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        검색결과 59

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This work involves the development of a novel waste-derived carbon dots (CDs) conjugated with silver (Ag) nanohybrid system-based Fluorescence Resonance Energy Transfer (FRET) sensor for the detection of melamine. CDs and Ag nanoparticles served as energy donors and energy acceptors, respectively. CDs were synthesized from orange peel waste through a combined hydrothermal and ultra-sonication route. The synthesized CDs had hydroxyl, amino, and carboxyl groups on their surface, explaining that waste-derived CDs can act as reducing and stabilizing agents and showed strong absorption and fluorescence emission at 305 and 460 nm, respectively. The bandgap, linear refractive index, conduction band, and valance band potential of CDs were observed to be 2.86, 1.849, 1.14, and 4.002 eV, respectively. No significant difference was observed in the fluorescence properties at different pH (acid and alkaline) and ionic concentrations. Given their fluorescent nature, the synthesized CDs were used for the detection of melamine. The fluorescence of CDs was found to be quenched by Ag+ due to the FRET energy transfer between CDs to Ag. Notably, the zeta potential of Ag@CDs was changed from − 28.7 mV to − 30.6 mV after the incorporation of Ag+. Ag@CDs showed excellent selectivity and sensitivity toward the sensing of melamine in the aqueous solutions with the limit of detection ~ 0.85 μM. Increasing the melamine level also raises the FL intensity of Ag@CDs. The substrate was effectively used in the detection of melamine in milk as a real application and the recovery percentage was found to be 98.03%. Moreover, other adulterants such as urea and formaldehyde can be detected selectively by Ag@CDs. Overall, the synthesized Ag@CDs can be used as an efficient material for sensing applications involving such food adulterants.
        4,600원
        3.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Flexible supercapacitors (FS) are ideal as power backups for upcoming stretchable electronics due to their high power density and good mechanical compliance. However, lacking technology for FS mass manufacturing is still a significant obstacle. The present study describes a novel method for preparing FS based on reduced graphene oxide (RGO) using the N+ plasma technique, in which N+ reduces graphene oxide on the surface of a cotton/polyester substrate. The effect of aloe vera (AV) as a natural reducing & capping agent and carbon nanotubes (CNT) as nanoconductors on the electrochemical performance of the electrodes is studied. FESEM and XPS were employed to investigate the electrodes' structural and chemical composition of electrodes. The galvanostatic charge–discharge curves of electrodes revealed the enhancement of the electrochemical activity of the as-prepared electrode upon additions of AV and CNT. The areal capacitance of the RGO, RGO/AV, and RGO/ AV/CNT supercapacitors at 5 mV/s was 511, 1244.5, and 1879 mF/cm2, respectively. The RGO electrode showed capacitive retention of 80.9% after 2000 cycles enhanced to 89.7% and 92% for RGO/AV and RGO/AV/CNT electrodes, respectively. The equivalent series resistance of the RGO electrode was 126.28 Ω, decreased to 56.62 and 40.06 Ω for RGO/AV and RGO/ AV/CNT electrodes, respectively.
        4,000원
        4.
        2023.05 구독 인증기관·개인회원 무료
        Рrecipitation of platinum group metals (Rh, Ru, Pd, so-called MPG) from the melt essentially affects the reliability of installations for vitrification of high-level liquid radioactive waste (HLW). To date, it is difficult to find an approach which allows simultaneous recovery of all three metals. The aim of our work was to select a sorbent that would provide simultaneous up to complete recovery of given metals. The following inorganic materials were tested as sorbents – yellow blood salt (YBS).and hexacyanoferrates of iron, aluminum, copper and nickel. The degree of metal recovery was studied is influenced by the temperature and concentration of nitric acid. Only palladium was completely recovered using YBS. At the same time, specially prepared iron hexacyanoferrate (HCF-Fe) under optimal experimental conditions recovers almost all Pd and more than 95% and 90% of Rh and Ru, respectively. The behavior of fission products, including the main dose-forming components of HLW (Cs, Sr) and Mo, U, Ag, REE) in the course of MPG recovery was studied. The experiments were carried using both multicomponent model solutions and real raffinates. Options for further management of the recovered metals have been worked out. Thus, the proposed method of metal recovery seems promising for the development of a technology for the removal of MPG from nitric HLW during the reprocessing of the spent nuclear fuel (SNF) before vitrification. The recovered metals can be probably used in various technological processes. Also, this method can provide the MPG recovery from low-concentration tail solutions.
        5.
        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
        6.
        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
        7.
        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
        8.
        2020.12 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        Gravitational lensing of point sources located inside the lens caustic is known to produce four images in a con guration closely related to the source position. We study this relation in the particular case of a sample of quadruply-imaged quasars observed by the Hubble Space Telescope. Strong correlations between the parameters de ning the image con guration are revealed. The relation between the image con guration and the source position is studied. Some simple features of the selected data sample are exposed and commented upon. In particular, evidence is found for the selected sample to be biased in favor of large magni cation systems. While having no direct impact on practical analyses of speci c systems, our results have pedagogical value and deepen our understanding of the mechanism of gravitational lensing.
        4,200원
        10.
        2020.09 KCI 등재후보 구독 인증기관 무료, 개인회원 유료
        Melia azedarach is commonly used in traditional and folk medicine in Korea and China to treat a variety of diseases including diarrheal, diabetic, rheumatic, and hypertensive disease. The aim of this study was to determine the potential prophylactic and therapeutic effects of Melia azedarach against a broad spectrum of viruses in in vitro cell culture model and the protective effect against different influenza A subtypes in BALB/c mice model. An effective dose of pre-treatment, co-treatment, and post-treatment of Melia azedarach significantly reduced the replication of coxsackievirus, herpes simplex virus, influenza A virus, enterovirus, and bovine rhinovirus in both epithelial and macrophage cell lines. Melia azedarach treatment remarkably promoted the phosphorylation of the key molecules associated with the type-1 interferon and NF-κB signaling pathways. Furthermore, it induced the secretion of type-1 interferon and pro-inflammatory cytokines and the subsequent stimulation of the antiviral state in both epithelial and macrophage cells. Interestingly, oral inoculation of an effective dose of herb extract significantly improved viral clearance in the lungs of BALB/c mice, thus exhibiting protection against several subtypes of influenza A virus. Together with our results indicate that an extracts of Melia azedarach and its components could exhibit a potential natural source of an antiviral drug candidate for a broad spectrum of viruses in animal and humans.
        4,300원
        11.
        2020.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present study aimed to investigate the conceptus-related changes during early pregnancy in the Black Bengal breed of goat. A total of 22 gravid genitalia of the Black Bengal goats were collected from local slaughterhouses. The crown-rump lengths (CRL) of the conceptuses were determined to estimate the gestational age (GA). The length and diameter of uterine horn and amniotic sac were measured, and volume of amniotic and allantoic fluid formed by individual conceptus were recorded. The results reveal that the CRL is positively correlated with GA of the conceptus (R2 = 0.89, p < 0.05); however, CRL was not influenced by number of conceptus. Both the left and the right uterine horn gradually increased in size with the advancement of pregnancy irrespective of conceptus number present in the horn. The size of the amniotic sac of conceptus gradually increased with the conceptus age but maintained spherical shape from 5 to 7 weeks of pregnancy. The amniotic fluid formed by individual conceptus rapidly increased from 5 weeks (3.4 ± 0.3 mL) to 7 weeks (21.0 ± 2.0 mL) and 9 weeks (111.5 ± 4.0 mL). The volume of allantoic fluid formed by individual conceptus was steadily increased until 7 weeks (60.0 ± 5.0 mL) and began to decline slowly thereafter (50.0 ± 5.0 mL at 9 weeks). Notably, there was no effect of conceptus number per pregnancy on individual amniotic and allantoic fluid volume. The cotyledons have first appeared on the allanto-chorionic surface from 4 to 5 weeks of pregnancy. The closed eye, nostril and hooves of the conceptus became visible at 7 weeks of pregnancy. The present study has shown the basic information on conceptus-related developmental changes during early pregnancy up to 9 weeks in Black Bengal goat.
        4,000원
        12.
        2020.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Assisted reproductive technologies (ART) merely depend on improving the oocyte maturation and their developmental competence to produce good quality embryos. Oocyte maturation passes through long and complex molecular steps starts from the early embryonic life and ends with sperm fertilization. Oocyte developmental competence can be attained by improving the nuclear and cytoplasmic mechanisms together with some epigenetic maturation. In this review, we highlight the cornerstones of oocyte maturation on both nuclear and cytoplasmic levels. Interfering or supporting these molecular mechanisms would help in the development of novel regulating agents for reproductive performance of humans and livestock species.
        4,000원
        13.
        2019.12 구독 인증기관 무료, 개인회원 유료
        Fatigue is not a trivial issue and needs much attention. On the other hand, fatigue among seafarers could lead to accidents at sea due to their inability and ineffectiveness in carrying out their work. Some were caused by sleepiness and lack of vigour, which, could not only affect their safety but compromising on other seafarers as well. In this study, factors that cause fatigue among seafarers were examined analytically and their quantitative priorities were determined using Analytic Hierarchy Process (AHP) method. Additionally, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is used to identify the best alternatives in minimizing fatigue among seafarers. For this, data is collected through interview involving those working in academic and maritime industry with more than 5 years of experiences in dealing with seafarers. The AHP result shows that fitness is the main cause that could affect fatigue on seafarers’ reliability. Besides, TOPSIS result shows that a well-maintained shipboard is the best way in sustaining seafarers’ energy. In sum, fatigue among seafarers could influence on safety and may lead towards precarious health issue over a long-term.
        4,000원
        14.
        2019.12 구독 인증기관 무료, 개인회원 유료
        Halal transportations will ensure that the Halal status of the products will be preserved. Halal certification is believed to increase the operation cost for the transport providers, which reflect the price paid by customers who choose to buy products transported by Halal transportation. Hence, it is worthwhile to investigate the willingness of Muslim consumers to pay extra for the Halal transportation cost. The study aims to identify factors influencing Muslim consumers’ attitude towards their willingness to pay for Halal transportation. Using the stimulus-organism-response model, attitude which represents the organism factor will be treated as a mediator for variables representing the stimulus factors and the variable for the response. On the other hand, the study will also examine the effect of knowledge as a moderating factor. The data was collected from Muslim consumers in Kuala Lumpur. Applying the purposive sampling method with a self-administered survey, 202 respondents agreed to participate in the study. The findings revealed that awareness and perceived behavioural control are a stimulus towards attitude, and attitude is a significant organism on willingness to pay. The study also found that attitude mediates the relationship between awareness and perceived behavioural control towards the willingness to pay for Halal transportation. Additionally, the knowledge has a moderating effect of the relationship between attitude and the willingness to pay. The findings of the study are not only beneficial for the Muslim community in Malaysia, but also the Muslims around the world.
        4,200원
        15.
        2019.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Comparisons between bare carbon (CPs) and nitrogen-doped carbon nanoparticles (N-CPs) synthesised using hydrothermal reaction are carried out. It was found that hydrothermal reaction of citric acid yields graphene-like sheets, while the nitrogen doping using ethylenediamine resulted in amorphous polymeric ball-like hydrocarbons devoid of any aromatic rings. Although the Fourier transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy indicate the presence of carbon–carbon double bonds (C=C), and the ground states of both materials are very deep (> 7.8 eV) as measured by ultraviolet photoelectron spectroscopy. This indicates the conjugation is very short. This is supported by the fact that both materials are UV blue emitting peaking at 375 nm probably originating from C=C.
        4,000원
        16.
        2019.06 구독 인증기관 무료, 개인회원 유료
        The IMO Standard Marine Communication Phrases (SMCP) has been established purposely to enhance the greater safety of vessel’s navigation by standardizing the language used among seafarers. However, accidents are still occurred due to communication failures among onboard merchant vessels’ crews. It is worth mentioning that the major cause of marine accidents is human error (80%) where one-third from it was due to communication failures. Ineffective communication, different culture and language among seafarers onboard are some instigators of human error that lead to accidents in marine operations. Therefore, the primary aim of this paper is to investigate and evaluate the causal factors that contributes to communication failures onboard merchant vessels. Then, this paper recommends possible solutions for minimizing the communication failures among seafarers. To achieve this research objectives, two decision-making tools which are the Analytical Hierarchy Process (AHP) and Evidential Reasoning (ER) was applied. Data and judgments are obtained from domains experts from four marine training providers and eight shipowners in Malaysia. The result has shown that lack of SMCP knowledge, prejudice and dialect varieties are the most significant factors that contribute to the communication failures onboard merchant vessels. Few suggestions and opinions from the experts are proposed in this paper. This research can assist marine training providers and shipowners to identify and evaluate the causal factors of communication failures thus corrective action can be taken.
        4,200원
        17.
        2018.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The world is becoming overwhelmed with widespread diseases as antibiotic resistance increases at an alarming rate. Hence, there is a demanding need for the discovery and development of new antimicrobial drugs. The ocean is gifted with many organisms like phytoplankton, algae, sponges, cnidarians, bryozoans, mollusk, tunicates and echinoderms, which are known to produce a wide variety of bioactive secondary metabolites with pharmacological properties. Many new therapeutic drugs have emerged from marine invertebrates, although the large algal community is yet to be explored. The bioactivity possessing secondary metabolites of marine algae include polyphenols, phlorotannins, alkaloids, halogenated compounds, sulfated polysaccharides, agar, carrageenan, proteoglycans, alginate, laminaran, rhamnan sulfate, galactosylglycerol, and fucoidan. These metabolites have been found to have great antimicrobial activities against many human aliments. Studies show that the algal community represents about 9% of biomedical compounds obtained from the sea. This review looks at the evolution of drugs from the ocean, with a special emphasis on the antimicrobial activities of marine algae.
        4,000원
        18.
        2017.12 구독 인증기관 무료, 개인회원 유료
        The punctuality of containerships has become the prevalent issue in container liner shipping operations, as the on-time arrival of a containership at the next port of call is paramount. When a delay occurs at the previous port of call, it may also cause a delay at the next port of call. This paper proposes a departure punctuality model of analysis. This model employs a Fuzzy Rule-Based Bayesian Belief Network (FRBBN) for predicting the departure punctuality of a containership. To ensure the reliability of the model, two containerships were tested. The results show that the prediction values from the model are between 95.6% and 99% accurate provided that no tactical strategy is implemented during the voyage. In addition, the most significant factors that determine the punctuality of departure were found to be punctuality of arrival at the same (base) port prior to departure, dangerous events and other unexpected delays during the port stay. It is expected that this model is capable of helping researchers and practitioners to understand the influence of the dynamic environment and to make predictions on the departure punctuality of containerships.
        4,200원
        19.
        2017.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The recent updates of the North Ecliptic Pole deep (0.5 deg2, NEP-Deep) multi-wavelength survey covering from X-ray to radio-wave is presented. The NEP-Deep provides us with several thousands of 15 μm or 18 μm selected galaxies, which is the largest sample ever made at these wavelengths. A continuous filter coverage in the mid-infrared wavelength (7, 9, 11, 15, 18, and 24 μm) is unique and vital to diagnose the contributions from starbursts and AGNs in the galaxies out to z=2. The new goal of the project is to resolve the nature of the cosmic star formation history at the violent epoch (e.g. z=1{2), and to find a clue to understand its decline from z=1 to present universe by utilizing the unique power of the multiwavelength survey. The progress in this context is brie y mentioned.
        4,000원
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