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The isolation of single cells and their further cultivation in confined chambers are essential to the collection of statistically reliable temporal information in cell-based biological experiments. In this work, we present a hydrodynamic single-cell trapping and culturing platform that facilitates biological analysis and experimentation of virus infection into host cells. To find the optimum design of the cell trap at the microscale, we evaluated hook traps with different widths and trap intervals to obtain a high trapping efficiency of a single cell. The proposed design leverages the stochastic position of the cells as they flow into the structured microfluidic channels, where hundreds of single cells are then arrayed in nanoliter chambers for simultaneous cell-specific data collection. Optimum design is used to devise and implement a hydrodynamic cell-trapping mechanism that is minimally detrimental to the cell viability and retains a high trapping efficiency (90%), with the capability of reaching high fill factors (90%) in short loading times (10 min) in a 450-trap device. Finally, we perform an analysis of host-viral interactions under the treatment of a drug concentration gradient as a proof of concept.

For the practical use of synthetic hydrogels as artificial biological tissues, flexible electronics, and conductive membranes, achieving requirements for specific mechanical properties is one of the most prominent issues. Here, we demonstrate superstrong, superstiff, and conductive alginate hydrogels with densely interconnecting networks implemented via simple reconstructing processes, consisting of anisotropic densification of pre-gel and a subsequent ionic crosslinking with rehydration. The reconstructed hydrogel exhibits broad ranges of exceptional tensile strengths (8–57 MPa) and elastic moduli (94–1,290 MPa) depending on crosslinking ions. This hydrogel can hold sufficient cations (e.g., Li+) within its gel matrix without compromising the mechanical performance and exhibits high ionic conductivity enough to be utilized as a gel electrolyte membrane. Further, this strategy can be applied to prepare mechanically outstanding, ionic-/electrical-conductive hydrogels by incorporating conducting polymer within the hydrogel matrix. Such hydrogels are easily laminated with strong interfacial adhesion by superficial de- and re-crosslinking processes, and the resulting layered hydrogel can act as a stable gel electrolyte membrane for an aqueous supercapacitor.

Marine plankton comprise the largest portion of the marine biomass, and play critical roles in the global carbon cycle. The carbon retention of marine-plankton communities is as important as their primary production; however, data on the annual carbon retention of marine-plankton communities based on daily sample analysis are limited. Using our published and unpublished data, we calculated the one-year integrated carbon retention of a marine-plankton community at an innermost fixed station in the highly eutrophic Masan Bay, Korea, collected daily from June 2004 to May 2005. The total one-year integrated carbon retention of all plankton taxa in the study period was 471 g C m−3 yr−1. The integrated carbon retentions by phytoplankton, heterotrophic protists, and heterotrophic bacteria were 344, 76, and 40 g C m−3 yr−1, respectively, whereas those by photosynthetic ciliates and metazooplankton were 9 and 2 g C m−3 yr−1, respectively. Among the plankton subgroups, the integrated carbon retention by the phototrophic dinoflagellates (109 g C m−3 yr−1) was highest, followed by raphidophytes (88), cryptophytes (73), diatoms (43), heterotrophic bacteria (40), and heterotrophic dinoflagellates (39). The total duration of the red tides by diatoms that grow using only photosynthesis (42 days), was considerably shorter than that of phototrophic dinoflagellates, raphidophytes, or cryptophytes, which can grow mixotrophically (56–135 days). The shorter duration of red tides by diatoms was primarily responsible for their lower carbon retention, although the maximum growth rates of the diatoms were considerably higher than those of the flagellates. The percentage of the 1-year integrated carbon retention of the heterotrophic protists relative to that of the phytoplankton was approximately 20%, similar to the mean-gross-growth efficiency of heterotrophic-protist grazers on phytoplankton, indicating a good balance between these two components in the planktonic food web. This study reported one-year integrated carbon retention of marine plankton at the species level, calculated based on daily samples, and thus gave an insight into which, and to what extent, species and groups contribute to the total carbon retention of plankton for one year in a highly eutrophic bay.

Among mixotrophic dinoflagellates, the maximum mixotrophic growth rate of the red-tide dinoflagellate Paragymnodinium shiwhaense is relatively high, whereas mortality due to predation is low. To investigate the effects of major environmental parameters on P. shiwhaense, growth and ingestion rates of one strain of P. shiwhaense on the algal prey species Amphidinium carterae (also a dinoflagellate) were determined under various light intensities (0-500 μE m-2s-1), water temperatures (5-30 °C), and salinities (5-40). Cells of P. shiwhaense did not grow well in darkness but grew well at light intensities ≥ 10 μE m-2s-1. There were no significant differences in either growth or ingestion rates of P. shiwhaense fed A. carterae at light intensities between 10 and 500 μE m-2s-1. Furthermore, P. shiwhaense did not grow at 5 °C or ≥ 28 °C. Its growth rates between 7 and 26 °C were significantly affected by temperature, and the optimal temperature for maximal growth was 25 °C. With increasing salinity from 5 to 20, the growth rate of P. shiwhaense fed A. carterae increased and became saturated at salinities between 20 and 40, while the ingestion rate at salinities between 10 and 40 did not significantly change. Thus, overall, the growth and ingestion rates of P. shiwhaense fed A. carterae were affected by temperature and salinity, but not by light intensity other than darkness. These findings provide a beginning basis for understanding the ecology of this potentially harmful algal species in marine coastal ecosystems.

Background Intra-operative estimation of stem anteversion in total hip arthroplasty (THA) using postero-lateral approach is made by the surgeon's visual assessment, using the tibia as a guide, with the assumption that tibial axis is vertical to the trans-epicondylar axis. However, the accuracy of the intra-operative estimation has rarely been verified with postoperative CT-scans, with controversies regarding these measurements particularly in case of knee osteoarthritis. Therefore we performed a prospective study to: (1) determine the accuracy of the intra-operative measurement and (2) investigate factors affecting the discrepancy between the surgeon's estimation and the real stem anteversion. Hypothesis Intra-operative estimation of stem anteversion correlated with the real stem anteversion on CT-scan. Patients and methods Sixty-seven THAs using cementless straight stems (65 patients) without ipsilateral total knee arthroplasty were prospectively evaluated to compare the intra-operative measurement of stem anteversion with the real stem anteversion on computed tomography (CT) scans. There were 33 men and 34 women with a mean age of 59.7 years (range, 27–84 years) at the time of surgery. Age, tibia plateau angle, native femoral anteversion, femoro-tibial angle, body mass index, operative site, gender, coronal and sagittal tilt of the stem, stem type, ipsilateral knee osteoarthritis, and preoperative diagnosis were analyzed to evaluate the factors affecting the discrepancy between the intra-operative and CT measurements. Results The intra-operative estimation (mean, 21.5° ± 8.5°; range, 5.0°–39.0°) was greater than the CT measurement (mean, 19.5° ± 8.7°; range, 4.5°–38.5°) by 2.0°. The mean absolute value of discrepancy was 4.5°. The correlation coefficient between intra-operative and CT measurements was 0.837. The femoro-tibial angle was associated with the discrepancy between the two measurements. In the presence of genu varum deformity, the intra-operative measurement underestimated the stem anteversion. Discussion Although intra-operative estimation of stem anteversion was slightly greater than the real stem anteversion, there was an excellent correlation between the two. The femoro-tibial angle should be considered to optimize the stem anteversion during cementless THA using postero-lateral approach. Level of evidence Level III, prospective case control study.

Stress corrosion cracking is one of the aging phenomena for the major structure components in nuclear power plant. During the operation of a power plant, stress corrosion cracks are initiated and g...

Here, we describe the study of a pneumatic bilayer valve-based microfluidic sorter to improve sorting performance and stability. Unlike conventional microfluidic fluorescence-activated droplet sorters, the mechanical flow shifting characteristics of the pneumatic bilayer valve are less affected by the physical properties of samples, making it widely applicable to various sample types. The optimization of the valve channel structure improves sorting accuracy and efficiency at higher throughput by reducing the actuation time by three times, and alignment of fluid flows reduces false-positive errors by 5.5 times which can directly affect sorting accuracy and efficiency. Under these optimized conditions, we achieve both sorting accuracy and efficiency more than 98% at 50 Hz throughput. This microfluidic sorter allows the sorting of various sample types, such as cell suspensions, cell-laden hydrogels, and cell-encapsulated droplets.

Thecadinium kofoidii is a marine sand-dwelling dinoflagellate that sometimes forms dense blooms. This species was previously thought to be an exclusively autotrophic dinoflagellate, and its mixotrophic ability has not been explored yet. By investigating its ecophysiology, its trophic mode should be revealed. We explored the mixotrophic ability of T. kofoidii by examining its protoplasm under light and transmission electron microscopes with diverse algal prey species. Furthermore, the feeding mechanism of T. kofoidii and prey species on which it feeds were investigated. In addition, the growth and ingestion rates of T. kofoidii as a function of prey concentration were determined when feeding on the benthic cryptophyte Rhodomonas salina. Thecadinium kofoidii was able to feed on R. salina and the dinoflagellate Symbiodinium voratum, which had equivalent spherical diameters (ESDs) ≤ 10.1 µm, while it did not feed on the benthic dinoflagellates Levanderina fissa, Prorocentrum concavum or Ostreopsis cf....

To investigate interactions between the nematocyst-bearing mixotrophic dinoflagellate Paragymnodinium shiwhaense and different heterotrophic protist and copepod species, feeding by common heterotrophic dinoflagellates (Oxyrrhis marina and Gyrodinium dominans), naked ciliates (Strobilidium sp. approximately 35μm in cell length and Strombidinopsis sp. approximately 100μm in cell length), and calanoid copepods Acartia spp. (A. hongi and A. omorii) on P. shiwhaense was explored. In addition, the feeding activities of P. shiwhaense on these heterotrophic protists were investigated. Furthermore, the growth and ingestion rates of O. marina, G. dominans, Strobilidium sp., Strombidinopsis sp., and Acartia spp. as a function of P. shiwhaense concentration were measured. O. marina, G. dominans, and Strombidinopsis sp. were able to feed on P. shiwhaense, but Strobilidium sp. was not. However, the growth rates of O. marina, G. dominans, Strobilidium sp., and Strombidinopsis sp. feeding on P. shiwhaense were very low or negative at almost all concentrations of P. shiwhaense. P. shiwhaense frequently fed on O. marina and Strobilidium sp., but did not feed on Strombidinopsis sp. and G. dominans. G. dominans cells swelled and became dead when incubated with filtrate from the experimental bottles (G. dominans+P. shiwhaense) that had been incubated for one day. The ingestion rates of O. marina, G. dominans, and Strobilidium sp. on P. shiwhaense were almost zero at all P. shiwhaense concentrations, while those of Strombidinopsis sp. increased with prey concentration. The maximum ingestion rate of Strombidinopsis sp. on P. shiwhaense was 5.3ngC predator-1d-1 (41 cells predator-1d-1), which was much lower than ingestion rates reported in the literature for other mixotrophic dinoflagellate prey species. With increasing prey concentrations, the ingestion rates of Acartia spp. on P. shiwhaense increased up to 930ngCml-1 (7180cellsml-1) at the highest prey concentration. The highest ingestion rate of Acartia spp. on P. shiwhaense was 4240ngC predator-1d-1 (32,610 cells predator-1d-1), which is comparable to ingestion rates from previous studies on other dinoflagellate prey species calculated at similar prey concentrations. Thus, P. shiwhaense might play diverse ecological roles in marine planktonic communities by having an advantage over competing phytoplankton in anti-predation against potential protistan grazers.

SummaryObjective Reproductive dysfunction is a co-morbidity that commonly occurs with temporal lobe epilepsy (TLE). Characterization of this co-morbidity in various models of TLE in mice will greatly facilitate mechanistic investigations of the relationship between reproductive disorders and seizures initiated in the hippocampus. Here we investigate the impact on female reproductive estrous cyclicity in the intrahippocampal kainic acid mouse model of TLE and demonstrate the utility of using this model for future mechanistic studies. Methods Kainic acid (KA) or saline vehicle was stereotaxically injected in the right dorsal hippocampus of adult female C57BL/6J mice. Development of epilepsy was assessed by video monitoring for behavioral seizures. Reproductive function was assessed by daily estrous cycle monitoring and ovarian morphology. Estrous cycles were monitored for up to 2 months after injection. Ovarian morphology was examined by histological staining and assessment of follicular and luteal development. Results We observed spontaneous behavioral seizures in 82% of kainic acid-treated mice. Irregular estrous cycles developed within 2 months after kainic acid injection. 67% of KA-treated mice showed disrupted estrous cycles, typically characterized by increased estrous cycle length, increased time spent in diestrus (non-fertile stage), and decreased time spent in estrus by 42 days post-KA injection. The estrous cycle disruption, however, was not accompanied by major changes in ovarian morphology or follicular development. KA-treated mice also displayed increased weight gain compared to control mice. Significance These data indicate that co-morbid female irregular estrous cyclicity arises in the intrahippocampal kainic acid mouse model of TLE. This is the first demonstration of disrupted reproductive endocrine function in a mouse model of TLE initially produced by an insult specifically targeted to the hippocampus. This model should thus be useful for basic studies investigating the neural mechanisms driving co-morbid reproductive dysfunction in epilepsy in women. This article is protected by copyright. All rights reserved.

Objectives To determine whether the combination therapy of niacin and selenium attenuates lung injury and improves survival during sepsis in rats and whether its benefits are associated with the activation of the glutathione redox cycle and up-regulation of nuclear factor erythroid 2-related factor 2. Design Prospective laboratory study. Setting University laboratory. Subjects Human lung microvascular endothelial cells and male Sprague-Dawley rats (n = 291). Intervention In lipopolysaccharide-exposed cells, the dose-related effects of niacin and selenium were assessed, and the therapeutic effects of the combination therapy of niacin (0.9 mM) and selenium (1.5 μM) were evaluated. The role of nuclear factor erythroid 2-related factor 2 was determined using nuclear factor erythroid 2-related factor 2 knockdown cells. In endotoxemic and cecal ligation and puncture with antibiotics rats, the therapeutic effects of the posttreatments of clinically relevant doses of niacin (360 mg/kg) and selenium (60 μg/kg) were evaluated. Measurements and main results Combination therapy reduced the hydrogen peroxide level via the synergistic activation of the glutathione redox cycle, which involves niacin-induced increases in glutathione reductase activity, and reduced the glutathione level and a selenium-induced increase in glutathione peroxidase activity. Combination therapy contributed to the up-regulation of nuclear factor erythroid 2-related factor 2, enhancement of glutathione synthesis, and down-regulation of nuclear factor κB signaling, but nuclear factor erythroid 2-related factor 2 knockdown inhibited the enhancement of glutathione synthesis and down-regulation of the nuclear factor κB pathway. The therapeutic effects of combination therapy on endotoxemic rats were consistent with those on lipopolysaccharide-exposed cells. In addition, the posttreatment of combination therapy attenuated lung injury and improved survival in endotoxemic and cecal ligation and puncture with antibiotics rats. However, individual therapies of niacin or selenium failed to achieve these benefits. Conclusions The combination therapy of niacin and selenium attenuated lung injury and improved survival during sepsis. Its therapeutic benefits were associated with the synergistic activation of the glutathione redox cycle, reduction of hydrogen peroxide level, and up-regulation of nuclear factor erythroid 2-related factor 2.

Background Bicycling is an increasingly popular recreation and mode of transportation in korea. Improved understanding of sex and gender-specific differences in epidemiologic features and clinical outcomes in bicycling injuries could help to understand bicycle-related injuries and develop preventative strategies. Aims This study aimed to investigate sex and gender-specific differences in epidemiologic features and clinical outcomes in bicycling injuries. Methods This is a cross-sessional study based on the Emergency Department(ED)–based Injury In-depth Surveillance(EDIIS) database from 23 EDs in Korea. All of injured bicyclists between January 1, 2011. and December 31, 2016. were eligible, excluding cases with unknown outcomes. The primary outcome was intracranial injury and the secondary outcomes were in-hospital mortality and clinical important injury (admission or in-hospital death). We calculated adjusted odds ratios (AORs) of gender(male) for study outcomes after adjusting for potential confounders. Results Among 24 306 eligible patients, 19 286 (79.3%) patients were male and 5 020 (20.7%) were female. The rate of helmets use was no diferrence(10.6% in male and 10.2% in female, respectively). Bicycling injuries of male occurred more in child and adolescent, evening and night(all p Discussion and conclusions There were gender-specific differences in epidemiologic features and clinical outcomes in bicycling injuries. Bicycling injuries of male occurred more in child and adolescent and had more severe outcomes than female. Preventative strategies to reduce the bicycling injuries targeting male (esp, child and adolescent male) are needed.

The characteristics of an estuary are determined by various factors as like as tide, wave, river discharge, etc. which also control the water quality of the estuary. Therefore, detecting the changes of characteristics is critical in managing the environmental qualities and pollution and so the locations of monitoring should be selected carefully. The present study proposes a framework to deploy the monitoring systems based on a graphical method of the spatial and temporal optimizations. With the well-validated numerical simulation results, the monitoring locations are determined to capture the changes of water qualities and pollutants depending on the variations of tide, current and freshwater discharge. The deployment strategy to find the appropriate monitoring locations is designed with the constrained optimization method, which finds solutions by constraining the objective function into the feasible regions. The objective and constrained functions are constructed with the interpolation technique such as objective analysis. Even with the smaller number of the monitoring locations, the present method performs well equivalently to the arbitrarily and evenly deployed monitoring system.

Background Posterior epidural lumbar disc fragment is infrequent because of anatomical barriers, and it is difficult to diagnose posterior epidural lumbar disc fragment because of its rare incidence and the ambiguity of radiologic evaluations. And it is difficult to differentiate it from other diseases such as spinal tumors. Objective Differential diagnosis of posterior epidural lumbar disc fragment is clinically important because its diagnosis can affect treatment and prognosis. To investigate the incidence, anatomical concern, etiology, symptom, diagnostic tool, management and prognosis of posterior epidural lumbar disc fragment, we reviewed articles including case report. Methods We performed a search of all clinical studies of posterior epidural lumbar disc fragment published to date. The following keywords were searched: Posterior epidural lumbar disc fragment, disc migration, posterior epidural disc, extradural migration, dorsal epidural migration, sequestrated disc, and disc fragment. Results We identified 40 patients of posterior epidural lumbar disc fragment from 28 studies. The most common presentation of posterior epidural lumbar disc fragment was sudden onset radiculopathy (70.0%), followed by cauda equina syndrome (27.5%). The most frequently used diagnostic modality was magnetic resonance imaging (MRI), conducted in 36 cases (90.0%), and followed by computed tomography in 14 cases (35.0%). After the imaging studies, the preoperative diagnoses were 45.0% masses, 20.0% lesions, and 12.5% tumors. Characteristic MRI findings in posterior epidural lumbar disc fragment are helpful for diagnosis; it typically displays low signals on T1-weighted images and high signals on T2-weighted images with respect to the parent disc. In addition, most of the disc fragments show peripheral rim enhancement on MRI with gadolinium administration. Electrodiagnostic testing is useful for verifying nerve damage. Surgical treatment was performed in all cases, and neurologic complications were observed in 12.5%. Conclusions As posterior epidural lumbar disc fragment could be masqueraded as spinal tumor, if rim enhancement is observed in MRI scans with sudden symptoms of radiculopathy or cauda equina syndrome, it should be taken into consideration. Early diagnosis can lead to early surgery, which can reduce complications.

An experiment was conducted to examine the effects of Kalopanax pictus Nakai (Kalopanax) on in vitro rumen fermentation and methane (CH4) reduction. Kalopanax trunk was extracted with 70% ethanol and 70% methanol. Rumen fluid, alfalfa hay and buffer (control: C) supplemented with 0.3% Kalopanx juice (T1), 0.3% ethanol extract (T2) and 0.3% methanol extract (T3) in the total volume of culture medium were incubated at 38 for 24h and 48h. Rumen pH was lower in all Kalopanax treatments during all incubations than that in control (p

Acoustic emission (AE) is one of the promising methods for detecting the formation of stress corrosion cracks (SCCs) in laboratory tests. This method has the advantage of online inspection. Some studies have been conducted to investigate the characteristics of AE parameters during SCC propagation. However, it is difficult to classify the distinct features of SCC behavior. Because the previous studies were performed on slow strain rate test or compact tension specimens, it is difficult to make certain correlations between AE signals and actual SCC behavior in real tube-type specimens. In this study, the specimen was a AISI 304 stainless steel tube widely applied in the nuclear industry, and an accelerated test was conducted at high temperature and pressure with a corrosive environmental condition. The study result indicated that intense AE signals were mainly detected in the elastic deformation region, and a good correlation was observed between AE activity and crack growth. By contrast, the behavior of accumulated counts was divided into four regions. According to the waveform analysis, a specific waveform pattern was observed during SCC development. It is suggested that AE can be used to detect and monitor SCC initiation and propagation in actual tubes.

To investigate red tides in Masan Bay, Korea, in which red tides have frequently occurred, we measured the abundance of red-tide organisms at a fixed station daily from June 2004 to May 2005. We daily measured physical, chemical, and biological properties. During the study period, 36 red-tide events occurred. Of these, 7 events were overwhelmingly dominated by cryptophytes, 5 by phototrophic dinoflagellates, 2 by diatoms, 2 by raphidophytes, 1 by a mixotrophic ciliate, and the rest by mixtures of several taxonomic groups. The durations of the red-tide events ranged from 1 to 40 days and total duration was 195 days. Most of the red tides occurred between June and September 2004 and between January and March 2005. The maximum abundance and biomass of total phototrophic dinoflagellates were 27,183 cells ml −1 and 3516 ng C ml −1 , respectively, while those of total diatoms were 71,538 cells ml −1 and 10,981 ng C ml −1 , respectively. Furthermore, the maximum abundance and biomass of total raphidophytes were 90,010 cells ml −1 and 10,177 ng C ml −1 . The biomass of total phototrophic dinoflagellates had significant positive correlations with salinity, pH, dissolved oxygen, euglenophytes, raphidophytes, cyanobacteria, and heterotrophic bacteria, but negative correlations with temperature, nitrite plus nitrate and phosphate concentrations. In addition, the biomass of raphidophytes had a significant positive correlation with temperature, pH, and heterotrophic bacteria, but a negative correlation with salinity and the phosphate concentration. This evidence suggests that red-tide dynamics dominated by these phototrophic dinoflagellates and raphidophytes may be mainly affected by potential prey concentrations rather than inorganic nutrient concentrations. Daily sampling is necessary to explore red-tide dynamics in Masan Bay because the generation time of the causative species is ∼0.5–3 days.

Received 8 July, 2013; received in revised form 9 September, 2013; accepted 12 September, 2013ABSTRACTThe requirement for high performance visualization of engineering analysis of digital products isincreasing since the size of the current analysis problems is more and more complex, whichneeds high-performance codes as well as high performance computing systems. On the otherhand, different companies or customers do not have all the facilities or have difficulties inaccessing those computing resources. In this paper, we present a multi-view supporting VR/ARsystem for providing supercomputing-based engineering analysis services. The proposed systemis designed to provide different views supporting VR/AR visualization services depending onthe requirement of the customers. It provides a sophisticated VR rendering directly dependenton a supercomputing resource as well as a remotely accessible AR visualization. By providingmulti-view centric analysis services, the proposed system can be more easily applied to variouscustomers requiring different levels of high performance computing resources. We will show thescalability and vision of the proposed approach by demonstrating illustrative examples with dif-ferent levels of complexity.Key Words: Augmented reality, Engineering analysis, Multi-view, Supercomputing, Virtual real-ity, Visualization, User interaction

To investigate the role of heterotrophic protists in the dynamics of red tides in Masan Bay, Korea, we measured the abundance of heterotrophic dinoflagellates, ciliates, and heterotrophic nanoflagellates in daily samples collected from June 2004 to May 2005. The abundance of heterotrophic dinoflagellates, tintinnid ciliates, naked ciliates, and heterotrophic nanoflagellates were high when red tides occurred, with maximum biomass of 1916, 1263, 1013, and 141 ng C ml−1, respectively. The HTDs Gyrodinium dominans/Gyrodinium moestrupii, Gyrodinium glaucum, Protoperidinium bipes, and Pfiesteria-like dinoflagellates (PLDs) as well as naked ciliates (≤50 μm) were present nearly all year and their maximum biomass was 235, 48, 298, 1020, and 1013 ng C ml−1, respectively. PLDs were the most abundant taxa during red tides dominated by Akashiwo sanguinea, Heterocapsa rotundata, summer populations of Prorocentrum minimum, Heterosigma akashiwo, Eutreptiella gymnastica, and cryptophytes, while G. dominans/G. moestrupii were most abundant during red tides dominated by Ceratium furca and Dinophysis acuminata. Naked ciliates were most abundant during red tides dominated by Cochlodinium polykrikoides, Prorocentrum triestinum, and winter populations of P. minimum. The maximum calculated grazing coefficients for each dominant heterotrophic protistan grazer on their respective co-occurring red-tide organisms in Masan Bay ranged from 0.0 to 6.8 h−1. The results of the present study suggest that populations of certain heterotrophic protistan grazers may have considerable potential grazing impact on populations of red-tide organisms in Masan Bay.

In this paper, an efficient catalytic route for the reduction of graphene oxide (GO) is described using hydrogen spillovered platinum (Pt) nanoparticles at room temperature. Pt nanoparticles were decorated on GO sheets using a hydrogen reduction of chloroplatinic acid. The Pt nanoparticles served as a catalyst for the process of hydrogen disassociation to atomic hydrogen, which spillovered onto the GO sheets which acted as a strong reducing agent for the reduction of GO. Reduced graphene oxide (RGO) obtained in this manner has a C/O atomic ratio as high as 22, which is one of the highest values ever reported for chemically converted graphenes. The electrical conductivity was greater than 8000 S m−1. Electrochemical studies revealed that the RGO–Pt hybrid exhibits excellent electrocatalytic activity toward the methanol oxidation reaction, with high CO tolerance and long-term stability.

The dinoflagellate Alexandrium spp. have received much attention due to their harmful effects on diverse marine organisms, including commercially important species. For minimizing loss due to red tides or blooms of Alexandrium spp., it is very important to understand the eco-physiology of each Alexandrium species and to predict its population dynamics. Its trophic mode (i.e., exclusively autotrophic or mixotrophic) is one of the most critical parameters in establishing prediction models. However, among the 35 Alexandrium species so far described, only six Alexandrium species have been revealed to be mixotrophic. Thus, mixotrophic ability of the other Alexandrium species should be explored. In the present study, whether each of three Alexandrium species (A. andersonii, A. affine, and A. fraterculus) isolated from Korean waters has or lacks mixotrophic ability, was investigated. When diets of diverse algal prey, cyanobacteria, and bacteria sized micro-beads were provided, A. andersonii was able to feed on the prasinophyte Pyramimonas sp., the cryptophyte Teleaulax sp., and the dinoflagellate Heterocapsa rotundata, whereas neither A. affine nor A. fraterculus fed on any prey item. Moreover, mixotrophy elevated the growth rate of A. andersonii. The maximum mixotrophic growth rates of A. andersonii on Pyramimonas sp. under a 14:10h light/dark cycle of 20μEm-2s-1 was 0.432d-1, while the autotrophic growth rate was 0.243d-1. With increasing mean prey concentration, the ingestion rate of A. andersonii increased rapidly at prey concentrations

Few protistan grazers feed on toxic dinoflagellates, and low grazing pressure on toxic dinoflagellates allows these dinoflagellates to form red-tide patches. We explored the feeding ecology of the newly described heterotrophic dinoflagellate Gyrodinium moestrupii when it fed on toxic strains of Alexandrium minutum, Alexandrium tamarense, and Karenia brevis and on nontoxic strains of A. tamarense, Prorocentrum minimum, and Scrippsiella trochoidea. Specific growth rates of G. moestrupii feeding on each of these dinoflagellates either increased continuously or became saturated with increasing mean prey concentration. The maximum specific growth rate of G. moestrupii feeding on toxic A. minutum (1.60/d) was higher than that when feeding on nontoxic S. trochoidea (1.50/d) or P. minimum (1.07/d). In addition, the maximum growth rate of G. moestrupii feeding on the toxic strain of A. tamarense (0.68/d) was similar to that when feeding on the nontoxic strain of A. tamarense (0.71/d). Furthermore, the maximum ingestion rate of G. moestrupii on A. minutum (2.6 ng C/grazer/d) was comparable to that of S. trochoidea (3.0 ng C/grazer/d). Additionally, the maximum ingestion rate of G. moestrupii on the toxic strain of A. tamarense (2.1 ng C/grazer/d) was higher than that when feeding on the nontoxic strain of A. tamarense (1.3 ng C/grazer/d). Thus, feeding by G. moestrupii is not suppressed by toxic dinoflagellate prey, suggesting that it is an effective protistan grazer of toxic dinoflagellates.

In this study, a new heat plate with a groove for butt-welding was developed to investigate the misalignment effects on the joining strengths of polyethylene double walled pipes. Thermal analyses of the material determined the temperature profile of the welding. After the welding, the joining characteristics of the pipes were compared with those welded by the conventional heat plate. The results of the stiffness and flattening tests showed that there were no big differences between the joints made from these two plates. In the leakage test, however, the pipes welded with the conventional heat plate leaked below the required test conditions, while the pipes welded with the grooved heat plate did not show any leakage, even in a range higher than the required conditions. The tensile and bending strength were also improved. The results demonstrated that the grooved heat plate accomplished more complete fusion at the pipe joints and induced high quality joints.

1990년대 자동차 산업에 있어 최대 관심사는 엔진 개발을 통한 최대의 연료 효율을 확보하고 자동차의 무게를 증가시켜 안전성과 편안함을 개선하고 차량 사용에 있어 기능적인 부분을 부가하는 것이었다. 하지만, 최근 전 세계적인 에너지 및 환경규제 등의 문제가 대두되기 시작하면서 일본, 유럽 등지에서 법제화를 통해 자동차 중량을 감소시키는 것이 큰 이슈로 대두되고 있다. 자동차에 있어 무게를 줄이게 되면 차량의 연비를 줄일 수 있으며, 배기가스 배출을 감소시키게 되어 화석연료의 소비 감소 및 환경오염 방지에 큰 역할을 할 수가 있다. 반면 자동차의 안전성, 편의성 등을 바라는 다양한 소비자의 욕구를 충족시키기 위해 많은 장치들을 자동차에 추가 장착함으로써 자동차의 중량은 증가하게 되었다. 따라서 이러한 상반되는 문제를 해결하기 위해 철강 소재에서 마그네슘 합금, 알루미늄 합금, 플라스틱 등의 가벼운 비철합금 소재의 사용이 제안되고 있으나 가격, 안전성, 내구성 등의 문제로 그 사용은 제한되고 있는 실정이다. 이에 따라 자동차구조용 소재는 안전성 및 내구성을 위해 높은 강도와 연성을 동시에 확보하고 있는 고장력강재의 사용이 증가하고 있다. DP 강, TRIP 강, CP 강, Hot-stamping 강 등 600MPa부터 1,500MPa까지 다양한 강도의 강재들이 차체 제작에 있어 사용되고 있다

Welding is an essential process in the automotive industry. Most welding processes that are used for auto body is spot welding. And CO 2 arc welding is used in a small part. In production field, CO 2 arc welding process is decreased and spot welding process is increased due to welding quality is poor and defects are occurred in CO 2 arc welding process frequently. But CO 2 arc welding process should be used at robot interference parts and closed parts where spot welding couldn’t. CO 2 welding is divided into lap welding and plug arc spot welding. In case of plug arc spot welding, burn through and under fill were caused in various welding environment such as different thickness combinations of base metal, teaching point, over the two steps welding and inconsistent voltage/current. It makes some problem like poor quality of welding area and decrease the productivity. In this study, we will evaluate the effect of teaching point through the weld pool behavior and bead geometry in the arc spot welding at the plut hole. Welding position is horizontal position. And galvanized steel sheet of 2.0mm thickness that has plug hole of 6mm diameter was used. Teaching point was changed by center, top, bottom, left and right of the plug hole. At each condition, the phenomenon of weld pool behavior was confirmed using a high-speed camera. As the result, we find the center of plug hole is the most optimal teaching point. In the other teaching point, under fill was occurred at the plug hole. This phenomenon is caused by gravity and surface tension. For performance of arc spot welding at the plug hole, the teaching condition should be controlled at a center of plug hole.Key Words : Arc spot welding, Plug hole, Teaching point, Gravity, Surface tension

This study detected SCC defects of dissimilar metal welded(STS304 and SA106 Gr. b) pipes using the ultrasonic infrared thermography method and the lock-in image treatment method among infrared thermography method. The infrared excitement equipment has 250 Watt of output and 20 kHz of frequency. By using the ultrasound infrared thermography method, the internal defects of dissimilar metal weld joints of pipes used at nuclear power plants could get detected. By an actual PT test, it was observed that the cracks inside the pipe existed not as a single crack but rather as a multiple cracks within a certain area and generated a hot spot image of a broad area on the thermography image. In addition, UT technology could not easily defects detected by the width of fine hair cracks. but, ultrasound infrared thermography technique was defect detected.

In this study, mechanical analyses of a butt welding technology for joining Polyethylene pipe are presented. The pipe had unique structure with double wall, and its section topology was not flat. For an effective repair of leakage and replacements of the pipe, the butt welding technology was developed and tested. For the material characterizations, thermodynamic analyses such as thermal gravimetric analysis and differential scanning calorimetry were performed. Based on the test results, the process temperature and time were determined to ensure safe joining of the pipes using a hot plate apparatus. The welding process was carefully monitored by measuring the temperature. Then, the joined pipes were tested by various methods to evaluate the quality. The analyses results showed the detail process mechanism during the joining process, and the test results demonstrated the successful application of the technology to the sewage pipe repairs.