본 연구는 RGB, 초분광 센서를 이용하여 시기별 사과 잎의 엽록소와 질소 함량을 예측하여 사과 나무 잎의 질소 영양을 진단하기 위해 수행되었다. 분광 데이터는 사과나무 ‘홍로 /M.9’ 2년생을 대상으로 고해상도 RGB와 초분광 센서로 촬 영 후 영상처리를 통해 취득하였다. 식물체 데이터는 촬영이 끝난 직후 엽록소와 잎 질소 함량을 측정하였다. 엽록소 측정 기의 SPAD meter, RGB 센서의 개별 파장, 컬러 식생지수 및 초분광 센서의 214개의 파장과 식물체 데이터를 이용하여 회 귀분석을 실시하였다. 엽록소와 잎 질소 함량 데이터는 시기 와 상관없이 질소 시비량에 따라 통계적으로 유의한 차이가 나타났다. 잎은 시기가 지나면서 잎에 있던 영양분이 과실로 전이되어 색이 옅어졌으며 RGB센서의 경우 Red파장에서 시 기와 상관없이 통계적으로 유의한 차이가 나타났다. 초분광 센서의 경우 두 시기 모두 질소 시비 수준에 따라 가시광 영역 보다 비가시광 영역에서 차이가 크게 나타났다. 반사값를 이 용하여 식물체 특성의 예측 모델 결과 엽록소, 잎 질소함량 모 두 초분광 데이터를 이용한 부분최소제곱 회귀분석을 이용하 였을 때 성능이 가장 높게 나타났다(chlorophyll: 81% / 63%, leaf nitrogen content: 81% / 67%). 이러한 원인은 RGB 센서 에 비해 초분광 센서는 좁은 FWHM과 400－1,000nm의 넓 은 파장 범위를 가지고 있어 질소 결핍에 의한 스트레스로 인 해 작물의 분광학적 해석이 가능했을 것으로 판단된다. 추후 분광학적 특성을 이용하여 전 생육 시기의 수체 생리, 생태 모 델 개발 및 검증 그리고 병해충 진단 등 연구를 통해 고품질, 안 정적인 과실 생산 기술 개발에 기여될 것으로 사료된다.

The aim of this study was to investigate dry matter productivity and nitrate nitrogen content in the growth stages of barnyard millet (Echinochloa esculenta) cultivated for feed, which was treated with different nitrogen fertilization levels. An early variety of barnyard millet (cv. Shirohie) was used for the test, and the different treatments with nitrogen fertilizer were as follows: 50% (N-40 kg/ha, T1), 100% (N-80 kg/ha, reference amount, T2), 150% (N-120 kg/ha, T3), 200% (N- 160 kg/ha, T4), 250% (N-200 kg/ha, T5), and 300% (N-240 kg/ha, T6). Sowing was done on May 13, 2021 and plants were harvested for four stage; vegetative stage, elongation stage, heading stage, and milk stage. The length of the millet increased significantly as the amount of nitrogen fertilization increased during the harvest period (p<0.05), but the difference was insignificant during the milk stage (p>0.05). Moreover, barnyard millet dry matter yield increased significantly as the levels of nitrogen fertilization increased (p<0.05), but there was no significant difference in dry matter yield among nitrogen fertilization levels during the heading stage (p>0.05). Chlorophyll also was significantly higher in T5 (250%) at all harvesting times, whereas nitrate nitrogen content was highest at the vegetative stage, gradually decreased as growth progressed, and lowest at the milk stage. Finally, as the nitrogen fertilization levels increased, the nitrate nitrogen content was significantly higher in all treatment groups (p<0.05). Therefore, our results suggest that the most appropriate nitrogen fertilizer levels is between 150%–200%, considering the dry matter yield, feed ingredients and nitrate nitrogen content in barnyard millet for feed.

Excess nitrogen (N) flowing from livestock manure to water systems poses a serious threat to the natural environment. Thus, livestock wastewater management has recently drawn attention to this related field. This study first attempted to obtain the optimal conditions for the further volatilization of NH3 gas generated from pig wastewater by adjusting the amount of injected magnesia (MgO). At 0.8 wt.% of MgO (by pig wastewater weight), the volatility rate of NH3 increased to 75.5% after a day of aeration compared to untreated samples (pig wastewater itself). This phenomenon was attributed to increases in the pH of pig wastewater as MgO dissolved in it, increasing the volatilization efficiency of NH3. The initial pH of pig wastewater was 8.4, and the pH was 9.2 when MgO was added up to 0.8 wt.%. Second, the residual ammonia nitrogen (NH4 +-N) in pig wastewater was removed by precipitation in the form of struvite (NH4MgPO4·6H2O) by adjusting the pH after adding MgO and H3PO4. Struvite produced in the pig wastewater was identified by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) analysis. White precipitates began to form at pH 6, and the higher the pH, the lower the concentration of NH4 +-N in pig wastewater. Of the total 86.1% of NH4 +-N removed, 62.4% was achieved at pH 6, which was the highest removal rate. Furthermore, how struvite changes with pH was investigated. Under conditions of pH 11 or higher, the synthesized struvite was completely decomposed. The yield of struvite in the precipitate was determined to be between 68% and 84% through a variety of analyses.

A thermally conductive film can be used to laterally conduct heat along the surface of glass windows, toward its edges where a heat sink could be located, thereby reducing temperature differential between the inside and outside surfaces of the window and thus lowering cross-sectional conductive heat transfer. This technique can offer optimized thermal energy management to modern buildings without the weight and cost of double- or triple-glazed window panels. In this work, a thermally conductive film was developed using carbon dots with inherently high thermal conductivity. Nitrogen atoms were then added to the carbon dots structure to intensify high-frequency phonon that would result in higher lateral thermal conductivity. The nitrogen-decorated carbon dots (NCDs) were prepared by a simple hydrothermal synthesis of citric acid with the addition of ethylenediamine as the N source. The NCDs were added to a cellulose-based solution and drop-casted onto FTO glass resulting in a transparent, laterally thermally conductive film, that also blocks ultraviolet (UV) and high-intensity blue light radiation. The visible-light transmission of the NCDs’ film was found to be up to 65%, comparable to the commercial solar films. The lateral thermal conductivity of the NCDs’ film increases with increasing N content up to an optimum level, suggesting the role of N to “concentrate’ the high-frequency phonons responsible for effective lateral thermal conductivity of the films.

Environmental regulations of the IMO (International Maritime Organization) are becoming more and more conservative. In order to respond to IMO, the demand for replacing the fuel of ships with eco-friendly fuels instead of conventional heavy oil is increasing in the shipbuilding and offshore industries. Among eco-friendly fuels, LNG (Liquefied Natural Gas) is currently the most popular fuel. LNG is characteristically liquefied at -163 degrees, and at this time, its volume is reduced to 1/600, so it is transported in a cryogenic liquefied state for transport efficiency. A tank for storing this should have sufficient mechanical/thermal performance at cryogenic temperatures, and among them, high manganese steel is known as a material with high price competitiveness and satisfying these performance. However, high manganese steel has a limitation in that the mechanical performance of the filler metal is lower than that of the base metal called ‘under matching’. In this study, to overcome this limitation, a basic study was conducted to apply the fiber laser welding method without filler metal to high manganese steel. To obtain efficient welding conditions, in this study, bead-on-plate welding was performed by changing the fiber laser welding speed and output using helium shielding gas, and the effect of each factor on the penetration shape was analyzed through cross-sectional observation.

기체투과막 기술을 이용하여 가축분뇨 폐기물 등으로부터 암모니아성 질소를 효과적으로 회수할 수 있다. 이는 폐기물 내 암모니아 기체가 폐기물에 함침된 기체투과막의 미세공극을 투과하여 막반대편에 도달하게 된다. 투과된 암모니아 기체분자는 막 반대편에 존재하는 용액 내 황산 등 산에 의해 포획 및 회수된다. 막 유입부 내 암모니아성 질소 제거 효과를 높이기 위해서는 우선 유입 폐기물 내 pH를 높게 유지해야 하는데 pH 상승에 필요한 염기성 약품 투입비용이 문제가 될 수 있다. 기존 연구에서는 보다 저렴한 소석회 투입하거나 폭기 혹은 질산화억제를 통해 높은 pH를 효과적으로 유지시키는 방 안이 거론되고 있다. 한편 암모니아성 질소 회수에 쓰이는 기체투과막의 재질은 적절한 내열성이나 내화학성 이외에도 소수 성을 띈다는 특징이 있으며 이를 통해 막기공을 통해 암모니아 기체를 선택적으로 투과시킬 수 있다. 향후 연구에서는 다양 한 성상을 가진 현장 폐기물을 이용하여 실증 Test를 수행하고 이를 기반으로 최적 설계/운전 조건 규명 및 경제성 제고 방안 을 수립하여야 한다.

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.

We present a method to determine nitrogen abundance ratios with respect to iron ([N/Fe]) from molecular CN-band features observed in low-resolution (R ∼ 2000) stellar spectra obtained by the Sloan Digital Sky Survey (SDSS) and the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST). Various tests are carried out to check the systematic and random errors of our technique, and the impact of signal-to-noise (S/N) ratios of stellar spectra on the determined [N/Fe]. We find that the uncertainty of our derived [N/Fe] is less than 0.3 dex for S/N ratios larger than 10 in the ranges Teff = [4000, 6000] K, log g = [0.0, 3.5], [Fe/H] = [−3.0, 0.0], [C/Fe] = [−1.0, +4.5], and [N/Fe] = [−1.0, +4.5], the parameter space that we are interested in to identify N-enhanced stars in the Galactic halo. A star-by-star comparison with a sample of stars with [N/Fe] estimates available from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) also suggests a similar level of uncertainty in our measured [N/Fe], after removing its systematic error. Based on these results, we conclude that our method is able to reproduce [N/Fe] from low-resolution spectroscopic data, with an uncertainty sufficiently small to discover N-rich stars that presumably originated from disrupted Galactic globular clusters.

The present study was performed to investigate the effects of NH3-N and nitrifying microorganisms on the increased BOD of downstream of the Yeongsan river in Gwangju. Water samples were collected periodically from the 13 sampling sites of rivers from April to October 2021 to monitor water qualities. In addition, the trends of nitrogenous biochemical oxygen demand (NBOD) and microbial clusters were analyzed by adding different NH3-N concentrations to the water samples. The monitoring results showed that NH3-N concentration in the Yeongsan river was 22 times increased after the inflow of discharged water from the Gwangju 1st public sewage treatment plant (G-1-PSTP). Increased NH3-N elevated NBOD levels through the nitrification process in the river, consequently, it would attribute to the increase of BOD in the Yeongsan river. Meanwhile, there was no proportional relation between NBOD and NH3-N concentrations. However, there was a significant difference in NBOD occurrence by sampling sites. Specifically, when 5 mg/L NH3-N was added, NBOD of the river sample showed 2-4 times higher values after the inflow of discharged water from G-1-PSTP. Therefore, it could be thought other factors such as microorganisms influence the elevated NBOD levels. Through next-generation sequencing analysis, nitrifying microorganisms such as Nitrosomonas, Nitroga, and Nitrospira (Genus) were detected in rivers samples, especially, the proportion of them was the highest in river samples after the inflow of discharged water from G-1-PSTP. These results indicated the effects of nitrifying microorganisms and NH3-N concentrations as important limiting factors on the increased NBOD levels in the rivers. Taken together, comprehensive strategies are needed not only to reduce the NH3-N concentration of discharged water but also to control discharged nitrifying microorganisms to effectively reduce the NBOD levels in the downstream of the Yeongsan river where discharged water from G-1-PSTP flows.

The objective of this study was to verify the effect of pig slurry application with acidification and biochar on feed value, nitrogen use efficiency (NUE) of maize forage, and ammonia (NH3) emission. The four treatments were applied: 1) non-pig slurry (only water as a control, C), 2) only pig slurry application (P), 3) acidified pig slurry application (AP), 4) acidified pig slurry application with biochar (APB). The pig slurry and biochar were applied at a rate of 150 kg N ha-1 and 300 kg ha-1, respectively. The AP and APB treatments enhanced all feed values compared to C and P treatments. The NUE for plant N was significantly increased 92.1% by AP and APB treatment, respectively, compared to the P treatment. On the other hand, feed values were not significantly different between AP and APB treatments. The acidification treatment with/without biochar significantly mitigated NH3 emission compared to the P treatment. The cumulative NH3 emission throughout the period of measurement decreased by 71.4% and 74.8% in the AP and APB treatments. Also, APB treatment reduced ammonia emission by 11.9% compared to AP treatment. The present study clearly showed that acidification and biochar can reduce ammonia emission from pig slurry application, and pig slurry application with acidification and biochar exhibited potential effects in feed value, NUE, and reducing N losses from pig slurry application through reduction of NH3 emission.

In this article, nitrogen (N) doped porous carbon nanofibers (N-PCNF) were prepared by carbonization of polymer-silica nanocomposite precursor, and its application for heavy metal ion removal was demonstrated. Carbon–silica composite nanofibers were obtained by carbonization of electrospun polyacrylonitrile (PAN)-silica nanofiber composites. Subsequent selective etching of silica porogen produced porous carbon nanofibers (PCNF). It was revealed by surface characterization with X-ray photoelectron spectroscopy (XPS) that the surface of the PCNF was nitrogen-doped because N atom from cyanide group in PAN chains remained in the hexagonal carbon structure. The use of the obtained N-PCNF for heavy metal ion ( Hg2+) removal was demonstrated using a simple adsorption test apparatus and 5, 10, 15, 20-tetraphenylporphine tetrasulfonic acid (TPPS) as an indicator. The N-PCNF showed a removal efficiency of 96 and 99% in 10 and 120 min, respectively, indicating a maximum heavy metal ion adsorption capacity at pH 7.0. In addition, heavy metal ion adsorption behavior was also analyzed using common adsorption isotherms. This article provides important information for future research activities regarding control over hazardous substances.

Here, a novel nitrogen-doped carbon nano-material (N-CGNM) with hierarchically porous structure was prepared from spent coffee ground for efficient adsorption of organic dyes by a simple one-step carbonization process (the uniform mixture consists of spent coffee ground, urea, and CaCl2 with the ratio of 1:1:1, which was heated to 1000 °C with a rate of 10 °C min− 1 and held at 1000 °C for 90 min in N2 atmosphere to carry out carbonization, activation, and N-doping concurrently). The morphology and structure analysis show that the prepared N-CGNM exhibits hierarchical pore structure, high specific surface area (544 m2/ g), and large numbers of positively charged nitrogen-containing groups. This unique structure and chemical composition endow N-CGNM with an excellent adsorption capacity toward anion Congo red (623.12 ± 21.69 mg/g), which is obviously superior to that (216.47 ± 18.43 mg/g) of untreated spent coffee ground-based carbon nano-materials (CGM). Oppositely, the adsorption capacity of N-CGNM towards cation methylene blue is inferior to that of CGM due to the existence of electrostatic repulsion. These findings show a great guidance for the development of low-cost but efficient selective adsorbent.

Thermal reduction of graphite oxide (GO) is considered as a prospective method for the preparation of high-performance graphene-based materials. However, this method has certain limitations, and the major is that this exothermic process is difficult to control. In this research, we focused on the kinetic studies of the reduction of graphite oxide using non-isothermal differential calorimetry (DSC) method. Six GO nanocomposites with dyes were tested to study the shift in kinetic parameters. The apparent reaction order is determined to be ca 0.7 for the thermal decomposition of pure GO, while in the presence of dye molecules it increases sometimes reaching a value of 2.0 for higher dye concentrations. Decisively, the thermal decomposition of pure GO can be presented as an intermediate between a zero- and first-order reaction, while the introduction of dye molecules turns a certain part of the energy consumption via the bimolecular pathway. Our research revealed that the process of GO thermal decomposition can be operated and properties of the final product (reduced graphene oxide (rGO) and its derivatives) can be adjusted more precisely using additive molecules, which interact with GO sheets.

The objective of this study was to prove the effect of pig slurry application with charcoal on nitrogen use efficiency (NUE), feed value and ammonia (NH3) emission from maize forage. The four treatments were applied: 1) non-pig slurry (only water as a control), 2) only pig slurry application (PS), 3) pig slurry application with large particle charcoal (LC), 4) pig slurry application with small particle charcoal (SC). The pig slurry was applied at a rate of 150 kg N ha-1, and the charcoal was applied at a rate of 300 kg ha-1 regardless of the size. To determine the feed value of maize, crude protein, dry matter intake, digestible dry matter, total digestible nutrient, and relative feed value were investigated. All feed value was increased by charcoal treatment compared to water and PS treatment. Also, the NUE for plant N was significantly higher in charcoal treatments (LC and SC) compared to PS treatment. On the other hand, there is no significant difference for feed value and NUE between LC and SC. The NH3 emission was significantly reduced 15.2% and 27.9% by LC and SC, respectively, compared to PS. Especially, SC significantly decreased NH3 emission by 15% compared to LC. The present study clearly showed that charcoal application exhibited positive potential in nitrogen use efficiency, feed value and reducing N losses through NH3 emission.

MMBR system has been suggested as a promising system to resolve harvesting problems induced from low settling efficiency of microalgae. And recently, a lot of research on reducing fouling at the MMBR system has investigated focused on EPS in many cases. EPS of microalgae mainly consists of polysaccharides and protein components, and is produced through photosynthesis and nitrogen-carbon metabolic pathways. Especially, P-EPS is one of major compounds which occur membrane fouling phenomenon, as its hydrophobic protein components cause floc formation and cake layer accumulation. And it is already known that almost every microalgae can metabolize P-EPS or Chl-a when nitrogen sources as a substrate is insufficient or exhausted situation. With the above backgrounds, uptake rates of P-EPS or Chl-a by Scenedesmus quadricauda according to the type of carbon source and nitrogen concentration were evaluated in order to verify correlation between carbon source vs P-EPS production, and indeed Scenedesmus quadricauda uses P-EPS or Chl-a when the amounts of nitrogen sourc es in the feed is not satisfied. As a result, it was shown that P-EPS and Chl-a production were increased proportional to nitrogen concentration under organic carbon condition. And especially, the amo unts of P-EPS and Chl-a in the cell were diminished with the nitrogen source becomes insufficient or exhausted. Because P-EPS accelerates fouling at the MMBR system, P-EPS degradation by Scenedesmus quadricauda in order to get nitrogen source may contribute to reducing fouling. About a affects of N-consumed Chl-a to the MMBR fouling, more survey is needed. On the contrary, considering the purpose of MMBR system of this study, i.e. harvesting useful high value microalgae efficiently feeding adequate industrial process wastewater, it seems like difficult to maintain satisfied metabolic activity and to harvest with high yield rate using nitrogen-poor MMBR feed.

Doped porous carbon materials have attracted great interest owing to their excellent electrochemical performance toward energy storage applications. In this report, we described the synthesis of nitrogen-doped porous carbon (N-PC) via carbonization of a triazine-based covalent organic framework (COF) synthesized by Friedel–Crafts reaction. The as-synthesized COF and N-PC were confirmed by X-ray diffraction. The N-PC exhibited many merits including high surface area (711 m2 g−1), porosity, uniform pore size, and surface wettability due to the heteroatom-containing lone pair of electron. The N-PC showed a high specific capacitance of 112 F g−1 at a current density of 1.0 A g−1 and excellent cyclic stability with 10.6% capacitance loss after 5000 cycles at a current density of 2.0 A g−1. These results revealed that the COF materials are desirable for future research on energy storage devices.