Developing centrifugal force real-time digital PCR for detecting extremely low DNA concentration.

Digital PCR (dPCR) is a technique for absolute quantification of nucleic acid molecules. To develop a dPCR technique that enables more accurate nucleic acid detection and quantification, we established a novel dPCR apparatus known as centrifugal force real-time dPCR (crdPCR). This system is efficient than other systems with only 2.14% liquid loss by dispensing samples using centrifugal force. Moreover, we applied a technique for analyzing the real-time graph of the each micro-wells and distinguishing true/false positives using artificial intelligence to mitigate the rain, a persistent issue with dPCR. The limits of detection and quantification were 1.38 and 4.19 copies/µL, respectively, showing a two-fold higher sensitivity than that of other comparable devices. With the integration of this new technology, crdPCR will significantly contribute to research on next-generation PCR targeting absolute micro-analysis.

Unraveling the unknown: Adaptive spatial planning to enhance climate resilience for the endangered Swamp Grass-babbler (Laticilla cinerascens) with habitat connectivity and complexity approach.

The endangered and poorly known Swamp Grass-babbler, Laticilla cinerascens (Passeriformes: Pellorneidae), confronts critical threats and vulnerability due to its specific habitat requirements and restricted populations in the northeastern region of the Indian Subcontinent. This study investigates the distribution of the species, habitat quality, geometry and shape complexity of connectivity among the protected areas (PAs), and responses to climate change in Northeast India under different climate change pathways by utilizing ensemble distribution models, and ecological metrics. From the total distribution extent (1,42,000 km2), approximately 9366 km2 (6.59 %) is identified as the suitable habitat for this threatened species. Historically centered around Dibru Saikhowa National Park (DSNP), the species faced a drastic decline due to anthropogenic activities and alteration in land use and lover cover. The study also reveals a significant decline in suitable habitat for L. cinerascens in future climate scenarios, with alarming reductions under SSP126 (>10 % in the timeframe 2041-2060 and > 30 % from 2061 to 2080), SSP245 (>90 % in both time periods), and SSP585 (>90 % in both timeframes) from the present scenario. At present, DSNP has the most suitable habitat within the distribution range but is projected to decline (>90 %) under more severe climate change scenarios, as observed in other PAs. Landscape fragmentation analysis indicates a shift in habitat geometry, highlighting the intricate impact of climate change. It predicts a substantial 343 % increase (in the SSP126) in small habitat patches in the future. Connectivity analysis among PAs shows a significant shift, with a decline exceeding 20 %. The analysis of shape complexity and connectivity geometry reveals a significant increase of over 220 % in the fragmentation of connectivity among PAs between 2061 and 2080 under the SSP585 climate change scenario compared to the present conditions. The study underscores the urgent need for conservation actions, emphasizing the complex interplay of climate change, habitat suitability, and fragmentation. Prioritizing PAs with suitable habitats and assessing their connectivity is crucial. Adaptive management strategies are essential to address ongoing environmental changes and safeguard biodiversity. Future research in critical areas is needed to establish long-term monitoring programs to lead/extend effective conservation strategies.

Association between heat and hospital admissions in people with disabilities in South Korea: a nationwide, case-crossover study.

BACKGROUND: Despite extensive findings on the hazardous impacts of environmental heat exposure, little is known about the effect on people with disabilities. This study aimed to estimate the association between environmental heat exposure and emergency department admissions for people with disabilities compared with people without disabilities. METHODS: In this nationwide, case-crossover study, we linked data on emergency department admissions (cases) for any cause in the warm season in South Korea from the Korean National Health Insurance Service (NHIS)-National Sample Cohort database (a nationally representative database of 1 million systematically sampled beneficiaries covering all ages) from Jan 1, 2002, to Dec 31, 2019, and short-term daily mean temperature exposure (measured via Google Earth Engine at a 9 km spatial grid, aggregated to district). We defined beneficiaries with disabilities as those who were registered as disabled in the NHIS; disabilities included in our study were physical disability, brain lesion disorders, blindness or vision loss, and deafness or hearing loss. Other types of disability were not included for confidentiality reasons. A time-stratified case-crossover design, in which participants served as their own control, was used with conditional logistic regression to estimate the association between heat and emergency department admissions in people with and without disabilities. FINDINGS: 23 792 emergency department admissions were recorded for 59 527 people with disabilities. Of these 23 792 admissions, 10 234 (43·0%) individuals were female and 13 558 (57·0%) were male. The odds ratio (OR) of emergency department admissions associated with heat (99th temperature percentile vs 75th percentile) was 1·15 (95% CI 1·07-1·24) in people with disabilities and 1·06 (1·04-1·09) in people without disabilities. The annual excess number of emergency department admissions attributable to heat per 100 000 persons-years was 27·81 admissions (95% CI 9·20-45·69) and excess medical costs were US$638 739·47 (95% CI 201 900·12-1 059 641·87) in people with disabilities; these values were more than four times that of the non-disabled population. People with brain lesion disorders, people with severe physical disabilities, female individuals, and those aged 65 years or older showed higher heat risks. The risks of emergency department admissions due to mental disorder (1·89, 95% CI 1·18-3·00) and respiratory diseases (1·34, 1·06-1·70) also showed higher heat risks than for the other two analysed causes of admission (cardiovascular and genitourinary diseases). INTERPRETATION: Heat was associated with increased risk of emergency department admissions for people with and without disabilities, but the risk appeared to be higher for those with disabilities. These results can inform policy makers when establishing action plans for people with disabilities. FUNDING: National Research Foundation of Korea, the South Korean Ministry of Environment, and the South Korean Ministry of Education.

Effect of socioeconomic disparities on the risk of COVID-19 in 8 metropolitan cities in the Korea: a community-based study.

OBJECTIVES: Socioeconomic disparities have been reported as major risk factors contributing to the spread of coronavirus disease 2019 (COVID-19) at the community level. We conducted an epidemiological study on COVID-19 incidence risk using area-based deprivation indices (DIs) reflecting the characteristics of the susceptible population. METHODS: A database of the confirmed COVID-19 cases in 8 metropolitan cities in Korea from January 20, 2020 to December 31, 2021 was combined with area-based DI scores and standardized prevalence rates of diabetes and hypertension from the Korean Community Health Survey. Relative risk (RR) levels were estimated using a generalized linear model with a Poisson distribution by age group. RESULTS: The risk of COVID-19 incidence generally increased with increasing age, especially in patients aged ≥75 years. The RR of COVID-19 incidence per interquartile range increment of the composite deprivation index (composite DI) was 1.54 (95% confidence interval [CI], 1.34 to 1.70). Notably, in the first wave, the risk of COVID-19 incidence was approximately 3 times higher in the region with the lowest socioeconomic status than in the region with the highest status (RR, 3.08; 95% CI, 2.42 to 3.78 based on the the composite DI and RR, 3.13; 95% CI, 2.53 to 3.83 based on the social deprivation index). CONCLUSIONS: This study provides scientific evidence that socioeconomic deprivation is an important risk factor for the spread of COVID-19. This finding suggests that a mid-term to long-term strategy is needed to protect susceptible populations and reduce the burden of COVID-19 in the community.

Avoidable Mortality between Metropolitan and Non-Metropolitan Areas in Korea from 1995 to 2019: A Descriptive Study of Implications for the National Healthcare Policy.

This study aims to investigate the trends of avoidable mortality and regional inequality from 1995 to 2019 and to provide evidence for policy effectiveness to address regional health disparities in Korea. Mortality and population data were obtained from the Statistics Korea database. Age-standardized all-cause, avoidable, preventable, and treatable mortality was calculated for each year by sex and region. Changes in mortality trends between metropolitan and non-metropolitan areas were compared with absolute and relative differences. Avoidable mortality decreased by 65.7% (350.5 to 120.2/100,000 persons) in Korea, 64.5% in metropolitan areas, and 65.8% in non-metropolitan areas. The reduction in avoidable mortality was greater in males than in females in both areas. The main causes of death that contribute to the reduction of avoidable mortality are cardiovascular diseases, cancer, and injuries. In preventable mortality, the decrease in non-metropolitan areas (-192.4/100,000 persons) was greater than that in metropolitan areas (-142.7/100,000 persons). However, in treatable mortality, there was no significant difference between the two areas. While inequalities in preventable mortality improved, inequalities in treatable mortality worsened, especially in females. Our findings suggest that regional health disparities can be resolved through a balanced regional development strategy with an ultimate goal of reducing health disparities.

Thermal Dynamics of a Novel Radio-Frequency Device for Endoscopic Spine Surgery: An Experimental Model.

STUDY DESIGN: Experimental study. OBJECTIVE: In this study, the ambient temperature of a radiofrequency (RF) electrode tip was compared and analyzed in terms of products, mode, flow quantity, and flow rate. SUMMARY OF BACKGROUND DATA: Endoscopic spine surgery is a widely used operation for degenerative lumbar stenosis and herniated lumbar disc. To perform endoscopic spine surgery, dedicated instruments like a RF generator and electrode are essential. METHODS: An evaluation system capable of measuring temperature under equal conditions at a certain distance from the electrode tip was manufactured. The distance between the electrode tip and the temperature sensor was set to 1, 5, and 10 mm. The flow quantities of 0, 50, 100, and 150 mL/min and the flow rates of 0, 0.20, 0.53, and 0.80 m/s were compared and statistically analyzed. RESULTS: The temperatures measured in the experiments conducted on the four combinations of RF device showed similar values, and showed differences according to the characteristics of each mode of the RF. As the distance between the electrode tip and the temperature sensor increased, the temperature decreased, and as flow quantity or flow rate increased, the temperature decreased. The maximum temperatures differed significantly according to flow quantity, between flow quantities of 0 and 100 mL/min (P  = 0.03) and between 0 and 150 mL/min (P ≤ 0.01). The maximum temperatures also differed significantly between the flow rate of 0 m/s, and the flow rates of 0.20, 0.53, and 0.80 m/s, with P ≤ 0.01 in all three comparisons. CONCLUSION: This is the first study in which we made a customized RF temperature evaluation system and verified the temperature changes in various environments. When irrigation was performed, we could confirm that the maximum temperature was less than 60°C. Irrigation is considered essential in endoscopic spine surgery. LEVEL OF EVIDENCE: 3.

Electrochemical properties of an activated carbon xerogel monolith from resorcinol-formaldehyde for supercapacitor electrode applications.

Activated carbon xerogel monoliths were prepared from resorcinol and formaldehyde via a catalyst-free and template-free hydrothermal polycondensation reaction, followed by pyrolysis and activation. The ratio of resorcinol (R) to distilled water (W) was varied to afford an interconnected pore structure with controlled pore size, while the pyrolysis temperature was optimized to give high specific surface area. Activation was carried out at 700 °C after soaking the samples in 6 M KOH aqueous solution. The same process, called "heat treatment", was also carried out without soaking in KOH for comparison. The weight loss upon pyrolysis, activation and heat treatment and the weight gain via KOH soaking were measured. Field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA) and an N2 sorption instrument were utilized for characterization. Additionally, electrochemical properties were evaluated using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) with a 3-electrode system, while a 2-electrode system was also employed for selected samples. The highest specific capacitance of 323 F g-1 via GCD at 1 A g-1 was obtained at the R/W ratio of 45 and with 500 °C pyrolysis. In addition, this sample also exhibited 89.4% retention at 20 A g-1 in the current density variation and 100% retention in 5000 cycling tests.

Electrochemical properties of kenaf-based activated carbon monolith for supercapacitor electrode applications.

Activated carbon monoliths of kenaf (ACMKs) were prepared by moulding kenaf fibers into a column-shape monolith and then carrying out pyrolysis at 500, 600, 700 or 800 °C, followed by activation with KOH at 700 °C. Then, the sample was characterized using thermogravimetric analyzer (TGA), field-emission scanning electron microscopy (FE-SEM), field-emission transmission electron microscopy (FE-TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, X-ray diffraction (XRD) and N2 sorption instruments. The prepared ACMK was subjected to electrochemical property evaluation via cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). The GCD study using a three-electrode system showed that the specific capacitance decreased with higher pyrolysis temperature (PYT) with the ACMK pyrolyzed at 500 °C (ACMK-500) exhibiting the highest specific capacitance of 217 F g-1. A two-electrode system provided 95.9% retention upon a 5000 cycle test as well as the specific capacitance of 212 F g-1, being converted to an energy density of 6 W h kg-1 at a power density of 215 W kg-1.

Numeric Evaluation of Innovate Spring Machined Nickel-Titanium Rotary Instruments: A 3-dimensional Finite Element Study.

INTRODUCTION: The purpose of this study was to investigate if machined springs in nickel-titanium (NiTi) rotary instruments can improve their mechanical properties. The bending and torsion properties were assessed using finite element (FE) model analysis. METHODS: A basic 3-dimensional file model without a spring was created with apical size #25, 25-mm full length, and 16-mm cutting flutes. Three other models were created with a spring machined into their shaft portion with different numbers of spring coils: standard (STspr), 10% more (INspr), and 10% less (DEspr). To compare the mechanical responses among the 4 FE models, file bending and torsion were simulated using FE analysis. RESULTS: Spring machined NiTi rotary instruments showed higher torsional resistance and less bending stiffness than the same instrument without. The spring machined models required more torque to bend or rotate the DEspr model than was required for the STspr and INspr models; however, the STSpr and INSpr models were similar. CONCLUSIONS: Within the limitations of this study, the FE analysis indicated that machining a spring into the shaft of NiTi rotary instruments improved torsional resistance and bending flexibility. Therefore, spring machining has the potential to increase the durability of the NiTi rotary instruments.

Factors associated with the rates of coronary artery bypass graft and percutaneous coronary intervention.

BACKGROUND: Korea has seen a rapid increase in the use of percutaneous coronary intervention (PCI) with the ratio of PCI to coronary artery bypass graft (CABG) the highest in the world. This study was performed to examine the factors associated with the rates of CABG and PCI. METHODS: The data were acquired from the National Health Insurance database in Korea in 2013. We calculated the age-sex standardized rates of CABG and PCI. We examined the factors associated with the CABG and PCI rates by performing a regression analysis. RESULTS: The rate of CABG showed a negative association with the deprivation index score, and other factors, such as the number of providers or hospital beds, did not show any significant association with the CABG rate. The rate of PCI had a strong negative association with the number of cardiothoracic surgeons and a strong positive association with the number of hospital beds. CONCLUSIONS: The positive association between the PCI rate and the number of hospital beds suggests that the use of PCI may be driven by the supply of beds, and the inverse association between the PCI rate and the number of cardiothoracic surgeons indicates the overuse of PCI due to lack of the providers of CABG. Policy measures should be taken to optimize the use of revascularization procedures, the choice of which should primarily be based on the patient's need.

Neighborhood Deprivation and Unmet Health Care Needs: A Multilevel Analysis of Older Individuals in South Korea.

OBJECTIVES: In this study the relationship between neighborhood deprivation and the unmet health care needs of elderly individuals (≥ 65 years) was examined. Some previous studies suggested that neighborhood characteristics affect access to health care, yet research on the unmet needs of older individuals is limited. METHODS: Multilevel logistic regression analysis was used to assess the relationship of neighborhood-level factors with unmet health care needs due to costs, adjusting for individual-level factors, in individuals ≥ 65 years in the 2017 Korean Community Health Survey (n = 63,388). RESULTS: There were 2.6% of elderly individuals who experienced unmet health care needs due to costs. Following adjustment for individual and neighborhood characteristics, the neighborhood deprivation in urban areas was found to have an inverse association with unmet needs (odds ratio = 0.50; 95% confidence interval = 0.24-1.06) for the most deprived quartile versus the least deprived quartile). However, in rural areas neighborhood deprivation was not a significant variable. Among the individual-level variables, household income was one of the strongest correlates with unmet needs in both urban and rural areas. CONCLUSION: The present findings suggest that targeted policy interventions reflecting both neighborhood and individual characteristics, should be implemented to reduce the unmet health care needs of elderly individuals.

Geographic variation and factors associated with rates of knee arthroplasty in Korea-a population based ecological study.

BACKGROUND: The recent increase in knee arthroplasty (KA) use in Korea is among the highest in the world. The rapid increase in KA use suggests that the KA use in Korea could have been affected by medically unjustifiable factors. This study aimed to examine the geographic variation in the rate of KA and its associated factors in Korea. METHODS: We used the data from the National Health Insurance in Korea in 2013, from which a total of 67,086 claims for KA were obtained. We calculated the age-sex-standardized KA rates of the entire population and the crude rates of the age groups 0-64 and 65 and over in 251 districts. We assessed the geographic variation of the KA rates and examined the associated factors with a multivariate linear regression with the KA rate as a dependent variable. RESULTS: The overall rate of KA in Korea was 132.7 per 100,000 persons. The rates of KA showed a four-fold variation. The deprivation index score and the number of beds in the small to medium sized hospitals showed a positive association with the rates of KA while the number of orthopedic surgeons showed a negative association. CONCLUSIONS: Korea has been experiencing a rapid increase in the use of KA for the last decade or so, which was most prominent among the elderly population aged 65 and older. Our results suggest that the higher rate of KA is strongly related to a higher supply of beds and the socioeconomically deprived conditions. Considering that the decision concerning KA has room for discretion and also affects a considerable portion of health care expenditures, the use of KA should be thoroughly monitored with more emphasis on standardization in the decision making process and preventive measures that can lessen the need for KA.

Rehabilitation of an Extremely Edentulous Atrophic Maxilla with a Pseudoskeletal Class III Relationship.

The skeletal class III relationship presents complex dentoalveolar problems, requiring multidisciplinary treatment. In edentulous people, severe atrophy of the jawbone simulates the clinical appearance of a skeletal class III relationship (pseudoskeletal class III), which presents major problems for rehabilitation. This article describes the rehabilitation of a 67-year-old patient with a pseudoskeletal class III relationship. The mandible was restored with two implant-supported bar-retained overdentures using clips for retention. The extremely atrophic maxilla was restored with a combination of sinus augmentation, implant placement, and classic prosthodontic treatment using an electroformed mesostructured overdenture with swivel lock attachments on an implant-supported bar. By performing minimal augmentative and implant surgeries and using the possibilities and advantages of classic prosthetic dentistry, the clinical situation described here could be managed and the atrophic maxilla could be rehabilitated.

An ecological study of geographic variation and factors associated with cesarean section rates in South Korea.

BACKGROUND: Korea is in a condition where the impact of patient and supplier factors on cesarean section rates can be clearly described. The cesarean section rates in Korea are among the highest in the world while the number of obstetricians is decreasing sharply. This study aimed to investigate the geographic variation in cesarean section rates in Korea and its factors. METHODS: The data were obtained from the National Health Insurance database in Korea in 2013. We calculated the age-standardized and crude cesarean section rates of 251 districts in Korea and variation statistics. A linear regression analysis was performed to determine factors for cesarean section rates. RESULTS: The overall cesarean section rate in Korea was 364.6 cases per 1000 live births. The deprivation index score was strongly associated with the increase in the cesarean section rate while the density of hospital obstetricians and hospital beds showed a negative association. Average maternal age and total fertility rate showed a negative relationship with the cesarean section rate. CONCLUSIONS: Korea is suffering from a continuing decrease in obstetricians. Our study shows that this decline has more of an effect on mothers in the disadvantaged areas. Securing equal access to obstetric care among areas is necessary, and measures to encourage obstetricians and mothers not to opt for cesarean section are required.

Hospitalizations for ambulatory care sensitive conditions as an indicator of access to primary care and excess of bed supply.

BACKGROUND: Ambulatory care sensitive conditions (ACSC) hospitalization is a widely accepted measure of the access to primary care. However, given its discretionary characteristics, the ACSC hospitalization can be a measure reflecting the influence of hospital bed supply. In Korea, where the quality of primary care and oversupply of hospital beds are coexistent concerns, ACSC hospitalization can be used to examine the impact of both factors. This study was performed to investigate the ACSC hospitalization rate as a measure of the hospital bed supply as well as access to primary care. METHODS: Data were obtained from the National Health Insurance Database for 2015. We calculated the age-sex standardized hospitalization rates for ACSC in the total population and crude rates of ACSC hospitalization for three different age groups in 252 districts in Korea. We calculated the variation statistics of ACSC hospitalization rates, and we estimated a linear regression model to investigate the factors for ACSC hospitalization. RESULTS: There was a very high geographic variation in ACSC hospitalization rates. Higher density of primary care physicians was associated with a decreased ACSC hospitalization rate while a higher density of hospital beds in small to medium sized hospitals was associated with an increased rate. The deprivation index score had a strongly positive association with the ACSC hospitalization rates. CONCLUSION: ACSC hospitalization, while being a negative index of primary care access, can also be a measure indicating the impact of the hospital bed supply, and it is still a valid measure of the disparity of health care, the original motivation for this topic.

A spatial analysis of geographic variation and factors associated with hospitalization for bacterial pneumonia in Korea.

BACKGROUND: The incidence of pneumonia in Korea started to increase in the 1990's after a period of decrease and stabilization, and the mortality and hospitalization rates for pneumonia in Korea are alarmingly high. This study was performed to examine geographic variation and factors associated with hospitalization for bacterial pneumonia in Korea. METHODS: Data were acquired from the inpatient claims of the 2015 period of the National Health Insurance Service. The age- and sex-standardized hospitalization rates for bacterial pneumonia were calculated for three age groups. Geographic variation was measured with the coefficient of variation, the ratio of the 90th to the 10th percentile of the distribution of rates, and the systematic component of variation. Considering the results of Moran's I statistic which suggested spatial autocorrelation, we estimated spatial regression models using spatial error models. RESULTS: The hospitalization rate for bacterial pneumonia was 79.1 per 10,000 population, and the rate was the highest in the age group 0-14 at 325.3, and it was 161.5 among the elderly. The geographic variation statistics showed high variation with the coefficient variation at 0.6. The deprivation score showed positive associations, and the number of primary care physicians had a negative association with the hospitalization rates across all age groups but the age group 0-14. The number of beds in hospitals with less than 300 beds had a positive association with the hospitalization rates for bacterial pneumonia, and the impact was the strongest in the age group 0-14. CONCLUSIONS: The present study shows that pneumonia can be a major public health issue even in a developed country. Socioeconomic conditions can still be a concern for pneumonia in developed countries, and the role of primary care physicians in preventing hospitalization for bacterial pneumonia needs to be recognized. Most of all, the strong impact of hospital beds on the hospitalization rates for pneumonia, especially for the children, should be addressed. High disease burden of pneumonia in Korea can partly be attributable to oversupply of hospital beds. These factors should be taken into consideration in establishing policy measures for the rise in pneumonia.

Monolithic carbon xerogel with co-continuous hierarchical porosity via one-step, template- and catalyst-free hydrothermal reaction with resorcinol and formaldehyde.

Monolithic carbon xerogel (MCX) with co-continuous hierarchical porosity was prepared via a one-step, template- and catalyst-free hydrothermal polycondensation reaction with resorcinol (R), formaldehyde (F) and distilled water (W), followed by pyrolysis and CO2 activation. The reaction was carried out in a pressurized Teflon mold at 100 °C for 6 h, while F/R (2.2, 2.4, 2.6, and 2.8) and R/W ratios (40 and 45) were varied to obtain a co-continuous pore structure with interconnected particles. Next, the gels were dried at 60 °C for 36 h and then at 100 °C for 12 h to produce xerogels, which were then subjected to pyrolysis at 900 °C for 2 h and CO2 activation at 1000 °C for 2, 4 or 6 h. A co-continuous pore structure with interconnected particles was observed in gels with F/R = 2.4 and 2.6 at R/W = 40 and with F/R = 2.2 at R/W = 45, but the gel with F/R = 2.4 at R/W = 40 was the only one that showed no crack generation upon 6 h CO2 activation. Thus, this gel was subjected to a N2 sorption study, which resulted in a specific surface area (SSA) of 1418, 2489 and 3418 m2 g-1 at 2, 4 and 6 h activation, respectively. This was attributed to the introduction of micro-pores via activation, which also generated meso- and macro-pores to form hierarchical porosity.

Genomic analysis of red-tide water bloomed with Heterosigma akashiwo in Geoje.

Microbial community structures of harmful algal bloom (HAB) caused by Heterosigma akashiwo in Geoje were analyzed using the MiSeq platform. To analyze phytoplankton communities without cross-reactivity with predominant bacteria, a new phytoplankton-specific 23S universal primer set was designed by modifying two previously used ones. The new universal primer set turned out to be a useful tool for the analysis of the phytoplankton community; it showed a high specificity for phytoplankton without cross-reactivity to bacterial sequences as well as the wide taxon coverage presenting from prokaryotic cyanobacteria to eukaryotic algae. Next Generation Sequencing (NGS) data generated by two universal primer sets (16S and 23S) provided useful information about the H. akashiwo bloom. According to the 23S universal primer set, proportions of H. akashiwo increased by more than 200-fold as the bloom occurred and its numbers were high enough to detect in control sites. Its operational taxonomic units (OTUs) were detected in the bloom sites at low proportions suggesting that the 16S universal primer set may not be as effective for monitoring harmful algal blooming (HAB) as the 23S universal primer set. In addition, several abundant OTUs in Chlorophyta were not presented by the 16S universal primer set in this study. However, the 16S primer set was useful for detecting decreases in Foraminifera as HAB occurred suggesting that genomic analyses using two universal primer sets would provide more reliable data for understanding microbial community changes by various environmental or ecological events, including HAB. Genomic analyses using two universal primer sets was also useful for determining a correlation between microbial components as HAB occurred. Heterosigma akashiwo was positively correlated with other bloom species, including Karenia mikimotoi, Teleaulax amphioxeia, and bacteria in Verrucomicrobia.

Millstone Exfoliation: a True Shear Exfoliation for Large-Size Few-Layer Graphene Oxide.

A millstone (MS) was introduced in the production of large-size few-layer-graphene oxide (FLGO) via true shear exfoliation in order to minimize fragmentation. The MS was constructed with two glass plates, where the top plate was designed to rotate against the stationary bottom plate, thereby generating true shear force. Mildly oxidized graphite (MOG) was used for MS exfoliation in order to obtain both good property and high yield. The rpm of rotation (10, 20, 30, 40, and 50), solution concentration (0.5, 1, and 2 mg/ml), and number of exfoliation (1, 2, and 3) were optimized by measuring the UV-vis absorption, and the effect of oxidation time (30, 60, and 90 min) was studied under the given optimum conditions. Next, the FLGO was isolated by centrifugation and characterized by TEM and AFM. The FLGO obtained was as large as ~ 10 µm in size, which was slightly smaller than the pristine graphite, suggesting a possibility of slight fragmentation. But it was still much larger than the FLGO obtained via sonication (< 1 µm), demonstrating successful MS exfoliation.

Metabarcoding analysis of the stomach contents of the Antarctic Toothfish (Dissostichus mawsoni) collected in the Antarctic Ocean.

Stomach contents of the Antarctic toothfish, Dissostichus mawsoni, collected from subareas 58.4 and 88.3, were analyzed using next generation sequencing (NGS) technology. After processing the raw reads generated by the MiSeq platform, a total of 131,233 contigs (130 operational taxonomic units [OTUs]) were obtained from 163 individuals in subarea 58.4, and 75,961 contigs (105 OTUs) from 164 fish in subarea 88.3. At 98% sequence identity, species names were assigned to most OTUs in this study, indicating the quality of the DNA barcode database for the Antarctic Ocean was sufficient for molecular analysis, especially for fish species. A total of 19 species was identified from the stomach of D. mawsoni in this study, which included 14 fish species and five mollusks. More than 90% of contigs belonged to fish species, supporting the postulate that the major prey of D. mawsoni are fish. Two fish species, Macrourus whitsoni and Chionobathyscus dewitti, were the most important prey items (a finding similar to that of previous studies). We also obtained genotypes of prey items by NGS analysis, identifying an additional 17 representative haplotypes in this study. Comparison with three previous morphological studies and the NGS-based molecular identification in this study extended our knowledge regarding the prey of D. mawsoni, which previously was not possible. These results suggested that NGS-based diet studies are possible, if several current technical limitations, including the quality of the barcode database or the development of precise molecular quantification techniques to link them with morphological values, are overcome. To achieve this, additional studies should be conducted on various marine organisms.