The Hangang River* is necessary to manage the water environment of severe pollution due to the high density of residential areas, parks, and agriculture and the large population concentrated there. Benthic macroinvertebrates, such as chironomids larvae, are bioindicator species that reflect environmental changes and are crucial for water quality monitoring. In this study, we investigated morphological characteristics and molecular analysis of the chironomids larvae inhabiting the Hangang River area for water environment surveys. For this research, 20 rivers, lakes, and urban area in the Hangang River basin were selected. Chironomids larvae were collected from July to September 2022, and their appearance and characteristics were identified through morphological identification. In addition, phylogenetic analysis was performed based on the mtCOI gene sequences of the collected chironomids larvae, and identification at the genus level was confirmed. As a result, 32 species and 18 genera of 3 subfamilies of Chironomidae larvae were identified, and Stictochironomus sp. dominated most sites (6 sites). The morphological characteristics of the identified chironomids larvae, such as the mentum, ventromental plate, and antenna, were organized into table and pictorial keys, and a Bayesian inference molecular phylogeny was presented. These results provide basic morphological information for genus-level identification and can be used as fundamental information for water quality management. *The public nomenclature following by NGII 2015

본 연구에서는 울산지역에서 유통되는 로컬푸드 농산물 367건에 대해 다성분 분석법을 이용하여 잔류농약 350종 을 분석한 결과 다음과 같다. 로컬푸드 농산물에 대한 잔류농약 분석 결과 21.5%(79 건)의 검출률을 보였으며 부적합률은 1.1%(4건)으로 나타 났다. 품목별로 과일류는 65건 중 27건(41.5%), 채소류는 242건 중 50건(20.7%), 두류는 7건 중 1건(14.3%), 곡류 11건 중 1건(9.1%) 검출률을 보였고, 취나물, 곤달비, 파, 살구에서 기준치 이상의 잔류농약이 검출되었다. 검출된 잔류농약은 총 58종 163회로 살충제 성분이 가 장 많이 검출되었고 고독성 농약 1회, 보통 독성 농약 9 회, 저독성 농약이 48종이었다. 부적합 처리된 품목을 포함한 검출된 잔류농약 항목에 대한 위해도 평가 결과 위해지수(%ADI) 가 0.0000- 63.1043% 으로 모두 100% 미만으로 위해하지 않은 수준 으로 판단되었다. 지속적으로 로컬푸드 농산물의 운동 추진 방향인 지역 활성화와 안전한 먹거리 공급체계구축의 목적을 위해 엄 격히 관리되는 기준으로 안전성 검사를 실시하고, 신뢰성 확보를 위한 생산자 교육 및 홍보, 출하 전 안전성 검사 관리시스템이 정착된다면 울산지역 로컬푸드 농산물 사업 이 더욱 활성화되고 지속적으로 추진 될 수 있을 것으로 판단된다.

Conventional flipped learning instructional models are operated in a blended learning environment online and offline. In contrast, this study moved onto fully online systems and explored how a sense of presence worked for students’ learning outcomes at university English writing courses. The two research questions for this study are: 1) What is the relationship between a sense of presence (teaching, cognitive, social presence) and learning outcomes (group cohesion, class satisfaction)? and 2) What are the variables among a sense of presence that affect group cohesion and class satisfaction? For the purposes of this study, 46 university students from English composition courses answered student questionnaires in the spring of 2021. Correlation and multiple-regression analyses were conducted to look into the relationships among the variables. Additionally, focus-group interviews were conducted and teaching journals were analyzed. The major findings were revealed as follows: Firstly, a sense of presence was significantly related to group cohesion and satisfaction. Secondly, social presence and cognitive presence only had a predictive power of group cohesion. Thirdly, cognitive presence and teaching presence were significant predictors of class satisfaction. Pedagogical implications are discussed for those interested in applying flipped learning in a fully online setting.

본 연구는 360도 파노라마 동영상을 활용하여 해상풍력 경관의 유형을 분류하고 유형별 경관 선호 매 트릭스 요소에 따른 경관 선호도를 분석하고자 한다. 이를 위해 첫째, 연구대상지로 제주 탐라해상풍력 단지로 선정하였으며, 연구대상지를 조망할 수 있는 지점들을 추출하고 방문하여 360도 파노라마 동영 상을 촬영하였다. 둘째, 구축된 360도 파노라마 동영상 자료를 바탕으로 경관의 미학적 특성을 분석하 고 해상풍력 경관의 유형을 분류했다. 셋째, 해상풍력 경관의 유형별로 경관 선호 매트릭스 요소와 경관 선호도를 설문조사했다. 넷째, 수집된 데이터를 활용하여 해상풍력 경관 유형별 선호 매트릭스 요소에 따른 경관 선호도 관계를 분석했다. 분석 결과 해상풍력 경관 유형이 High Continuity(HCN), High Color (HCL), Low Visual Impact(LVI), High Visibility(HVI)로 분류되었다. 또한, HCN경관 선호도에 영향을 주 는 요소로는 응집성이, HCL경관 선호도에 영향을 주는 요소로는 응집성과 신비성이, LVI경관 선호도 에 영향을 주는 요소로는 응집성과 복잡성이, HVI 경관 선호도에 영향을 주는 요소로는 응집성과 가독 성이 도출되었다. 본 연구 결과를 바탕으로 해상풍력 경관 선호도 향상을 위한 전략으로 (1)시각적 영향 을 줄일 수 있는 식재계획 및 동선설계, (2)해상풍력 터빈의 생상 대비 극대화, (3)해상풍력 터빈 설치전 경관 시뮬레이션을 제안하였다.

Measuring the concentration of corrosion products or nuclear fission products (FPs) in molten salts is crucial for pyroprocessing and molten salt reactors. Electrochemical analysis methods that can be performed in situ offer significant advantages for monitoring the concentration of corrosion products or FPs in molten salts. A microelectrode is an electrode with a length of several tens of micrometers on one side. The use of a microelectrode for electrochemical analysis has several advantages due to its small size, including rapidly reaching the limiting current regardless of the scan rate, immediate attainment of the limiting current upon applying an overpotential for instant monitoring within milliseconds, accurate measurement even in low convection systems, a small iR drop resulting from low flowing current and high signal accuracy, and high current density resulting in a high signal-tonoise ratio (SNR). Among various methods for making microelectrodes, techniques involving cutting a thin wire or using capillaries (such as the dual-bore capillary and pulled glass capillary methods) require precise manual skills and experience. Therefore, the results may vary depending on the maker’s skill level, and it can be difficult to control the electrode’s area, thickness, and surface uniformly. Recent research has focused on using semiconductor processes to fabricate microelectrodes, where CVD, metal sputtering, photolithography, and etching processes work together to deposit, refine, and shape the required material on a silicon wafer to create microelectrodes. However, the durability of microelectrodes produced this way is still low (usable for about 15-30 minutes), and there is no clear research on the degradation mechanism over time. To verify the proper operation of the fabricated microelectrodes, cyclic voltammetry (CV) is performed at various scan rates (from 10 mVs-1 to 2 Vs-1), and chronoamperometry (CA) is also examined to confirm whether the electrodes rapidly reach a steady-state current. After confirming their proper operation, CV is continuously measured until the microelectrodes are destroyed in a LiCl-KCl solution containing a small amount of FPs (Sm 340 mM) at 450°C. By observing changes in the electrical signal of the microelectrodes over time, the durability is evaluated, and the mechanism of performance degradation of the electrode is discovered. The experiment is then repeated by gradually increasing the temperature by 30°C from 450°C up to 600°C to observe the changes with temperature. This study provides basic information for future microelectrode experiments, and by diagnosing the cause of destruction, a more durable microelectrode structure can be manufactured.

Change in chemical constitution of a zirconium sample treated at the simulated condition of a pressurized water reactor (water at 315°C and 15.5 MPa) was investigated using X-ray diffraction (XRD) and Raman spectroscopy. We observed swelling of the zirconium sample as well as the change in its color from silver to gray treated after the pressurized water at high temperature. On the basis of XRD and Raman data, we confirmed that the variation in composition of zirconium specimen from hexagonal Zr to monoclinic ZrO2 occurred at the simulated PWR condition. Therefore, we suggested that the oxidation of zirconium appeared due to the reaction with water at high temperature and pressure, as shown in the following reaction: Zr + 2H2O → ZrO2 + 2H2.

Support for nuclear power plant (NPP) dismantling & decommissioing (D&D) industry is necessary through development of the infrastructure and the D&D technology. Because KORI#1 and Wolsong#1 is planned to decommission until around 2030. Korea research institute of decommissioing (KRID) was established through the preliminary feasibility study. KRID has plan to support nuclear companies to join D&D industry. Normal facilities (Lv.1) of KRID infracstucture are currently being constructed and radiation management facilities (Lv.2) construction is expected to begin in October. Further, KRID is planning the construction of equipment to develop the procedure for radionuclide analysis through R&D project. A total period of the R&D project is 45 months, and the total R&D funding for this period is 19.4 billion won. The ultimate goal of the R&D project is to build the infractstucture base to analyze decommissioning radioactive wastes. Furthermore, the R&D project is important to reliably perform the NPP D&D.

A molten salt reactor (MSR) is a conceptual nuclear reactor that uses molten salt with liquid fuel as its primary coolant. Based on the thermophysical and neutronic properties, MSR has advantages such as high efficiency, safety, combustion of transuranic (TRU) elements, and availability of miniaturization and on-power refueling. Various research on MSR such as system development, neutronic analysis, material development, and molten salt property analysis has been conducted, but the biggest problem is the molten salt corrosion. The molten salt corrosion on structural materials can be explained by two processes; electrochemical and chemical reactions. The reduction of oxidative ions such as fuel and TRU elements is one of the major causes of molten salt corrosion. Contamination by humidity and oxygen is also known as the accelerating factor of molten salt corrosion. Also, molten salt corrosion behaviors on structural material deteriorate when dissimilar alloys are introduced in the molten salt system. Various techniques to mitigate molten salt corrosion in fluoride system has been developed, but these are not well-verified in chloride system. In this research, various methodologies to mitigate molten salt corrosion are studied. The corrosion behaviors of 80Ni-20Cr alloy in molten eutectic NaCl-MgCl2 salt at 973 K are analyzed with various applications such as salt purification, sacrificial metal injection, and salt redox potential control. Oxygen and water impurities that can accelerate molten salt corrosion have been removed by electrochemical and chemical methods; Applying the reduction potential for H+/H2 and oxidation potential for O2-/O2, introducing HCl and CCl4 gas, and introducing the metallic Cr and recovering the ionized Cr. Corrosion acceleration/deceleration effects were analyzed when introducing the reducing reagent such as Mg and Nb or oxidizing reagent such as metallic Mo and the effect of inert metallic element (W) was also investigated. The salt potential was controlled by applying the potential to the salt and adjusting the Eu3+/Eu2+ ratio.

According to ISO 4037, the thickness of the inherent filtration for the radiation qualities L-40 to L- 240, N-40 to N-400, W-60 to W-300 and H-80 to H-400 shall be equivalent to 4 mm Al for matched reference radiation fields or adjusted as far as possible to 4 mm Al for characterized reference radiation fields. And for matched reference fields, the tube window must be made of beryllium and its thickness should not exceed 10 mm. In the case of characterized reference fields, the thickness of the beryllium window should not exceed 10 mm, but it is acceptable to use an aluminum window with a maximum thickness of 1.5 mm. 320 KV X-ray tube installed at KHNP-CRI has been designed to equipped with a 3 mm Be for tube window and an additional 4 mm Al to obtain a total inherent filtration equivalent to that of 4 mm Al. In the previous study, the inherent filtration of 320 kV X-ray tube at KHNP-CRI has been verified by MCNP simulation. However, the ISO standards suggest a method for determining the thickness of the inherent filtration by half-value layer (HVL) measurement and spectrometry. In this regard, the inherent filtration was reassessed using HVL measurement. To determine the inherent filtration, 1st HVL of the beam generated by the tube at a tube potential 60 kV was measured. The measurements were conducted with a calibrated spherical ionization chamber (model A3, Exradine) placed at a distance of 1 m from the target, at the center of the radiation field size. The X-ray tube current was set to 2 mA. The thickness of aluminum absorbers was gradually adjusted in subsequent measurements until approached the 1st HVL. 1st HVL were estimated using the linear regression equation computed with the current values for the thickness of the absorbers. As a results, the thickness of the 1st HVL was estimated as 2.845 mm Al. According to the correlation between the inherent filtration and 1st HVL suggested in ISO standard, the value of the inherent filtration was deduced as 4.25 mm Al that is rounded to the nearest 0.05 mm by interpolation. Further studies on the effects of the inherent filtration thickness determined in this study will be conducted.

The nuclear facilities at Korea Atomic Energy Research Institute (KAERI) have generated a variety of liquid radioactive waste and most of them have low-level radioactive or lower levels. Some of the liquid radioactive waste generated in KAERI is transported to Radioactive Waste Treatment Facility (RWTF) in 20 L container. Liquid radioactive waste transported in a 20 L container is stored in a Sewer Tank after passing through a solid-liquid separation filter. It is then transferred to a very low-level liquid radioactive waste Tank after removing impurities such as sludge through a pre-treatment device. The previous pre-treatment process involved an underwater pump and a cartridge filter device passively, but this presented challenges such as the inconvenience of having to install the underwater pump each time, radiation exposure for workers due to frequent replacement of the cartridge filter, and the generation of large amounts of radioactive waste from the filter. To address these challenges and improve efficiency and safety in radiation work, an automated liquid radioactive waste pre-treatment device was developed. The automated liquid radioactive waste pre-treatment device is a pressure filtration system that utilizes multiple overlapping filter plates and pump pressure to effectively remove impurities such as sludge from liquid radioactive waste. With just the push of a button, the device automatically supplies and processes the waste, reducing radiation hazards and ensuring worker safety. Its modular and mobile design allows for flexible utilization in various locations, enabling efficient pre-treatment of liquid radioactive waste. To evaluate the performance of the newly constructed automated liquid radioactive waste treatment device, samples were taken before and after treatment for 1 hour cycling and analyzed for turbidity. The results showed that the turbidity after treatment was more than about four times lower than before treatment, confirming the excellent performance of the device. Also, it is expected that the treatment efficiency will improve further as the treatment time and number of cycles increase.

The acceptance criteria for low and intermediate level radioactive waste disposal facilities in Korea to regulate that homogeneous waste, such as concentrated waste and spent resin, should be solidified. In addition, solidification requirements such as compressive strength and leaching test must be satisfied for the solidified radioactive waste solidified sample. It is necessary to develop technologies such as the development of a solidification process for radioactive waste to be solidified and the characteristics of a solidification support. Radioactive waste solidification methods include cement solidification, geopolymer solidification, and vitrification. In general, low-temperature solidification methods such as cement solidification and geopolymer solidification have the advantage of being inexpensive and having simple process equipment. As a high-temperature solidification method, there is typically a vitrification. Glass solidification is generally widely used as a stabilization method for liquid high-level waste, and when applied to low- and intermediate-level radioactive waste, the volume reduction effect due to melting of combustible waste can be obtained. In this study, the advantages and disadvantages of the solidification process technology for radioactive waste and the criteria for accepting the solidified material from domestic and foreign disposal facilities were analyzed.

As if the wet storage of Spent Nuclear Fuel (SNF) becomes saturated, a transition from wet storage to dry storage could be required. The first process for dry storage is to move SNF from the wet storage into a canister for dry storage, and secondly perform a drying process to remove the moisture in the canister to prevent a potential impact such as deterioration of cladding or corrosion of the interior material. Nuclear Regulatory Commission (NRC) accepts the conditions describing the adequate dryness state that remain below the pressure of 3 Torr for 30 minutes in the drying process. That is, the most pressure of water vapor that may exist inside the canister is 3 Torr. If it is maintained below 3 Torr, it can be determined that the dryness criterion is satisfied. Based on this, relative humidity and dew point trends can be identified. Relative Humidity (RH) is calculated by dividing the vapor pressure by the saturated vapor pressure. Here, if the vapor pressure is fixed at 3 Torr, which is the dryness criterion value, the relative humidity has a value according to the saturated vapor pressure. Saturated vapor pressure is a value that varies with temperature, so relative humidity varies with temperature. On the other hand, the dew point temperature has a value according to the water vapor pressure. Therefore, when the internal temperature of the canister is 120°C and the water vapor pressure is 3 Torr, the relative humidity is 0.2% and the dew point temperature is -4.4°C. We will confirm the suitability of the dryness criterion through the drying tests, and secure a technology that can measure and evaluate the amount of moisture remaining inside the canister.

The purpose of this study is to provide technical issues in upgrade and modification of fuel handling equipment at operating nuclear power plants. The improvement for safety function and performance enhancement of fuel handling equipment has been going on for 20 years since the early 2000’s. This improvement is recently focused on the replacement of components through the performance analysis and the operation and maintenance plan based on replacement cycle of its component. Additionally, it is required to secure spare parts so that it can be operated at all times with compatibility and standardization to other domestic nuclear power plants. The fuel handling equipment is consisted of refueling machine, upender and carriage of fuel transfer system, spent fuel handling machine, new fuel elevator and various tools, and the equipment are linked in systematic interlocks. Fuel handling is a critical task during a nuclear power plant refueling outage. Even minor component defects may stop operation of the whole system and have a significant impact on the overall system process. To achieve this goal, major components that are expected to be replaced for reliable operation are summarized as follows; 1) motor assembly with AC servomotors and driver for bridge, trolley and hoist of refueling machine and spent fuel handling machine, 2) winch motor and drive for upender and carriage of fuel transfer system, 3) operator control console with a HMI PC base PLC (Programmable Logic Controller) control system, 4) positioning and load weighing sensors such as an encoder and a load cell with its support for periodic calibration and maintenance, 5) main power drapped style festoon cable assembly for bridge of refueling machine, 6) pneumatic control assembly for gripper operation of refueling machine, 7) active components (e. g., air motor, hydraulic cylinder and limit switch) to be removable and reinstallable without requiring the water level to be lowered. It is advisable to utilize such various information as it can help to improve reliability of fuel handling as a critical path in upgrade and modification of fuel handling equipment at operating nuclear power plants.

Separating nuclides from spent nuclear fuel is crucial to reduce the final disposal area. The use of molten salt offers a potential method for nuclide separation without requiring electricity, similar to the oxide reduction process in pyroprocessing. In this study, a molten salt leaching technique was evaluated for its ability to separate nuclides from simulated oxide fuel in MgCl2 molten salts at 800°C. The simulated oxide fuel contained 2wt% Sr, 3wt% Ba, 2wt% Ce, 3wt% Nd, 3wt% Zr, 2wt% Mo, and 89wt% U. The separation of Sr from the simulated oxide fuel was achieved by loading it into a porous alumina basket and immersing it in the molten salt. The concentration of Sr in the salt was measured using ICP analysis after sampling the salt outside the basket with a dip-stick technique. The separated nuclides were analyzed with ICP-OES up to a duration of 156 hours. The results indicate that Ba and Sr can be successfully separated from the simulated fuel in MgCl2, while Ce, Nd, and U were not effectively separated.

In the wake of the Fukushima NPP accident, research on the safety evaluation of spent fuel storage facilities for natural disasters such as earthquakes and tsunamis has been continuously conducted, but research on the protection integrity of spent fuel storage facilities is insufficient in terms of physical protection. In this study, accident scenarios that may occur structurally and thermally for spent fuel storage facilities were investigated and safety assessment cases for such scenarios were analyzed. Major domestic and international institutions and research institutes such as IAEA, NEA, and NRC provide 13 accident scenario types for Spent Fuel Pool, including loss-of-coolant accidents, aircraft collisions, fires, earthquakes. And 10 accident scenario types for Dry Storage Cask System, including transportation cask drop accidents, aircraft collisions, earthquakes. In the case of Spent Fuel Pool, the impact of the cooling function loss accident scenario was mainly evaluated through empirical experiments, and simulations were performed on the dropping of spent nuclear fuel assembly using simulation codes such as ABAQUS. For Dry Storage Cask System, accident scenarios involving structural behavior, such as degradation and fracture, and experimental and structural accident analyses were performed for storage cask drop and aircraft collision accidents. To evaluate the safety of storage container drop accidents, an empirical test on the container was conducted and the simulation was conducted using the limited element analysis software. Among the accident scenarios for spent fuel storage facilities, aircraft and missile collisions, fires, and explosions are representative accidents that can be caused by malicious external threats. In terms of physical protection, it is necessary to analyze various accident scenarios that may occur due to malicious external threats. Additionally, through the analysis of design basis threats and the protection level of nuclear facilities, it is necessary to derive the probability of aircraft and missile collision and the threat success probability of fire and explosion, and to perform protection integrity evaluation studies, such as for the walls and structures, for spent fuel storage facilities considering safety evaluation methods when a terrorist attack occurs with the derived probability.

본 연구는 팀발명의 정도에 있어서 상당한 차이를 보이면서 전자산업, 자동차산업에서 가장 많은 특허를 출원해온 삼성전자와 현대자동차 발명자들을 대상으로 네트워크 특성들이 발명 자들 간 혁신성과 차이를 가져오는지를 분석하였다. 네트워크 내에서 더 많은 발명자들과 연결 되어 있을수록 더 높은 혁신성과를 보였다. 기존 문헌들이 산업내 및 산업간, 그룹내 및 그룹외 파급효과를 조직 수준에서 다루었는데, 본 연구는 이러한 논의를 발명자 수준으로 확장하였다. 본 연구는 네트워크로부터의 파급효과풀을 새롭게 추가하여 네트워크 내외, 그룹 내외, 산업 내외의 3가지 차원에서 파급효과풀들을 구성한 후 각 파급효과풀들이 미치는 효과를 분석하였 으며 서로 간에 비교하였다. 발명자 수준에서 다양한 파급효과풀들이 혁신에 미치는 효과가 확인되었다. 본 연구의 결과는 발명자의 네트워크 특성들과 파급효과풀들이 발명자의 혁신 성과에 대한 예측에 활용될 수 있음을 시사한다.

In order to provide basic data to increase the efficiency and stability of seamanship at anchoring, the characteristics of the hull motion including dragging anchor due to external forces were observed at Mokpo and Jinhae anchorage for the avoidance of the typhoon. As a result, it is necessary to check the embedding motion and holding power of the anchor according to at initial position to decrease dragging anchor. Dragging anchor at anchorage seems to have been easily caused according to discrepancy between embedded anchor flukes and the towing direction due to the change in wind direction, rather than the wind speed. This discrepancy, thus, should be considered when anchoring. This test vessel with a small radius of curvature of the stem is relatively vulnerable to the influence of wind direction and wind speed, so it is easy to cause a decrease in the holding power due to an increase in the rate of turn. When the current speed is greater than or equal to 1 knot, the range of the rate of turn is reduced resulting in a relatively increased holding power. In addition, during the swing, the tension of the chain was high according to the angular velocity change of heading at three-quarters of the swing length rather than the left and right ends.

This study was carried out to determine the sprouting period of early and mid-season varieties, which includes ‘Atlantic’, ‘Chubaek’, and ‘Superior’, during the summer storage period in a semi-underground warehouse without cooling system. And also it was investigated the effect of chlorpropham [Propan-2-yl N-(3-chlorophenyl)carbamate, CIPC] treatment on the sprouting inhibition for the varieties. This study was conducted to figure out a sprout inhibitory effect when CIPC was applied to 1kg of the potato tubers at concentrations of 10 mg and 20 mg which are lower than the treatment concentrations of ca 30 mg prescribed by the positive list system (PLS). The internal temperature of the warehouse used in this experiment was lowered by 5°C or more than the outside temperature. The difference between the lowest and highest temperature during the experiment throughout the day was 5°C. It showed the effect of reducing to 1/2 of the difference in outdoor temperature. As for the sprouting of potatoes, the extremely early variety ‘Chubaek’ sprouts appeared at the 6th week of storage of control and it was the fastest sprouting potato among the control groups of the varieties. Sprouting began to appear in the Superior at the 6th week of storage, while the ‘Atlantic’ sprouted at the 8th week of storage. The appearance of sprouts was suppressed in all treatment groups of ‘Atlantic’ and ‘Superior’ varieties in CIPC treatments. Sprouts were observed in all treatment groups of ‘Chubaek’ after the 7th week, but the elongations of the sprouts in tubers were completely inhibited until the 8th week of storage. ‘Atlantic’ and ‘Superior’ seemed to have a sprouting inhibitory effect even with a low CIPC concentration of 10 mg·kg-1, with the exception of extremely early variety ‘Chubaek’ that breaks out of the dormancy quickly. Although weight loss occurred continuously during storage, it was minor loss of 0.7-1.6%. There was no consistent trend for changes of the loss in the varieties and CIPC treatments. Most common pathological disorder was the dry rot during the experiment, but only few were affected. The use of the tubers treated at 18°C and 90% RH for 10 days and the rack of refrigeration system which lead to lack of convection seemed to have suppressed the spread of pathogens.