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        검색결과 1,887

        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
        2.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Modification of the surface of raw activated carbon using chemical solvents can significantly improve the adsorption performance of activated carbon. Triethylenetetramine is one of the most important chemical solvents used to modify raw activated carbon for formaldehyde removal indoor. We conducted the liquid impregnation experiments at different initial concentrations, temperatures, adsorbent dosage and time ranges to fully investigate the adsorption of triethylenetetramine on the surface of raw activated carbon for modification. We found that the Langmuir isotherm model and pseudo-first-order kinetic model fit quite well with the experimental data and the R2 are 0.9883 and 0.9954, respectively. The theoretical maximum adsorption capacity is 166.67 mg/g. The change in Gibbs free energy (ΔG0), enthalpy change (ΔH0) and entropy change (ΔS0) were also calculated to study the direction and driving force of the liquid adsorption process. In order to understand the adsorption process at the molecular level, a new activated carbon model based on the actual physical and chemical properties of activated carbon was carefully established in the Materials Studio to simulate the liquid-phase adsorption. The pore structure, elemental composition, functional group content, density, pore volume, and porosity of the activated carbon model converge close to the actual activated carbon and the adsorption isotherms obtained from the simulation agree well with the experimental results. The results show that the adsorption of triethylenetetramine on activated carbon is a spontaneous, endothermic and monolayer physical adsorption process.
        4,800원
        3.
        2023.11 구독 인증기관·개인회원 무료
        In all geodisposal scenarios it is key to understand the interaction of radionuclides with mineral particles during their formation/recrystallisation. Studying processes at the molecular scale provides insight into long-term radionuclide behaviour. Uranium is a significant radionuclide in higher activity wastes destined for geological disposal, and iron (oxyhydr) oxides (e.g. goethite, 􀟙-FeOOH). are ubiquitous in and around these systems, formed via processes including metal corrosion and microbially induced reactions. There are numerous reports of uranium-incorporation into iron (oxyhydr) oxides, therefore it has been suggested that they may be a barrier to uranium migration in geodisposal systems. However, long-term stability of these phases during environmental perturbations are unexplored. Specifically, U-incorporated iron (oxyhydr) oxide phases may interact with Fe(II) and sulphide from biological or geological origin. Firstly, electron transfer occurs between adsorbed Fe(II) and iron oxyhydroxides, with potential for changes in the speciation of incorporated uranium e.g. oxidation state changes and/or release. Secondly, on exposure to aqueous sulfide, iron (oxyhydr) oxides undergo reductive dissolution and recrystallisation to iron sulphides. Understanding the fate of incorporated uranium during these process in key to understanding its long term behaviour in subsurface systems. A series of experimental studies were undertaken where U(VI)-goethite was synthesized then reacted with either aqueous Fe(II) or S(-II), and the system monitored over time using geochemical analysis and X-ray absorption spectroscopy (XAS) techniques e.g. U LIII-edge and MIV-edge HERFD-XANES. Reaction with aqueous Fe(II) resulted in electron transfer between Fe(II) and U(VI)-goethite, with > 50% U(VI) reduced to U(V). XAS analysis revealed that U remained within the goethite structure, and electron transfer only occurred within the outermost atomic layers of goethite. which led to U reduction. Rapid reductive dissolution of U(VI)-goethite occurred on reaction with sulfide at pH7. A transient release of aqueous U was observed during the first day, likely due to uranyl(VI)-persulfide species. However, U was retained in the solid phase in the longer term. In contrast, the sulfidation of U adsorbed to ferrihydrite at pH 12.2 led to the immediate release of U (< 10% Utotal) associated with a colloidal erdite (NaFeS2·2H2O) phase. Moreover, in the bulk phase the surface of ferrihydrite was passivated by sulfide, and U was found to have been trapped within surface associated erdite-like fibres. Overall, these studies further understanding of the long-term behaviour of U-incorporated iron (oxyhydr)oxides supporting the overarching concept of iron (oxyhydr) oxides acting as a barrier to U migration.
        4.
        2023.10 구독 인증기관·개인회원 무료
        매년 국내로 비래해 오는 해충인 벼멸구는 그 기원이 중국 또는 중국 남부일 것으로 예상해왔으나, 이에 대한 유전학적 근거는 Mun et al. (1999)에 의해 제시된 세 가지 COI haplotype 비교가 유일하다. Mun et al. (1999)은 국내에 서 확인된 두 가지 haplotype 유형이 인도차이나반도 이남의 균일한 한 가지 haplotype 집단 유형과 중국에서 확인 된 또 다른 haplotype 집단 유형임을 근거로 국내 벼멸구의 기원을 중국으로 특정한 바 있다. 본 연구는 국내 및 동남아시아 5개국(부탄, 미얀마, 캄보디아, 라오스 및 태국)으로부터 직간접적으로 확보한 개체들을 대상으로 GBS (genotyping by sequencing) 및 NGS 기법을 통해 PCA를 포함한 다양한 집단유전학적 분석을 수행하였다. 그 결과 인도차이나반도의 벼멸구 집단은 크게 북부와 남부로 나뉘며, 국내 개체들은 북부에 비해 남부(캄보디 아, 태국)에 더 가깝다는 사실을 확인하였다. 따라서 벼멸구의 국내 비래는 중국으로부터의 기원 이전에 장마전 선이 형성될 무렵부터 인도차이나반도 남쪽의 고온다습한 서풍이 남남서풍으로 바뀌면서 중국 내륙을 거쳐 국내로 비래하는 경로를 따르는 것으로 보인다. 하지만 태안의 개체 중에는 인도차이나반도 집단들의 외군으로 확인되는 개체가 있었고, 이는 인도차이나반도 외의 샘플링되지 않은 다른 지역에서도 벼멸구가 국내로 비래할 수 있다는 가능성을 제시하였다. 따라서 국내로 유입되는 벼멸구의 유전적 기원을 확인하기 위해서는 인도차이 나반도 남쪽 지역에서 시작한 동아시아 여름 몬순의 바람이 한국으로 도착하는 경로에 위치한 다른 지역에서의 추가적인 샘플링 및 지속적인 관심과 추적이 필요할 것이다.
        5.
        2023.10 구독 인증기관·개인회원 무료
        Insect eggshell and cuticle/exoskeleton play vital roles in protecting them from natural environmental stresses. However, these chitinous cuticular extracellular matrices must be degraded at least in part during embryo hatching and molting/ecdysis periods to accommodate continuous growth all the way to the adult stage. In this study, we investigated the functional importance of groups I and II chitinases, TcCHT5 and TcCHT10, in the turnover of chitinous cuticle during both embryonic and post-embryonic development in Tribolium castaneum. RNAi and TEM analyses revealed that TcCHT10 is required for digestion of chitin in the serosal cuticle for embryo hatching as well as in the old cuticle during post-embryonic molts including larval-pupal and pupal-adult metamorphosis. TcCHT10 appears to be able to substitute for TcCHT5 in all these vital physiological events except for the pupal-adult molting in which TcCHT5 is indispensable for complete digestion of chitin in the old pupal cuticle.
        15.
        2023.07 구독 인증기관·개인회원 무료
        This research aims to understand how academic articles stimulate knowledge progress by addressing two questions: Does the level of contribution vary between different methods of research (e.g., conceptual, theoretical, and empirical)? How do we assess the potential of scholarly articles to impact and further innovate the field?
        16.
        2023.07 구독 인증기관·개인회원 무료
        In recent years E-commerce platforms recommend some products for consumers based on their shopping history and user persona. However, sometimes, unfamiliar products or styles would be recommended to consumers unintentionally or intentionally. Curiosity drives consumers to try but this idea would be declined with the consideration of product fit uncertainty. Augmented Reality (AR) is the integration of digital information with the user‘s environment in real-time (Hilken et al. 2018), it can deal with issues related to physical apprehension that hinder consumers’ online shopping (i.e, clothes, cosmetics), especially for the unfamiliar style. This study aims to investigate whether AR technology could improve consumers' purchase likelihood. Augmented Reality (AR) can enhance customer experiences in a multichannel environment (Hilken et al. 2017). AR Integrates online experiences into the offline experience (Hilken et al. 2018), such as virtual try-on or magic mirrors. Customers often find it difficult to imagine how firms’ products and services fit them personally or fit with their environment (Hilken et al. 2018). Drawn on AR, consumers can easily evaluate the fitness between themselves and the selected products. Prior studies have explored the different underlying processes of why AR technology could improve consumer purchase intention and customer experience. For instance, according to the situated cognition theory, AR creates a feeling of spatial presence (Hilken et al. 2017). The usage of AR benefits mental imagery, improving decision comfort (Heller et al. 2019). AR can compensate for consumers’ need for touch and offer hedonic and/or utilitarian benefits (Gatter et al. 2022). Based on media richness theory, AR offers more information for customers (Hoffmann et al. 2022), which represents a fitting concept for customers to evaluate the product (Javornik 2016).
        17.
        2023.07 구독 인증기관·개인회원 무료
        While companies and brands have always collected and used customer data for multiple purposes, the advent of smart devices, Internet of Things (IoT), and big data has made it much easier to access and utilize consumers’ personal information. For consumers, however, such ease of access to their personal data and frequent cases of data breach have increased their concerns about data privacy (Harris & Associates, 1996; Milne et al., 2004). Nevertheless, consumers continue to share their personal information with companies and brands in the digital environment (Turow et al., 2015).
        18.
        2023.07 구독 인증기관·개인회원 무료
        A bibliometric analysis, spanning five decades of knowledge is employed with the aim of: (i) assessing core intellectual knowledge of international services research; (ii) examining the contribution of international services marketing to broader research disciplines; and, (iii) estimating forecasting trends for the most promising international services research directions.
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