In environments where buffer materials are exposed to increased temperature due to the decay heat emitted by radioactive waste, it is crucial to assess the performance of the buffer material in relation to temperature effects. In this study, we conducted experiments using Bentonil-WRK, a calcium-type bentonite, compacted to a dry density of 1.65 g/cm3 and an initial water content of 15%. The experimental temperature conditions were set to 30, 60, 90, 110, and 130°C. We observed that the swelling pressure of the compacted bentonite buffer decreased as the temperature increased. The findings from this study can provide valuable guidance for the design of high-level waste repository in Korea.

Backfill is one of the key elements of deep geological disposal. The backfill material is used to fill disposal tunnels and is mainly composed of swellable clay, preventing the migration of nuclide and structurally supporting the tunnel. The selection and application of backfill material are critical for the stable and efficient disposal of spent fuel. Therefore, it is essential to secure various candidate materials for backfill and to comprehensively understand the properties and behavior of these materials. Recently, the Korea Atomic Energy Research Institute has selected a candidate material called Bentonil-WRK and is evaluating its applicability. To utilize this material as backfill, the safety function of a mixed backfill concept, consisting of sand and Bentonil-WRK, was assessed. The swelling pressure was measured as a function of dry density for a bentonite/silica sand mix ratio of 3/7. The results showed that the swelling pressure ranged from 0.15 to 0.273 MPa, depending on the dry density, with higher dry densities resulting in higher swelling pressures. The measured swelling pressure met the target performance criteria suggested by SKB and Posiva (i. e., 0.1 MPa), but did not meet the design requirement for swelling pressure (i. e., 1 MPa). This indicate the need for further research after increasing the mass fraction of bentonite (e. g., mix ratio 4/6 or more). The results of this study are expected to be used in the selection of candidate backfill materials and the establishment of design guidelines for engineered barrier backfill.

Compacted bentonite buffer materials are a key component of the engineered barrier system for high-level radioactive waste disposal. The bentonite buffer is saturated via groundwater flow through the excavation damaged zone in the adjacent rock mass. Bentonite saturation results in bentonite swelling, gelation and intrusion into the nearby rock discontinuities. Groundwater flow can cause bentonite erosion and transportation of bentonite colloids. This bentonite mass loss can negatively impact the long-term integrity of the engineered barrier system. Hence, it is necessary to understand the effects of erosion on the properties of the bentonite buffer. In this study, a series of artificial fracture erosion experiments are conducted to investigate the erosion characteristics of compacted Ca-bentonite buffer materials for different initial dry density conditions. Compacted bentonite blocks and bentonite pellets were manufactured using the cold isostatic pressing technique and granulation compactor respectively. The specimens were placed in a custommade transparent artificial fracture cell and the bentonite intrusion characteristics were monitored for two months under free swelling conditions with no groundwater flow. The radial expansion of the bentonite specimens within the artificial fracture was measured using a digital camera. In addition, the swelling pressure, displacement, and saturation were determined using a load cell-piston system, LVDT, and electrical resistivity electrodes respectively. A hydro-mechanical-chemical coupled dynamic bentonite diffusion model was applied to model the bentonite erosion characteristics using COMSOL Multiphysics.

Increasing thermal conductivity of buffer materials makes the disposal tunnel and hole spacings in high-level radioactive waste (HLW) repositories decrease, so that the area of the HLW repository decreases, which gives more choices to choose the HLW repository site and economical cost savings to construct HLW repositories. Thus, developing enhanced buffer materials with improved thermal conductivity is needed. One of the methods to develop enhanced buffer materials is to add additives to the bentonite which is main material for buffer materials. Most additives have high thermal conductivity, but most additives do not swell or less swell than bentonite, so that the swelling pressure of the enhanced buffer materials by additives decreases compared to the swelling pressure of pure bentonite buffer materials. Swelling pressure is an important performance criterion to design buffer materials. Thus, it is important to confirm the swelling pressure of the enhanced bentonite. However, it is not simple to measure the swelling pressure of the buffer materials and furthermore, it takes several days to measure the swelling pressure of the buffer materials. For these reasons, swelling index can be considered to predict the swelling pressure of the enhanced buffer materials relatively. In this study, it was investigated through tests how the swelling index of bentonite-sand mixtures change according to the amount of sand and it was found that the linear relationship between swelling index and sand amount in the bentonite-sand mixtures.

Swelling of the heat-treated netting for gillnet was estimated through the netting height in square acrylic tank. Experimental Nylon netting and PBSAT netting were heat-treated by using the high-degree vacuum method in hot water after net making. Heat-treatment temperatures were conducted with Nylon netting 105°C and PBSAT netting 62°C, 65°C, 66°C, 67°C. The swelling measurement method of a netting using the square tank was capable of the reduction measurement errors comparing with measurement methods of a mesh inner angle and the shortening rate of a mesh size. In addition, this method was available to comparison evaluation for each netting more easily. Wet type heat-treatment apparatus with high-degree vacuum was shown higher 7∼8°C inner side temperature than a setting temperature. The tensile strength and elongation of Nylon netting and PBSAT netting were shown higher wet condition than dry condition. The tensile strengths of PBSAT monofilaments in dry and wet condition were sharply decreased at heat-treatment temp. 75°C than heat-treatment temp. 74°C

국산 칼슘 벤토나이트를 대상으로 온도가 팽윤압에 미치는 영향을 관찰하였다. 벤토나이트를 건조밀도 1.6 g/㎤으로 압축하고, 0.69 MPa의 일정한 수압으로 증류수를 공급하여 팽윤압을 측정하였다. 온도 영향 실험은 25℃, 30℃, 40℃, 50℃, 60℃, 70℃에서 승온조건과 감온조건으로 수행하였다. 압축 벤토나이트가 물과 접촉하여 상온에서 5.3 MPa의 충분히 높은 팽윤압이 작용하는 것을 실험적으로 확인하였다. 팽윤압 은 온도가 높을수록 감소하는 것으로 나타났다. 승온조건과 감온조건에서의 온도에 따른 팽윤압 거동에 차이를 보이며, 승온조건에서 온도에 따른 변화가 심하게 나타났다. 향후 온도 조건 외에 벤토나이트의 압축 밀도 변화, 지하수 조성에 따라 팽윤압 특성이 어떻게 변화하는지에 대해 평가한다면, 앞으로 국내 고준위 폐기물 처분장의 개념 설계에 유용하게 활용될 수 있을 것으로 본다.

The role of Cl channels in regulatory volume decrease (RVD) in human salivary gland acinar cells was examined using a whole-cell patch clamp technique. Human tissues were obtained from healthy volunteers or from patients with oromaxillofacial tumors. During the measurements, K+-free solutions were employed to eliminate contamination of whole-cell conductance by K+ currents. When the cells were exposed to a 70% hypotonic solution, outward-rectifying currents, which were not observed in the resting state, were found to have significantly increased both in human labial and parotid gland acinar cells. The amplitudes of the currents were reduced in a low CI bath solution. Furthermore, the addition of 100μM 5-Nitro-2- (3-phenyl propylamino) benzoic acid (NPPB) or 100μM 4,4'-diisothio cyanatostilbene-2,2'-disulphonic acid (DIDS), known to partially block Cl channels, significantly inhibited these currents. Its outward-rectifying current profile, shift in reversal potential in a low Cl bath solution and pharmacological properties suggest that this is a Cα2+ independent, volume activated Cl current. We conclude therefore that volume activated Cl channels play a putative role in RVD in human salivary gland acinar cells.

Superporous Hydrogels (SPHs) have been extensively investigated for various biomedical applications due to their fast swelling and superabsorbent properties. In this study, glycol chitosan that is one of most abundant natural polymers was used as a cross-linking agent instead of bisacrylamide (BIS), which is a broadly used crosslinking agent for preparation of SPHs. Glycol chitosan was modified to have reactive vinyl groups by chemical conjugation with glycidyl methacrylate (GMA). The vinyl group-containing glycol chitosan (GC-GMA) was characterized by FT-IR and 1H-NMR measurements. SPHs have been prepared in various synthetic conditions to establish the optimum synthetic process for making superporous structure, where the inner pores are interconnected to each other to form a open channel structure. Various SPHs with different GC-GMA contents have been successfully prepared and have been observed to show faster swelling properties than other conventional SPHs. From the study on the swelling behavior of SPHs, the GC-GMA content is considered to be an important factor for controlling their swelling properties.

Purposes : The effect on corneal swelling and curvature changes in the region of center and peripheral under wearing of therapeutic lenses on a daily and extended wear basis is analyzed. Methods : Thirty three college students(22.4±1.92 years old. 12 males and 21 femaJes) who consent to this clinical triaJ and have no ocuJar surgicaJ history and contact Jens complications were participated in clinical trial. Six therapeutic Jenses which are being prescribed most commonly in the clinic were fitted on the r ight eye(wear group) and no Jens fitted on the Jeft eye(control group). Each eye was examined after 8hours and 24 hours to compare cornea thickness and curvature changes. ln order to fit another Jens in turn. 48 hours interval at the !east was required and no other lenses were not allowed during trial Jens wear. Results : Comeal swelling induced by therapeutic soft contact Jens wear was significantly different in 8 hours(F=33.00. p=O.OO) and in 24 hours(F=38.83. p=O.OO). The degree of swelling in 8 hours of Jens wear was : A Jens(HENIA+ NV. WC : 38%. Dk/t : 7.86) 3.57±2.22%. D Jens(HEMA, WC : 55%. Dkft: 15.68) 3.18±2.05%. F Jens(HEMA+NVP, WC: 55%, Dk/t: 15.92) 2.79±1.61%. C Jens(Vifilcon A. WC: 55%, Dk/t : 23.88) 1.54±1.66%. B Jens(Ocufilcon D. WC: 55%. Dk/t : 26.85) -0.59±2.13%, E Jens(Lotrafilcon A. WC : 24%, Dk/t : 160.92) -0.70±1.53% in that order. The degree of swelling in 24 hours was : A Jens 8.50±3.71. D Jens 8.16±3.58%. F Jens 6.68±3.66%, C Jens 4.31±2.11%. B Jens 2.86±2.84%. E lens -0.03±1.97% respectiveJy. The order in 8 hours was ass that in 24 hours. Conclusions : Therefore. B Jens, C lens, E Jens are found to be more suitabJe for therapeutic Jens in this study. In case of A Jens, D Jens, F Jens which caused significant swelling, in order to confirm if those lenses are suitable for therapeutic Jens, further study on deswelling during day time after extended Jens wear is needed.

고준위폐기물처분장의 완충재 물질로 사용되는 팽윤성 점토는 방벽재로서 그 기능을 제대로 발휘하기 위해 오랫동안 물리 화학적으로 안정해야 한다. 팽윤성 점토의 장기건전성 관련인 자들을 검토하고, 처분장 성능에 대한 각 인자의 중요성을 평가하였다. 검토결과, 붕괴 열에 의한 온도상승, 지하수 화학, 콘크리트에 의한 pH 증가, 유기물과 미생물, 방사선 조사 및 기계적 교란은 완충재물질로서 팽윤성 점토의 장기건전성에 중요한 인자임을 확인하였다. 본 연구는 고준위폐기물 처분장에서 팽윤성 점토의 완충재 설계를 위한 기초자료로 유용하게 활용될 것이다.

The objective of this study was to establish the optimal conditions for hypoosmotic swelling (HOS) test to assess the functional integrity of the membranes of boar fresh or frozen/thawed spermatozoa. When pooled semen sample was incubated for 30 min at 37℃ with different test solution of varied osmolarity, the highest percentage of HOS positive spermatozoa was observed in a 150 mOsmol fructose/Na-citrate solution (33.6%). Incubation time did not affect significantly the score of HOS positive spermatozoa observed in a 150 mOsmol fructose/Na-citrate solution at 37℃, but the osmolarity affected the score of HOS positive spermatozoa under the same condition above. Fresh semen was significantly better than frozen/thawed semen in semen parameters evaluated such as motility, viability, membrane integrity and lipid peroxidation (p<0.05). In the relationships of sperm parameters, motility vs viability, motility vs membrane integrity and viability vs membrane integrity were positively correlated (0.82～0.94) but lipid peroxidation vs other estimated factors was negatively correlated (－0.90～－0.98). Among the evaluation methods, motility vs viability, motility vs membrane integrity and lipid peroxidation vs other estimated factors were significantly correlated (p<0.05). These results of this study indicate that the optimal condition of HOST in boar spermatozoa is a 150 mOsmol fructose/Na-citrate solution for 30 min incubation at 37℃ and HOST can substitute the examination of motility, viability and lipid peroxidation.

Hypoosmotic swelling test (HOST) is used for evaluating the plasma membrane function and fertilizing ability in mammal spermatozoa. However, HOS solutions and experimental conditions have not been determined clearly for assessing canine spermatozoa. This study was conducted to examine the HOS solutions and assay conditions, including incubation time (30 to 120 min), storage temperature (4, 17 and 20℃), semen status (fresh and frozen). Maximum spermatozoal plasma membrane swelling was obtained in an 150 mOsm Na-citrate/Fructose solutions with an incubation time for 45 min. The storage temperature and semen status affected the percentage of HOS positive spermatozoa. The HOS test adapted to canine spermatozoa in this study was simple and highly consistent assay with good repeatability. The optimal condition of HOST in canine spermatozoa is an 150 mOsm Na-citrate/Fructose solutions with an incubation time for 45 min regardless of semen storage temperature and semen status.