본 연구는 환경측정용 센서 위치에 따른 온실 환경의 공간· 수직적 특성을 조사하고 온실 종류에 따른 온도, 광도 및 CO2 농도 간의 상관관계를 구명하고자 수행하였다. 벤로형 온실의 공간적인 5지점을 선정한 후 각 지점에서 대표적 작물의 수 직적 높이 4지점과 지면부, 지붕 공간에 온도, 상대습도, CO2, 엽온 및 광센서를 설치하였다. 벤로형 온실과 반밀폐형 온실 에서 온도, 광도 및 CO2 농도 변화의 관계성을 Curve Expert Professional 프로그램을 이용하여 비교하였다. 벤로형 온실 의 공간적 위치에 따른 편차는 CO2 농도가 다른 요인보다 큰 것으로 나타났다. CO2 농도는 평균 465－761μmol·mol-1 범 위였고, 편차가 가장 큰 시간대는 오후 5시였으며, 최고 농도 는 액화 탄산가스 공급장치의 메인 배관(50∅)과 가까운 위치 인 중앙 후부(Middle End, 4ME)에서 646μmol·mol-1, 최저 농도는 좌측 중앙(Left Middle, 5LM)에서 436μmol·mol-1이 었다. 수직적 위치에 따른 편차는 온도와 상대습도가 다른 요 인보다 큰 것으로 나타났다. 평균 기온의 편차가 가장 큰 시간 대는 오후 2시대이며, 최고 기온은 작물 위 공기층(Upper Air, UA)에서 26.51℃, 최저 기온은 작물의 하단부(Lower Canopy, LC)에서 25.62℃였다. 평균 상대습도의 편차가 가장 큰 시간 대는 오후 1시대로 나타났으며, 최고 습도는 LC에서 76.90%, 최저 습도는 UA에서 71.74%이다. 각 시간대에 평균 CO2 농 도가 가장 높은 수직적 위치는 지붕 공간 공기층(Roof Air, RF)과 시설 내 지면(Ground, GD)이었다. 온실 내 온도, 광도 및 CO2 농도의 관계성은 반밀폐형 온실의 경우 결정계수(r2) 가 0.07, 벤로형 온실은 0.66이었다. 결과를 종합하여 볼 때, 온실 내 CO2 농도는 공간적 분포, 온도와 습도는 작물의 수직 적 분포 차이를 측정하여 분석할 필요가 있고 환기율이 낮은 반밀폐형 온실의 경우 목표 CO2 시비 농도가 일반 온실과 다 르게 설정해야 할 것으로 판단된다.

We investigated physicochemical properties and isotopic compositions of organic matter (δ13CTOC and δ15NTN) in the old fish farming (OFF) site after the cessation of aquaculture farming. Based on this approach, our objective is to determine the organic matter origin and their relative contributions preserved at sediments of fish farming. Temporal and spatial distribution of particulate and sinking organic matter (OFF sites: 2.0 to 3.3 mg L-1 for particulate matter concentration, 18.8 to 246.6 g m-2 day-1 for sinking organic matter rate, control sites: 2.0 to 3.5 mg L-1 for particulate matter concentration, 25.5 to 129.4 g m-2 day-1 for sinking organic matter rate) between both sites showed significant difference along seasonal precipitations. In contrast to variations of δ13CTOC and δ15NTN values at water columns, these isotopic compositions (OFF sites: -21.5‰ to - 20.4‰ for δ13CTOC, 6.0‰ to 7.6‰ for δ15NTN, control sites: - 21.6‰ to - 21.0‰ for δ13CTOC, 6.6‰ to 8.0‰ for δ15NTN) investigated at sediments have distinctive isotopic patterns (p<0.05) for seawater-derived nitrogen sources, indicating the increased input of aquaculture-derived sources (e.g., fish fecal). With respect to past fish farming activities, representative sources (e.g., fish fecal and algae) between both sites showed significant difference (p<0.05), confirming predominant contribution (55.9±4.6%) of fish fecal within OFF sites. Thus, our results may determine specific controlling factor for sustainable use of fish farming sites by estimating the discriminative contributions of organic matter between both sites.

한반도의 탄소중립 문제는 시일을 미룰 수 있는 문제도 아니며, 북한 과의 협력 없이 우리 단독으로 성과를 거둘 수 있는 문제도 아니다. 북 한의 기후변화대응 능력 강화를 지원하고 한반도 탄소중립을 위한 대응 체계를 마련하는 것은 남북 모두에게 직접적 이익이 있을 뿐 아니라 다 른 분야로의 교류와 협력이 연계, 확산할 수 있는 계기를 마련하여 중장 기적으로는 통일비용을 감소하고 한반도의 평화에도 기여하게 될 것이 다. 새 정부 출범에도 남북관계 해결의 실마리를 찾지 못하는 상황에서 대화의 계기를 마련하고, 지속적이고 안정적인 교류협력체계를 구축하기 위해서는 환경협력이 사실상 유일한 이슈일 수 있다. 기후변화에 대한 대응문제는 북한 역시 정책적 노력을 지속해 왔으며 여러 국제기후협약 에도 적극적으로 참여해 왔다는 점에서 더욱 긍정적이다. 2021년 시행된 파리협정이라는 국제환경협력 패러다임의 변화에 적절하게 대응하기 위 해서라도 지금부터라도 한반도 탄소중립을 위한 남북공동대응체계 구축 이라는 장기적인 목표를 세우고, 지속적인 교류를 통해 ‘남북 그린데탕트 구현’을 제도화하려는 노력이 절실할 것이다.

The electrochemical capacitive properties of biomass-derived activated carbons are closely dependent on their microscopic structures. Here, activated carbon fibers (ACFs) were prepared from natural cattail fibers by carbonization and further chemical activation. The activation temperature affected on the microscopic structures and electrochemical properties of the activated carbon fibers. The results show that the optimum activation temperature is 800 °C. And the as-prepared ACF- 800 possesses high micropore specific surface area of 710.4 m2 g− 1 and micropore volume of 0.313 cm3 g− 1, respectively. For supercapacitor applications, the ACF-800 displays a high specific capacitance of 249 F g− 1 at a current density of 0.05 A g− 1, excellent rate performance and cycle stability in a three-electrode system. The excellent electrochemical performance indicated that the obtained activated carbon fibers could be a promising electrode material in supercapacitor.

Electrochemical water splitting is an important process for next generation of eco-friendly energy systems. The oxygen evolution reaction (OER), which occurs at an anode during the process, requires efficient electrocatalysts to reduce activation energies. Although Ru- or Ir-containing materials show excellent electrocatalytic activities, their high cost is a critical drawback. Consequently, the development of efficient electrocatalysts composed of low-cost metal components is a great challenge. In this study, we develop a new route to produce a hybrid material (Fe–NC) containing Fe3C particles dispersed on the surface of N-doped carbon (NC) materials by heat treatment of a mixture of urea and Fe(II)Cl2(H2O)4. Microscopic analyses prove that the Fe3C particles are placed on the surfaces of thin NC materials. Additionally, various characterizations reveal that the particles contain Fe3C structure. Fe–NC shows good electrocatalytic properties with onset and overpotentials of 1.57 V and 545 mV, respectively, for OER in KOH electrolyte. This study suggests the possibility of the use of Fe3C- based composites as OER electrocatalysts.

A porous-carbon material UiO-66-C was prepared from metal–organic frameworks UiO-66 by carbonization in inert gas atmosphere. Physicochemical properties of UiO-66-C materials were well characterized by Powder X-ray diffraction (PXRD), Scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), Raman spectrometer, N2 adsorption/ desorption isotherms (BET), and the adsorption properties of the products were studied UiO-66-C has a high specific surface area up to 1974.17 m2/ g. Besides, the adsorption capacity of tetracycline could reach 678.19 mg/g, the adsorption processes agreed well with the pseudo-second-order kinetic model and Langmuir isotherm model.

In view of the activated carbon pore-forming mechanism, the fractal hypothesis of pore interior growth was proposed by optimizing the structure of Sierpinski sponge. Based on the hypothesis and the definition of fractal dimension, the function relationship between the reaction degree, reaction step length, specific surface area and pore volume was deduced, and the pore fractal growth model of activated carbon activation process was established. Semi-coke, apple charcoal and lychee charcoal were used to prepare activated carbon. The pore size distributions of the activated carbons are in accordance with the fractal growth hypothesis. Further, the reaction degree and reaction step length can be determined by the experimental data of pore and surface structure, which verified the feasibility of the pore fractal growth model.

Hypercrosslinked polymers HCPs have been widely used as precursors to prepare porous carbon materials because of their highly ordered porous structure and large specific surface area. In this paper, we used a solvothermal method to prepare a hypercrosslinked polymer, and the HCPC-700-A was prepared using an activation method with the hypercrosslinked polymer as the precursor. The effects of different carbon–alkali ratios on the microstructure, composition and electrochemical properties of porous carbon HCP were studied. The results show that the surface of porous carbon HCPC-700-A presents a relatively regular geometric shape, and a large number of pore structures are mainly micro- and mesopores. The specific surface area is 2074.53 m2 g− 1, and the average pore size is between 1.29 and 1.93 nm. Porous carbon HCPC-700-1:2 has excellent electrochemical performance in 1 M H2SO4, and the specific capacitance is up to 464.4 F g− 1 at a current density of 1 A g− 1. The specific capacitance decay rate is 29.72% when the current density is increased from 1 A g− 1 to 8 A g− 1. After 5000 cycles, the capacitance retention rate is 91.16% at a current density of 2 A g− 1, showing excellent electrochemical performance, good cycle stability and perfect energy storage performance. This research provides new experimental ideas for HCPs in the electrochemical energy storage field.

In this present investigation, machinability studies on novel aluminum composite with hybrid reinforcements of copper-coated 4% carbon fibers (CFs) and 3% nanoclay in AA6026 matrix fabricated by compocasting method is performed. Step drill bit and multifaceted drill bit are used by adopting central composite design (CCD) in response surface methodology (RSM). The outcomes show that, with a rise in rotational speed surface irregularities, resultant force and material removal rate (MRR) intensifies, and with the additional rise in rotational speed, all the outputs decrease considerably. High MRR, resultant cutting force, and surface roughness are obtained with multifaceted carbide drills, compared with a step drill. Desirability function is used to maximize the MRR and minimize the resultant cutting forces considering the constant surface roughness of 3 μm. The optimal values are rotational speed of 1285 rpm, feed rate of 60 mm/min with the step drill bit, producing an MRR of 0.0439 kg/sec and a resultant cutting force of 185.818 N. The second-order empirical models are developed for outputs, which are fed into the non-traditional metaheuristic Evaporation Rate-based Water Cycle Algorithm (ER-WCA) therefore the lower objective value is achieved with step drill of 51.7421. It is found that using a step drill the machinability performance of this hybrid nanocomposite is well improved than the machining with other drill bits. This composite fulfills the norms of 2000/53/CE-ELV European environmental directives.

Electrochemical reduction of carbon dioxide to valuable chemicals is a promising way of storing renewable energy through electric-to-chemical energy conversion, while its large-scale application is in urgent need of cheap and high-performance catalysts. Herein, we invent a convenient method to synthesize N-doped porous carbon by ammonia etching the pyrolysis carbon of petroleum pitch. We found the ammonia etching treatment not only increase the pyridinic-N content, but also enlarge the specific surface area of the petroleum pitch-based porous carbon. As a cheap and easily available catalyst for carbon dioxide electroreduction, up to 82% of Faradaic efficiency towards carbon monoxide was obtained at − 0.9 V vs the reversible hydrogen electrode in 0.1 M KHCO3. After a long time electrocatalysis of more than 20 h, the Faradaic efficiency of carbon monoxide remains 80%, indicating the porous carbon as made have an ultra-high stability as catalyst for carbon dioxide reduction. Our work provides a new technology to economically prepare efficient electrocatalysts for carbon dioxide reduction.

To thoroughly analyze the mechanical properties and surface conditions of HF50S carbon fibers, the tensile properties, surface morphology, surface chemical element, surface energy, sizing agent properties, and Naval Ordnance Laboratory (NOL) ring of their composites were characterized. Furthermore, the aforementioned properties were exhaustively compared with those of T1000G carbon fibers. The results showed that the tensile strength, modulus, and elongation of the HF50S carbon fibers were 6638 MPa, 297 GPa, and 2.2%, respectively, thus demonstrating that the mechanical properties of the HF50S carbon fibers were on par with those of the T1000G carbon fibers, in addition, the coefficient of variation (Cv) indices of HF50S carbon fiber were below 3%, indicating good stability. The HF50S carbon fibers have a smooth surface without grooves, which is analogous to that of the T1000G carbon fibers prepared by the typical dry jet–wet spinning process. The main component of the sizing agent of the HF50S carbon fibers is an epoxy resin, which is also used for the preparation of epoxy matrix composites. Because the HF50S carbon fiber surface has greater O and N contents than the T1000G carbon fiber surface, the HF50S carbon fibers have more active functional groups and higher surface activity. The surface energy of the HF50S carbon fibers is 30.13 mJ/m2, which is higher than that of the T1000G carbon fibers (28.42 mJ/m2). Owing to the higher strength and surface activity of the HF50S carbon fibers than those of the T1000G carbon fibers, the strength and strength conversion of NOL ring based on the former are slightly higher than those of that prepared using the latter.

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.

Graphitic carbon nitride ( C3N4) has been intensively studied in the last 25 years. Although the number of papers about C3N4 published per year has been growing exponentially, there are still some unclear issues with this material. One of them is s-triazine C3N4 (s-C3N4), which is an allotrope of C3N4. The theoretical computational as well as experimental synthetic results are not unambiguous. The properties of s-C3N4 have been described only in two papers, and no similar and reproducible results have been obtained so far. This paper provides a brief overview of s-C3N4 to bring attention to this material, for example, as a potential photocatalyst.

Fluorescent carbon nano-materials with quantum confinement and edge effects have recently piqued attention in a variety of applications, including biological imaging, drug delivery, optoelectronics and sensing. These nano-materials can be synthesized from a variety of carbon-based precursors using both top-down and bottom-up methods. Coal and its derivatives typically include a vast crystalline network and condensed aromatic ring cluster, which can be easily exfoliated by chemical, electrochemical, or physical processes to produce nano-materials. As a result, they are regarded as a low-cost, abundant and efficient carbon source for the fabrication of high-yield nano-materials. Nano-materials synthesized from coal-based precursors have outstanding fluorescence, photostability, biocompatibility and low toxicity, among other properties. Their properties in optical sensors, LED devices, bio-imaging, and photo and electro-catalyst applications have already been investigated. In this review, we have highlighted current developments in the synthesis, structural properties and fluorescence properties of nano-materials synthesized from coal-based precursors.

Graphene, the wonder material has brought a revolutionary change in the field of nanotechnology owing to its tremendous properties. Though different methods for the synthesis of graphene have been reported, the chemical synthesis route offers a scalable and high-volume production of graphene. The unreliability of graphite and hydrocarbon resources to serve as steady supplies of carbon resources and further in the synthesis of graphene has led to the exploration and use of alternative low-cost carbon-rich resources (coal, graphite, rice husk, sugarcane bagasse, peanut shells, waste tyres, etc.) as precursors for graphene synthesis. The use of untraditional carbon resources reduces dependence on traditional resources (coal, graphite), reduced cost, increased reliability, and provides a way for the management of waste biomass. This review hence focuses on the synthesis of graphene by the most common approachable method, oxidation–reduction of graphite, along with the various other chemical methods of synthesis from varied carbon resources.

In this study, N/S co-doped carbon felt (N/S-CF) was prepared and characterized as an electrode material for electric double-layer capacitors (EDLCs). A commercial carbon felt (CF) was immersed in an aqueous solution of thiourea and then thermally treated at 800 oC under an inert atmosphere. The prepared N/S-CF showed a large specific surface area with hierarchical pore structures. The electrochemical performance of the N/S-CF-based electrode was evaluated using both 3- electrode and 2-electrode systems. In the 3-electrode system, the N/S-CF-based electrode showed a good specific capacitance of 177 F/g at 1 A/g and a good rate capability of 41% at 20 A/g. In the 2-electrode system (symmetric capacitor), the freestanding N/S-CF-based electrode showed a specific capacitance of 275 mF/cm2 at 2 mA/cm2, a rate capability of 62.5 % at 100 mA/cm2, a specific power density of ~ 25,000 mW/cm2 at an energy density of 23.9 mWh/cm2, and a cycling stability of ~ 100 % at 100 mA/cm2 after 20,000 cycles. These results indicate the N/S co-doped carbon felts can be a promising candidate as a new electrode material in a symmetric capacitor.

As the number of nuclear power plants whose design life has expired worldwide increases, the attempts are continuing to complete the project of nuclear back-end cycle, the last task of the nuclear industry. Decontamination is essential in the process of dismantling nuclear facilities and restoration sites to remove all or some of the regulatory controls from an authorized facility. Among radioactive wastes, particularly contaminated soil is characterized by difficult physical decontamination because radionuclides are adsorbed between soil particles, that is, pores. Therefore, chemical decontamination is mainly used, which has the disadvantage of generating a lot of secondary waste. In order to overcome these disadvantages, an eco-friendly soil decontamination process is being developed that can drastically reduce the amount of secondary waste generated by using supercritical carbon dioxide. Supercritical carbon dioxide can easily control its physical properties and has both liquid and gas properties. However, since supercritical carbon dioxide is non-polar, additives are needed to extract polar metal ions, which are the goal of decontamination. Therefore, ligand with both CO2-philic and metal binding regions was selected. In previous studies, the decontamination efficiency of soil was evaluated by reacting contaminated soil with solid ligand and co-ligand at once. When solid ligands were used, the decontamination efficiency was lower than expected, which was expected because chemical substances were somewhat difficult to exchange in the closed process. In this study, in order to increase the efficiency of the decontamination process, the need for a process of liquefying ligand and continuously flowing it has been raised. Therefore, a co-solvent that dissolves well at the same time in SCCO2, ligand, and co-ligand was selected. In the selection process, a total of eight substances were selected by dividing into six polar substances and two non-polar substances through various criteria such as economic feasibility, eco-friendliness, and harmlessness. Thereafter, ethanol was finally selected through solubility evaluation for SCCO2 and additives. It is expected that a more effective decontamination process can be constructed when the additive is liquefied using a solvent selected from the results of this study.