본 연구의 목적은 남자 대학 엘리트 조정선수의 2000 m 로잉 에르고미터 수행 후 저온침수 처 치를 통해 혈중 젖산, LDH, MDA 및 SOD의 변화에 긍정적인 영향을 주어 피로 회복에 미치는 영향을 구명하는 데 있다. 이에 남자 대학 엘리트 조정선수 10명을 대상으로 고강도 로잉 에르고미터 2,000 m 수 행 후 비 처치와 저온 침수 처치의 효과를 비교하였다. 측정 변인들에 대한 결과를 검증하기 위해 처치 및 시기 간 상호작용 효과를 분석하기 위해 ANOVA를 실시하였고 각 항목별 유의수준 .05로 설정하여 다음 의 결과를 도출하였다. 젖산은 시기 간 주효과가 나타났고(p<.001) 그룹 내 시기별 차이가 났다(p<.001). 또한, LDH는 그룹 내 시기별 차이가 나타났다(p<.05). MDA는 그룹×시기 간 상호작용 효과가 나타났고 (p<.05), 그룹 간(p<.05), 시기 간(p<.001) 주효과가 나타났다. SOD는 그룹 간, 시기 주효과가 나타났고 (p<.05) 회복 30분 후 그룹 간 차이가 나타났다(p<.05). 이를 종합해 볼 때, 본 연구에서 실시한 저온침수처치가 조정 선수의 혈중 피로 물질, 활성산소 및 항산화 효소에 유의한 효과를 나타냈다. 따라서 운동선수 의 고강도 훈련 후 저온침수를 적극 활용할 것을 권장한다.

The oxygen evolution reaction (OER) is very sluggish compared to the hydrogen evolution reaction (HER). Considering this difference is essential when designing and developing a cost-effective and facile synthesis method for a catalyst that can effectively perform OER activity. The material should possess a high surface area and more active sites. Considering these points, in this work we successfully synthesized sheets of cobalt phosphate hydrate (CP) and sulphurated cobalt phosphate hydrate (CPS) material, using simple successive ionic layered adsorption and reaction (SILAR) methods followed by sulfurization. The CP and CPS electrodes exhibited overpotentials of 279 mV with a Tafel slope of 212 mV dec1 and 381 mV with a Tafel slope of 212 mV dec1, respectively. The superior performance after sulfurization is attributed to the intrinsic activity of the deposited well-aligned nanosheet structures, which provided a substantial number of electrochemically active surface sites, speeded electron transfer, and at the same time improved the diffusion of the electrolyte.

A Cu-15Ag-5P filler metal (BCuP-5) is fabricated on a Ag substrate using a high-velocity oxygen fuel (HVOF) thermal spray process, followed by post-heat treatment (300oC for 1 h and 400oC for 1 h) of the HVOF coating layers to control its microstructure and mechanical properties. Additionally, the microstructure and mechanical properties are evaluated according to the post-heat treatment conditions. The porosity of the heat-treated coating layers are significantly reduced to less than half those of the as-sprayed coating layer, and the pore shape changes to a spherical shape. The constituent phases of the coating layers are Cu, Ag, and Cu-Ag-Cu3P eutectic, which is identical to the initial powder feedstock. A more uniform microstructure is obtained as the heat-treatment temperature increases. The hardness of the coating layer is 154.6 Hv (as-sprayed), 161.2 Hv (300oC for 1 h), and 167.0 Hv (400oC for 1 h), which increases with increasing heat-treatment temperature, and is 2.35 times higher than that of the conventional cast alloy. As a result of the pull-out test, loss or separation of the coating layer rarely occurs in the heat-treated coating layer.

본 연구는 비산소 분쇄 및 포장이 해조류 분말의 색도, 항산화활성 및 미생물 수에 미치는 영향을 조사하였다. 대조구로는 산소 조건하에서 분쇄 및 포장을 진행하였다. 색도는 대조구가 저장기간이 지남에 따라 L값과 b값은 감소하고 a값이 증가하여 갈변현상이 일어나는 것을 확인하였다. 또한, 총 페놀함량 (9.8~8.0mg GAE/100g dw), DPPH (12.57~11.00mg BHAE/100g dw), ABTS (13~8.4mg AAE/100g dw) 및 FRAP (11.2~8.0mg Fe(II)/100g dw)활성이 모두 감소하는 것으로 나타났다. 반면에, 진공-질소치환에 의한 비산소 분쇄 및 포장의 경우 유의적으로 차이가 없는 것으로 나타났다. 미생물수는 대장균군, 일반세균수, 효모 및 곰팡이를 분석하였고 대장균군과 곰팡이는 모든 샘플에서 불검출되었다. 대조구는 0~8주차에서 일반세균수와 효모가 각각 1.52~1.96 log CFU/g, 0~1.77 log CFU/g으로 증가하는 것으로 나타났다. 비산소 분쇄 및 포장 조건은 0~8주차에서 일반세균수와 효모가 각각 1.52~1.53 log CFU/g, 0~1.25 log CFU/g으로 각각 나타나 일반세균수는 유의적으로 차이가 없었으나 효모는 약간 증가한 것으로 나타났다. 따라서, 색도유지, 높은 총 페놀함량 및 항산화 활성 유지, 일반세균 및 효모의 성장 억제를 위해서는 진공-질소치환에 의한 비산소 분쇄 및 포장 조건하에서 품질특성과 미생물수를 유지하는데 효과적일 것으로 판단된다.

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.

Metal–organic frameworks (MOFs) are widely used as supports for single-atom catalysts (SACs) owing to their high specific surface area, porosity, and ordered metal–ligand structure. Their activity can be increased by increasing the number of electrochemically accessible active sites via the formation of atomically dispersed metal catalysts (M–Nx) that coordinate with nitrogen atoms on the MOF. Herein, we introduce the relationship between the size of the MOF as a starting material and the catalytic activity for the oxygen reduction reaction in alkaline media. The morphology and features of the MOFs are critically dependent on their size. Remarkably, cage-like MOFs below 33 nm are converted into collapsed structures and are connected between each MOF, even carbon fiber- or tube-like features, after carbonization. SACs derived from medium-sized MOFs exhibit excellent activity and are comparable to commercial Pt/C catalysts owing to their porous structure. Therefore, we believed that controlling the size of MOFs containing active atoms is an effective method of modulating the morphological properties of the support and even the number of active sites that are closely related to the activity.

Mass mortality of mariculture fish due to high summer temperatures is a major issue in the mariculture industry in many coastal waters of Korea, yet measures to mitigate the impact are generally limited. We injected a micro-bubble of liquefied oxygen into the bottom of rockfish cages (about 6-8 m deep) in order to maximize the dispersal of micro-bubbled seawater and reduce fish mortality. The injection of low-temperature oxygen in micro-bubbles lowered the water temperature at the injection area by as much as 1℃ and increased dissolved oxygen concentration by 0.5 ppm. In early August, following a week with persistent high water temperature (above 28.5℃), there was an increase in fish mortality despite the micro-bubble system, which resulted in approximately 7% death of the total introduced fish population. However, this mortality appeared to be much lower than mortality reported in a neighboring mariculture facility (approximately 50% mortality). We also estimated the volume that can be recirculated with pumped seawater using a micro-bubble system. We suggest that this approach of injecting liquefied oxygen through a micro-bubble system may reduce fish mortality during high temperature periods.

ZnO thin-films are grown on a p-Si(111) substrate by RF sputtering. The effects of growth temperature and O2 mixture ratio on the ZnO films are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), and roomtemperature photoluminescence (PL) measurements. All the grown ZnO thin films show a strong preferred orientation along the c-axis, with an intense ultraviolet emission centered at 377 nm. However, when O2 is mixed with the sputtering gas, the half width at half maximum (FWHM) of the XRD peak increases and the deep-level defect-related emission PL band becomes pronounced. In addition, an n-ZnO/p-Si heterojunction diode is fabricated by photolithographic processes and characterized using its current-voltage (I-V) characteristic curve and photoresponsivity. The fabricated n-ZnO/p-Si heterojunction diode exhibits typical rectifying I-V characteristics, with turn-on voltage of about 1.1 V and ideality factor of 1.7. The ratio of current density at ± 3 V of the reverse and forward bias voltage is about 5.8 × 103, which demonstrates the switching performance of the fabricated diode. The photoresponse of the diode under illumination of chopped with 40 Hz white light source shows fast response time and recovery time of 0.5 msec and 0.4 msec, respectively.

Needle-like NiO protecting layers on NiCrAl alloy foam, used as support for hydrogen production, are introduced through electroplated Ni and subsequent microwave annealing. To improve the stability of the NiCrAl alloy foam, oxygen concentration of microwave annealing to form a needle-like NiO layer with good chemical stability and corrosion resistance is controlled in a range of 20 and 50 %. As the oxygen concentration increases to 50 %, needle-like NiO forms a dense coating layer on the NiCrAl alloy foam; this layer formation can be attributed to accelerated growth of the (200) plane. In addition, the increased oxygen concentration causes increased NiO/Ni ratio of the resultant coating layer on NiCrAl alloy foam due to improved rate of the oxidation reaction. As a result, the introduction of dense needle-like NiO layers formed at 50 % oxygen concentration improves the chemical stability of the NiCrAl alloy foam by protecting the direct electrochemical reaction between the electrolyte and the foam. Thus, needle-like NiO can be proposed as a superb protecting layer to improve the chemical stability of NiCrAl alloy form.

곤충의 혈액순환은 심장 박동에 의해 도움을 받는다. 다양한 생리적 변화는 심장 박동 조절을 수반하게 된다. 심장박동에 대한 교란은 곤충 의 생존을 위협하게 된다. 본 연구는 활성산소를 유발하여 살충력을 발휘하는 이산화염소가 혈액순환계에 미치는 영향을 심장박동을 통해 분석하 였다. 화랑곡나방(Plodia interpunctella) 유충의 등핏줄은 몸의 윗면 중앙에 위치하고 후방으로 복부 10번째 마디에서 시작하여 전방으로 첫 번째 가슴 마디까지 연결된 관 구조를 나타냈다. 등핏줄의 수축과 이완은 주로 복부 3-10번째 마디에 위치한 등핏줄에서 일어났으며 이 부위에 5개의 심실이 관찰되었다. 심장박동빈도는 25°C에서 분당 평균 118.6회의 수축 리듬을 보였다. 그러나 온도에 따라 심장박동빈도는 현격한 변화를 보 였다. 혈강에 이산화염소를 다양한 농도로 투여한 경우 심장박동빈도는 약제 농도 증가에 따라 감소하였다. 이산화염소(100 ppm)을 훈증 처리할 경우 노출 시간의 경과에 따라 심장박동리듬이 현격하게 감소하였다. 이러한 이산화염소의 심장박동 억제효과는 활성산소 저해제인 비타민 E와 함께 주입할 경우 회복되는 현상을 나타냈다. 이상의 결과는 이산화염소가 화랑곡나방의 심장박동에 억제효과를 주었으며 이러한 억제효과는 이 물질이 유발하는 활성산소에 기인된 것으로 해석된다.

The present study was aimed to determine the effect of green tea extract (GTE) and beta-mercaptoethanol (β-ME) supplementation in boar sperm freezing extender on sperm motility, viability and reactive oxygen species (ROS) level. Experimental groups were allocated into Lactose-egg yolk (LEY) without antioxidant (control), GTE (1,000 mg/L GTE in LEY) and β-ME (50 μM β-ME in LEY). Spermatozoa extended with LEY were cooled to 5°C for 3 h and then kept at 5°C for 30 min following dilution with LEY containing 9% glycerol and 1.5% Equex STM (final sperm concentration: 1 × 108/mL). Spermatozoa were loaded into straws and frozen in nitrogen vapor for 20 min. Following thawing at 37°C for 25 sec, sperm viability and ROS level were measured using fluorescent double stain Fertility® and cytometry, respectively. Motility and viability of GTE supplemented-group were higher than those of control and β-ME without significance. ROS level in GTE group showed significantly lower than control (P < 0.05). In conclusion, GTE supplementation in boar sperm freezing extender can reduce ROS generation during freezing.

We determined the effects of different water temperatures (15, 20, and 25℃) and photoperiod cycles (24L:0D, 12L:12D, and 0L:24D) on the oxygen consumption of the offspring of a cultured Japanese strain (JJ), a selected Korean strain (KK), and intraspecific hybrid strains (JK and KJ) of red seabream, Pagrus major, under starvation conditions. The different fish strains, water temperatures, and photoperiod cycles had effects on the mean oxygen consumption of fish. Oxygen consumption increased with increasing water temperatures for all photoperiod treatments (p <0.001). Fish held in continuous darkness (0L:24D) used consistently less oxygen than fish exposed to continuous light (p <0.05). The oxygen consumption of fish exposed to the light phase in a 12L:12D photoperiod was higher than that of fish in the dark phase of the 12L:12D cycle, and differences were significant in three of the strains: JJ (15℃), KK (15 and 20℃), and KJ (25℃). The oxygen consumption of the inbred (JJ and KK) and intraspecific hybrid (JK and KJ) strains varied with differing water temperatures and photoperiod cycles. The JK strain displayed significantly higher oxygen consumption than the other strains under all experimental conditions except 15℃ with a 0L:24D photoperiod. The JK and KJ strains usually showed the highest and lowest oxygen consumption values, respectively, whereas the inbred strains exhibited intermediate values. Oxygen consumption in the JJ and JK strains was usually higher than that of the KK and KJ strains. We propose that differences in the thermal sensitivity and photosensitization properties of the strains contribute to differences in their ability to adapt to changes in water temperature and photoperiod, thus resulting in differences in the amplitude of their metabolic rates.

Chronic/cyclic neutropenia, leukocyte adhesion deficiency syndrome, Papillon-Lefèvre syndrome, and Chédiak-Higashi syndrome are associated with severe periodontitis, suggesting the importance of neutrophils in the maintenance of periodontal health. Various Toll-like receptor (TLR) ligands are known to stimulate neutrophil function, including FcR-mediated phagocytosis. In the present study, the effect of TLR2 activation on the non-opsonic phagocytosis of oral bacteria and concomitant production of reactive oxygen species (ROS) by human neutrophils was evaluated. Neutrophils isolated from peripheral blood were incubated with Streptococcus sanguinis or Porphyromonas gingivalis in the presence of various concentrations of Pam3CSK4, a synthetic TLR2 ligand, and analyzed for phagocytosis and ROS production by flow cytometry and chemiluminescence, respectively. Pam3CSK4 significantly increased the phagocytosis of both bacterial species in a dose-dependent manner. However, the enhancing effect was greater for S. sanguinis than for P. gingivalis. Pam3CSK4 alone induced ROS production in neutrophils and also increased concomitant ROS production induced by bacteria. Interestingly, incubation with P. gingivalis and Pam3CSK4 decreased the amounts of ROS, as compared to Pam3CSK4 alone, indicating the possibility that P. gingivalis survives within neutrophils. However, neutrophils efficiently killed phagocytosed bacteria of both species despite the absence of Pam3CSK4. Although P. gingivalis is poorly phagocytosed even by the TLR2-activated neutrophils, TLR2 activation of neutrophils may help to reduce the colonization of P. gingivalis by efficiently eliminating S. sanguinis , an early colonizer, in subgingival biofilm.

Many forest pests present a problem during wood quarantine. The effectiveness of phosphine (PH3), which is an altered form of MB, was examined in Monochamus saltuaris and M. alternatus. After 24 h, the larvae and the adults of both insects were susceptible to PH3 at 3 mg/L at 20°C. However, the larvae of both pests were rather than dead, seem to have been quiescent condition. PH3 showed increasing insecticidal activity in a time-dependent manner in the larva stage of both pests. We investigated the fumigants at all stages of M. saltuaris and M. alternatus, as well as the synergistic effects of PH3 in controlled atmospheres of 50% and 80% oxygen. The atmospheric oxidation of PH3 fumigation slightly increased the toxicity of the fumigant to larva stages in 125 L container at 4 mg/L. These results indicate that highly concentrated atmospheric oxidation of PH3 could be useful as a fumigant agent against M. saltuaris and M. alternatus.

Effect of oxygen content in the ultrafine tungsten powder fabricated by electrical explosion of wire method on the behvior of spark plasma sintering was investigated. The initial oxygen content of 6.5 wt% of as-fabricated tungsten powder was reduced to 2.3 and 0.7 wt% for the powders which were reduction-treated at 400˚C for 2 hour and at 500˚C for 1h in hydrogen atmosphere, respectively. The reduction-treated tungsten powders were spark-plasma sintered at 1200-1600˚C for 100-3600 sec. with applied pressure of 50 MPa under vacuum of 0.133 Pa. Maximun sindered density of 97% relative density was obtained under the condition of 1600˚C for 1h from the tungsten powder with 0.7 wt% oxygen. Sintering activation energy of 95.85kJ/mol-1 was obtained, which is remarkably smaller than the reported ones of 380~460kJ/mol-1 for pressureless sintering of micron-scale tungsten powders.

본 연구에서는 LSCF/GDC (20 : 80 vol%) 복합 분리막 표면에 LSC/GDC (50 : 50 vol%) 활성층을 코팅한 후 활성층의 열처리 온도, 두께, 침투법을 이용한 STF 도입이 산소투과 특성에 미치는 영향을 고찰하였다. 활성층 도입은 복합 분리막의 산소 투과 유속을 급격히 증진시켰으며 이는 활성층 성분인 LSC/GDC (50 : 50 vol%)가 전자 전도성 및 표면 산소 분해 반응을 증진시켰기 때문이었다. 활성층의 열처리 온도가 900˚C에서 1000˚C로 증가한 경우, 산소 투과 유속은 증가하였고 이는 분리막과 활성층 사이 그리고 활성층의 결정입간 접촉이 증진하여 산소이온과 전자 흐름을 증진시켰기 때문으로 설명되었다. 코팅층의 두께가 약 10μm에서 약 20μm로 증가한 경우, 산소 투과 유속은 오히려 감소하였는데 이는 코팅층의 두께가 증가할수록 기공을 통한 공기 중의 산소 유입이 어려워지기 때문으로 설명되었다. 또한, 코팅층에 침투법을 이용하여 STF를 도입한 경우가 STF를 도입하지 않은 경우 보다 높은 산소 투과 유속을 보였는데 이는 도입된 STF가 산소 분해하는 표면 반응 속도를 촉진시키기 때문이다. 본 연구로부터 LSC/GDC (50 : 50 vol%) 활성층 코팅 및 특성 제어는 LSCF/GDC (20 : 80 vol%) 복합 분리막의 산소투과 증진에 매우 중요함을 확인하였다.

미더덕의 집단폐사가 주로 발생하는 여름철 고수온 및 빈산소에 의한 생물학적 지표를 찾아 대량폐사 원인 구명을 위한 기초자료로 활용하기 위하여 수온상승 및 용존산소농도 감소에 따른 미더덕의 생존율, 생리적 반 응 및 조직학적 변화 등을 조사하였다. 수온상승에 따른 생존율은 수온 23􀆆C에서 63.3%, 26􀆆C 에서 56.6%였으며, 수온 29􀆆C에서 노출 6일째 모두 사 망하여 노출 6일 동안의 반수치사 수온은(6day-LT50)은 24.58􀆆C (19.48~35.48􀆆C)였다. 용존산소 농도 감소에 따 른 생존율은 노출 11일째 용존산소농도 4.0 mg L-1에서 20%였으며, 2.0 mg L-1에서는 모두 사망하였고, 반수치사 용존산소 농도 (11day-LC50)는 3.88 mg L-1 (3.29~4.57 mg L-1)였다. 산소소비율과 암모니아질소 배설률은 임계 수온 및 임계용존산소 농도이하에서 감소하였다. 수온 상승 및 용존산소 농도 감소에 따른 미더덕의 새낭, 소화관 및 피낭의 병리조직학적 결과는 각 기관을 구성하고 있는 상피세포층의 증식, 응축 및 괴사, 식세포 및 혈구침윤, 섬모탈락, 근섬유 변성 등의 변성이 공통적 으로 관찰되었다. 미더덕은 수온 24􀆆C 이상, 용존산소 3.8 mg L-1 이하에서 조직학적 병변, 대사율 감소 등으로 환 경변화에 매우 민감한 생물이므로 여름철에 양성되고 있는 미더덕의 양식장관리에 세심한 관리가 요구된다.