutions of various concentrations (300–600 g L− 1). The amorphous nature of silica in C/SiO2 and the presence of β-SiC in C/SiC are evidenced from XRD and TEM analysis. The compressive strength and thermal conductivity are depending on the foam density which is tailored by sucrose solution concentration. The compressive strength in the ranges of 0.32–1.67 and 0.19–1.19 MPa are observed for C/SiO2 and C/SiC foams, respectively, with density in the ranges of 0.26–0.37 and 0.18–0.29 g cm− 3. The C/SiO2 and C/SiC exhibited thermal conductivity in the ranges of 0.150–0.205 W m− 1 K− 1 and 0.165–0.431 W m− 1 K− 1, respectively. The C/SiO2 and C/SiC composite foams show absorption dominated EMI shielding effectiveness in the ranges of 18–38.5 dB and 20–43.7 dB, respectively. The inherent pore channels and corrugated surface structure in rice husk, electrically conducting carbon and dielectric SiO2 and SiC contribute to the total EMI shielding.
        4,500원
        60.
        2022.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Cerium oxide decorated on nickel hydroxide anchored on reduced graphene oxide (Ce-Ni(OH)2/rGO) composite with hexagonal structures were synthesized by facile hydrothermal method. Fourier transform infrared spectroscopy (FT-IR), highresolution transmission electron microscopy with selected area diffraction (HRTEM-SAED), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer– Emmett–Teller (BET) surface area analysis and electrochemical technology were used to characterize the composite. Due to its unique two-dimensional structures and synergistic effect among Ce2O3, Ni(OH)2 and rGO components indicated twodimensional hexagonal nano Ce-Ni(OH)2/rGO composite is promising electrode material for improved electrochemical H2O2 sensing application. From 50 to 800 μM, the H2O2 concentration was linearly proportional to the oxidation current, with a lower detection of limit of 10.5 μM (S/N = 3). The sensor has a higher sensitivity of 0.625 μA μM−1 cm− 2. In addition, the sensor demonstrated high selectivity, repeatability and stability. These findings proved the viability of the synthetic method and the potential of the composites as a H2O2 sensing option.
        4,600원
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