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        검색결과 2,489

        1.
        2024.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In the present study, a novel pH-sensitive hydrogel composite of pectin-grafted-poly (acrylic acid-co-itaconic acid)/MWCNTs- COOH was prepared by using graft copolymerization of acrylic acid and itaconic acid on pectin backbone with incorporation of MWCNTS- COOH. The prepared hydrogel composite has been employed for the adsorption and controlled release of the diclofenac sodium (DS) drug. The hydrogel composite was characterized by the analysis methods: FTIR, XRD, SEM, and TGA to analyze structural characteristics before and after DS drug adsorption. The swelling ratio of the hydrogel composite was investigated at different pH values from pH 1.2 to 10. According to the results, the swelling ratio of the hydrogel composite was found 4195% at pH 7.4. Adsorption process parameters such as pH, contact time, adsorbent dose, and temperature were investigated and found to have a significant influence on DS drug adsorption. The maximum DS drug loading through adsorption of 91% was obtained at pH 3, adsorbent dose of 0.05 g, contact time of 150 min, and temperature of 15 °C. The adsorption isotherm and kinetic results were well-fitted to Freundlich and second-order models. Thermodynamic parameters including changes in Gibb’s free energy, enthalpy, and entropy suggested that the adsorption of DS drug onto hydrogel composite was a spontaneous and exothermic process. The in vitro drug release experiment showed that the cumulative release of DS drug from hydrogel composite after 35 h was significantly higher in simulated intestinal fluid at pH 7.4 than in simulated gastric fluid at pH 1.2.
        5,100원
        2.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Geopolitical risk is now among the most important factors in the formulation of multinational corporate strategy and the US trade policy. The US has aggressively enacted national-security-based trade sanctions, which recently include export controls on semiconductor chips and restrictions on outbound and inbound investment. The US has also adopted major legislation providing historical subsidies and tax breaks. Congress and the courts have upheld the president’s use of national security as a basis of trade actions and generally supported his protectionist policies. Trade should not be restricted or weaponized. Global and national rules need to be strengthened and, perhaps, a bit updated, but protectionism in the name of national security is a losing argument. The growing movement by the US to rely more on national security and protectionism in formulating trade policy is a very worrisome development. No one in Washington is proposing a return to pre-Trump policies. The real question is how far US trade policy will continue to change in the near future. Geopolitics will give us the answer.
        4,000원
        3.
        2024.05 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The most significant threat to the ecosystem is emerging pollutants, which are becoming worse each year and harming the planet severely and permanently. Many organic and inorganic contaminants are present and persistent due to various world events and population growth. As a result, there is a greater need for new technology and its application to address the problems caused by developing pollutants. Carbon composite nanomaterials have significant potential in the fight against numerous environmental contaminants due to their distinctive attributes. This review discusses the reports of customized carbon composite nanomaterials to meet the need for specific elimination of emerging contaminants. Physical and chemical features such as high surface area, conductivity (thermal and electrical), and vibroelectronic properties, size, shape, porosity, and composite nature are making these tailored materials of carbon-based nanomaterials an emerging and sustainable tool to remove persistent compounds like emerging contaminants in aqueous solution. Different composite materials are well discussed in this review, along with their adsorption efficiency of diverse emerging contaminants, including Bisphenol A, estradiol, metformin, etc. This review provides insight into the recent trends limited to 2017–2023. The limitations of carbon-based nanomaterials, such as regeneration and cost-effectiveness, have also been overcome in recent years by diverse modifications in the production process, which can be further improved to make these materials well suited for an extended group of emerging contaminants.
        6,100원
        4.
        2024.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The detailed understanding of fluorescence emission processes is still unclear. This study demonstrates Aegle marmelos derived luminescent heteroatoms (N, Ca, K) doped carbon quantum dots (CQDs) using an economically and ecologically sustainable synthesis process without the necessity for any doping precursors due to its phytochemical, vitamin and mineral content. Carboxyl functionalization was done by adding lemon juice to the fruit extract. The morphological, physiochemical, compositional, crystallinity, and surface functional groups having heteroatom doped CQDs were analysed by HRTEM, EDX, XPS, XRD, FTIR etc. Besides, CQDs exhibited pH and solvent-dependent tuneable fluorescence characteristics. In fact, beyond pH 7.77, a protonation-deprotonation-driven red-shift was observed together with a decrease in the contribution of prominent peaks. Meanwhile, the features of solvatochromic fluorescence were examined in a range of aprotic and protic solvents with low and high polarity. Based on the studied Kamlet–Taft parameters and the obtained spectroscopic characterizations, a suitable fluorescence emission mechanism is provided. The observed solvatochromic fluorescence is thought to be caused by a combination of dipole moment polarisation, intramolecular charge transfer processes with or without H-bond stabilisation via the interaction of heteroatoms doped CQDs with solvent mediated by electron donation and acceptance from various surface functional groups such as hydroxyl, carboxyl with solvent molecules. Hence, this study is believed to promote the development of eco-tuneable fluorescent heteroatom doped CQDs and provide further insights into the fundamental fluorescence mechanisms, which include the relationship between morphology, surface properties and plausible quantum effects between CQDs and solvents.
        4,000원
        5.
        2024.04 구독 인증기관·개인회원 무료
        Six new species are described that are members of the New Zealand endemic genus Adalmus Reitter (Staphylinidae: Pselaphinae: Euplectitae: Trichonychini: Panaphantina): A. bullerensis sp. nov., A. kanierensis sp. nov., A. karekarensis sp. nov., A. mangamukaensis sp. nov., A. puberilumbus sp. nov., and A. serrilumbus sp. nov. In addition, Dalmisus Sharp is placed as a junior synonym of Adalmus (gen. syn.) and the species Dalmisus batrisodes Sharp, 1886, Plectomorphus longiceps Broun, 1913 and P. longipes Broun, 1912 are placed as junior synonyms of A. velutinus Reitter, 1885 spp. syn. Also, P. rugiceps Broun, 1921 is transferred to the genus Adalmus, comb. nov. Adalmus now holds eight species.
        6.
        2024.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The untreated effluent dropping into the environment from various textile industries is a major issue. To solve this problem, development of an efficient catalyst for the degradation of macro dye molecules has attracted extensive attention. This work is mainly focused on the synthesis of nickel–manganese sulfide decorated with rGO nanocomposite (Ni–Mn-S/rGO) as an effective visible photocatalyst for degradation of textile toxic macro molecule dye. A simple hydrothermal method was used to synthesize Ni–Mn-S wrapped with rGO. The prepared composites were characterized using various techniques such as X-ray diffraction (XRD), high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectrometer (FTIR), and ultra violet–visible (UV–Vis) spectroscopy. The photocatalytic performance of nickel sulfide (NiS), manganese sulfide (MnS), nickel–manganese sulfide (Ni–Mn-S), and Ni–Mn-S/rGO nanocomposite was assessed by analyzing the removal of acid yellow (AY) and rose bengal (RB) dyes under natural sun light. Among these, the Ni–Mn-S/rGO nanocomposite showed the high photocatalytic degradation efficiency of AY and RB dyes (20 ppm concentration) with efficiency at 96.1 and 93.2%, respectively, within 150-min natural sunlight irradiation. The stability of photocatalyst was confirmed by cycle test; it showed stable degradation efficiency even after five cycles. This work confirms that it is an efficient approach for the dye degradation of textile dyes using sulfide-based Ni–Mn-S/rGO nanocomposite.
        4,600원
        7.
        2024.02 KCI 등재 구독 인증기관 무료, 개인회원 유료
        이 연구에서는 Inception V3, SqueezeNet(local), VGG-16, Painters 및 DeepLoc의 다섯 가지 인공지능(AI) 모 델을 사용하여 차나무 잎의 병해를 분류하였다. 여덟 가지 이미지 카테고리를 사용하였는데, healthy, algal leaf spot, anthracnose, bird’s eye spot, brown blight, gray blight, red leaf spot, and white spot였다. 이 연구에서 사용한 소프트웨 어는 데이터 시각적 프로그래밍을 위한 파이썬 라이브러리로 작동하는 Orange3였다. 이는 데이터를 시각적으로 조작하여 분석하기 위한 워크플로를 생성하는 인터페이스를 통해 작동되었다. 각 AI 모델의 정확도로 최적의 AI 모 델을 선택하였다. 모든 모델은 Adam 최적화, ReLU 활성화 함수, 은닉 레이어에 100개의 뉴런, 신경망의 최대 반복 횟수가 200회, 그리고 0.0001 정규화를 사용하여 훈련되었다. Orange3 기능을 확장하기 위해 새로운 이미지 분석 Add-on을 설치하였다. 훈련 모델에서는 이미지 가져오기(import image), 이미지 임베딩(image embedding), 신경망 (neural network), 테스트 및 점수(test and score), 혼동 행렬(confusion matrix) 위젯이 사용되었으며, 예측에는 이미 지 가져오기(import image), 이미지 임베딩(image embedding), 예측(prediction) 및 이미지 뷰어(image viewer) 위젯 이 사용되었다. 다섯 AI 모델[Inception V3, SqueezeNet(로컬), VGG-16, Painters 및 DeepLoc]의 신경망 정밀도는 각 각 0.807, 0.901, 0.780, 0.800 및 0.771이었다. 결론적으로 SqueezeNet(local) 모델이 차나무 잎 이미지를 사용하여 차 병해 탐색을 위한 최적 AI 모델로 선택되었으며, 정확도와 혼동 행렬을 통해 뛰어난 성능을 보였다.
        4,200원
        8.
        2024.01 KCI 등재 SCOPUS 구독 인증기관 무료, 개인회원 유료
        A force-free field (FFF) is determined solely by the normal components of magnetic field and current density on the entire boundary of the domain. Methods employing three components of magnetic field suffer from overspecification of boundary conditions and/or a nonzero divergence-B problem. A vector potential formulation eliminates the latter issue, but introduces difficulties in imposing the normal component of current density at the boundary. This paper proposes four different boundary treatment methods within the vector potential formulation. We conduct a comparative analysis of the vector potential FFF solvers that we have developed incorporating these methods against other FFF codes in different magnetic field representations. Although the vector potential solvers with the new boundary treatments do not outperform our poloidal-toroidal formulation code, they demonstrate comparable or superior performance compared to the optimization code in SolarSoftWare. The methods developed here are expected to be readily applied not only to force-free field computations but also to time-dependent data-driven simulations.
        4,300원
        9.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Achieving cost-effective and defect-free graphene sheets is highly desirable for sensor devices. Aiming this, few-layer graphene (~ 3) sheets are prepared by an electrochemical exfoliation with [NMP] [ HSO4] electrolyte (i.e., Bronsted acidic ionic liquid). A novel approach for the effective exfoliation of graphene sheets is demonstrated by (i) simultaneously applying a constant potential through an electrochemical cell (with different electrolyte concentrations) and (ii) together with sonication. The exfoliated graphene sheets are characterized through state-of-the-art techniques and sprayed on a glass substrate at optimum conditions. Thus, the transparent conducting sensor device is fabricated with a suitable contact electrode and used for ammonia vapor sensing and the sensor performances are highly dependent on the concentration of the ionic liquid used during the electrochemical exfoliation. The sensing response and limit of detection for the exfoliated graphene-based film were calculated as 3.56% and 432 ppb, respectively. Further studies indicated that the fabricated sensors are more selective towards ammonia molecules with quick response and recovery times.
        4,200원
        10.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Photoanode optimization is a fascinating technique for enlightening the power conversion efficiency (PCE) of dye-sensitized solar cells (DSSCs). In this present study, V2O5/ ZnO and reduced graphene oxide (rGO)-V2O5/ZnO nanocomposites (NCs) were prepared by the solid-state technique and used as photoanodes for DSSCs. A wet chemical technique was implemented to generate individual V2O5 and ZnO nanoparticles (NPs). The structural characteristics of the as-synthesized NCs were investigated and confirmed using powder X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), and Scanning electron microscope (SEM) with energy dispersive X-ray (EDX) analysis. The average crystallite size (D) of the as-synthesized V2O5/ ZnO and rGO-V2O5/ZnO NCs was determined by Debye-Scherer’s formula. The bandgap (eV) energy was calculated from Tauc’s plots, and the bonding nature and detection of the excitation of electrons were investigated using the Ultra violet (UV) visible spectra, Fourier Transform infrared (FTIR) and photoluminescence (PL) spectral analysis. Electrical studies like Hall effect analysis and the Nyquist plots are also described. The V2O5/ ZnO and rGO-V2O5/ZnO NCs based DSSCs exhibited 0.64% and 1.27% of PCE and the short circuit current densities and open circuit voltages improved from 7.10 to 11.28 mA/cm2 and from 0.57 to 0.68 V, respectively.
        4,300원
        11.
        2024.01 KCI 등재 구독 인증기관 무료, 개인회원 유료
        We present a practical vacuum pressure sensor based on the Schottky junction using graphene anchored on a vertically aligned zinc oxide nanorod (ZnO-NR). The constructed heterosystem of the Schottky junction showed characteristic rectifying behavior with a Schottky barrier height of 0.64 eV. The current–voltage (I–V) features of the Schottky junction were measured under various pressures between 1.0 × 103 and 1.0 × 10− 3 mbar. The maximum current of 38.17 mA for the Schottky junction was measured at – 4 V under 1.0 × 10− 3 mbar. The high current responses are larger than those of the previously reported vacuum pressure sensors based on ZnO nanobelt film, ZnO nanowires, and vertically aligned ZnO nanorod devices. The pressure-sensitive current increases with the vacuum pressure and reaches maximum sensitivity (78.76%) at 1.0 × 10− 3 mbar. The sensitivity and repeatability of the Schottky junction were studied by the current–time (I–T) behavior under variation of vacuum pressure. The sensing mechanism is debated from the surface charge transfer doping effect by oxygen chemisorption. The results suggest that this simple graphene/ZnO-NR Schottky junction device may have potential in the fabrication of vacuum pressure sensor with high sensitivity.
        4,200원
        12.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The present research focuses on the tribological behavior of the AA5083 alloy-based hybrid surface composite using aluminosilicate and multi-walled-carbon nanotube through friction stir processing for automotive applications. The friction stir processing parameters (tool rotation and traverse speed) are varied based on full factorial design to understand their influence on the tribological characteristics of the developed hybrid composite. The surface morphology and composition of the worn hybrid composite are examined using a field-emission scanning electron microscope and an energy-dispersive x-ray spectroscope. No synergistic interaction is observed between the wear rate and friction coefficient of the hybrid composite plate. Also, adhesive wear is the major wear mechanism in both base material and hybrid composite. The influence of friction stir process parameters on wear rate and the friction coefficient is analyzed using the hybrid polynomial and multi-quadratic radial basis function. The models are utilized to optimize the friction stir processing parameters for reducing the rate of wear and friction coefficient using multi-quadratic RBF algorithm optimization.
        4,800원
        13.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this research, in order to increase the oxidation resistance of graphite, kaolin and alumina powder with different ratios (26A-74S, 49A-51S, 72A-28S) and slurry method were used to create an aluminosilicate coating on the graphite substrate. In order to reduce the difference in the coefficients of thermal expansion of graphite with aluminosilicate coating, aluminum metaphosphate coating as an interlayer was prepared on the surface of graphite by cathodic electrochemical treatment. The isothermal oxidation test of the samples was carried out in air at a temperature of 1250 °C for 1, 3 and 5 h. The microstructure, chemical composition, and phase components of the coating were, respectively, analyzed by scanning electron microscope equipped with an energy-dispersive spectrometer and X-ray diffraction. The results indicated that, by increasing the withdrawal speed of the samples in slurry method, the amount of changes in the weight of the samples has increased and therefore had a direct effect on oxidation. In addition, it was approved that, at high-temperature oxidation, AlPO4 glass phase forms on aluminum metaphosphate interlayer which retards graphite oxidation. Along with aluminum metaphosphate, aluminosilicate coating also produces a glass phase which fills and seals the voids on the surface which prevents the oxygen to reach the surface of graphite. The created double-layer coating including an interlayer of aluminum metaphosphate + slurry coating prepared with the ratio of 26A-74S as the optimal coating in this research was able to increase the oxidation resistance of graphite by 73% at a temperature of 1250 °C.
        4,600원
        14.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study was conducted to determine the acceptability of locally accepted japonica rice varieties among 53 farmers in Bohol and 38 farmers in Nueva Ecija, who were further classified into adopters and non-adopters of the GUVA japonica rice variety. Snowball sampling was made on farmer adopters/cooperators of a high-quality seed multiplication and dissemination project in the said provinces. The farmer respondents were mostly male whose ages ranged from 30 to 80 years and with farm sizes from 0.5 to 16 hectares. The farmers’ rice variety and usage were assessed by comparing the GUVA japonica rice variety with their commonly planted indica rice variety based on its agronomic characteristics, yield and income potential, and seed purity concerns. The barriers/hesitations to adoption of the GUVA japonica rice variety, namely seed availability, varietal information, and market potential, must be complemented with the suggested improvements on the variety together with factors that convince the farmers for committed use of this variety. Researchers together with partner agencies must put a lot of thought on how to integrate and synchronize these concerns so that the farmers can adopt GUVA japonica rice. Interest check on the usage of GUVA japonica rice variety in rice production as well as suggested improvements were solicited as the basis for continuous R&D pursuits that would eventually promote and adopt the GUVA japonica rice variety from these provinces.
        4,200원
        15.
        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.
        16.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The mechanism of resonant light scattering in single-layer graphene is discussed. A new concept of electron–hole selfphotorecombination is proposed, which makes it possible to clearly separate the phenomena of resonant light scattering and resonant photoluminescence. It is established that Rayleigh resonant radiation has been found to consist of virtual and non-virtual components. It has been shown that Rayleigh radiation is mainly caused by resonant non-virtual optical transitions. The band of Rayleigh radiation due to resonant virtual transitions is quite wide, and the intensity is extremely low. On the basis of the presented theory, the results of numerical estimates of the linewidth and intensity of the Rayleigh band of single-layer graphene are in fairly good agreement with the experimental data.
        4,000원
        18.
        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.
        19.
        2023.10 구독 인증기관·개인회원 무료
        The subfamily Pselaphinae is one of the largest groups in the family Staphylinidae. Pselaphine beetles consists of 6 supertribes. The supertribe Faronitae consists of 30 genera worldwide, with 14 genera in Australia and New Zealand. While examining faronite specimens, we separated 366 specimens that did not belong to any known faronite genera. Species of this genus can be separated from other faronite genera by the foveal system, features of the aedeagus, and collection localities which are only collected in the southern part of Australia. Through this study, we describe seven new species and three new combinations that previously belonged to the genus Sagola.
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